rjardy

that optimum air fuel equation, i believe it is called stioch or stiochataic equation or some thing, not reall sure just looking for some help thanks

ROB

inspyral

Stoich is like 14.5:1
For turbo cars, 12.5:1 is good.

rjardy

okay, but can you tell me what that means, like is it what parts air what parts fuel? thnks a bunch


ROB

Stock@$$GSR

You're close, but off by .2. Stoich is 14.7:1.

I see everyone on this board saying that 12.5:1 is the magic number for turbo'd cars, but what if you run on 100+ octane all the time? Does anyone know what is the highest A/F you can run without causing detonation? Since 14.7 is optimum, can you run 14.7 A/F if you take detonation out of the equation? Or are you also running richer to cool the mixture?

BlueShadow

yup, thats pretty much why you do it, for safety purposes. If you run a leaner mixture you will be more likely to detonate. Thats what I hear everyone saying, stoich is good for lower RPMs but at higher RPMs you'll want a slightly richer mixture. I guess it's sorta like how a stock Honda will dump more fuel when it goes from low RPM to high RPM (open loop to closed loop).

also a wideband o2 like FJO or UEGO tells you the A/F ratio right? do they actually give you the A/F ratio like 12.5, 13.0 etc on a readout or guage?

and also a wideband 02 sensor measures the exhaust for oxygen content right? someone let me know if I'm wrong.



[Modified by BlueShadow, 12:04 PM 5/12/2002]

rjardy

okay i read up some more on stoich, it is actually a formula that explains what happens when particles change ...(air fuel mixture burning) so im kinda on tip about what it is but its still not real clear.....they explaind 14.7 moles oxygen to 1 mole of fuel is like an optimium for it to burn ( a mole is a mesurment) so does this sound right to any one.

thanks Chris you cleared it up a bit but im still kinda hayzey on it.

ROB

BlueShadow

yah, that's right 14.7 parts of air and 1 part fuel, 14.7:1 = stoichiometric.

but remember you dont want a stoich mixture for turbo motors, like everyone said 11:1 or 12:1 is a good air/fuel ratio that provides some margin for safety. If you lean it out to 14.7:1 you'll be stoich but you'll have NO MARGIN for error and you are getting to the verge of leaning out.

BTW when you get it out stoich (leaner) you'll obviously get more power, but thats power you'll want to sacrifice for safety, so rather than leaning it out, just be safe and run it rich.

BlueShadow... who is getting delirious and has no tuning experience whatsoever.

I'm going to sleep



[Modified by BlueShadow, 3:24 PM 5/12/2002]

Lsos

Why does running it leaner give you more power?

dbman96

Well in theory running any richer than 14.7:1 means you're adding fuel that doesn't have enough oxygen to burn, so it's just blown out the tailpipe. But that unburned fuel can cool the combustion which does produce a little less power but as mentioned before, that's a safety mechanism too.

Stock@$$GSR

Is detonation the ONLY problem you're worried about when running leaner? Cause if you can resolve detonation by running higher octane, wouldn't it then be safe to run leaner? If you could theoretically always fill your tank with 100+ octane, can't you maybe run 13.5:1 A/F and still be safe??

inspyral

d'oh