Does anyone here have quantifiable data regarding the relationship between maximum power and air fuel ratio? For example, do all sbc engines make peak power at 12.8:1 or do some make peak power at 12:1 while others make peak power at 13.5:1? Do thermal and flow dynamics contribute to that (assumed) difference? Additional thoughts?

 

It varies.
While not SBC, I got to spend a couple days with an Innovative, and made a bunch of short passes, in some 10 sec GNs, and saw anything from low 10:1s, to high 11:1s. While I'm a firm believer in giving the engine what it wants, that solidifed the concept.

 

Grumpy, I remember a post you made quite some time ago regarding the coolant temperature relationship to power and, if I remember correctly, you believe a hot (200+*) engine makes more power than a warm (160*) engine. Do you have a temperature you are particularly fond of? Secondly, what AFR makes your engine most happy?

 

~190dF.

Depends on the type of tune, I'm running. While I generally favor a low timing style of tune, I've been also known to play with high timing. While 4-6d really isn't alot, at the higher boost levels it means running 10.8s compared to 11.8s. I've also run leaner AFRs at lower boost levels.