Project84

If the A/F ratio is, say 11.3:1 on person A's car, that wouldn't be any more rich or lean on person B's car would it? (this is with the barometer, temprature, specific gravity, relative humidity and all other meteorlurgical conditions being the same.)

And what is the unit of measurement in the expressed form 11:1 Is it parts per million is it? cause I know for every gallon of fuel, many many gallons of air are passed through the intake.

Thanks for the info guys.

diabolical1

iTrader: (3)

oh boy ... you've got me on this. gonna have to dust off the ol' Physics book.

Evil Aviator

The AFR is a mass ratio. Mass = weight in layman's terms (lol, no I'm not going into the gravity issue for you physics types out there). If measured accurately, 11.3:1 in car A is the same as 11.3:1 in car B, even if one engine is a piston and the other is a rotary, or turbojet engine, or whatever. None of the other factors you mentioned makes any difference, either, as the measured ratio is the measured ratio, period. This is because a pound of fuel (or air) still weighs a pound at any temperature, pressure, etc., and a pound of 93 octane fuel also weighs the same as a pound of jet fuel which weighs the same as a pound of dog doo, etc. The AFR units don't matter, because the ratio is the same regardless:
13 lbs air / 1 lb fuel = 13:1 AFR
13 oz air / 1 oz fuel = 13:1 AFR
13 tons air / 1 ton fuel = 13:1 AFR
13 kg air / 1 kg fuel = 13:1 AFR

Where the differences come in is that engine A may run better at a given AFR than engine B, especially with different fuels. Also, since the engine displacement is based on volume, as is the fuel injection rate, those environmental conditions you mentioned will change the AFR as the conditions change because of the resulting density changes.

Project84

I did some searches and found out that the same things you were saying. I came here to post it but you got it. Thanks a bunch for helping me out though