I understand the different octane values and its impact on combustion (kind of). What I don't understand is how does changing octane change the air fuel ratio. I'm new to tuning, just bought a CPC stage three this year so I'm sure I've got a lot to learn.
I can't answer that properly. So i won't toss myself under the bus.
All i know is what we saw. If we had less octane it would back fire through the throttle body or it was hesitate.
The higher octane we got the more crisp it started to sound,harder pulling outta the hole and more a/f gauge linned up.
GRANTED we did have a set boost we aimed for,maxing the controller out on 91.. less on av.. and so on.
MAYBE you could run 5-6psi fine on av gas. but that was not our target, I'm just stating the results we got. With different levels of octane and different blends you have LOTS of factors.
To name a couple: MON,Cooling affect,it's combustion, compatibility with your set up.
You can throw jet fuel in a stock m6. don't mean it'll run good just because it has a higher octane rating. You'll actual run WAY worst as the motor doesn't have the power or the set up to properly combust ATDC.
That leads to pre ignition or the lovely ignition in your exhaust both are not good to have...
We heard everything from at 2500' you can run 91 at 6 psi. to run c111 at 6 psi... We found the sled ran best with mixxing a 110L drum 91 octane-34L and 117 octane-76L and 20:1 oil mix in there aswell.
Like humans every machine is different, try stuff stay rich and slowly lean out. Pay a little more at the pump other paying motor builders a little more
