vettenutchas

Going to get my car tuned and was wondering what is the best fuel air ratio for max power and what would be a safe ratio to ensure no problems like a lean condition at wide open throttle?

eboggs_jkvl

Depends. What do you have as far as mods to the car? Heads & Cam? FI?

Can't say much without some information.

Elmer

vettenutchas

LT header's and Haltech CAI. Motor is stock other wise.

Boomer111

Right around 12.5 seems to be the usually consistent A/F ratio I see. Give or take a 1/10. Given your mods.

FI is a different case.

haljensen

There is no fixed A/F ratio. The computer is constantly adjusting it depending on load. Cruise is ideally 14.6 to 1, hard acceleration can be into the 11.00 to 1 range on FI cars..

eboggs_jkvl

Usually during a tune, the tuner will lean out the engine under WOT to where there is a little KR. Then they will fatten the mixture back up to where the KR is fully gone. That will then usually give you the most power for your car. When you're out of WOT, the ECM runs the engine at 14.7:1 using the O2 sensors to trim out the mixture.

So, as far as a number for A/F at WOT, I can't tell you a concrete number. Two of the above posts are in the ballpark. FI needs to be fatter 11-12.0 or the engine isn't happy. The more modded the car, the fatter the mixture to keep the ping away.

When you're tuned, you'll have the A/F number for your car, on that day, at that temperature, at that altitude. That's the only real answer for your question.

Elmer