Got my car dynoed today, 324rwhp/340rwtq, air fuel max was 17.5 but was around the 12 mark from 4000 to 6000 rpms, what is a good air/fuel number for an N/A motor? How much can I expect by tweeking the car now, any gains?
A/F of 11.5:1 = Rich best power, cools the engine with the excess fuel. Not good for fuel ecomomy.
A/F of 13.5 = Lean best power, more power, but engine will run hotter, more tendency for detonation.
A/F of 14.7:1 = Best ecomomy, what the stock computer tries to do in cruse mode.
A/F ratio should be flat +/- .5 from 1000 RPM to redline for best power, Ratio should be 12.5:1-13.5:1 depending on the engine's spark advance, forced induction & tendecy for detonation.
You need a Tweecer or custom burned prom to make the A/F ratio do what you want it to do.
If you're at 12 now, you might see another 5-10HP by leaning it to 13. If it's running good, reasonable drivability, etc., I wouldn't mess with it unless you have other issues you want to address with the chip.