Quote Originally Posted by jeffreycastgsx View Post
TOO rich can't cause detonation, many factory boosted run in the 9's for there tune just to be EXTREMELY safe, leaning them out usually wakens these cars up a lot. The extra fuel in a way cools everything, opposite of what a lean mixture causes, heat.
GM never runs them that rich. take the ssr and cobalt for example, every time i tune one of those vehicles, the a/f ratio stays at 12.2 to 12.5 all the way up to 100mph (not that mph has anything to do with it), and 1-4 gears.
So if anything, GM runs them on the edge, but they are forged and can take it.
After i'm done with them, they are set at 11.7 and run much smoother and stronger than before. Never understood why GM runs these little engines so lean at wot, maybe they don't make enough power vs the parts they are built with to cause any damage, not sure.

9:1 a/f ratio is way to rich for any of our gm setups. I've run the avalanche for a while at 12.4 just to test power and drivability, runs good there too, but feels better, stronger and smoother in the 11's.
I haven't tested it, but the truck feels the same at 11.9 to 11.0, so i guess it's reasonable to say that 11.0 is probably better, since it's safer and cooler.

just my experience.