I’m toying with the idea of a car engine + generator for power backup

[Jester]

Our power here is pretty reliable, that being said if it goes down during the winter, not so pleasant that happened a few years ago during a nasty ice storm, no power for about 2-3 days, I’m glad we had a conventional fireplace.

I’m pretty comfortable with auto engines as one of my hobbies is auto racing so I have assembled and disassembled plenty of engines etc.

 I have a cheap 7kW generator (Neighbour gave it to me in broken state and I fixed it), however the thing is really loud when under load. Honda makes some really quiet small generators and some sort of quiet mid size generators, but they are fairly expensive and not really quiet.

My thought of the day is to pickup a used small engine from a wrecked econo-box car perhaps 1.5 litre and mate it to a suitable generator something about 20-30kW (will depend on what is available used and cheap). I will need some sort of gear box to increase speed to generator perhaps 2:1 or  2.5:1 would allow the engine to run at about  1500 rpm. Will need to make some sort of speed control to keep the generator at 3600 rpm as load changes.

If I re-use the original exhaust and plumb it up say 8’ and away from the house I would think that it would be near  in-audible from the house. I would mount this contraption in the smallest metal shed I can find on craigslist and about 100’ from the house.

Wacky idea or fun project what do you think?

Keep in mind I’m retired and enjoy pet projects.

[jpanhalt]

Here in Amish counties, that is quite commonly done.  Many people believe Amish won't use electricity as it is evil or something.  That is not so.  The prohibition is against using electrical power from public power lines.  Many of their industries generate electricity on site.  As one example, they are well known for work with canvas materials for tents/boat covers/etc.  Sewing machines don't run on diesel or horses.  Those enterprises generate on site.  Woodworking is another example.

I don't have access to any of those plans, but it is certainly not a crazy idea.  An old 4-cylinder, air-cooled VW engine might be simple.  Meeting pollution restrictions might be a problem.  Small diesels (Kubota, Yanmar, others) are another possibility, but will likely be more expensive than a used automotive engine.  Riding mower engines  (e.g., Kohler 25 HP) do not have a very good record for longevity. 

[tpowell1830]

Our power here is pretty reliable, that being said if it goes down during the winter, not so pleasant that happened a few years ago during a nasty ice storm, no power for about 2-3 days, I’m glad we had a conventional fireplace.

I’m pretty comfortable with auto engines as one of my hobbies is auto racing so I have assembled and disassembled plenty of engines etc.

 I have a cheap 7kW generator (Neighbour gave it to me in broken state and I fixed it), however the thing is really loud when under load. Honda makes some really quiet small generators and some sort of quiet mid size generators, but they are fairly expensive and not really quiet.

My thought of the day is to pickup a used small engine from a wrecked econo-box car perhaps 1.5 litre and mate it to a suitable generator something about 20-30kW (will depend on what is available used and cheap). I will need some sort of gear box to increase speed to generator perhaps 2:1 or  2.5:1 would allow the engine to run at about  1500 rpm. Will need to make some sort of speed control to keep the generator at 3600 rpm as load changes.

If I re-use the original exhaust and plumb it up say 8’ and away from the house I would think that it would be near  in-audible from the house. I would mount this contraption in the smallest metal shed I can find on craigslist and about 100’ from the house.

Wacky idea or fun project what do you think?

Keep in mind I’m retired and enjoy pet projects.

A few observations:
1. For 2.5 gears you would need at least a 2.5, but most likely a 3 multiple for engine power. So for 30kW you would need an engine 3 X desired kW in order to run said generator. Also, those small engines do not develop power at 1500 RPM. but more like at around the 3600 RPM that you will require. You possibly could get a diesel that can do this.

2. Placing this generator so far from the house would mean large gage wire in order to carry 30kW 100' to house. This , along with the switch and protection equipment, would be expensive.

3. The ICE engine will be all but eliminated for most uses in the next 20 years, so that is a consideration as far as fuel cost and availability. Have you considered a battery based power wall, such as the one Tesla offers?

Hope this helps...

[SeanB]

Probably use an old differential unit, with the spider gears welded together to make a locker, as the gearbox. That way you run the engine at around 22oo RPM, where most small engines, like the 1.4l VW engines, are reasonably fuel efficient, and low noise, but pretty far along the torque curve. 3600RPM and straight in to the alternator, probably a 2 pole version with that speed, and you will pretty much match peak torque and power of the engine easily. Not going to be the best fuel economy wise, but you will have the most power output from the alternator, and it will still last a long time in use.

[bdunham7]

I would consider a 1.0L engine from an early Honda Insight, with the (IMA) Integrated Motor Assist still attached.  That motor will run quite efficiently at 3600RPM, but if you are particularly clever you can use slower speeds and the IMA to generate lower levels of power when demand is low, then spin it up to use the main generator for full loads. 

[AaronD]

I don't see why not. 

Thinking about the gear-up from 1500 (engine) to 3600 (generator), I wonder how tall of an overdrive you can get in an automotive transmission?  I'm guessing it's not that much.  Or maybe you could manage to turn a transmission around so that 1st gear has the engine practically idling, and what used to be overdrive has it close to redline for the same generator speed?

Or maybe you could just do a single-stage fixed-speed arrangement by sourcing your own two pulleys and a belt.  That'd be a lot easier!  And it would disconnect the shaft requirements from each other as well.  And the mounting requirements.

---

For a governor, the cost and complexity depend on how tightly you want to control it.  A single-purpose lawnmower engine might simply have a vane in the airflow of the mechanical cooling fan, which acts against a spring to control the throttle.  You probably want something better than that!  The John Deere 140 that my family had for a LONG time (Kohler 14hp single-cylinder) had flyweights on the camshaft, that acted against a spring.  The other end of that spring went to the operator's throttle control.

I'd thought for a while about making a DIY cruise control for my '97 Jeep (Inline 6 with a manual 5-speed) out of the assumed-good actuator from a failed aftermarket cruise control (possibly bad assumption, never tried it) and the tachometer.  Never actually did it, but one of my potential uses, allowed by using the tach instead of the speedo, was to be a stationary electric generator as well.  (disconnect the rear driveshaft and hook it up to the generator; then use 4-wheel-drive, which would now be front-only, to drive with that arrangement)

Just letting my mind run with that for a while, got me the idea to use an ammeter and/or torque sensor as a feedforward component.  (put load cells in either the engine mounts or the generator mounts, to be that torque sensor)  The idea being that the rotating mass takes a while to change speed, but that doesn't help at all with long-term trends.  So if I can tune it so that the average throttle is well matched to the immediate load, and make that work in real-time, then the actual control loop simply does an offset around that average in response to speed.  Should allow for tighter control that way.  Probably would have used an 8-bit PIC or AVR running all custom code, to actually do it.

Caveat:
The "immediate load" feedforward component is essentially positive feedback.  Too much of that, and the system becomes unstable, especially if the AC load has a net-positive impedance.  (it'll just run up to redline or down to idle, and stay there)  The speed control loop provides negative feedback, so if that's "stronger", then it can still be okay overall.  Several things to tune here, all of which lead to runaway or oscillation if the combination isn't good, so you have to watch very carefully and simulate it in your head, to know what to adjust and how.
Once you get it all right though, it can be amazing!  Switching a massive load on and off results in only a volume change from the exhaust, and not a speed change at all...

---

I had also thought about the engine speed itself.  My 4th gear, in a 5-speed, is 1:1, so I do have an overdrive.  That would allow me to run the engine a little bit slower for a 1:1 tailshaft-to-generator connection at 3600rpm, but with a redline of 5k, that speed is also inside of the normal operating range for this engine.  (my experience with highway entrance ramps tells me that it's about in the middle of the "power band" )  So...does it actually hurt anything to let it sit at 3600 all day with varying load??? 

[electr_peter]

There are ways to muffle the sound from generators ranging from simple plywood sheets to sound absorbing materials placed at strategic angles. Sound comes from both intake and exhaust, so muffler on exhaust may not be enough. Construct a sound deadening box for generator or car engine of your choice if you have dedicated space for it.

[Jester]

What would be really cool / (uhm hot actually) is if that engine can supply your house radiators as well. I guess in the US they most often pump hot air around but what is common in Canada?

Some houses here have boilers and circulating hot water, however the majority have natural gas forced air. I only need a few amps to run the furnace (more during spin up of the fan).

[Jester]

Here in Amish counties, that is quite commonly done.  Many people believe Amish won't use electricity as it is evil or something.  That is not so.  The prohibition is against using electrical power from public power lines.  Many of their industries generate electricity on site.  As one example, they are well known for work with canvas materials for tents/boat covers/etc.  Sewing machines don't run on diesel or horses.  Those enterprises generate on site.  Woodworking is another example.

I don't have access to any of those plans, but it is certainly not a crazy idea.  An old 4-cylinder, air-cooled VW engine might be simple.  Meeting pollution restrictions might be a problem.  Small diesels (Kubota, Yanmar, others) are another possibility, but will likely be more expensive than a used automotive engine.  Riding mower engines  (e.g., Kohler 25 HP) do not have a very good record for longevity.

Agree on the reliability aspect, I can probably get a used Toyota engine with 250k that will be 10x more reliable than any typical small engine, and something like a 1.2 - 1.5 litre should make plenty of power even at  say 1500 rpm. Probably be better on fuel as well. I’m okay with water cooled, I will just grab the radiator at the same time.
Water cooled should be quieter.

Regarding your comment about the Amish, I totally get it, when I was in high school I had a summer job at a place that made electronic farm control equipment for a similar group as the Amish, these guys were no fools I think they were way more automated than the typical farm of their time.

[Jester]

I would consider a 1.0L engine from an early Honda Insight, with the (IMA) Integrated Motor Assist still attached.  That motor will run quite efficiently at 3600RPM, but if you are particularly clever you can use slower speeds and the IMA to generate lower levels of power when demand is low, then spin it up to use the main generator for full loads.

I will need to read up on that engine, 1l seems ideal

[Jester]

There are ways to muffle the sound from generators ranging from simple plywood sheets to sound absorbing materials placed at strategic angles. Sound comes from both intake and exhaust, so muffler on exhaust may not be enough. Construct a sound deadening box for generator or car engine of your choice if you have dedicated space for it.

I have watched a few videos (with sound meters) of this, it helps, however the results are not that great, especially if the goal is to have it car idling quiet.

[David Hess]

Our power here is pretty reliable, that being said if it goes down during the winter, not so pleasant that happened a few years ago during a nasty ice storm, no power for about 2-3 days, I’m glad we had a conventional fireplace.

I had that experience during the 2007 North American Ice Storm.  I burned a month's worth of wood in one week to keep from freezing.  Since then I bought a backup generator, which I have used yearly since, and backup propane and kerosene heating.

My thought of the day is to pickup a used small engine from a wrecked econo-box car perhaps 1.5 litre and mate it to a suitable generator something about 20-30kW (will depend on what is available used and cheap). I will need some sort of gear box to increase speed to generator perhaps 2:1 or  2.5:1 would allow the engine to run at about  1500 rpm. Will need to make some sort of speed control to keep the generator at 3600 rpm as load changes.

For simplicity, I would consider using pulleys and belts instead of a geared transmission.

They are less common, but a 4-pole generator head would allow engine operation at 1800 RPM.  They are more common with backup diesel generators.

[james_s]

ICE will not be going away any time soon, they will be around in some capacity until after all of us here are dead and gone. A battery is completely unsuitable for occasional emergency needs, the cost is HUGE compared to a generator and it will deteriorate just sitting there waiting for something to do. Gasoline is a less than ideal fuel for emergency use though as it goes bad fairly quickly. Do you have natural gas service at your house? Converting a car engine to run on natural gas or propane is fairly easy and both are much better fuels for this application.

For a 7kW generator you will only need about 15HP so while a car engine may not produce much power at 1500 RPM it doesn't need to. Most car engines will be rated for >100HP and you only need a small fraction of that. I would look for the smallest, simplest engine I could find, more than 2 valves per cylinder is fairly pointless for low RPM low power use, and stuff like variable valve timing and other fancy features will be useless. Remove the fuel injection and replace it with a demand regulator metering propane or natural gas into the intake manifold. For the ignition you might look at the ignition system from an older car or a standalone aftermarket system, you want simple. For a conventional generator you will also need to devise a governor to keep the frequency relatively constant regardless of demand. Typically this is a centrifugal mechanism acting against a spring but an electronic solution with a servo operating the throttle body may be more flexible and possibly easier to implement.

Making use of the waste heat is definitely worthwhile. Forced air heating is the norm almost everywhere in North America but that doesn't preclude setting up an auxiliary heat source using a fancoil or radiator. Another option is a water to water heat exchanger to heat your hot water tank.

[james_s]

There are ways to muffle the sound from generators ranging from simple plywood sheets to sound absorbing materials placed at strategic angles. Sound comes from both intake and exhaust, so muffler on exhaust may not be enough. Construct a sound deadening box for generator or car engine of your choice if you have dedicated space for it.

There's no way you'll ever get one anywhere near as quiet as a typical car engine. Not only does sound come from the intake and exhaust, but there is a lot of mechanical noise from small air cooled engines. There is no water jacket in the block or head, it is just thin aluminum, everything is thin and light, they are not particularly well balanced, and a conventional generator screams along at 3600 RPM regardless of load so it's going to be noisy no matter what you do.

Personally I got a Honda EU2000i inverter generator a few years ago and it's a lovely little machine. Despite the fact that it is also a small air cooled engine they have done a remarkable job of making it quiet, and since engine speed is decoupled from the frequency of the generated power, it spends most of its time near idle. It's quiet enough that I can let it run all night long without disturbing my neighbors. With it sitting out in front of my garage I can't hear it at all inside the house.

[Jester]

Our power here is pretty reliable, that being said if it goes down during the winter, not so pleasant that happened a few years ago during a nasty ice storm, no power for about 2-3 days, I’m glad we had a conventional fireplace.

I had that experience during the 2007 North American Ice Storm.  I burned a month's worth of wood in one week to keep from freezing.  Since then I bought a backup generator, which I have used yearly since, and backup propane and kerosene heating.

My thought of the day is to pickup a used small engine from a wrecked econo-box car perhaps 1.5 litre and mate it to a suitable generator something about 20-30kW (will depend on what is available used and cheap). I will need some sort of gear box to increase speed to generator perhaps 2:1 or  2.5:1 would allow the engine to run at about  1500 rpm. Will need to make some sort of speed control to keep the generator at 3600 rpm as load changes.

For simplicity, I would consider using pulleys and belts instead of a geared transmission.

They are less common, but a 4-pole generator head would allow engine operation at 1800 RPM.  They are more common with backup diesel generators.

Another great idea 4 pole generator

The belt and pulleys suggestion is also a great idea, makes  things much simpler, need to figure out belt requirements, probably need one of those double or triple wide pulleys for 25 ish HP?

[james_s]

I would consider a 1.0L engine from an early Honda Insight, with the (IMA) Integrated Motor Assist still attached.  That motor will run quite efficiently at 3600RPM, but if you are particularly clever you can use slower speeds and the IMA to generate lower levels of power when demand is low, then spin it up to use the main generator for full loads.

That's going to require an inverter, which is going to make the whole project vastly more complex. Inverter generators are pretty much exactly what that is, a 3 phase permanent magnet generator attached directly to an engine. The resulting AC is rectified and feeds the DC bus of an inverter that produces clean 60Hz AC regardless of engine speed.

[james_s]

Another great idea 4 pole generator

The belt and pulleys suggestion is also a great idea, makes  things much simpler, need to figure out belt requirements, probably need one of those double or triple wide pulleys for 25 ish HP?

4 pole generators are definitely nice, but they're hard to find. If you want to go that route you could look for one of the old Kohler light plants, I saw one for sale a few years ago for a few hundred bucks, they were mostly made in the 1950s I think, nice machines.

Rather than V-belts which are fairly inefficient you could look at toothed belts. The sort that are used to drive superchargers on drag racers can transmit many horsepower, I'm sure there must be a wide range of sizes available in that style. Another option is a chain drive, I would think a motorcycle/ATV shop would be a good place to look for that sort of thing.

[Jester]

There are ways to muffle the sound from generators ranging from simple plywood sheets to sound absorbing materials placed at strategic angles. Sound comes from both intake and exhaust, so muffler on exhaust may not be enough. Construct a sound deadening box for generator or car engine of your choice if you have dedicated space for it.

There's no way you'll ever get one anywhere near as quiet as a typical car engine. Not only does sound come from the intake and exhaust, but there is a lot of mechanical noise from small air cooled engines. There is no water jacket in the block or head, it is just thin aluminum, everything is thin and light, they are not particularly well balanced, and a conventional generator screams along at 3600 RPM regardless of load so it's going to be noisy no matter what you do.

Personally I got a Honda EU2000i inverter generator a few years ago and it's a lovely little machine. Despite the fact that it is also a small air cooled engine they have done a remarkable job of making it quiet, and since engine speed is decoupled from the frequency of the generated power, it spends most of its time near idle. It's quiet enough that I can let it run all night long without disturbing my neighbors. With it sitting out in front of my garage I can't hear it at all inside the house.

Your right on about all of this, Honda did some serious engineering on the sound side to achieve this with an air cooled engine. The inverter aspect surely helps. As soon as you start stepping up to the larger generators (even the Honda’s), they are not nearly as quiet as the EU2000i series.

[John B]

Weigh up the pro and cons of your fuel source. While a diesel engine would be more efficient, in practical terms it will only ever run on diesel without major, expensive and probably excessively difficult modification.

A regular port injection (important!) petrol can be tuned to run on a variety of fuel sources including ethanol and combustable gases relatively easily.

Also, have you looked into electronic regulation of the output voltage? I think you will be disappointed if you rely on purely mechanical means (trying to maintain the RPM through a gearbox). Remember any variation/pulsation of torque through the engine rotation will translate to voltage fluctuation. You'd be looking at a very heavy flywheel to negate this.

I've always wondered how feasible, or efficient it would be to build something more like an inverter generator. Use the motor to produce DC through rectifying a 3 phase generator, then buy a beefy off the shelf 48V low frequency inverter. You'd need some kind of control loop to change the engine RPM in response to electric loads.

I figured this approach would only be worth it if you acquired a number of the large components, like the engine, for free.

[electr_peter]

Gasoline is a less than ideal fuel for emergency use though as it goes bad fairly quickly.

Yeah, regular gasoline has very short shelf life as it is made to be as cheap as possible (2-4 weeks, maybe up to 3 months in some cases - due to evaporation, chemical spoiling, water ingestion, ethanol content, layer separation). This is all very bad for small petrol engines (fuel lines, rubber seals, carburetors gum up and metals rot from inside). Car engines can deal it with it better due to bigger lines and fuel injection.
If petrol generator is intended to be used only in emergencies, regular fuel may be spoiled from sitting. One solution (although not the most economical) is to store more expensive alkalyte fuel (synthetic petrol fuel mix, stable for 2-4 years). There are few manufacturers of it.

[langwadt]

get decent muffler and build box lined with rockwool?

[james_s]

Conventional generators regulate the output voltage by regulating the field. They do still rely on regulating engine speed ot maintain the frequency, although it is normally not a problem if that varies a few percent depending on load and other factors.

[langwadt]

Gasoline is a less than ideal fuel for emergency use though as it goes bad fairly quickly.

Yeah, regular gasoline has very short shelf life as it is made to be as cheap as possible (2-4 weeks, maybe up to 3 months in some cases - due to evaporation, chemical spoiling, water ingestion, ethanol content, layer separation). This is all very bad for small petrol engines (fuel lines, rubber seals, carburetors gum up and metals rot from inside). Car engines can deal it with it better due to bigger lines and fuel injection.
If petrol generator is intended to be used only in emergencies, regular fuel may be spoiled from sitting. One solution (although not the most economical) is to store more expensive alkalyte fuel (synthetic petrol fuel mix, stable for 2-4 years). There are few manufacturers of it.

propane tanks?

[Jester]

Perhaps I’m suffering from generator jealousy syndrome, my neighbor a few doors down has a really big generator powered by natural gas. This thing looks appropriate to power a small hospital or police station etc (about the size of full sized van. Every once in a while the power goes off and thing automatically starts up.
LOL

[jpanhalt]

@Jester @post #10
Re: Amish communities

Absolutely right.  No fools, but you always get what you pay for.  No more, no less.  Love them.

[BrokenYugo]

I'd suggest hitting the auctions and finding a commercial skid mount or trailer 1800rpm diesel genset. It is difficult to beat a mature commercial product at it's own game.

[Jester]

I'd suggest hitting the auctions and finding a commercial skid mount or trailer 1800rpm diesel genset. It is difficult to beat a mature commercial product at it's own game.

Your probably right.

Are they as quiet as a car engine?

Takes some of the fun out of it.

[Ian.M]

What heating fuel do you have on site?  There's a considerable advantage in regularly 'turning over' the fuel supply so when you fire up the genset you are using fairly fresh fuel.

Natural gas, or propane would give a significant advantage to a gasoline engine.

Low sulfur heating oil is very close to being diesel fuel, and it may well be practical to run older mechanically injected diesel engines on it with minimal modification.  Mix in additives for lubricity and to improve the cetane rating in a day tank and you'll get very similar performance and reliability.  Its also worth noting that mechanically injected and governed marine diesels are effectively constant speed rated for constant power and can be expected to run continuously for days at a time as long as you stay on top of maintenance, so are ideal for conventional genset service.

Kerosene is more problematic, as little except vintage hot bulb and military multifuel engines can run on just kerosene without substantial modifications.

If you use solid fuel you are probably S.O.L as your only options would be a gasifier to run a gasoline engine, or a steam or sterling engine.

I'd suggest hitting the auctions and finding a commercial skid mount or trailer 1800rpm diesel genset. It is difficult to beat a mature commercial product at it's own game.

If you want to indulge your shadetree mechanic tendencies, rebuilding the engine of an old commercial/industrial 1800rpm  genset may be the way to go.  However if the generator head shows significant signs of distress, probably best not to bid!

[james_s]

Kerosene is more problematic, as little except vintage hot bulb and military multifuel engines can run on just kerosene without substantial modifications.

I have a Briggs & Stratton service manual from the early 70s that covers kerosene engines. Apparently they were available off the shelf at one time and there is a conversion procedure which IIRC mostly involves reducing the compression by installing two head gaskets and adding a small gasoline tank for starting. You start the engine on gas, let it warm up and then switch to kerosene. I doubt it is as efficient as an engine designed to burn kerosene though.

[AaronD]

Kerosene is more problematic, as little except vintage hot bulb and military multifuel engines can run on just kerosene without substantial modifications.

And aviation turbines.  Jet fuel is essentially kerosene, so that's where it all went. 

[Jester]

In all likelihood I would run this off regular gas (possibly propane if conversion was easy enough). I would keep the fuel tank empty and fill it when needed. Perhaps with a very small alternate tank 1L or so for periodic start-ups that I would run dry.

[David Hess]

Gasoline is a less than ideal fuel for emergency use though as it goes bad fairly quickly.

Yeah, regular gasoline has very short shelf life as it is made to be as cheap as possible (2-4 weeks, maybe up to 3 months in some cases - due to evaporation, chemical spoiling, water ingestion, ethanol content, layer separation). This is all very bad for small petrol engines (fuel lines, rubber seals, carburetors gum up and metals rot from inside). Car engines can deal it with it better due to bigger lines and fuel injection.
If petrol generator is intended to be used only in emergencies, regular fuel may be spoiled from sitting. One solution (although not the most economical) is to store more expensive alkalyte fuel (synthetic petrol fuel mix, stable for 2-4 years). There are few manufacturers of it.

propane tanks?

Propane is a great option if you can find the parts to convert the engine to run on it.  The tanks are not cheap, but sometimes you can find deals on 30 and 40 pound tanks.

[bdunham7]

That's going to require an inverter, which is going to make the whole project vastly more complex. Inverter generators are pretty much exactly what that is, a 3 phase permanent magnet generator attached directly to an engine. The resulting AC is rectified and feeds the DC bus of an inverter that produces clean 60Hz AC regardless of engine speed.

Well, this is EEVBlog not American Chopper, so an inverter seems more appropriate than things like welding up old differentials as a gear reduction system.  Actually I see that he has only a 7kW generator, so he could easily just use the Insight engine w/ IMA and charge a series of 10 or so SLA batteries, then use an inverter from there, leaving his existing generator aside.  That way the backup could be instantaneous and the engine start can be delayed.  The Insight also has a standard 12V starter as an auxiliary backup, so you wouldn't need to copy the full two-way power system of the original IMA design--you can just wire it up as a generator.  The result is just a big version of the small EU-series inverter generators.  Unfortunately I don't know enough about the specific details of the control systems to know how much of the car's electronics could be readily repurposed for a stationary generator.  The early models (which were all manual transmissions) did not have an electronic throttle AFAIK. 

Someone mentioned waste heat.  An efficiently operating Insight engine at idle or just above will struggle to keep itself warm in very cold weather, so there just isn't going to be a whole lot left over.  Probably the only viable source of waste heat would be some sort of exchanger on the exhaust--and you don't want to be heating your house that way.

[jpanhalt]

If  your concern is the shelf life of regular gasoline, you can use marine gasoline.  It is alcohol free, about 90 octane, and is a little more expensive than regular gasoline in Ohio  (USA), but it has great shelf life.  I have used it exclusively in my 2-cycle engines (e.g., string trimmers, leaf blower, other trimmer, and chainsaw) for the past 10 years.  It stores well and has not caused any corrosion in the carburetors of those engines.

[james_s]

Well, this is EEVBlog not American Chopper, so an inverter seems more appropriate than things like welding up old differentials as a gear reduction system.  Actually I see that he has only a 7kW generator, so he could easily just use the Insight engine w/ IMA and charge a series of 10 or so SLA batteries, then use an inverter from there, leaving his existing generator aside.  That way the backup could be instantaneous and the engine start can be delayed.  The Insight also has a standard 12V starter as an auxiliary backup, so you wouldn't need to copy the full two-way power system of the original IMA design--you can just wire it up as a generator.  The result is just a big version of the small EU-series inverter generators.  Unfortunately I don't know enough about the specific details of the control systems to know how much of the car's electronics could be readily repurposed for a stationary generator.  The early models (which were all manual transmissions) did not have an electronic throttle AFAIK. 

Well I think that building a reliable multi-kW inverter that can run off of a variable DC bus voltage from a permanent magnet alternator is a very advanced project. Going by the OP's post, it sounds like he has a small 3600 RPM generator head already and just wants to bolt it up to a quieter less stressed engine. It is much easier to just buy a proper backup generator with a liquid cooled engine than to build such an advanced thing from junk. If a person has the knowledge to build a project like that, they probably would not need to ask here how to do it.

One issue with trying to gear up a salvaged generator head is that many of the sort of generators that come attached to a small air cooled engine have only one bearing, the other end of the rotor fits over the engine shaft and relies on the bearing in the engine.

[Berni]

I wouldn't say fuel would be that big of a problem.

A diesel engine will not only run on Diesel but also on kerosine(jet aircraft will be needed) or cooking oil(people need to eat). While a gasoline engine can resonably easily be made to run on ethanol(industrialy important) or propane(heats peoples houses and runs stoves).

The whole idea is not that bad in my opinion. You can buy generators that connect onto the PTO output shaft of a tractor(Used for backup power or power out in the field). They do tend to be in the 10 to 40 kW range, so all you need is to couple one of those to a car engine and you are set. You can probably use the engines existing gearbox to get it spinning at the right speed (PTO shafts are not very high rpm). The generators have built in voltage regulation electronics but the Hz will likely be tied to the engine rpm (having a VFD on board is expensive so they will try to avoid it). The technical bit here might be the need to adjust the engine throttle according to load for a steady rpm.

But thing is car engines seam so quiet because you mostly hear them at/near idle throttle. When a car engine is producing >30kW it might still be pretty loud.

[CJay]

It occurs to me that a REx from something like a BMW i3 might be worth investigating if you have a wrecker's yard that takes EVs.

But if I were at significant risk of being cut off from electricity for an extended period of time I'd probably go for a mil surplus generator that runs on kerosene/diesel and have the ability to run my home heating on it as well.

[Ed.Kloonk]

Not disagreeing with the replies above.

But my own experience with a number of very old but well built alternators that I've got in the 5-10 kW range, 3 phase. These things I've had since the fuel crisis in the 70's. Still going strong. Sadly their original motors are not.

I suggest a stationary engine, at least 16 HP. I used 2 of these motors with my 7.5kw and 5kw. The five is a spare without a starting battery (pull start only) and has slightly different pulleys so it runs about 2800 rpm vs 3000 rpm.

The reason I would use the stationary motor off ebay before a car engine is what you get for the price. The stationary motor will have all the throttle control figured out so you can set and forget and the governor will regulate the throttle to the varying loads. An ordinary car motor's carburettor won't allow you to do that without serious modification.

The next problem is engine compression. The car motor will typically be higher and more difficult to crank.

Fuel tank. The stationary motor will have a fuel tank on top ready to go.

Engine speed. I don't believe it is a good idea to run normal car engines at one continuous speed for some reason. I don't know why. A mechanic told me once and I forgot the reason.

Output shaft. Will be standard 1"(25mm) and be very easy to change different pulleys for it if you want to tweak the run speed.

Fuel/choke levers above carby are easy to locate and use. (in the dark!)

I could go on. But I've got plenty of old motors laying around here but I've always opted for the new motors just because of the sheer ease and reliability. Run them at least every three months. 

Search ebay: 16HP stationary motor.

Sing out if you need help choosing pulley sizes, v-groove type, number of grooves, fan belt length etc.
 

[langwadt]

What heating fuel do you have on site?  There's a considerable advantage in regularly 'turning over' the fuel supply so when you fire up the genset you are using fairly fresh fuel.

Natural gas, or propane would give a significant advantage to a gasoline engine.

Low sulfur heating oil is very close to being diesel fuel, and it may well be practical to run older mechanically injected diesel engines on it with minimal modification.  Mix in additives for lubricity and to improve the cetane rating in a day tank and you'll get very similar performance and reliability.  Its also worth noting that mechanically injected and governed marine diesels are effectively constant speed rated for constant power and can be expected to run continuously for days at a time as long as you stay on top of maintenance, so are ideal for conventional genset service.

Kerosene is more problematic, as little except vintage hot bulb and military multifuel engines can run on just kerosene without substantial modifications.

I thought airports and military ran everything diesel on  Jet-A1 which is basically kerosine

[Gyro]

In all likelihood I would run this off regular gas (possibly propane if conversion was easy enough). I would keep the fuel tank empty and fill it when needed. Perhaps with a very small alternate tank 1L or so for periodic start-ups that I would run dry.

LPG conversions used to be quite common for cars over here, particularly on fleet vehicles. They had a gas cylinder fitted in the boot (trunk). Look in the right place and you can probably find all the required kit off the shelf, probably with changeover switching too.


EDIT: I don't know if you get any similar hits on ebay in Canada... https://www.ebay.co.uk/sch/6030/i.html?_nkw=lpg+conversion&LH_TitleDe&_odkw=lpg+conversion+kit&_osacat=131090&sc=0

[Jester]

In all likelihood I would run this off regular gas (possibly propane if conversion was easy enough). I would keep the fuel tank empty and fill it when needed. Perhaps with a very small alternate tank 1L or so for periodic start-ups that I would run dry.

LPG conversions used to be quite common for cars over here, particularly on fleet vehicles. They had a gas cylinder fitted in the boot (trunk). Look in the right place and you can probably find all the required kit off the shelf, probably with changeover switching too.


EDIT: I don't know if you get any similar hits on ebay in Canada... https://www.ebay.co.uk/sch/6030/i.html?_nkw=lpg+conversion&LH_TitleDe&_odkw=lpg+conversion+kit&_osacat=131090&sc=0

At one point a lot of taxis were using propane, I’m not sure if that is still going on. If the conversion is straightforward seems like a good idea, when we had the really BIG power outage in 2003 getting gas was a problem, propane was generally available because they didn’t need electricity to pump. Lots of BBQing during that outage.

I’m completely comfortable fabricating, welding etc. I have every thing I need; lathes, milling machine etc.
For speed control small uC and possibly a stepper or servo to drive the throttle.

I like the suggestions for either pulleys and belts or chain and sprocket, that will make tweaks to fine tune the ratio easy and Princess Auto stocks a great selection of both (10 minutes away).

[Berni]

I thought airports and military ran everything diesel on  Jet-A1 which is basically kerosine

Yep kerosine has pretty similar properties to diesel. The older diesel engines run at lower compressions with less tight tolerance fuel handling components. So almost anything that lubricates, burns well and doesn't eat the seals will run fine in it. Old tractors run great on heating oil (tho its illegal because it means less tax dollars for uncle sam)

The new engines are more problematic because the fuel runs trough a more advanced fuel system with fine tolerances and jets. They easily clog with dirt, they are picky about viscosity and lubrication...etc. So you probably don't want to feed heating oil, cooking oil. kerosine..etc into one of these new fanged electronic injection common rail engines. And even if it works mechanically then the electronics being pedantic about modern strict emissions control might get upset with it.

LPG conversions are also pretty common. My previous car was converted to run on it. The spare tire is replaced with a cylindrical tank and an extra filling hole is added under the gas flap. The fuel injector signals are tapped into by a box of electronics that switch the signal over to separate gas injector valves in the intake manifold. The problem however is that LPG has a low boiling point, so the electronics keep running it on gasoline mode until the engine block is no longer cold. So i assume starting it in a cold winter night might not work on pure LPG.

[David Hess]

Propane in a gasoline engine has advantages.  It does not mix with the oil, so the oil lasts longer and the engine wears less, and the exhaust is not nearly as noxious, which is why propane powered forklifts are allowed indoors.

Propane in a gasoline engine also results in about 20% less power, but this would only matter in an engine properly sized for the application using gasoline.  Converted backup generators have to be power derated.

Old tractors run great on heating oil (tho its illegal because it means less tax dollars for uncle sam)

In the US, fuel used for farm equipment which is not driven on public roads is not generally taxed.  Farmers either buy untaxed fuel or apply to the taxing agencies for a refund.

Where I am in Missouri, propane costs significantly less if purchased for a motor vehicle.

[james_s]

Yep kerosine has pretty similar properties to diesel. The older diesel engines run at lower compressions with less tight tolerance fuel handling components. So almost anything that lubricates, burns well and doesn't eat the seals will run fine in it. Old tractors run great on heating oil (tho its illegal because it means less tax dollars for uncle sam)

At one point for a couple of years a British acquaintance of mine was running his diesel van on vegetable oil he was buying at Costco, for a period of time it was more economical than buying diesel at a fuel station. It was an old mechanically injected engine and apparently it ran just fine on it.

[james_s]

Propane in a gasoline engine has advantages.  It does not mix with the oil, so the oil lasts longer and the engine wears less, and the exhaust is not nearly as noxious, which is why propane powered forklifts are allowed indoors.

Propane in a gasoline engine also results in about 20% less power, but this would only matter in an engine properly sized for the application using gasoline.  Converted backup generators have to be power derated.

Old tractors run great on heating oil (tho its illegal because it means less tax dollars for uncle sam)

In the US, fuel used for farm equipment which is not driven on public roads is not generally taxed.  Farmers either buy untaxed fuel or apply to the taxing agencies for a refund.

Where I am in Missouri, propane costs significantly less if purchased for a motor vehicle.

Propane conversion is very easy to do though, all you need is a demand regulator. You can even retain the existing gasoline injection system to make it duel fuel. The propane just gets fed into the intake manifold after the throttle body.

There's a co-op not too far from here that sells untaxed agricultural diesel, IIRC it's dyed red to prevent it from being used in road vehicles. It will work of course, but if they catch you doing it you can get in trouble.

[David Hess]

Propane conversion is very easy to do though, all you need is a demand regulator. You can even retain the existing gasoline injection system to make it duel fuel. The propane just gets fed into the intake manifold after the throttle body.

I have seen the kits but I am never sure if they will fit on my less common 3 kilowatt backup generator.

There's a co-op not too far from here that sells untaxed agricultural diesel, IIRC it's dyed red to prevent it from being used in road vehicles. It will work of course, but if they catch you doing it you can get in trouble.

I have heard about them running checks on RVs and pickups at motor race events.

[Berni]

There's a co-op not too far from here that sells untaxed agricultural diesel, IIRC it's dyed red to prevent it from being used in road vehicles. It will work of course, but if they catch you doing it you can get in trouble.

Over here due to zoning you will almost always need to use a road to get your tractor from the farm to the field, so it is a road vehicle that needs to be registered and road worthy. Farmers have to buy diesel just like everyone else, but they do get a bunch of subsidies back on a lot of stuff instead.

Heating oil is colored red here to make it easy to tell apart, and you do get in trouble if you are found having it in the tank of your vehicle. It's not just diesel with a die, the stuff is less pure and is generally only a good idea to put into old simple diesel engines. Seen plenty of 50 year old tractors that ran on only heating oil and they still run. Yet since a generator is not a vehicle its perfectly legal to run on cheep heating oil here.

The massive diesel engines in ships also tend to run on so called fuel oil (same stuff). Those use extra tricks too such as switching the engine mapping once out in sea where they escape strict emissions standards. So they crank up the compression to get more efficiency out of the same amount of fuel while making lots more NOX

[langwadt]

Propane in a gasoline engine has advantages.  It does not mix with the oil, so the oil lasts longer and the engine wears less, and the exhaust is not nearly as noxious, which is why propane powered forklifts are allowed indoors.

Propane in a gasoline engine also results in about 20% less power, but this would only matter in an engine properly sized for the application using gasoline.  Converted backup generators have to be power derated.

why is that? I don't see why an engine properly tuned for propane shouldn't make just as much power as on gasoline

[John B]

why is that? I don't see why an engine properly tuned for propane shouldn't make just as much power as on gasoline

Propane has a lower energy density compared to petrol, combined with the fact that propane has a slightly higher stoichiometric air-fuel ratio compared to petrol. Only way to increase the power would be to increase the mass of air (ie forced induction).

Not a problem at all in this application though.

[bdunham7]

why is that? I don't see why an engine properly tuned for propane shouldn't make just as much power as on gasoline

80% is actually optimistic for many engines because of more complex factors, but the simple analysis is that for two otherwise equivalent engines, the propane both displaces more air and produces less energy per equivalent mass of air due to the C/H ratio and enthalpy of the shorter alkane.  The assumption is that the two 'equivalent' engines are pumping the same volume of charge gas, whether that be air with a small fraction of evaporated gasoline or air with a larger fraction (volume) of propane.

[james_s]

IIRC propane also has a higher octane rating than gasoline, so you can run a higher static compression ratio to get some of that power back. Granted you can't really just adjust the compression ratio at will, but if you're ever building an engine to run on propane it's something to keep in mind.

[james_s]

Over here due to zoning you will almost always need to use a road to get your tractor from the farm to the field, so it is a road vehicle that needs to be registered and road worthy. Farmers have to buy diesel just like everyone else, but they do get a bunch of subsidies back on a lot of stuff instead.

Heating oil is colored red here to make it easy to tell apart, and you do get in trouble if you are found having it in the tank of your vehicle. It's not just diesel with a die, the stuff is less pure and is generally only a good idea to put into old simple diesel engines. Seen plenty of 50 year old tractors that ran on only heating oil and they still run. Yet since a generator is not a vehicle its perfectly legal to run on cheep heating oil here.

The massive diesel engines in ships also tend to run on so called fuel oil (same stuff). Those use extra tricks too such as switching the engine mapping once out in sea where they escape strict emissions standards. So they crank up the compression to get more efficiency out of the same amount of fuel while making lots more NOX

I'm not a farmer but I believe there is a provision in the law here that allows transporting farm equipment on public roads without licensing them as a road vehicle. You're not allowed to commute to work on a tractor or take it on a highway but you can drive it on local roads as needed for agricultural purposes.

I thought ships typically ran on bunker oil? Nasty sludgy stuff that is left over from refining the lighter hydrocarbons into other fuels.

[langwadt]

why is that? I don't see why an engine properly tuned for propane shouldn't make just as much power as on gasoline

80% is actually optimistic for many engines because of more complex factors, but the simple analysis is that for two otherwise equivalent engines, the propane both displaces more air and produces less energy per equivalent mass of air due to the C/H ratio.  The assumption is that the two 'equivalent' engines are pumping the same volume of charge gas, whether that be air with a small fraction of evaporated gasoline or air with a larger fraction (volume) of propane.

With liquid injection the charge will be cooler and denser, the octane rating is higher so it can handle higher compression ratio and because it is slower burning more needs ignition advance, but that of course requires more substantial engine changes

[james_s]

Well ignition advance is usually pretty trivial to provide. With a turbocharged engine you can increase the boost easily, which has a similar effect to increasing the compression ratio.

[bdunham7]

but if you're ever building an engine to run on propane it's something to keep in mind.

I've (re) built a fair number, and LPG/propane (not exactly the same thing depending on where and when you are) and conversions of existing designs really had issues, largely thermal.  Many older engines would have valve issues and overall shorter engine life unless severely derated for power and run at slower speeds.  Forklift engines, for example, were run at power to displacement levels that are pitifully low compared to modern gas auto engines.  They also needed special lubricants when used with 'sour' fuels, which were common.  A more modern, efficient, high compression ratio engine with customized camshaft profiles and engine controls would probably improve things, but I don't know of anyone making anything that advanced.  It seems the emphasis is on CNG, which has its own challenges. 

[John B]

but if you're ever building an engine to run on propane it's something to keep in mind.

I've (re) built a fair number, and LPG/propane (not exactly the same thing depending on where and when you are) and conversions of existing designs really had issues, largely thermal.  Many older engines would have valve issues and overall shorter engine life unless severely derated for power and run at slower speeds.  Forklift engines, for example, were run at power to displacement levels that are pitifully low compared to modern gas auto engines.  They also needed special lubricants when used with 'sour' fuels, which were common.  A more modern, efficient, high compression ratio engine with customized camshaft profiles and engine controls would probably improve things, but I don't know of anyone making anything that advanced.  It seems the emphasis is on CNG, which has its own challenges.

Were the valve issues due to the fact that no fuel spray was cooling the valves in port injected engines?

If so, you simply need to add compression ratio increasing, valve cooling water injection to the DIY fuel-converted-car-motor 3 phase inverter generator project.

The real hurdle is integrating it with cloud based services.

[langwadt]

but if you're ever building an engine to run on propane it's something to keep in mind.

I've (re) built a fair number, and LPG/propane (not exactly the same thing depending on where and when you are) and conversions of existing designs really had issues, largely thermal.  Many older engines would have valve issues and overall shorter engine life unless severely derated for power and run at slower speeds. 

seems odd to have thermal issues with less power. Timing set too low, power wasted out the exhaust burning up the valve on the way?

[DenzilPenberthy]

My 2p worth for OP:

 Get a Honda Eu2000i. They really are very impressively quiet.  If you want to run it off propane to avoid issues with stale fuel, than you can get a kit to convert it to propane.


 Alternatively, if you want more power, get an old small tractor and a generator to fit on the 3 point linkage and PTO shaft. If you want a hobby project then  a classic tractor might fit the bill. If you've got heating oil on site, then you could find a 1940 or 50s one that runs on kerosene.

[bdunham7]

seems odd to have thermal issues with less power. Timing set too low, power wasted out the exhaust burning up the valve on the way?

IC engines are an advanced science and management of the thermal issues is a complicated subject.  Yes, the burn time is an issue and you can't completely solve it with more and more spark advance.  But there is also a phenomenon called a 'quench layer' where the propagating flame is extinguished just short of a combustion chamber boundary and the remaining unburned area serves as an insulating layer.  Propane mixtures don't quench as easily, so more heat is transferred.  Older engine designs often rely on a 'quench' feature to control combustion and introduce turbulence, which is accomplished by having part of the piston come very close to the cylinder head.  Unless you make this clearance very tight, the quench doesn't work as well with propane.  This is similar to what happens when you run an engine on a lean mixture at high power levels--things melt.

[james_s]

Getting a tractor just to generate electricity seems to be a bit Rube Goldberg-esq.

I think if I were going to take the hobby route I'd look for an antique diesel stationary engine or a steam engine and fire the boiler with natural gas then run the exhaust steam through a heat exchanger to heat the house. Not very practical but it sounds like fun.

[Circlotron]

But there is also a phenomenon called a 'quench layer' where the propagating flame is extinguished just short of a combustion chamber boundary and the remaining unburned area serves as an insulating layer.

That quench or boundary layer is pretty important. It's what allows you to use aluminium pistons despite the high flame temperature present. If detonation occurs, that insulating layer gets swept away by the extremely violent gas movement therefore allowing much greater heat transfer to the piston, ending up with a hole melting in it.

[David Hess]

IIRC propane also has a higher octane rating than gasoline, so you can run a higher static compression ratio to get some of that power back. Granted you can't really just adjust the compression ratio at will, but if you're ever building an engine to run on propane it's something to keep in mind.

The same issue occurs with high ethanol content gasoline.  An engine intended for E85 could support higher compression so E85 vehicles which run on either E85 or standard gasoline are less efficient than they could be on E85.

I think if I were going to take the hobby route I'd look for an antique diesel stationary engine or a steam engine and fire the boiler with natural gas then run the exhaust steam through a heat exchanger to heat the house. Not very practical but it sounds like fun.

I have seen recommendations to get one of those very old single cylinder "Lister" mechanical injection diesel engines.  The US banned their import a couple years ago.  They are something like this:

https://www.purusharthdieselengine.com/single-cylinder-water-cooled-diesel-engine.html

[bdunham7]

The same issue occurs with high ethanol content gasoline.  An engine intended for E85 could support higher compression so E85 vehicles which run on either E85 or standard gasoline are less efficient than they could be on E85.

That was true before variable cam timing became popular, but nowadays you actually can vary the effective compression ratio fairly easily by delaying the closing of the intake valve, as well as reducing combustion temps by leaving some exhaust behind.  There are production gasoline motors with open multivalve combustion chambers, 12:1 compression ratios and superchargers.  Obviously that would blow up pretty quickly at low speed and high torque without some valve timing wizardry.  I don't know how many current E85 vehicles have these features since E85 isn't such a big deal anymore. 

[james_s]

I have seen recommendations to get one of those very old single cylinder "Lister" mechanical injection diesel engines.  The US banned their import a couple years ago.  They are something like this:

https://www.purusharthdieselengine.com/single-cylinder-water-cooled-diesel-engine.html

The Lister engines and copies are great, they're dead simple and will run forever, and they look cool. It's a shame they banned the import, and kind of strange too, it's been a niche thing for many decades, it's not like everyone has one and runs it all day.

[Berni]

Yep gasoline engines are very optimized for gasoline(even a certain octane rated one) so running most other fuels in one of those tend to need some derating or adjustment. You could tweak a lot of modern engines to better run on it tho since electronics control so much of it now. All it needs is a ECU flash to crank up the boost on that turbo, adjust the fuel quantity, ignition, valves etc. Then again such a high tech engine is the last thing id want as a backup generator.

Diesel doesn't care so much since there self ignition is required rather than problematic. So compression can be cranked up as high as the engine components can survive without breaking (Until emissions laws step in). The only challenge there is that the fuel system runs at insane pressures so it might not survive moving any fuel. A possibly even more fuel universal engine are turbine engines where they also just simply need a fuel that can burn, but does not need nearly as high pressures in the fuel system. Tho i am pretty sure the neighbors would not appreciate the noise it makes and they are not the most efficient of things(the small ones). It also sounds like the kind of insane project someone like Colin Furze would make.

I'm not a farmer but I believe there is a provision in the law here that allows transporting farm equipment on public roads without licensing them as a road vehicle. You're not allowed to commute to work on a tractor or take it on a highway but you can drive it on local roads as needed for agricultural purposes.

I thought ships typically ran on bunker oil? Nasty sludgy stuff that is left over from refining the lighter hydrocarbons into other fuels.

When it comes to vehicles the laws are sometimes tight ass ridiculousness here in Europe. They don't even let you put a aftermarket sport air filter in your car without a bunch of paperwork. Even a bicycle legally involves paperwork if you fit an electric motor with >300W of power on it since it becomes a 'motorcycle'.

Yes fuel oil is a general term for all the messy crap that is too dirty to be called diesel. The heating/furnace oil is the cleaner variety of fuel oil, the bunker fuel that the ships can run on would probably gum up a typical home furnace burner. Then again when an engine the size of a house has injectors the size of a persons leg, that probably makes it easier to handle a much messier/gooeyer fuel.

[brucehoult]

The whole idea is not that bad in my opinion. You can buy generators that connect onto the PTO output shaft of a tractor(Used for backup power or power out in the field). They do tend to be in the 10 to 40 kW range

No one was quite sure what was going to happen at Y2K and farmers were worried about things such as being able to milk their cows if the electricity system was disrupted. My father bought a tractor mounted 3-phase generator which I think was around 40 or 50 kVA. He got his milking shed set up to be able to take power from it. He also offered to provide neighbouring farms with electricity from the generator in the event that something happened, and changed them essentially an insurance premium in advance for this. There were enough takers to pretty much pay for the generator I think :-)

Of course in the end a lot of computer programmers put in long hours and did actually find and fix a number of bugs, and nothing bad happened.

[brucehoult]

Personally I got a Honda EU2000i inverter generator a few years ago and it's a lovely little machine. Despite the fact that it is also a small air cooled engine they have done a remarkable job of making it quiet, and since engine speed is decoupled from the frequency of the generated power, it spends most of its time near idle. It's quiet enough that I can let it run all night long without disturbing my neighbors. With it sitting out in front of my garage I can't hear it at all inside the house.

Nice and small and cheap at around US$1300, but it's not enough to power a house -- it's not even enough to run a hairdryer or kettle. It's also pretty inefficient with the fuel. The 7 kW model for $5549 looks like a much better deal long term. Enough power to actually run things, and about 50% better fuel economy thanks to fuel injection.

[electr_peter]

Personally I got a Honda EU2000i inverter generator a few years ago and it's a lovely little machine. Despite the fact that it is also a small air cooled engine they have done a remarkable job of making it quiet, and since engine speed is decoupled from the frequency of the generated power, it spends most of its time near idle. It's quiet enough that I can let it run all night long without disturbing my neighbors. With it sitting out in front of my garage I can't hear it at all inside the house.

Nice and small and cheap at around US$1300, but it's not enough to power a house -- it's not even enough to run a hairdryer or kettle. It's also pretty inefficient with the fuel. The 7 kW model for $5549 looks like a much better deal long term. Enough power to actually run things, and about 50% better fuel economy thanks to fuel injection.

Consider portability factor as well.
Several Honda EU2000 units can be connected in parallel (there are 4mm banana sockets on front panel) to boost output. They are very silent for generators and pretty good overall. EU2000/2200 is the biggest model one can still call truly portable. There is also lower power and lighter EU1000i unit - very portable as well with 4mm parallel sockets. 3-7kW units are only "portable" in the sense that handles are attached. Depends on your needs, of course.

[AaronD]

But there is also a phenomenon called a 'quench layer' where the propagating flame is extinguished just short of a combustion chamber boundary and the remaining unburned area serves as an insulating layer.

That quench or boundary layer is pretty important. It's what allows you to use aluminium pistons despite the high flame temperature present. If detonation occurs, that insulating layer gets swept away by the extremely violent gas movement therefore allowing much greater heat transfer to the piston, ending up with a hole melting in it.

Slightly off-topic, but could that be what happened to my '97 fuel-injected Jeep?  I'd think that the FI computer would have enough sensors and smarts to prevent it, but I'm on my second engine now because the first one did that.  Lost a ton of power on the highway, billows of smoke, and when I took the pan off and looked up, I could see valves.

My conclusion at the time was that cooling system insisted on leaking and so I couldn't keep water in it.  I replaced a lot of that, so it doesn't anymore, but your comment got me wondering.

(the temp. gauge on the dash always showed good, so I figured it was reading wrong for lack of water )

[Jester]

If I ever do this I’m going to try to keep the budget under 1k. I think should be able to get a severely wrecked civic or Corolla preferably a roll-over for about $500-700 Salvage the motor, computer, cooling and exhaust system and then send the carcass to the wrecker for scrap metal. There seems to be countless free non working small generators available (because people leave them filled with gas for a few years and they just want them gone) however I like the idea of the 4 pole and that will be harder to find hopefully I can find one for a good price with a dead engine. Then it’s just chain and sprockets, scrap metal and welding supplies. Control board and stepper another $100. I think the key will be to find a 20 or so kW 4 pole generator.

Look at this:  https://www.ebay.ca/itm/144318753004?hash=item219a1168ec:g:KqAAAOSw-VlhXWQN

[NorthGuy]

Honda EU2000i inverter generator

It's also pretty inefficient with the fuel.

It is very efficient. Unlike a normal generator it can adjust the rotation speed depending on the load. This saves lots of fuel at lower loads.

[NorthGuy]

That would allow me to run the engine a little bit slower for a 1:1 tailshaft-to-generator connection at 3600rpm, but with a redline of 5k, that speed is also inside of the normal operating range for this engine.

You can also run it at 1800 rpm. Look, for example, at this Kohler generator based on GM car engine.

[langwadt]

If I ever do this I’m going to try to keep the budget under 1k. I think should be able to get a severely wrecked civic or Corolla preferably a roll-over for about $500-700 Salvage the motor, computer, cooling and exhaust system and then send the carcass to the wrecker for scrap metal. There seems to be countless free non working small generators available (because people leave them filled with gas for a few years and they just want them gone) however I like the idea of the 4 pole and that will be harder to find hopefully I can find one for a good price with a dead engine. Then it’s just chain and sprockets, scrap metal and welding supplies. Control board and stepper another $100. I think the key will be to find a 20 or so kW 4 pole generator.

Look at this:  https://www.ebay.ca/itm/144318753004?hash=item219a1168ec:g:KqAAAOSw-VlhXWQN

how fast can you run a chain before you need to start looking at running it in an oil bath?

[BrokenYugo]

If you can find a 20 kw 4 pole genset cheap you'd be better off fixing the industrial engine in it (which likely has excellent parts support if it isn't super old) than using some auto engine not really designed for the purpose with limited, if any, long term parts support. That industrial stuff is a whole different, better world.

[AaronD]

how fast can you run a chain before you need to start looking at running it in an oil bath?

I was wondering that too, which is why I suggested a belt.  The general rule, to me, seems to be: fast = belt, slow = chain.  So you could have one of each on either side of a gearbox.  An el-cheapo riding lawnmower, for example, which my brother and I as kids took the drivetrain out of and put in a home-made go-kart, with an oversized pulley on the crankshaft and an oversized sprocket on the transmission output.  I did a lot of math (for a kid) to determine the right sizes, and got it just about perfect.  When it worked, it would go about 30mph according to a handheld GPS, almost wide-open at the engine's rated speed in 5th gear.

That was also a good lesson in parts being designed for the actual load of the intended application and not the maximum possible load.  (most of the power went to the mower deck, and it didn't take much to drive the wheels)  The original 5-speed gearbox was constantly breaking in our go-kart, somewhere different every time because we would reinforce it and then something else would go, etc.

It was essentially a complete manual transmission car, minus the safety features and any instruments.  The clutch was a spring tensioner for the belt that connected the engine to the transmission, with a pedal (gate hinge) in the normal position to pull it away from the belt.  A loose belt would hardly transmit any power at all, and a tight one could stall the engine at full throttle without slipping.  You might do something similar for a DIY genset, or you might have an electrical disconnect before any distribution, that essentially does the same thing.

For an industrial application, I've seen about 10 discrete 1/2" V-belts running in parallel between a dedicated 200-hp 480v 3-ph motor and an extruder screw.  I didn't see a way to tension each one individually, but it seemed to work just fine.  The pulleys were single-piece 20-groove or so.

[james_s]

Well, motorcycles can go >140mph with an open chain drive, I haven't tried calculating the wheel RPM of a typical crotch rocket but it wouldn't be too hard to do. The horsepower of a bike is going to be more than any reasonable domestic load on a generator will be.

[brucehoult]

Honda EU2000i inverter generator

It's also pretty inefficient with the fuel.

It is very efficient. Unlike a normal generator it can adjust the rotation speed depending on the load. This saves lots of fuel at lower loads.

All the Honda units run the engine slower at light loads. But the bigger ones make more electricity from less fuel.

It does make me wonder how they react to sudden increases in load. There may be a really serious voltage droop while they accelerate the engine, unlike something that is already at speed. Unless there's energy storage (battery, capacitor, independent flywheel) sufficient to cover the deficit for 1/4 (?) of a second.

The 2200 W unit uses 1.14 l/hour at rated load or 0.52 litres of fuel per kWh
The 7000 W unit uses 2.9 l/hour at rated load or 0.41 litres per kWh

The bigger unit is 27% more efficient.

More than that, if you run the 7000 W unit at 1/4 power  (1750 W) it will run for 18 hours instead of 6.5, for about 1.05 l/hour or about 0.6 litres per kWh, so you're not losing much at lighter loads (unless your lighter load is 500 W or something)


It's all pretty expensive electricity. At my current local prices for regular petrol the 7 kW unit is US$0.69/kWh. The 2200 W unit is $0.86/kWh.

That's not counting depreciation and maintenance.

[brucehoult]

Here are some diesel generators. An 8 kW one using 2.4 l/hour at full load and 0.8 l/hour at 1/4 load. So that's less fuel consumption than the Honda petrol engines, and using much cheaper fuel too (at least here in NZ diesel is $1.62 vs 91 petrol at $2.42 right now)

I didn't check prices or noise levels. But 0.3 litres and US$0.33 per kWh is attractive vs 2x or 2.5x the fuel cost.

https://www.ablesales.com.au/blog/diesel-generator-fuel-consumption-chart-in-litres.html

[bdunham7]

It does make me wonder how they react to sudden increases in load. There may be a really serious voltage droop while they accelerate the engine, unlike something that is already at speed. Unless there's energy storage (battery, capacitor, independent flywheel) sufficient to cover the deficit for 1/4 (?) of a second.

They sag.  My Generac version adjustable as to how far it spools down at low load.  If you have a desktop computer without a UPS, you need to not allow it to idle all the way down or you'll have a dropout.

The 2200 W unit uses 1.14 l/hour at rated load or 0.52 litres of fuel per kWh
The 7000 W unit uses 2.9 l/hour at rated load or 0.41 litres per kWh


The bigger unit is 27% more efficient.

You're using the wrong numbers, I think.  0.41L/kWh would be astonishingly efficient for a single-stage (no heat recovery) gasoline IC generator system. The nameplate rating is the surge rating, the rated load is somewhat less.  And while I would expect the larger unit to be more efficient, that doesn't make the small one "very inefficient".

It's pretty expensive electricity. At my current local prices for regular petrol the 7 kW unit is US$0.69/kWh. The 2200 W unit is $0.86/kWh.

Expensive compared to what?  Using a generator implies that your normal utilities have gone offline.  As demonstrated recently in Texas, people will pay a lot more than $1/kWh if they need to in an emergency.

[brucehoult]

The 2200 W unit uses 1.14 l/hour at rated load or 0.52 litres of fuel per kWh
The 7000 W unit uses 2.9 l/hour at rated load or 0.41 litres per kWh


The bigger unit is 27% more efficient.

You're using the wrong numbers, I think.  0.41L/kWh would be astonishingly efficient for a single-stage (no heat recovery) gasoline IC generator system. The nameplate rating is the surge rating, the rated load is somewhat less.  And while I would expect the larger unit to be more efficient, that doesn't make the small one "very inefficient".

As long as Honda is using comparable numbers for both units the comparison should be valid.

It's pretty expensive electricity. At my current local prices for regular petrol the 7 kW unit is US$0.69/kWh. The 2200 W unit is $0.86/kWh.

Expensive compared to what?  Using a generator implies that your normal utilities have gone offline.  As demonstrated recently in Texas, people will pay a lot more than $1/kWh if they need to in an emergency.

My use-case for a generator would be to supplement solar to charge batteries in bad weather, as an alternative to being connected to grid power for the bad weather days.

Here in NZ, even in a town you're charged about US$1.25/day just to be connected to the grid, before you even use any electricity.

I'm considering the equations to go live somewhere that would require $30k or $100k or more to get connected to the grid in the first place. Solar plus (occasional use) generator for computers, lighting, fridge and bottled gas for cooking and heating (maybe wood fire too) seems completely doable these days. AC is optional in northern NZ, though nice. But it's something you only need on days with an excess of solar anyway, so that's probably fine.

St Elon takes care of the internet.

[Gyro]

Just a thought about the discussions on multiple tensioned belts or chains for coupling. These will impose a significant radial load on either the crankshaft end or the transmission output shaft, depending on configuration. There is of course a timing belt / chain and auxiliary belt at the front of the engine, but nowhere near the radial load of a power takeoff. These don't normally see any radial load, maybe intermittent axial load on in the case of a manual transmission, but otherwise they are just splined connections.

It might not be an issue, but is probably worth consideration.

[bdunham7]

It might not be an issue, but is probably worth consideration.

It's a huge issue.  There are, or at least were, industrial engines designed for this purpose with huge roller bearings and extra-stout crankshaft stubs, but absent those design features a radial load is not good for long term operation and may even snap a crankshaft quite quickly unless you used a coupling shaft driving a pulley with its own very robust bearings.  Most designs using belts for power transfer are crude, low-volume machines that just weren't worth the effort to engineer a proper powertrain.  There are exceptions as belts do protect from extreme shock loading for things like concrete saws and stump grinders.  Even there, though, belts are less common these days.

Belt driven generator setups are not unknown, but to connect them directly with belts you do need a generator assembly that is designed for the purpose, just like the engine.  I've never seen a chain drive and suspect that it would be challenging to make that quiet and reliable.

[Gyro]

It's a huge issue.

Yes, I should probably have added 'in a limited life application, using a small percentage of the engine's maximum output torque'. The best solution would be to put the pulleys on a dual bearing supported sub axle and either couple using the existing splines (if loose enough accurately aligned) or a flexible coupling.

[Jester]

I though about the radial loading, I would support the shaft with bearings on either end, that should take care of that., I doubt it would snap the crankshaft, but it would likely do a number on the rear bearing and seal.

I was in my car today and made a point of listening to how loud it was at say 1500, 1800 3600 RPM, pretty darn quiet at 1500-1800 RPM even while accelerating, not a completely fair comparison though as my daily driver is a 3.0 litre V6.

I also tried to find HP vs. RPM graphs for 1.5l engines, no shortage for “hopped up” engines, I did not find a graph for a totally stock Toyota or Honda, but I’m guessing it will make plenty of power at 1500RPM to comfortably power the house. I’m really not concerned with consumer reliability vs. industrial, if people put 400km+ on these engines without a rebuild I’m guessing running for a few days at 1500RPM will be nothing.

[langwadt]

I though about the radial loading, I would support the shaft with bearings on either end, that should take care of that., I doubt it would snap the crankshaft, but it would likely do a number on the rear bearing and seal.

I was in my car today and made a point of listening to how loud it was at say 1500, 1800 3600 RPM, pretty darn quiet at 1500-1800 RPM even while accelerating, not a completely fair comparison though as my daily driver is a 3.0 litre V6.

I also tried to find HP vs. RPM graphs for 1.5l engines, no shortage for “hopped up” engines, I did not find a graph for a totally stock Toyota or Honda, but I’m guessing it will make plenty of power at 1500RPM to comfortably power the house. I’m really not concerned with consumer reliability vs. industrial, if people put 400km+ on these engines without a rebuild I’m guessing running for a few days at 1500RPM will be nothing.

it adds up quickly, say a 5000km oil change interval, guessing an average speed of 50km/h, that's only 100hours

[james_s]

All the Honda units run the engine slower at light loads. But the bigger ones make more electricity from less fuel.

It does make me wonder how they react to sudden increases in load. There may be a really serious voltage droop while they accelerate the engine, unlike something that is already at speed. Unless there's energy storage (battery, capacitor, independent flywheel) sufficient to cover the deficit for 1/4 (?) of a second.

The 2200 W unit uses 1.14 l/hour at rated load or 0.52 litres of fuel per kWh
The 7000 W unit uses 2.9 l/hour at rated load or 0.41 litres per kWh

The bigger unit is 27% more efficient.

More than that, if you run the 7000 W unit at 1/4 power  (1750 W) it will run for 18 hours instead of 6.5, for about 1.05 l/hour or about 0.6 litres per kWh, so you're not losing much at lighter loads (unless your lighter load is 500 W or something)


It's all pretty expensive electricity. At my current local prices for regular petrol the 7 kW unit is US$0.69/kWh. The 2200 W unit is $0.86/kWh.

That's not counting depreciation and maintenance.

I have a Honda EU2000i, like the rest in the series it has an "Eco-throttle" switch on the front and if you turn this on it throttles down under light load which results in a substantial fuel savings and equally important to me, a large reduction in noise. The downside is that yes it does take a moment for the engine to respond to an increase in load, it will cause the lights to dim briefly when something like the refrigerator or furnace blower starts up but since I have UPS's on everything that matters this is not an issue for me. Honda says to turn off eco throttle when using large loads but I generally don't bother since that requires going outside. Even at full throttle these things are so much quieter than a conventional generator that I'd never even consider owning a conventional non-inverter type anymore.

Yes if you run it at full load a conventional generator is going to be more fuel efficient, however in the real world in a domestic setting a generator is going to spend more than 90% of the time operating at probably 1/4 load or less. My house typically "idles" at around 250-500 watts depending on the time of day and what I'm doing so during a power outage the little Honda spends most of its time just puttering at or near idle. When my heat comes on, or the refrigerator, or some other large load it spools up and then whenever that shuts off it returns to idle. It's absolutely brilliant, I can run it all day long on a gallon of gas. A comparably sized conventional generator will consume several times that while emitting a deafening roar the entire time.

Yes, it is expensive electricity relative to utility power, but during a power outage when utility power is not an option it's really nice to have a backup source. When considering the fuel efficiency, don't forget to look at the big picture and consider the average load you're going to be drawing. A 7kW generator is going to burn a lot more fuel delivering 400 watts than a 2kW generator will, even when it's an inverter generator that can throttle down, it's still a much larger displacement engine. Many people get hung up on needing to run everything in their house at once and size a generator accordingly. I look at it from an emergency standpoint and don't mind doing some manual power management to get by with a much smaller generator, I have gas heat, hot water and cooking so I find a 2kW inverter generator to be perfectly capable of running my entire house. I can't use my microwave oven but so what, at least I'm not using candles to see and freezing my butt off like back in the day.

[james_s]

it adds up quickly, say a 5000km oil change interval, guessing an average speed of 50km/h, that's only 100hours

100 hours is a lot of power outages. I've put 33 hours on my generator in the ~3 years I've owned it. I change the oil once a year regardless of the hours. Unless you're living off grid and using the generator full time this is not going to be an issue. If you are, it might be worth considering an external oil tank as is used with dry sump engines.

[james_s]

Just a thought about the discussions on multiple tensioned belts or chains for coupling. These will impose a significant radial load on either the crankshaft end or the transmission output shaft, depending on configuration. There is of course a timing belt / chain and auxiliary belt at the front of the engine, but nowhere near the radial load of a power takeoff. These don't normally see any radial load, maybe intermittent axial load on in the case of a manual transmission, but otherwise they are just splined connections.

It might not be an issue, but is probably worth consideration.

The superchargers on drag racers are belt driven, and they draw tens of horsepower at least. Running an engine at full load that would be a big issue, but he's talking about maybe 15-20 horsepower from an engine that is probably rated to produce 150 or so.

[langwadt]

it adds up quickly, say a 5000km oil change interval, guessing an average speed of 50km/h, that's only 100hours

100 hours is a lot of power outages. I've put 33 hours on my generator in the ~3 years I've owned it. I change the oil once a year regardless of the hours. Unless you're living off grid and using the generator full time this is not going to be an issue. If you are, it might be worth considering an external oil tank as is used with dry sump engines.

I think I remember one power out in the last 20 years and it lasted for a few hours

[james_s]

I think I remember one power out in the last 20 years and it lasted for a few hours

Well, some places have much more reliable power than others. I suspect you pay quite a bit more for that reliable power than the $0.10/kWh I pay for mine, so I don't mind it going out for a few hours a year when storms knock down trees.

[langwadt]

I think I remember one power out in the last 20 years and it lasted for a few hours

Well, some places have much more reliable power than others. I suspect you pay quite a bit more for that reliable power than the $0.10/kWh I pay for mine, so I don't mind it going out for a few hours a year when storms knock down trees.

price of the electricity about the same, but price I pay close to triple that because of taxes

[Jester]

Just a thought about the discussions on multiple tensioned belts or chains for coupling. These will impose a significant radial load on either the crankshaft end or the transmission output shaft, depending on configuration. There is of course a timing belt / chain and auxiliary belt at the front of the engine, but nowhere near the radial load of a power takeoff. These don't normally see any radial load, maybe intermittent axial load on in the case of a manual transmission, but otherwise they are just splined connections.

It might not be an issue, but is probably worth consideration.

The superchargers on drag racers are belt driven, and they draw tens of horsepower at least. Running an engine at full load that would be a big issue, but he's talking about maybe 15-20 horsepower from an engine that is probably rated to produce 150 or so.

Re blower belt…..
I read the other day that a top fuel engine produces 400HP at idle, not sure how much of that is going to the blower, but I’m sure it’s plenty when the engine is making 11,000 HP at 9500RPM,

[bdunham7]

The superchargers on drag racers are belt driven, and they draw tens of horsepower at least. Running an engine at full load that would be a big issue, but he's talking about maybe 15-20 horsepower from an engine that is probably rated to produce 150 or so.

Depending on what class of drag racing the blower can take a lot more horsepower than that, but those engines also have massive 4340 forged crankshafts with a very limited lifetime.  I used to know someone that raced in the methanol class (not nitro) and was on a budget so he would try and salvage the crankshafts and other parts that were discarded by the nitro guys.  He would bring me a batch of cranks and probably a third of them were scrapped because the front of the crank was bent from the blower belt load. 

I realize we're talking about lower power settings (at lower RPMs as well--so torque may still be moderately high) but a typical small 4-banger with a nodular iron crank is not likely to last long with the side loading that come from even 20 HP.  They just aren't designed for it.  The crankshafts can't take the rotational flex loading and the bearings aren't designed for any side load at all.  An industrial engine designed for v-belt drive at say 45HP @ 3000RPM would have a 1-3/4" or so forged steel crankshaft stub and huge tapered roller bearings that weigh 5 lbs (as big as the axle bearings on a 1-ton truck) on each end of the crank.  This is an order of magnitude stronger than a typical econo-4-banger.  I don't know how you would even attach a pulley to the back of a small car engine in a way that wouldn't disintegrate in short order.  Perhaps replace the flywheel with a huge machined multi-groove pulley?

https://www.ebay.com/itm/173977620548?hash=item2881dfd044:g:luUAAOSwN3BdO1Q6

[langwadt]

Just a thought about the discussions on multiple tensioned belts or chains for coupling. These will impose a significant radial load on either the crankshaft end or the transmission output shaft, depending on configuration. There is of course a timing belt / chain and auxiliary belt at the front of the engine, but nowhere near the radial load of a power takeoff. These don't normally see any radial load, maybe intermittent axial load on in the case of a manual transmission, but otherwise they are just splined connections.

It might not be an issue, but is probably worth consideration.

The superchargers on drag racers are belt driven, and they draw tens of horsepower at least. Running an engine at full load that would be a big issue, but he's talking about maybe 15-20 horsepower from an engine that is probably rated to produce 150 or so.

Re blower belt…..
I read the other day that a top fuel engine produces 400HP at idle, not sure how much of that is going to the blower, but I’m sure it’s plenty when the engine is making 11,000 HP at 9500RPM,

I think a blower can take something like 20% of the engine output, but a topfuel engine also get rebuild every ~900 revolution, probably less than half run in anger

[james_s]

price of the electricity about the same, but price I pay close to triple that because of taxes

Those taxes probably pay for things like putting power lines underground and trimming trees and such. I live in a heavily forested and mountainous region, there are lots of trees and lots of hills, the soil is mostly glacial till that is full of rocks. It rains a lot and when the wind blows it knocks trees down or causes them to lose branches. A lot of the power lines between towns are overhead and in the winter some power outages are just a fact of life. They have been noticeably more common in the last couple of years and I don't know why for sure but I suspect Covid has resulted in less preventative maintenance like tree pruning. In the cities most wiring is underground and outages are very rare, in more rural areas most wiring is overhead and outages are a lot more common. I much prefer living in a more rural area and will take the occasional power outage as a cost of living here. At least it isn't like some countries where outages happen all the time.

[brucehoult]

Yes if you run it at full load a conventional generator is going to be more fuel efficient, however in the real world in a domestic setting a generator is going to spend more than 90% of the time operating at probably 1/4 load or less. My house typically "idles" at around 250-500 watts depending on the time of day and what I'm doing so during a power outage the little Honda spends most of its time just puttering at or near idle.

My house also uses around 500 W on average most of the year, 800 W in winter (added dehumidifier load).

Many people get hung up on needing to run everything in their house at once and size a generator accordingly. I look at it from an emergency standpoint and don't mind doing some manual power management to get by with a much smaller generator

For me it's not a matter of running everything at once. I'd just like to be able to run anything by itself. 2000 W isn't even enough for a kettle, hairdryer, vacuum cleaner, microwave *individually*.

That's if powering things directly from the generator.

If/when I go off grid the generator will be for charging the batteries, so peak loads don't matter, but neither does an econo mode on the generator -- I'd just want to charge the batteries using as little fuel as possible, and ideally as little time as possible. It should ideally be a fairly rare event, when there's bad weather for several days in a row.

I have gas heat, hot water and cooking so I find a 2kW inverter generator to be perfectly capable of running my entire house.

Gas for the high powered things certainly helps a lot.

No doubt there are very good uses for a $1300 2200 W light weight generator and it would be handy to have one around.

[Circlotron]

I don't know how you would even attach a pulley to the back of a small car engine in a way that wouldn't disintegrate in short order.  Perhaps replace the flywheel with a huge machined multi-groove pulley?

I'd say leave the flywheel and clutch in place and attach the bell housing as well. Get a manual trans input shaft and put it in it's normal place in the spigot bush and make something to hold a bearing in the bell housing. Then put a pulley or sprocket on the shaft but mount it close to the bell housing end of the shaft either inside or outside but close to the bearing so the engine bearing is not stressed so much.

[Ed.Kloonk]

Oh yeah. Leave the flywheel.

[Jester]

Hopefully I will be able to find a stick car with a flywheel instead of auto with a flex plate. Making a plate for a suitable bearing where the transaxle was should be easy enough on the mill. A RWD configuration with the old style bellhousing would be simpler yet. I have to say these new engines although efficient are really ugly and complicated compared to engines of the 60’s, my hot rod engine had one vacuum hose, and the original K-code 289 engine had no vacuum hoses.

[Berni]

I though about the radial loading, I would support the shaft with bearings on either end, that should take care of that., I doubt it would snap the crankshaft, but it would likely do a number on the rear bearing and seal.

I was in my car today and made a point of listening to how loud it was at say 1500, 1800 3600 RPM, pretty darn quiet at 1500-1800 RPM even while accelerating, not a completely fair comparison though as my daily driver is a 3.0 litre V6.

I also tried to find HP vs. RPM graphs for 1.5l engines, no shortage for “hopped up” engines, I did not find a graph for a totally stock Toyota or Honda, but I’m guessing it will make plenty of power at 1500RPM to comfortably power the house. I’m really not concerned with consumer reliability vs. industrial, if people put 400km+ on these engines without a rebuild I’m guessing running for a few days at 1500RPM will be nothing.

it adds up quickly, say a 5000km oil change interval, guessing an average speed of 50km/h, that's only 100hours

Well on my modern Volvo the service intervals are 25 000km. This is about how much i drive in a year, so it gets a yearly oil change. Most of this time is spent going 130km/h on a highway. Googling around it seams to take about 40 HP to maintain this speed in an average car. So on the typical commute to work it is continually producing 40 HP for about 30 minutes. This ads up to about 240 hours of running at 40 HP between oil changes.

So it looks like a typical car engine should be able to produce about 30kW for 10 days straight without service. In the process it would burn about 1500 liters of fuel(or about 1000$ to 4000$ worth of fuel depending on where you live). Tho 30kW is a lot of power so a house probably won't use nearly that much 24/7

[Jester]

I though about the radial loading, I would support the shaft with bearings on either end, that should take care of that., I doubt it would snap the crankshaft, but it would likely do a number on the rear bearing and seal.

I was in my car today and made a point of listening to how loud it was at say 1500, 1800 3600 RPM, pretty darn quiet at 1500-1800 RPM even while accelerating, not a completely fair comparison though as my daily driver is a 3.0 litre V6.

I also tried to find HP vs. RPM graphs for 1.5l engines, no shortage for “hopped up” engines, I did not find a graph for a totally stock Toyota or Honda, but I’m guessing it will make plenty of power at 1500RPM to comfortably power the house. I’m really not concerned with consumer reliability vs. industrial, if people put 400km+ on these engines without a rebuild I’m guessing running for a few days at 1500RPM will be nothing.

it adds up quickly, say a 5000km oil change interval, guessing an average speed of 50km/h, that's only 100hours

Well on my modern Volvo the service intervals are 25 000km. This is about how much i drive in a year, so it gets a yearly oil change. Most of this time is spent going 130km/h on a highway. Googling around it seams to take about 40 HP to maintain this speed in an average car. So on the typical commute to work it is continually producing 40 HP for about 30 minutes. This ads up to about 240 hours of running at 40 HP between oil changes.

So it looks like a typical car engine should be able to produce about 30kW for 10 days straight without service. In the process it would burn about 1500 liters of fuel(or about 1000$ to 4000$ worth of fuel depending on where you live). Tho 30kW is a lot of power so a house probably won't use nearly that much 24/7

Exactly, the 20-30kW is a pie in the sky number based on:
If I do this I may as well do it well enough once, so if I want to use worst case power; electric range, furnace etc. I don’t need to think about what breakers do I need to turn on and off now or worry about exceeding the current limit while two motors decide to start simultaneously. I want to simply start the generator, transfer over and forget about it while the fuel lasts or until the power comes back on. In reality will probably average 2kW. The chances of a 10 day outage are really really low, worst case we have had in the last 60 years was about 2-3 days.

It would also allow us to send a little power to our neighbours to keep their heat on in a pinch.

[brucehoult]

So it looks like a typical car engine should be able to produce about 30kW for 10 days straight without service. In the process it would burn about 1500 liters of fuel(or about 1000$ to 4000$ worth of fuel depending on where you live). Tho 30kW is a lot of power so a house probably won't use nearly that much 24/7

There was this interesting example, almost 33 years ago in early 1989: take a standard family car (1st gen Subaru Legacy with 2.0 turbo engine) chosen by the FIA at random from the production line and do 100,000 km in it as quickly as possible.

The result? 447 hours, 44 minutes, and 9.887 seconds (about 18.6 days), at an average speed of 223.345 km/h (138.78 mph)

They refuelled and changed drivers every two hours, and tyres every 96 hours (about 21500 km). I know they also did oil changes, but I don't know how often.

As the average speed includes all the stops, the actual speed when moving was normally around 145 mph.

That will have been putting out a bit more than 30 kW :-) That engine was rated at about 160 kW, and will have been using most of that.

[james_s]

There was this interesting example, almost 33 years ago in early 1989: take a standard family car (1st gen Subaru Legacy with 2.0 turbo engine) chosen by the FIA at random from the production line and do 100,000 km in it as quickly as possible.

The result? 447 hours, 44 minutes, and 9.887 seconds (about 18.6 days), at an average speed of 223.345 km/h (138.78 mph)

They refuelled and changed drivers every two hours, and tyres every 96 hours (about 21500 km). I know they also did oil changes, but I don't know how often.

As the average speed includes all the stops, the actual speed when moving was normally around 145 mph.

That's a shockingly high average speed. Most cars of that era are incapable of reaching 145 mph due to the gearing regardless of available power, the vast majority of those that can will struggle to reach it and require a long flat straightaway to get there. I'm very surprised that a little 2.0L Subaru could manage to sustain a nearly 140mph average for more than an hour or two without something blowing up.

[brucehoult]

I'm very surprised that a little 2.0L Subaru could manage to sustain a nearly 140mph average for more than an hour or two without something blowing up.

I expect they surprised a lot of people. I believe this record category was previously held by Mercedes.

They started with three cars. All three finished the 100,000 km at the same time, side by side.

[langwadt]

There was this interesting example, almost 33 years ago in early 1989: take a standard family car (1st gen Subaru Legacy with 2.0 turbo engine) chosen by the FIA at random from the production line and do 100,000 km in it as quickly as possible.

The result? 447 hours, 44 minutes, and 9.887 seconds (about 18.6 days), at an average speed of 223.345 km/h (138.78 mph)

They refuelled and changed drivers every two hours, and tyres every 96 hours (about 21500 km). I know they also did oil changes, but I don't know how often.

As the average speed includes all the stops, the actual speed when moving was normally around 145 mph.

That's a shockingly high average speed. Most cars of that era are incapable of reaching 145 mph due to the gearing regardless of available power, the vast majority of those that can will struggle to reach it and require a long flat straightaway to get there. I'm very surprised that a little 2.0L Subaru could manage to sustain a nearly 140mph average for more than an hour or two without something blowing up.

specs say 200hp and 230km/h topspeed

[brucehoult]

specs say 200hp and 230km/h topspeed

Which specs?

At 3:10 this video shows specs of 220 PS @6400 RPM, 27.5 kgf-m @4000 RPM.

US models often have larger engines (e.g. 2.2 in 1st gen Legacy), lower power output, and weigh more than JDM (and often Aus/NZ) models.

For example my Japanese 2008 Outback 2.5XT is rated at 265 HP @5600 (250 N-m, 35.7 kgf-m, 258 lbf-ft @2400). The model with the same name in the US was rated at 250 HP.

Here's Subaru's press release at the time https://www.subaru.co.jp/news/archives/08_04_06/08_05_08_02.html

My car is doing 2100 RPM at 100 km/h, so in theory is geared for 266 km/h at RPM for maximum power. It's got quite a lot more power than that 1989 model, and I'd say better aerodynamics, so it might be possible.

I was very happy to pick it up in excellent condition for US$5900 with 87,000 km on the clock and I've done another 40,000 so far.

https://pbs.twimg.com/media/FFBMxKbVUAENFD9.jpg

Having dynamic cruise control, lane departure warning, automatic pre-collision braking etc in a 2008 car is really great. It's even got quite reasonable fuel consumption :-)

https://pbs.twimg.com/media/FFBMxKbVUAENFD9?format=jpg&name=large

(every tank with worse than 10 l/100km or 24 USMPG was towing something)

[BrokenYugo]

Another concern with putting a car engine in generator service comes to mind, oil capacity and control. Most auto engines have small sumps, no low oil level detection/shutdown, and piston rings oriented more towards minimal drag than perfect oil control, even when they aren't gunked up from insufficient oil changes or puttering around constantly. Not unusual for it to be perfectly acceptable for such an engine, in warranty, to blow though a whole sump load of oil (or more!) within the recommended oil change interval, and put a rod through the block if the owner doesn't keep up with it.

[langwadt]

Another concern with putting a car engine in generator service comes to mind, oil capacity and control. Most auto engines have small sumps, no low oil level detection/shutdown, and piston rings oriented more towards minimal drag than perfect oil control, even when they aren't gunked up from insufficient oil changes or puttering around constantly. Not unusual for it to be perfectly acceptable for such an engine, in warranty, to blow though a whole sump load of oil (or more!) within the recommended oil change interval, and put a rod through the block if the owner doesn't keep up with it.

doesn't many newish cars with long service intervals have oil level and quality sensors? if modern cars didn't have pretty good oil control they would fail emissions miserably 

[BrokenYugo]

We're talking about cheap junkyard stuff here though, late 90s-00s. And the latest still have consumption issues here and there. Seems it was actually a fairly narrow window between good hard rings and bores that would keep an engine tight for 200k+ (early 90s?) and everybody getting greedy with ring tension and whatnot.

You would think it'd trash the cats too fast, but even now the threshold for "you get a free motor" is usually somewhere around 1000 mile/qt.

[langwadt]

We're talking about cheap junkyard stuff here though, late 90s-00s. And the latest still have consumption issues here and there. Seems it was actually a fairly narrow window between good hard rings and bores that would keep an engine tight for 200k+ (early 90s?) and everybody getting greedy with ring tension and whatnot.

You would think it'd trash the cats too fast, but even now the threshold for "you get a free motor" is usually somewhere around 1000 mile/qt.

do junkyards still have stuff that is +20 years old?

[brucehoult]

do junkyards still have stuff that is +20 years old?

Pretty sure it's still easy to get parts for any reasonably popular model from the 90s here in New Zealand. I only just sold my 1997 Outback 2 1/2 years ago, and that was only because I was moving to the USA and thought I might not be back for 5 or 10 years (that didn't work out) so no point storing it and coming back to a 30+ year old car.

My new car is 13 years old and I see no reason I won't still be driving it in a decade from now -- I'm more likely to die than it is.

[james_s]

do junkyards still have stuff that is +20 years old?

They do around here, occasionally quite a bit older. It really bugs me when I see a reasonably nice straight older car in the yard though, usually with some fairly easily repairable fault, sometimes nothing wrong at all. There's a "cash for junk cars" thing around here that advertises pretty heavily, a lot of people think the cars are going to charity but in reality they go to their huge chain of salvage yards to get scrapped.

[bdunham7]

do junkyards still have stuff that is +20 years old?

Here they haven't gotten the 20-year old cars yet except for wrecks--the rest are still out on the road.  I see 50+ year old cars out on the road regularly and even 100-year old cars on occasion.  Junkyards are full of stuff going back to the 80's, but probably only the stuff that still has some demand.

[Berni]

There was this interesting example, almost 33 years ago in early 1989: take a standard family car (1st gen Subaru Legacy with 2.0 turbo engine) chosen by the FIA at random from the production line and do 100,000 km in it as quickly as possible.

The result? 447 hours, 44 minutes, and 9.887 seconds (about 18.6 days), at an average speed of 223.345 km/h (138.78 mph)

That is indeed rather impressive.

I was mostly talking about average numbers that most car engines should easily meet since its part of what these cars do in regular daily use while abiding by the manufacturers recommended service interval. Most engines will likely do 4x more miles than the service interval without a oil change and still run fine. It's just not a good idea to do on an engine you care about (especially modern ones) since one important oil passage clogging up with gunk is all it takes to seriously wreck the engine.

Another good example of how long an engine can run is the record attempt for the longest duration flight where two guys flew circles for 64 days in a little Cesna. Tho aircraft engines are designed for running at high throttle for long periods, but this put 1500 hours on that poor engine, well over the short service intervals for these engines. To do this they not only did in flight refueling but also inflight oil changes by running hoses to the engine and flushing new oil trough a few times. Eventually the engine got gunked up with enough carbon to make it loose power and they had to land.

doesn't many newish cars with long service intervals have oil level and quality sensors? if modern cars didn't have pretty good oil control they would fail emissions miserably 

Even very old engines typically have oil pressure lights, this comes on when the oil pump starts sucking air. Slightly more modern ones typically have oil level sensors too, very nice to give you a warning before shit hits the fan. Especially since modern engines indeed drink a bit of oil even new.(Optimized for low drag and using low viscosity oils)

However i don't think car engines turn off when they run out of oil. Typically they will throw up plenty of warnings on the dash, but keep on running, presumably until they seize up or break.

[james_s]

Even very old engines typically have oil pressure lights, this comes on when the oil pump starts sucking air. Slightly more modern ones typically have oil level sensors too, very nice to give you a warning before shit hits the fan. Especially since modern engines indeed drink a bit of oil even new.(Optimized for low drag and using low viscosity oils)

However i don't think car engines turn off when they run out of oil. Typically they will throw up plenty of warnings on the dash, but keep on running, presumably until they seize up or break.

They don't shut off, I've known a couple different idiots who ran their cars out of oil. A friend of mine used to be a professional mechanic and a girl he knew told him the "low oil light" on her car had been on for 3 days and then it wouldn't start, this was of course the low oil pressure light and the engine was completely destroyed.

I've never understood why there is not an obnoxious buzzer for low oil pressure and high coolant temperature. Lots of cars had a buzzer like that if you don't have the seatbelt on but I've never seen anything more than a warning light and gauge for lack of oil pressure.

[Jester]

IMO the odds of those three Subaru’s being truly stock is zero!

You can be sure those cars were disassembled blueprinted ( probably tweaked) and reassembled by a specialist with years of experience.

I recently read an article about an endurance test Goodyear did To promote their new tire of the day, I think they raced a Mustang or Shelby around Indy or some similar oval track at high speeds like that for an extended period.

Apparently the entire power train, cooling system etc. was tweaked, better bearings, cooled transmission and differential etc.

I’m not saying you could not put a bone stock production car through this this and not have it fail, but plenty of them would and that would pretty much defeat the point of the advertising gimmick, so you invest the time and money upfront to minimize the odds of a failure.

I don’t know what kind of cars you guys are driving that burn through a pan of oil between changes, but on every Toyota and Lexus that we have had in the family about 10 over the years the oil level does not go down any noticeable amount between changes, in fact my Lexus for the first 150,000 km or so the oil still looks clean clearish yellow not brown at oil change time. I have a friend with a Corolla with 450,000km fluid and plug changes I think one new water pump. I have high confidence that even a high mileage engine could survive at 1500 RPM producing 10-20 kW for a good long time.

My wife had an outback, must have been really unlucky engine failed twice under warranty and it did consume oil between changes typically at least a litre. Shortly after warranty it started knocking again, traded it in for a Sienna, will never buy a Subaru again. I have had a lot of really reliable cars over the years and only two duds, that required more repairs than all the others combined, last place was the Pinto and runner up was the outback.

[langwadt]

IMO the odds of those three Subaru’s being truly stock is zero!

You can be sure those cars were disassembled blueprinted ( probably tweaked) and reassembled by a specialist with years of experience.

I recently read an article about an endurance test Goodyear did To promote their new tire of the day, I think they raced a Mustang or Shelby around Indy or some similar oval track at high speeds like that for an extended period.

Apparently the entire power train, cooling system etc. was tweaked, better bearings, cooled transmission and differential etc.

I’m not saying you could not put a bone stock production car through this this and not have it fail, but plenty of them would and that would pretty much defeat the point of the advertising gimmick, so you invest the time and money upfront to minimize the odds of a failure.

I don’t know what kind of cars you guys are driving that burn through a pan of oil between changes, but on every Toyota and Lexus that we have had in the family about 10 over the years the oil level does not go down any noticeable amount between changes, in fact my Lexus for the first 150,000 km or so the oil still looks clean clearish yellow not brown at oil change time. I have a friend with a Corolla with 450,000km fluid and plug changes I think one new water pump. I have high confidence that even a high mileage engine could put along at 1500 RPM producing 10-20 kW for a good long time.

My wife had an outback, must have been really unlucky engine failed twice under warranty and it did consume oil between changes typically at least a litre. Shortly after warranty it started knocking again, traded it in for a Sienna, will never buy a Subaru again.

"Toyota and Lexus" thats' why, expect for certain years of Avensis with high fuel comsumption that was later fixed, afaik they are pretty much bulletproof
 

[AaronD]

I don’t know what kind of cars you guys are driving that burn through a pan of oil between changes, but on every Toyota and Lexus that we have had in the family about 10 over the years the oil level does not go down any noticeable amount between changes, in fact my Lexus for the first 150,000 km or so the oil still looks clean clearish yellow not brown at oil change time. I have a friend with a Corolla with 450,000km fluid and plug changes I think one new water pump. I have high confidence that even a high mileage engine could survive at 1500 RPM producing 10-20 kW for a good long time.

My Jeep takes 6 quarts of fossil 10W-30, and I typically get 5 quarts out after 5,000 miles.  Still more than plenty.

I'm having a hard time finding pure fossil oil though, so what's in it now is a "synthetic blend".  The engine is new enough that (according to what I've heard through the grapevine) I could probably switch to full synthetic and still be okay, which is supposed to come with a longer service interval.  That would make the synthetic cheaper overall, despite being more expensive to buy the same volume of it, but does it really work like that for an engine that is designed for fossil oil?

[james_s]

There is absolutely no problem with running synthetic oil in any engine, it is superior in every way except cost to conventional oil, it's all made from the same crude oil stock anyway. The *only* time when it may be preferable to run conventional oil is during break-in of a newly rebuilt engine when you want parts to wear slightly to seat the rings and such and in that case the superior lubricity of synthetic oil can work against you.

I've run synthetic oil in my turbo cars for as long as I've had them, the oldest is a 1984 which was made back when I don't think synthetic oil was around. Never had any issues at all related to the oil.

[AaronD]

That's good to know.  I've also heard something about conventional oil being a natural leak stopper as well, because the sludge that it breaks down into, tends to get stuck there.  When you switch to synthetic, all that sludge slowly comes out of its little crevices, and you start getting leaks that you never had before.  Is that true?

[bdunham7]

There is absolutely no problem with running synthetic oil in any engine, it is superior in every way except cost to conventional oil, it's all made from the same crude oil stock anyway.

That's a bit of an overgeneralization.  Although mostly true nowadays, there are plenty of past examples that would refute each of those statements.  There's quite a bit of variation in synthetic oils and it it takes a PhD in tribology to comprehend them all.  And it is perfectly possible to synthesize a terrible quality motor oil,  a feat which was accomplished in earlier years.

[Jester]

There is absolutely no problem with running synthetic oil in any engine, it is superior in every way except cost to conventional oil, it's all made from the same crude oil stock anyway. The *only* time when it may be preferable to run conventional oil is during break-in of a newly rebuilt engine when you want parts to wear slightly to seat the rings and such and in that case the superior lubricity of synthetic oil can work against you.

I've run synthetic oil in my turbo cars for as long as I've had them, the oldest is a 1984 which was made back when I don't think synthetic oil was around. Never had any issues at all related to the oil.

Synthetic oil has been around for a while, I recall reading that the finer machinery used in the panzer tanks was jamming up in the frigid temperatures of Russia, while the cruder Russian tanks had no problems with the cold temperatures because of the loose tolerances. Solution synthetic oil.

I use conventional oil in my daily driver, synthetic in my hot rod.

[bdunham7]

That's good to know.  I've also heard something about conventional oil being a natural leak stopper as well, because the sludge that it breaks down into, tends to get stuck there.  When you switch to synthetic, all that sludge slowly comes out of its little crevices, and you start getting leaks that you never had before.  Is that true?

Group iV PAO-based synthetics are actually not the best lubricants and don't have the same effect on seals that mineral-based oils do, so they need to be properly blended with additives (esters) that could mimic those functions.  Some early synthetics were not all that well engineered and had some of the issues you mentioned.  I'm pretty sure any reputable manufacturer nowadays has solved those issues by now, so you only need to make sure that the oil you buy has the specific ratings required by your vehicle's manufacturer to be at least minimally sure of having the right stuff.  I wouldn't recommend extending the service intervals though, so I'm not sure you will get any advantages with so-called full-synthetic product over a good quality blend.

[james_s]

That's a bit of an overgeneralization.  Although mostly true nowadays, there are plenty of past examples that would refute each of those statements.  There's quite a bit of variation in synthetic oils and it it takes a PhD in tribology to comprehend them all.  And it is perfectly possible to synthesize a terrible quality motor oil,  a feat which was accomplished in earlier years.

Of course it's possible to synthesize a terrible oil, but that's a good product vs terrible product comparison, not a synthetic vs conventional oil comparison. I am not aware of any engine that will not perform properly or that will be damaged somehow by using a synthetic oil of the proper viscosity. Engine oils are tested and certified to meet standards, I forget what it's called, but any oil that meets the standard and has the correct ratings for the engine should be fine. There have been numerous cars in my family with over 200k miles on them, one that my mother has owned since new has over 340k on it and I had a daily driver that had 330k when somebody rear ended me and totaled it. I've never done anything special with the oil other than making sure there was always oil in them and changing it on a reasonable basis.

[james_s]

That's good to know.  I've also heard something about conventional oil being a natural leak stopper as well, because the sludge that it breaks down into, tends to get stuck there.  When you switch to synthetic, all that sludge slowly comes out of its little crevices, and you start getting leaks that you never had before.  Is that true?

I'm of the opinion that if something starts leaking, it probably was time to replace the seal/gasket/whatever anyway. I know that after years of running synthetic when I remove the valve cover everything looks much cleaner than similar engines that have always run conventional oil so it certainly does seem to dissolve a lot of crud that wasn't getting dissolved before. I personally have not had issues caused by that but I suppose anything is possible. If you are curious about change intervals, there are companies you can send a sample of the used oil to and they will analyze it and send you a report showing the lubricity, state of the various additives, acidic content, quantities of various metals and other wear products from the engine and that can give you a good idea of the overall condition of the oil. If the oil is still in good shape when you change it that's a good indication that you can safely extend the change interval. Always use a good quality filter too.

[Gyro]

I remember when Mobil 1 synthetic first came out. Big advertising campaign - quieter operation, more power, longer life etc. I decided to try it in my old VW Golf.  It proceeded to pi$$ out of every seal and gasket on the previously dry engine! 

[bdunham7]

I remember when Mobil 1 synthetic first came out. Big advertising campaign - quieter operation, longer life etc. I decided to try it in my old VW Golf.  It proceeded to pi$$ out of every seal and gasket on the previously dry engine! 

Yes, that was a Group IV PAO synthetic without an adequate additive package and that was not an uncommon result.  Certain seal polymers could actually become 'crispy' in fairly short order.  Lubrication was an issue as well and if you had the original SOHC VW engine, you may have ground up the camshaft lobes as well.

[Gyro]

Lubrication was an issue as well and if you had the original SOHC VW engine, you may have ground up the camshaft lobes as well

Ha, yes, quite possibly. Luckily the sills rusted out not long after - It had been previously owned by a garage and had been steam cleaned within an inch of its life, removing all the protective coatings!

[AaronD]

I remember when Mobil 1 synthetic first came out. Big advertising campaign - quieter operation, longer life etc. I decided to try it in my old VW Golf.  It proceeded to pi$$ out of every seal and gasket on the previously dry engine! 

Yes, that was a Group IV PAO synthetic without an adequate additive package and that was not an uncommon result.  Certain seal polymers could actually become 'crispy' in fairly short order.  Lubrication was an issue as well and if you had the original SOHC VW engine, you may have ground up the camshaft lobes as well.

That would explain the rumors then.  I guess it's similar to the idea that "vinyl and tube amps are sacred and everything else is ****!"  That opinion was formed when it was a new technology compared to a mature one, and it stuck.  But now that we've figured out how to do the new stuff right, it's far superior.

[brucehoult]

IMO the odds of those three Subaru’s being truly stock is zero!

You can be sure those cars were disassembled blueprinted ( probably tweaked) and reassembled by a specialist with years of experience.

I recently read an article about an endurance test Goodyear did To promote their new tire of the day, I think they raced a Mustang or Shelby around Indy or some similar oval track at high speeds like that for an extended period.

Apparently the entire power train, cooling system etc. was tweaked, better bearings, cooled transmission and differential etc.

Yeah, it's hard to say. I took a look at the FIA's appendix D. There is a list of allowed modifications (many compulsory for speeds over 250 km/h, optional below) to production cars (Category B) including adding a roll cage, racing seat and harness, safety fuel tank. No mention is made of what if anything may or may not be done to things such as the drivetrain between being picked from the production line and used for the record attempt.

You'd think it would defeat the purpose if parts with higher specification were allowed to be fitted. Selecting three vehicles from the production line and then allowing the competitor to decide which one to run seems to be the intended mechanism for dealing with manufacturing variations.

Wikipedia cites a case "Category B Group III had a Dodge Dakota with a top speed of 217.395 mph.[16] Forums citing the Dakota's top speed indicate a standard production Dakota R/T would only reach about 125 mph." If true, that makes an absolute mockery of Category B being "production" vehicles.

In April/May 2005 Mercedes took the 100000 km record from Subaru and also set a new 100000 mile record.

From their press release (https://www.mercedes-benz-media.co.uk/en-gb/releases/233):

"The world-record run took place under the supervision of the FIA, which sets strict rules for tests of this kind. The participating vehicles were selected at random, sealed and shipped to the USA by the FIA officials at DaimlerChrysler’s Sindelfingen plant. Before, during and after the record run, the test vehicles were monitored continuously by the FIA until the world record was recognised officially. In accordance with the globally recognised regulations, the extent of any repairs which may be performed is limited and the replacement of entire assemblies such as the engine, transmission or exhaust system is not allowed."

That sure sounds as if nothing can be touched in Category B. (there is a defined 2000 km run-in period allowed)

[Circlotron]

Wikipedia cites a case "Category B Group III had a Dodge Dakota with a top speed of 217.395 mph.[16] Forums citing the Dakota's top speed indicate a standard production Dakota R/T would only reach about 125 mph." If true, that makes an absolute mockery of Category B being "production" vehicles.

Seeing required tractive effort goes up with the square of the speed, and power with the cube of the speed, that vehicle would need 5.26 times as much power to go at 217 mph vs 125 mph. Doesn't sound like a standard vehicle by a long shot.

[james_s]

That depends on what is limiting the top speed. In some cars it is the gearing, the engine will redline in top gear and that is your top speed. In other cars it is power, many cars have a higher top speed in 4th gear than in 5th due to the increased torque available.

[brucehoult]

Wikipedia cites a case "Category B Group III had a Dodge Dakota with a top speed of 217.395 mph.[16] Forums citing the Dakota's top speed indicate a standard production Dakota R/T would only reach about 125 mph." If true, that makes an absolute mockery of Category B being "production" vehicles.

Seeing required tractive effort goes up with the square of the speed, and power with the cube of the speed, that vehicle would need 5.26 times as much power to go at 217 mph vs 125 mph. Doesn't sound like a standard vehicle by a long shot.

It would be completely ridiculous.

I think someone has confused km/h with mph.

The highest speed for any record in Category B Group III is currently 141.604 mph 227.889 km/h for a 1 mile flying start by a Mazda6 4-Door Skyactiv-D, followed closely by the same vehicle's 1 km flying start, 100 mile standing start, and 1 hour standing start. That and the Mercedes E320CD (1 hour standing start, 50000 miles, 100000 km) are the only vehicles to break 140 mph in Category B Group III (diesel, "supercharged" by which I take it they really mean forced induction of any kind).

So that Dakota, if it had a record at some time (it doesn't now) was almost certainly 135.083 mph 217.395 km/h.

[james_s]

(diesel, "supercharged" by which I take it they really mean forced induction).

That's exactly what supercharged has always meant, forced induction. Turbochargers were originally called turbo-superchargers, and before that crankshaft driven superchargers have been around for a long time.

[John B]

Interesting bit of trivia: try to find the supercharger that was crank driven, but also exhaust powered. I can think of 1 car that it was used in.

[bdunham7]

Interesting bit of trivia: try to find the supercharger that was crank driven, but also exhaust powered. I can think of 1 car that it was used in.

Is that a trick question and you are referring to the Chrysler Turbine Car?  The only (piston) engines I know of with an arrangement like you describe are large radials with power recovery turbines.  Did someone put one in a car?

[james_s]

Interesting bit of trivia: try to find the supercharger that was crank driven, but also exhaust powered. I can think of 1 car that it was used in.

I don't know about a car, but that has been used in large diesel engines like the sort used in locomotives and tugboats and such.

[John B]

No trick question. It was used in a diesel, but nothing exotic. A regular Japanese brand car manufacturer. This supercharger design was probably also used in a few niche applications.

[bdunham7]

I don't know about a car, but that has been used in large diesel engines like the sort used in locomotives and tugboats and such.

If you mean turbo-compounding, I'm not sure that is exactly what he is describing.  There are actually over-the-road trucks that use turbo-compounding as well (Detroit DD15). 

[brucehoult]

IMO the odds of those three Subaru’s being truly stock is zero!

You can be sure those cars were disassembled blueprinted ( probably tweaked) and reassembled by a specialist with years of experience.

Ah-ha! I think I've gotten to the bottom of this.

The 2005 Mercedes effort that holds the current 100,000 km (and also 100,000 mile) outright records were set with a Category B genuine mass production car.

The 1989 Subaru effort that held the outright 100,000 km record until 2005 was in a Category A car -- that is: anything goes. They actually still today hold the Category A record. Preparing the cars for the 1989 run was the start of Subaru's "STi" performance group. According to the article at ...

https://www.jcars.co.nz/blog/2020/4/10/jdm-unicorns-episode-5-subaru-legacy-rs-ra-a-type

"The year is 1988 and Subaru establishes a new performance motor sport wing called Subaru Technica International “STi” to take charge of all of Subaru’s motor sport conquests. STi’s first mission was to prepare a group of new Legacy RS BC’s for Subaru’s purpose of beating a series of land speed records including the big one, the 100,000km land speed record endurance test. With Subaru seeing some success with the Leone in rallying a RS “Rally Sport” variant of the Legacy was to be produced to celebrate this and provide a base as Subaru’s new WRC car. The RS Legacy’s 2L EJ20G closed deck, quad cam, intercooled, turbo boxer engine produced an impressive 220PS for its day. STi took this base and enhanced it further fitting forged pistons and strengthened connecting rods along with porting and polishing the inlet and exhaust ports on the heads. The Crankshaft, Flywheel and even the clutch cover was hand balanced by STi. A second radiator fan was also added for enhanced cooling which was a fair call considering the test would take place at the Arizona Test Center. The suspension was upgraded along with the steering ratio quickened. In January 1989 STi with a team of 24 drivers and 3 cars hit the track for the 100,000km endurance sprint. STi pushed the cars to the limit running them flat out around the massive 5.7 mile banked speedway non stop over 18 and a half days smashing the previous record along with 13 others at the same time with an average speed of 223.34km/ph. Cars only took a pit stop every two hours to change drivers whilst refueling, changing oil or tires. The record stood for 15 years until it was beaten. But more impressively Subaru encountered rain which is rare in Arizona but still succeeded. Prior to that the cars had been averaging 233.35km/ph. 10km/h might not sound much but Mercedes Benz who broke the record and still hold it today achieved a 225.9km/h average speed meaning had it not rained Subaru’s old faithful BC Legacy RS could still hold the record some 31 years later."

STi's involvement is also mentioned in wikipedia: https://en.wikipedia.org/wiki/Subaru_Tecnica_International#Endurance_record

[james_s]

I don't know about a car, but that has been used in large diesel engines like the sort used in locomotives and tugboats and such.

If you mean turbo-compounding, I'm not sure that is exactly what he is describing.  There are actually over-the-road trucks that use turbo-compounding as well (Detroit DD15).

The turbo-compounding I'm familiar with is the Wright R-3350 which in some configurations had three power recovery turbines that recovered energy from the exhaust flow and used viscous couplings to transfer it to the crankshaft. I don't remember where I read about the mechanically assisted turbocharger but I found mention of it in a wikipedia article, apparently it was used by some EMD 2 stroke medium speed diesel engines. A 2 stroke diesel requires forced induction since it has a conventional lubricated crankcase and cannot use the underside of the piston to push air into the cylinder to drive the exhaust out.

"In the case of Electro-Motive Diesel's two-stroke engines, the mechanically assisted turbocharger is not specifically a twincharger, as the engine uses the mechanical assistance to charge air only at lower engine speeds and startup. Once above notch # 5, the engine uses true turbocharging. This differs from a turbocharger that uses the compressor section of the turbo-compressor only during starting and, as two-stroke engines cannot naturally aspirate, and, according to SAE definitions, a two-stroke engine with a mechanically assisted compressor during idle and low throttle is considered naturally aspirated."

[John B]

OK, it was the pressure wave supercharger:

https://en.wikipedia.org/wiki/Pressure_wave_supercharger

The crankshaft connection provides a quasi-timing role, but essentially the intake air is compressed by directly being forced by exhaust gas.



Here's a video of it in action on a Mazda capella 626. Note that this video is from only January 2020, although I've known about these things since 2004? when I was more into the mazda 6 platform, finding videos of this one is like finding hens teeth, let alone seeing a running example in person.

[David Hess]

It's a huge issue.  There are, or at least were, industrial engines designed for this purpose with huge roller bearings and extra-stout crankshaft stubs, but absent those design features a radial load is not good for long term operation and may even snap a crankshaft quite quickly unless you used a coupling shaft driving a pulley with its own very robust bearings.  Most designs using belts for power transfer are crude, low-volume machines that just weren't worth the effort to engineer a proper powertrain.  There are exceptions as belts do protect from extreme shock loading for things like concrete saws and stump grinders.  Even there, though, belts are less common these days.

Belt driven generator setups are not unknown, but to connect them directly with belts you do need a generator assembly that is designed for the purpose, just like the engine.  I've never seen a chain drive and suspect that it would be challenging to make that quiet and reliable.

The reason I like the idea of using a belt and pulleys is that I think it would be easier than finding a 4-pole generator.  A 1:2 or whatever transmission would work just as well but I know I can get belts, pulleys, and whatever is required to use them.

That would explain the rumors then.  I guess it's similar to the idea that "vinyl and tube amps are sacred and everything else is ****!"  That opinion was formed when it was a new technology compared to a mature one, and it stuck.  But now that we've figured out how to do the new stuff right, it's far superior.

There are definite differences in performance, like with dampening, but comparisons are usually made with flawed solid state designs that suffered in clipping.  Frequency compensation is not bandwidth control!

The cobbler's children go shoeless, right?  The amplifier that I use has a pair of Texas Instruments class-D TPA3116D2 chips.  If I ever get back into audio amplifier design, maybe I will build something for myself.

100 hours is a lot of power outages. I've put 33 hours on my generator in the ~3 years I've owned it. I change the oil once a year regardless of the hours. Unless you're living off grid and using the generator full time this is not going to be an issue. If you are, it might be worth considering an external oil tank as is used with dry sump engines.

I have ended up using my backup generator for between 6 to 12 hours per year.

[SeanB]

If going belt driven you will first need to add a flexible coupling to the generator input shaft, then have a pair of bearings in pillow blocks mounted to drive it, and then the pulley for the belt or chain drive. Reason is because most alternator drive shaft input bearings are not rated for large radial loading, they merely are there to align the rotor with the stator, and the bearings do not have the load ability to handle your belt tension plus the torque the belt or chain will create on them.

You will need the coupling to isolate the radial torque, and the pillow blocks, with appropriately sized shaft, generally a few sizes bigger than the input shaft for stiffness, and the pillow blocks to handle this very large load. Your pillow blocks will handle the radial load perfectly fine with the larger bearings they have, and in general you sort out most of your alignment there, leaving the flexible coupling to take up the rest, plus any vibration from the belt or chain. All standard parts available off the shelf from mechanical parts suppliers, including the ready made stub shafts with keyways already cut.

Same for the car engine output, the bearings there are also not rated for radial load, and need the same treatment. the crankshaft axial load rating is there only for the thrust from the clutch or torque converter, and radial loading capacity is there only to keep the crankshaft centred, as the set of main bearings in parallel absorb the thrust of the pistons only, they have an oil film that will only handle that.

[bdunham7]

OK, it was the pressure wave supercharger:

https://en.wikipedia.org/wiki/Pressure_wave_supercharger

The crankshaft connection provides a quasi-timing role, but essentially the intake air is compressed by directly being forced by exhaust gas.

I thought I'd seen it all.  I guess not! 

[NiHaoMike]

How come nobody mentioned the idea of just using the engine and generator as they are in the car, with the car still usable as a car for normal times?
http://priups.com/riddle/answer-1.htm

[David Hess]

How come nobody mentioned the idea of just using the engine and generator as they are in the car, with the car still usable as a car for normal times?
http://priups.com/riddle/answer-1.htm

Some hybrid vehicles can be used that way, but a 12 volt alternator is only large enough to provide a minimum of backup power.  I guess you could make a Rube Goldberg setup with multiple car alternators feeding a big inverter.

[BradC]

How come nobody mentioned the idea of just using the engine and generator as they are in the car, with the car still usable as a car for normal times?

Because it's only < $1000 if you already own a Prius?

[brucehoult]

How come nobody mentioned the idea of just using the engine and generator as they are in the car, with the car still usable as a car for normal times?

Because it's only < $1000 if you already own a Prius?

I just checked trademe.co.nz and it's now possible to pick up a 2004 or so Prius for NZ$3500 (US$2400), so it's not crazy.

The quoted power levels are surprisingly low though -- there are normal cars with alternators that can put out 2500 or 3000 W. Hell, my 1995 BMW motorcycle does 800 W so you can run electrically-heated clothing for rider and passenger.

[Berni]

The idea of using a hybrid car is pretty good, however you will most likely have to build your own inverter.

In order to still use the car as is, you would have to tap off the high voltage battery pack and make sure you do it in a way that does not upset the cars electronics. That thing is about 150 to 350V of rather intimidating DC. So you really need to know what you are doing, while you can't easily buy an off the shelf inverter for the correct input voltage. Best bet might be buying an giant old UPS and modifying it.

Taking just the engine of a hybrid car does already solve the mechanical problem of mounting a generator onto the internal combustion engine. The motor/generator on it will be 3 phase but most likely will not produce 50/60Hz at the correct voltage. So you still likely need big power electronics to turn it into DC and then convert that up to mains AC.

Doing it from the 12V system is not even worth a try because the alternator can't produce that much. You might get about 300W to 1000W out of there.

[David Hess]

The idea of using a hybrid car is pretty good, however you will most likely have to build your own inverter.

Many hybrid vehicles have a built in inverter to provide AC power, and some are quite powerful.  The 2021 Ford F150 hybrid is 7.2 kilowatts.

[Jester]

Many hybrid vehicles have a built in inverter to provide AC power, and some are quite powerful.  The 2021 Ford F150 hybrid is 7.2 kilowatts.

Those 7.2kW inverters are going to be a hot commodity in the wrecking yards I wonder what the input voltage is?

Probably 120V out better yet if 120/240V, 7.2kW goes a long way when you have no power. A good inverter would simplify the engine control requirements.

Just looked it up, indeed 240V

https://news.pickuptrucks.com/2020/06/5-fun-facts-about-the-2021-f-150s-onboard-generator.html

$750 option, I would not skip that option. What a great idea.

[langwadt]

Many hybrid vehicles have a built in inverter to provide AC power, and some are quite powerful.  The 2021 Ford F150 hybrid is 7.2 kilowatts.

Those 7.2kW inverters are going to be a hot commodity in the wrecking yards I wonder what the input voltage is?

I believe the battery  is ~400V

[james_s]

I expect it will be tightly enough integrated into the other systems in the truck that it will be quite an undertaking to get it working on its own, but I'm sure somebody will try once the trucks have been around for a while.

[NiHaoMike]

while you can't easily buy an off the shelf inverter for the correct input voltage.

https://www.aliexpress.com/item/4001209712872.html

[AaronD]

while you can't easily buy an off the shelf inverter for the correct input voltage.

https://www.aliexpress.com/item/4001209712872.html

Ah yes, the chinesium firelighter company with no accountability........

[james_s]

I have a similar board and it does work, but keep in mind it needs a regulated input voltage in order to get a regulated output voltage, at least mine does.

[Jester]

I have a similar board and it does work, but keep in mind it needs a regulated input voltage in order to get a regulated output voltage, at least mine does.

The link provided does not specify the "correct" input voltage whatever that is?

Do these output 120V or 240V?
How are they with loads such as a motor starting?
3kW is smaller than I would like.  Any links to an affordable, reliable inverter in the >7kW range?

[langwadt]

I have a similar board and it does work, but keep in mind it needs a regulated input voltage in order to get a regulated output voltage, at least mine does.

The link provided does not specify the "correct" input voltage whatever that is?

Do these output 120V or 240V?
How are they with loads such as a motor starting?
3kW is smaller than I would like.  Any links to an affordable, reliable inverter in the >7kW range?

looks like it based on these:

https://www.amazon.com/Inverter-EGS002-EG8010-IR2110-Driver/dp/B01E8X64CC
https://www.lz2gl.com/data/power-inverter-3kw/eg8010_datasheet_en.pdf

[james_s]

The link provided does not specify the "correct" input voltage whatever that is?

Do these output 120V or 240V?
How are they with loads such as a motor starting?
3kW is smaller than I would like.  Any links to an affordable, reliable inverter in the >7kW range?

The one I have requires about 400VDC on the input to get 240V out. I don't remember off hand if it will work from a lower input voltage to produce 120V. I'm only familiar with inverters up to about 2kW but maybe someone who has worked with solar systems will be more knowledgeable about larger ones. I'm forgetting what the context is though, most inverters are designed to accept a battery voltage, some multiple of 12V, others like these bare boards are the output section and are designed to run from a ~400VDC regulated bus.

[Berni]

That is actually a pretty neat module. Not sure i would trust using it at anywhere near its max power rating since i had chinese crap blow up well before the max ratings. When such a high power inverter blows up, it can be pretty spectacular with a bang, smoke, sparks, fire etc.

By the looks of it this is basically a really big open loop D Class audio amplifier. That in itself is just a pair of buck switchmode converters with an agile output voltage. So this setup will not be able to boost voltage, So the DC input determines the largest peak to peak AC signal it can make (minus some headroom for losses). So for making 220V AC it should need about >340V DC of input.

The encouraging thing is that is does have an adjustment pot to tune the output voltage, but it is not closed loop, so even if you do tweak it to make the right output voltage, it will still ride up and down with any variations in input voltage. But i suppose it wouldn't be too hard to add some circuitry to make it actually sense the input voltage.

I suppose the only thing that determines the max output power is the power transistors and output choke. So the same PWM driver module could be used to build a bigger model for say 10kW. Also since you are from the US you will need a way to get split phase in order to run a house. So you either need an inverter capable of that, or use a large transformer to provide the center tap for the 'neutral'. For EU houses its easier since even tho there is often 3 phase, we typically don't need it to actually be 3 phase in residential houses, so all 3 phases could simply be powered from 1 phase.

[james_s]

When I power my house from my generator I just tie the inputs together so both bus bars are fed from the same source. All of my 240V loads are much too large to run from my generator so this doesn't cause any problems. Obviously if you need to power 240V loads from the generator then this will matter.

[BradC]

By the looks of it this is basically a really big open loop D Class audio amplifier. That in itself is just a pair of buck switchmode converters with an agile output voltage. So this setup will not be able to boost voltage, So the DC input determines the largest peak to peak AC signal it can make (minus some headroom for losses). So for making 220V AC it should need about >340V DC of input.

The 8010 is actually an ASIC that drives a H-bridge. It does closed loop voltage regulation within reason and it's pretty good at working with perverse load waveforms. The rest is just a big H-bridge and output filter.

[langwadt]

That is actually a pretty neat module. Not sure i would trust using it at anywhere near its max power rating since i had chinese crap blow up well before the max ratings. When such a high power inverter blows up, it can be pretty spectacular with a bang, smoke, sparks, fire etc.

By the looks of it this is basically a really big open loop D Class audio amplifier. That in itself is just a pair of buck switchmode converters with an agile output voltage. So this setup will not be able to boost voltage, So the DC input determines the largest peak to peak AC signal it can make (minus some headroom for losses). So for making 220V AC it should need about >340V DC of input.

The encouraging thing is that is does have an adjustment pot to tune the output voltage, but it is not closed loop, so even if you do tweak it to make the right output voltage, it will still ride up and down with any variations in input voltage. But i suppose it wouldn't be too hard to add some circuitry to make it actually sense the input voltage.

if you need to boost the voltage like in a 12V inverter, that could be handled by the boost converter at the front

I suppose the only thing that determines the max output power is the power transistors and output choke. So the same PWM driver module could be used to build a bigger model for say 10kW. Also since you are from the US you will need a way to get split phase in order to run a house. So you either need an inverter capable of that, or use a large transformer to provide the center tap for the 'neutral'. For EU houses its easier since even tho there is often 3 phase, we typically don't need it to actually be 3 phase in residential houses, so all 3 phases could simply be powered from 1 phase.

for higher powerlevels you might need to beef up the gate drivers

[NiHaoMike]

3kW is smaller than I would like.  Any links to an affordable, reliable inverter in the >7kW range?

Use multiple boards? There's not many single >3kW residential loads that are essential to run on backup power. It's also not that difficult to mod the boards to do V/Hz scaling to allow turning down the power of motor loads. (For that matter, VFDs would be a good choice to run motor loads from HVDC.)

You can also get a Prius inverter (about $100) and hack it, but it's far from a plug and play solution at this point.

[Ed.Kloonk]

I'll just leave this here.

The pedant in me wonders if it should be Piston. Fore!

[Vtile]

Our power here is pretty reliable, that being said if it goes down during the winter, not so pleasant that happened a few years ago during a nasty ice storm, no power for about 2-3 days, I’m glad we had a conventional fireplace.

I had that experience during the 2007 North American Ice Storm.  I burned a month's worth of wood in one week to keep from freezing.  Since then I bought a backup generator, which I have used yearly since, and backup propane and kerosene heating.

My thought of the day is to pickup a used small engine from a wrecked econo-box car perhaps 1.5 litre and mate it to a suitable generator something about 20-30kW (will depend on what is available used and cheap). I will need some sort of gear box to increase speed to generator perhaps 2:1 or  2.5:1 would allow the engine to run at about  1500 rpm. Will need to make some sort of speed control to keep the generator at 3600 rpm as load changes.

For simplicity, I would consider using pulleys and belts instead of a geared transmission.

They are less common, but a 4-pole generator head would allow engine operation at 1800 RPM.  They are more common with backup diesel generators.

Another great idea 4 pole generator

The belt and pulleys suggestion is also a great idea, makes  things much simpler, need to figure out belt requirements, probably need one of those double or triple wide pulleys for 25 ish HP?

How much a typical timing belt stand tension. It might be enough and pulleys can be found on car graveyards.

[Milmat1]

A co-worker and I had discussed building a generator that would run from rollers that you would drive the front wheels onto (front-wheel drive cars). Then the vehicle's speed could be adjusted using the cruise control to maintain the generator's output. For emergency situations. We even began building the prototype. But we got distracted and never finished the project.
Anyway, it was a cool idea...

[Ed.Kloonk]

A co-worker and I had discussed building a generator that would run from rollers that you would drive the front wheels onto (front-wheel drive cars). Then the vehicle's speed could be adjusted using the cruise control to maintain the generator's output. For emergency situations. We even began building the prototype. But we got distracted and never finished the project.
Anyway, it was a cool idea...

The trick is picking what ratios to use. Just comparing very rough numbers, a car would have at least an order of magnitude more power available than the generator needs. There should be a frequency meter visible so the operator can rev the engine to the correct speed. As for coupling the car, look at how dynos work. Take note how the car -must- be strapped down to avoid slip (wasted energy) and worse yet, slip off! (youtube videos if you want to see what happens).

Another problem is, generally, the weight of a contraption that receives such horse power from something like a car is the unit itself prolly should be at least as heavy as the car or perhaps even heavier and fixed down. Portability can be an issue.

Sounds like a fun project tho.  I hope you do end up making it.

[james_s]

That sounds like a very inefficient way to make a generator. You've got all those different coupling stages between the engine and the generator, surely it would be more efficient to just use a portable generator.

[Ed.Kloonk]

That sounds like a very inefficient way to make a generator. You've got all those different coupling stages between the engine and the generator, surely it would be more efficient to just use a portable generator.

I know. It'd be fun to tease the neighbors with it though..

[Berni]

That sounds like a very inefficient way to make a generator. You've got all those different coupling stages between the engine and the generator, surely it would be more efficient to just use a portable generator.

Well it is not that bad of an idea really.

Sure you might use some more fuel to generate the same amount of power, but a car already has a powerful engine that you regularly maintain anyway, while you rarely need a backup generator.

There is no need to adjust the throttle because the the cruise control does the job on its own. It will keep the wheels turning at exactly the same speed no matter the load put on it, so the more load you put on the generator the more the throttle opens to keep it going. You also don't need to hit exactly 50/60 Hz, going +/- 10Hz is going to work just fine.

You also don't need to run it all the time. If you are this serious about power then you probably would also want to own a sizable battery bank to make it so you don't need to run the generator on any short few minute power outage and give you time to get the generator up during a long outage. This way you can run things from battery backup for light loads to keep fridges running and lights on. If you have a central heating system it it also plenty of power to run the furnace and pump hot water around.

That being said for a lot of cases people can get by using a little 2kW generator just fine. You just avoid turning on any large loads. Using a car makes more sense when you want like 20kW of backup power.

[AaronD]

There is no need to adjust the throttle because the the cruise control does the job on its own. It will keep the wheels turning at exactly the same speed no matter the load put on it, so the more load you put on the generator the more the throttle opens to keep it going. You also don't need to hit exactly 50/60 Hz, going +/- 10Hz is going to work just fine.

The cruise controls that I've used aren't exactly "precision".  In terms of PID control (not the only way to make a control system, but very common), I wouldn't be surprised if they were purely proportional (throttle = gain x error), with low enough gain to guarantee that it doesn't oscillate ever.  That goes for both vacuum and electric ones.  The speed does droop with increasing load (non-zero throttle requires non-zero error), though it might manage to keep +/-10% at highway speed.

For comparison, the mechanical governors on small engines are almost always purely proportional (flyweights (or a paddle in the fan) control the throttle directly, while the speed control pulls on a spring), and some of them do have high enough gain to oscillate.

[james_s]

I think a cruise control is going to be precise enough for this application, there is quite a lot of mechanical inertia in such an arrangement and the governors on conventional portable generators aren't exactly precision devices. It's normal for the frequency to be around 64 Hz at light load and 56 Hz under load. For most things this doesn't really matter.

[brucehoult]

There is no need to adjust the throttle because the the cruise control does the job on its own. It will keep the wheels turning at exactly the same speed no matter the load put on it, so the more load you put on the generator the more the throttle opens to keep it going. You also don't need to hit exactly 50/60 Hz, going +/- 10Hz is going to work just fine.

The cruise controls that I've used aren't exactly "precision".  In terms of PID control (not the only way to make a control system, but very common), I wouldn't be surprised if they were purely proportional (throttle = gain x error), with low enough gain to guarantee that it doesn't oscillate ever.  That goes for both vacuum and electric ones.  The speed does droop with increasing load (non-zero throttle requires non-zero error), though it might manage to keep +/-10% at highway speed.

The cruise control on my 2008 Subaru (Outback 2.5xt) droops a maximum of about 5 km/h from the set speed at the start of a steep hill, but if the hill continues at the same steepness long enough (a km maybe) then it does get back to zero error.

It's obviously deliberately tuned for smoothness/comfort rather than precision at all costs. When following another vehicle it maintains a very steady 2 seconds behind (that's the setting I use) with gradual speed changes, but it only does what can be adjusted with coasting or with acceleration in top gear (and torque converter locked up) unless the following distance changes quite a lot.  I've never actually measure it, but at a guess it starts actually braking when the following distance drops to about 1 second, or will change down if it drops maybe 4 seconds behind (it's quite a bit). Once speeds are again roughly matched it takes maybe 10-15 seconds to adjust the following distance back to 2 seconds.

I had an almost ten years newer Outback (2017) for the year I lived in California and the cruise control on that was probably a bit more proactive on making bigger adjustments, both in braking earlier if the following distance started to rapidly drop, and in accelerating harder to stay with the vehicle in front.

But the older 2008 model works very acceptably and a heck of a lot better than not having the system!

[langwadt]

There is no need to adjust the throttle because the the cruise control does the job on its own. It will keep the wheels turning at exactly the same speed no matter the load put on it, so the more load you put on the generator the more the throttle opens to keep it going. You also don't need to hit exactly 50/60 Hz, going +/- 10Hz is going to work just fine.

The cruise controls that I've used aren't exactly "precision".  In terms of PID control (not the only way to make a control system, but very common), I wouldn't be surprised if they were purely proportional (throttle = gain x error), with low enough gain to guarantee that it doesn't oscillate ever.  That goes for both vacuum and electric ones.  The speed does droop with increasing load (non-zero throttle requires non-zero error), though it might manage to keep +/-10% at highway speed.

you also want it to be a bit sluggish so that if you hit resume with it set at 130km/h while doing 20km/h it doesn't just floor it

[Ed.Kloonk]

I think a cruise control is going to be precise enough for this application, there is quite a lot of mechanical inertia in such an arrangement and the governors on conventional portable generators aren't exactly precision devices. It's normal for the frequency to be around 64 Hz at light load and 56 Hz under load. For most things this doesn't really matter.

Yeah.
I think that if our hero has only a generator that requires a car to spin it, running old mechanical clocks to the precise second or perhaps listening to a vinyl record on an old turntable at the correct speed is prolly among the least of things to worry about.

A good reason might be when using a radio that still gets it sync from the line frequency. If the radio is out of tune, you might miss the broadcast announcement from the truth ministry instructing you to prepare to be put on the train bound fo...

Ahem.

[Berni]

The cruise control in my 2013 Volvo keeps the speed nailed pretty much nailed on the set speed. The dash is digital and so you can see how the spedometer needle stays perfectly covered up over the green set speed marker.

They tend to use the old "fade in" control trick to get it to behave more comfortably. You don't need to instantly give all throttle control to the PID loop, but instead you can gradually ramp up how much it is allowed to affect the throttle. That way is slowly starts accelerating and it gives the PID loop some time to get settled in before it fully takes control. This trick can be used on most PID loops to smoothly switch them on without the whole thing going crazy in its first moments.

If you are to run a generator using cruise control and suddenly go from no load to turning on a 10kW flowtrough shower heater then yeah pretty sure it will not keep the the speed perfectly steady, likely dropping in RPM a lot before recovering back up, that would happen to all generators because the throttle response is not instant, so it has to rely on the inertia of the system to fill in the gap a bit, in order to get kinetic energy from inertia back you have to slow down the RPM. But as long as the engine doesn't stall and quickly recovers it is fine. The small generators indeed tend to have very simple mechanical governors and they work well enough for the job.

[AaronD]

I may have mentioned before (didn't go back and look) that at one time I was thinking about making a temporary generator with my Jeep.  The idea was to drive with the front axle, using the 4x4 setting, and "somehow" spin the generator from where the rear driveshaft used to be.  5-speed manual transmission: 4th is 1:1, 5th is overdrive.

I also happen to have the remains of a failed aftermarket cruise control, so I was going to resurrect it with my own electronics and software.  Given that, I was wondering about the wisdom of adding a feedforward component based on either an ammeter or a torque sensor (engine- or generator-mounts on load cells?)...and that's about where I abandoned it.