Check out Cochise.uia.com

They have a formula. You need cam specs. It's complicated as heck. Lsa, cam degree, pistons, volume at bottom of stroke, volume at tdc, the list goes on and on. Quench is a big deal on a racing engine also. Not so much on a stock motor that doesn't see wot. More info than most people care to think about.

Pretty much your static is compression at idle or lower rpm. Actual compression will increase over the rpm range. The piston is traveling so fast your volumetric efficency can't keep up. That's on a stock/mild motor. With milled heads and valve jobs and domed Pistons and cam lsa, lift, duration and all that fun stuff, your VE increases but rarely to 100%. Boosted engines with VE of 100% or more gain almost 50% more compression at rpm. My motor goes from 8:1 static to 15:1 actual @ 12# of boost and 7200rpm. Anything over 9.5-10:1 needs more than today's pump gas.

Last edited by Hollow65; 11/08/2014 9:30 PM.
I can explain it to you, I can't understand it for you.