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Ignition systems

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Benta:

--- Quote from: bdunham7 on October 01, 2021, 06:09:18 pm ---
--- Quote from: Benta on October 01, 2021, 04:58:21 pm ---Please give an example of a production engine that uses multipulse ignition.

--- End quote ---

I've seen both Ford and BMW products that use multistrike.  Ford in particular has been using it for a decade-plus now.

--- End quote ---

This does not sync with my knowledge. AFAIK, only Mercedes is (half-heartedly) following this track lately. Everything else is aftermerket/tuning accessories.

bdunham7:

--- Quote from: Benta on October 01, 2021, 08:33:30 pm ---This does not sync with my knowledge. AFAIK, only Mercedes is (half-heartedly) following this track lately. Everything else is aftermerket/tuning accessories.

--- End quote ---

I've seen, tested and measured these systems and I assure you they are common in at least Ford products.  You can just google 'Ford multistrike' to read about it.  This system famously killed a Ford engineer a while back--it turns out that the rapid succession is much better at stopping the heart than single pulses.

BrokenYugo:

--- Quote from: langwadt on October 01, 2021, 04:40:36 pm ---
--- Quote from: SeanB on October 01, 2021, 02:52:31 pm ---Going to guess that is for multipulse ignition, for ultra lean operation, so you will have enough spark to ignite the fuel mix, even if the plug area is transiently non combustible, you have enough high energy sparks that the lean mix will strike before TDC and complete combustion to a large degree.

I helped my father install high energy inductive ignition, that used a vane that blocked an optical sensor, that then triggered a low resistance (IIRC under 0,8R primary) coil, to provide the ignition pulse. Had to use inductive wound Bougicord leads, as the carbon ones basically melted, and spark plugs had to be special Lodge ones, as the other brands like NGK or Champion would only last a week before misfiring. But was able to run really lean, and provide extra power at the top end of the RPM, even if your 10 000km service was change 4 spark plugs, rotor and distributor cap, as they would all be badly eroded, and not likely to make another service.

Big difference, made it a stealth supercar, well capable of beating the common sports models, 3 series BMW, low end Porsche, VW 1st generation GTI. None of them thought an Alfasud 1.5l was capable of beating them stop to stop, or at top end. He kept the stock exhaust as well, so it did not sound any different. Just used to eat gearbox synchros, and brake disks.

--- End quote ---

sound like a story that gets better every time it is told, adding lots of spark energy isn't going to magically add sginificant power and running lean definitely isn't

--- End quote ---

Definitely a bit of a "bigger fish" story (though a tuned up Alfasud outrunning a stock Mk1 GTI or 3 series BMW is certainly well within the realm of plausibility), but there is some truth to it. The big deficiency of points ignition is you have a dwell angle energizing the coil, not dwell time, so as revs climb at some point you aren't closing the points long enough to saturate the coil and ignition energy falls off. This is where "dual point" distributors came in, by staggering a pair of rubbing blocks (the cam that operates the points) and points a longer dwell better suited to high RPM operation could be achieved with realistic rubbing block geometries.

langwadt:

--- Quote from: BrokenYugo on October 01, 2021, 10:33:16 pm ---
--- Quote from: langwadt on October 01, 2021, 04:40:36 pm ---
--- Quote from: SeanB on October 01, 2021, 02:52:31 pm ---Going to guess that is for multipulse ignition, for ultra lean operation, so you will have enough spark to ignite the fuel mix, even if the plug area is transiently non combustible, you have enough high energy sparks that the lean mix will strike before TDC and complete combustion to a large degree.

I helped my father install high energy inductive ignition, that used a vane that blocked an optical sensor, that then triggered a low resistance (IIRC under 0,8R primary) coil, to provide the ignition pulse. Had to use inductive wound Bougicord leads, as the carbon ones basically melted, and spark plugs had to be special Lodge ones, as the other brands like NGK or Champion would only last a week before misfiring. But was able to run really lean, and provide extra power at the top end of the RPM, even if your 10 000km service was change 4 spark plugs, rotor and distributor cap, as they would all be badly eroded, and not likely to make another service.

Big difference, made it a stealth supercar, well capable of beating the common sports models, 3 series BMW, low end Porsche, VW 1st generation GTI. None of them thought an Alfasud 1.5l was capable of beating them stop to stop, or at top end. He kept the stock exhaust as well, so it did not sound any different. Just used to eat gearbox synchros, and brake disks.

--- End quote ---

sound like a story that gets better every time it is told, adding lots of spark energy isn't going to magically add sginificant power and running lean definitely isn't

--- End quote ---

Definitely a bit of a "bigger fish" story (though a tuned up Alfasud outrunning a stock Mk1 GTI or 3 series BMW is certainly well within the realm of plausibility), but there is some truth to it. The big deficiency of points ignition is you have a dwell angle energizing the coil, not dwell time, so as revs climb at some point you aren't closing the points long enough to saturate the coil and ignition energy falls off. This is where "dual point" distributors came in, by staggering a pair of rubbing blocks (the cam that operates the points) and points a longer dwell better suited to high RPM operation could be achieved with realistic rubbing block geometries.

--- End quote ---

sure if the ignition system is marginal upgrading it will help, but there's no point is going to plug melting levels

amazing how long it took before they figured out an extra coil and wasted spark was smarter than all the distributor nonsense

Circlotron:
Probably one of the driving forces for getting rid of the distributor was simplifying engine assembly on a production line. Now no need to get it all synced up. Just attach all the parts and it is ready to run.

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