Search isn't helping me much here...


Anyone know if/how compression ratio effects air fuel ratio?

I pulled my heads, had them milled (raised compression about 0.5) put them back on and see no noticable difference in my logs. It was a small change in compression, so maybe the AFR change is small and I'm just not picking up on it. I dunno. I expected to see a change in the logs.

 

I think the only effect is, the amount of spent gas
remaining for the next cycle. This should be pretty
neutral and affect more the AFR needed to suppress
ping, than the actual AFR received.

 

the only way i could see it affecting it is if there was a bigger gain in compression and you didnt need as much spark as you were currently running and you had to lower to get rid of any knock, which would/should affect your ve...thats about all i can think of.

 

Thanks for the perspective's guys.

 

Like this gentleman stated it will not effect what you see but it is possible that you would need a slightly richer mixture. The thing that this will affect the most is Ignition Timing because of the direct affect on cylinder pressure.

This is true in your instance specifically due to no other variables coming into play but the increase in compression.


Chris Macellaro