Goofy question, whats the best Air/Fuel ratio?

[definitiveno]

This is not really a tuning problem I am trying to sort out or any thing just a question I have wondered about for a while. I read some where that 14.7:1 was stoichiometric, where all carbons would be consumed or some thing, and I also read that 11.5:1 produced the most cylinder pressure, it's ignition produced the most energy. Is there any truth in that? If not what Air/Fuel Ratio makes the most power, there has to be a scientific answer for this. It just seems that there would be a balance of air and fuel that would make the biggest pow. Any ideas? Any one?

 

[GVR4592]

http://www.max-boost.co.uk/max-boost/internet_articles/Air fuel metering.htm

 

[Caithness]

That is an excellent link.


My personal experience on my 14b car and my friend's 16g car, all WOT stuff as I am only starting to understand how to tune light throttle stuff (more complicated than the WOT, IMO):

The cars generally seem happiest between 11:1 and 11.5:1 on pump 93, though I've never tried running leaner than 11.5:1. Everything I've read indicates that more power can be made with the richer mixtures so I haven't bothered. Around 10:1 and less, the cars have an obvious bog and will misfire out if you go much below 10:1. Going from low 10.x:1 to 11:1 is a very noticeable improvement in power and how smoothly the car runs. I wouldn't run lower than around 10.5:1 at the minimum. 11:1 seems to be a good happy medium setting that has allowed for decent power on my car and on my friend's car, so I usually just peg it there and go focus on getting boost to a reasonable range and then bumping timing. I'm currently running my car a bit leaner, 11.3:1 and I really don't notice much of a difference. In my experience 11:1 is a good WOT afr for pump gas with our cars and more can be had by cranking the boost and then seeing how far you can push the timing. Just a few degrees of timing advance can make a huge difference in power while a 10.8:1 to 11.5:1 isn't all that noticeable.

 

[Defiant]

DSMs, and many factory-turbocharged cars, use fuel as a cooling medium as well as a source of power.
The "correct" ratio will dance all around. Then, there's the smog considerations, which don't seem to have a number stated for incinerated aluminum vapor.