Air flow rate into car engine

[HLA-27b]

It would be interesting to see how ambient temperature throws the results.  Say from -20 to +60 (under bonnet).

[Zad]

A modest (but real world) 10hp supercharger would require 625 Amps. A higher powered engine with, say 50% more power, would double the power requirement. Good luck generating 1250A.

[IanB]

I wonder how much power it would be for my integrales 30psi!

To do that we need an estimate of the air flow. I'm looking for a number for the fuel efficiency of a typical engine. One number I found was 240 g of petrol per kWh of output, but I'm looking for more data for verification. Apparently engine dynamometer charts give this info. Any petrolheads got an example? Once we have this we just have to go with the power output of the engine and we can figure the fuel flow and the air flow from that.

Wikipedia says the 1.9 Twinturbo Multijet 16V Integrale develops 190 hp.

[IanB]

It would be interesting to see how ambient temperature throws the results.  Say from -20 to +60 (under bonnet).

See below. High ambient temperatures significantly increase the power requirement on the compressor for the same boost.

Edit: This is not strictly true. It is more realistic to maintain the same volumetric air flow rather than the same mass air flow. In this case the power requirement doesn't vary so much.

[Uncle Vernon]

Toyota and Ford are both developing workable electric supercharging. (I gave up looking for the Toyota one after googling 10 pages of fan in pipe junk. Here is the Ford offering which proves that no you cannot change the laws of physics, with the supercharger achieving small amounts of boost by helping to spin up a too big turbo on a too small engine.
http://news.drive.com.au/drive/motor-news/fords-electric-supercharger-20120703-21esd.html

Simon the small high volume compressor falls into the same capacity as the compact lightweight high delivery battery,  both would be revolutionary if only they existed and more importantly were available at low cost.

[Chet T16]

To do that we need an estimate of the air flow. I'm looking for a number for the fuel efficiency of a typical engine. One number I found was 240 g of petrol per kWh of output, but I'm looking for more data for verification. Apparently engine dynamometer charts give this info. Any petrolheads got an example? Once we have this we just have to go with the power output of the engine and we can figure the fuel flow and the air flow from that.

Wikipedia says the 1.9 Twinturbo Multijet 16V Integrale develops 190 hp.

I did have it on a dynamometer but the chart went when i sold the car. It made 219 bhp at 15 psi and 241 at 20 psi. It was running on 95RON petrol at the time so that was as much boost as i could run. This was a '91 HF Integrale 16V

[HLA-27b]

See below. High ambient temperatures significantly increase the power requirement on the compressor for the same boost.

Thanks. Not as much increase in pumping energy as I expected but 131 degrees inlet manifold temp is not pretty.

[IanB]

Thanks. Not as much increase in pumping energy as I expected but 131 degrees inlet manifold temp is not pretty.

Note that I did that calculation with the same mass flow of air in each case, which is not realistic. I have fixed it to keep the same volumetric flow and now the power requirement doesn't change. However the mass flow changes a lot, which corresponds to a significant loss in engine power in the hot conditions.

[GK]

I wonder how much power it would be for my integrales 30psi!

To do that we need an estimate of the air flow. I'm looking for a number for the fuel efficiency of a typical engine. One number I found was 240 g of petrol per kWh of output, but I'm looking for more data for verification. Apparently engine dynamometer charts give this info. Any petrolheads got an example? Once we have this we just have to go with the power output of the engine and we can figure the fuel flow and the air flow from that.

Wikipedia says the 1.9 Twinturbo Multijet 16V Integrale develops 190 hp.

Fuel efficiency is irrelevant. All you need is the engines displacement, the RPM and a fair estimation of the volumetric efficiency.
I did mention the TurboZet and the associated Autospeed article:

http://autospeed.com/cms/title_The-Twin-Turbo-Zet/A_110827/article.html

[IanB]

Fuel efficiency is irrelevant. All you need is the engines displacement, the RPM and a fair estimation of the volumetric efficiency.
I did mention the TurboZet and the associated Autospeed article:

http://autospeed.com/cms/title_The-Twin-Turbo-Zet/A_110827/article.html

Not irrelevant, just a different way of getting at the answer. But you are right, the RPM and volumetric displacement does give an alternative route to the information needed. In this case you would need to know the RPM and volumetric efficiency at the conditions of maximum power output, and also the actual boost pressure at the air inlet valves (which will be lower than the turbocharger outlet pressure)--especially if the throttle isn't wide open.

For estimates, these nuances won't matter too much.

If we happen to know the fuel rate at maximum power and the fuel/air ratio, then we directly get the mass flow of air without going round the houses.

[Uncle Vernon]

Any petrolheads got an example?

For aspirated

http://www.csgnetwork.com/cfmcalc.html

eg: 5L at 7500 rpm = 662 CFM

With boost the calculation takes on an variable try here.

http://www.lovehorsepower.com/joomla/index.php?option=com_content&view=article&id=35:compressor-flow-map-calculator&catid=8:mr2-helpful-stuff&Itemid=49

Same engine at 6psi boost = 840 CFM


The calculation

CFM = L x RPM x VE x Pr / 5660

Where L = engine capacity in liters
RPM = maximum engine speed (we'll adjust this later)
VE = engine volumetric efficiency.
Stock 2-valve = 85%
Stock 4-valve = 90%
Street modified = 93%
Competition = 105%
Pr = pressure ratio

To calculate the pressure ratio you need to know what boost pressure you want to run and then plug that into the following formula:

Pr = 14.7 + Boost  / 14.7


Guestimates abound!!!

[HLA-27b]

Wikipedia says the 1.9 Twinturbo Multijet 16V Integrale develops 190 hp.

This happens to be one of the best documented engines out there.

Here are a few bits from Guy Croft's Modifying and Tuning FIAT/Lancia Twin-Cam Engines
http://www.guy-croft.com/

(I used to have an old Fiat  )

[Chet T16]

But isn't that assuming you have a stoichiometric mixture when generally you won't, especially for a turbocharged engine.

FWIW max power on the integrale was at ~5700 rpm and the pressures were measured at the inlet manifold.

[Chet T16]

Wikipedia says the 1.9 Twinturbo Multijet 16V Integrale develops 190 hp.

This happens to be one of the best documented engines out there.

Here are a few bits from Guy Croft's Modifying and Tuning FIAT/Lancia Twin-Cam Engines
http://www.guy-croft.com/

The 1.9 there, is actually a diesel (yuck) A shame for it to have the integrale name!

[Chet T16]

 

[Chet T16]

Oh, just found this too

[HLA-27b]

It's a petrolhead thread now 
Congrats on the nice Llancia.

[GK]

But isn't that assuming you have a stoichiometric mixture when generally you won't, especially for a turbocharged engine.

No.

FWIW max power on the integrale was at ~5700 rpm and the pressures were measured at the inlet manifold.

 

The engine I bolted together for my 1300 kg daily hack does >300hp at the wheels at the same RPM with no forced induction on LPG.
And that is with a choking 3.5psi of exhaust back pressure. I really need to ditch the single 3" for a twin 3".

[Chet T16]

It's a petrolhead thread now 
Congrats on the nice Llancia.

Thanks  But its gone about a year now  Getting an education isn't cheap and it had to go!

About time there was a petrol head thead too!

The engine I bolted together for my 1300 kg daily hack does >300hp at the wheels at the same RPM with no forced induction on LPG.
And that is with a choking 3.5psi of exhaust back pressure. I really need to ditch the single 3" for a twin 3".

What car is this?

[GK]

OK, I confess, not a fair comparison.  The stroker kit brought the displacement out to 6.3L.

[Uncle Vernon]

The engine I bolted together for my 1300 kg daily hack does >300hp at the wheels at the same RPM with no forced induction on LPG. And that is with a choking 3.5psi of exhaust back pressure. I really need to ditch the single 3" for a twin 3".

What car is this?

An Aussie one. Here's a few minor mods on a stocker Falcon s/c 5L . 

And we just get the US throwbacks

[Chet T16]

OK, I confess, not a fair comparison.  The stroker kit brought the displacement out to 6.3L.

50 bhp/litre? Have you tried running it on something that burns? :p

[GK]

OK, I confess, not a fair comparison.  The stroker kit brought the displacement out to 6.3L.

50 bhp/litre? Have you tried running it on something that burns? :p

Accounting for tyre friction on the dyno rollers, auto trans dissipation in 2nd and other driver train losses it's closer to 64 hp per litre. It would be in the order of 20% better on petrol instead of the dedicated gas setup, but doing ~350 kilometers per week I prefer 58c per litre to 140c per litre. 

Also, LPG is cleaner burning. I'm a greenie.

[Mechatrommer]

providing the car is moving the radiator fan will not need to come on.

how can you be sure? what "test distance" we talking about? ps: ferrari is fanless radiator though

I think.....   in fact this explains why if i open the throttle more the petrol consumption does not massively go up but the car accelerates

maybe its time to provide your car model and test procedure details.

is your car VVt-i/VTec/i-DSi/dvvt capable?

[Simon]

providing the car is moving the radiator fan will not need to come on.

how can you be sure? what "test distance" we talking about? ps: ferrari is fanless radiator though

I'm sure, I know radiators, I work for the company that makes radiators. The car is a ford fiesta with a 1.3L engine (not a duratec/zetec)