AFR's

[red2005ss]

Seriously what is rich/lean?
I think 14.5 to 9.0 is rich and anything above 14.5 is lean.
Please someone set me straight, I have been told by some people and some gm techs it the other way around.

[bc3tech]

it kind of depends on the setup of the engine.

N/A, your engine and ECM will want and gun for a 14.7:1 afr, also called stoich. This is the optimal AFR for combustion and efficiency. However, an N/A engine could be tuned for a 13.1:1 AFR and glean a few more ponies out of the current setup, while sacrificing fuel economy (lower number means more fuel in the chamber)

for forced induction, it's a general rule to keep the car at 12.5:1 while boosting (+ pressure in the manifold) and to err on the side of being rich (a lower number, 12.0:1, 11.8:1, etc) while at higher RPMs to futher prevent against detonation. Running "lean" means that you have more air in the engine, so your AFR (air to fuel ratio) will be higher, like 15:1, 16:1, etc and this is bad as leaves the combustion process very prone to detonation, or "knock," which can severely damage an engine in a matter of seconds.

answer your questions?

[06blackg85ss]

for the cobalt ss/sc it likes to run rich.. specially with more boost. I run @11.4 afr mid range and a 10.8 up top to keep her alive. 20.50psi and 290+whp and car is still going strong at 21000 miles

[bc3tech]

rich huh? interesting - i'd heard that the v8 guys were amazed at how the ecotecs like to be on the lean side (13.1:1 under boost)... have you tried leaning her out much? just curious

[Doc]

I run ~12.3:1 all the way across. I need to add some fuel once it gets past max torque for more hp though.

[red2005ss]

Thank you guys