Hey,

I'm confused a little on tuning out the air/fuel ratio.
Now the ideal air/fuel ratio is 14.7:1 right? So when tuning the car on a dyno with air/fuel gauge wouldn't you want a nice flat line across at 14.7?
Why would you want to run the car richer at wot in high rpms and leaner down low?

Can anyone point me in the right direction, I'm confused.

Mike

 

I'm not sure about your numbers so I can't argue with you there, but if you ran rich all of the time you would dump a lot more fuel than is necessary. At WOT and especially high RPM's where timing is electronically advanced you need to have the extra fuel to avoid detonation. A car is going to produce the most power when it is on the edge of detonation, but detonation can fatally harm your motor. If you have the ability to tune your fuel & timing per RPM w/ an ApexFC or similar electronic hardware, you will find your best power potential just richer than the point at which you detonate.

GL

 

14.7 : 1 is the stoichiometric ratio, where chemically there is just the right mix of oxygen and fuel to make a complete reaction. In the real world 13-13.5:1 makes the most power, but this can be dangerously lean for forced induction cars. Its always a tradeoff of leaning out to make more power vs causing detonation and damage to the engine.

Please don't go tuning around with an AFC unless you have access to a wideband O2 sensor and/or professional help. Be especially careful around the torque peak, and pull a few degrees of timing in that region if you feel you are close.