Sorry about bringing the "math" into it. Just a thought. Who would ever think about actually checking their compression ratio and measuring cc volumes during engine assembly. Certainly not, hell just throw a guess out there. I love the "round-about" method, sure makes a whole hell of alot of sense to me. I mean 9.5:1 shouldn't make a difference, I mean I'm only planning to run alcohol..... :shock: DOH! Now lets turn the whole conversation into cylinder pressures and make a whole tutorial out of it. How informative you little stinkers are :idea: .