is it 12/1 or 14 to 1?

 

For your car. 12:1 14:1 is stoic. Meaning it's equal parts air to fuel. Going rich means your using up all the air you can to burn the fuel. For a Natural Aspiration car 13:1 is perfect because they conduct less hear than a Forced Induction car. Forced cars have very hot intake temps, and as such require the extra fuel to act as a kind of chemical intercooler.

This only applies to WOT though. At part throttle/crusing 14:1 is prefectly aceptable, along wiht even leaner mixtures. Since you arne't actually stressing the motor, much.

 

wonderful explaination thank you.

 

That's what I've been reading in all the tuning books aswell.

 

Well cobalts have "fuel trims" which add or subtract fuel no matter what you do with piggyback tuning software *ie HPTuners* making it relatively difficult to mess up part throttle tuning. Granted you dont want your fuel trims to be fighting your tune, but it would be very unlikely that you would damage your motor at part throttle. FYI, 14.7 is *exactly* stoich...but your car will fluctuate with throttle pressure, etc. Finally, I would shoot for
11.5-11.7 when you are tuning WOT, thats about the leanest you want to go on pump.

 

14.7 actually...

generally speaking 11.5-12.5 is the range used in FI aplicatication for WOT, 12.5-13.1 for NA applications.