Originally posted by "Someone"
Originally posted by freak007
one way you can calculate existing compression ratiois to take a compression testand divide the results by 14.7it will be relatively close...
Originally posted by rb77413
How close? On my 383 I have a adv 277^ w/ .477 lift. My compression test was 160-170 That comes out to about 11:1 Is that right? I was trying to figure out the same thing. Trying to figure if I can use a bigger cam.
Bob
This is from another BB that we are on. The formula that Freak007 posted assumes 100% Volumetric Efficency as the Exhaust/Intake valves close at exactly TDC/BDC. Obviously this isnt true to life. 100% VE is impossible. But I was wondering if any of you that Know your CRs from the formula CR=Vcyl+Vcc/Vcc [Vcyl = Volume of cylinder Vcc = Volume of Combustion Chamber] can tell me how close this formula gets you. Please those of you that dont know you CR by the formula dont respond. I am trying to figure out specific math formulas. I dont mean to be rude but just because you use a 12:1/11:1 piston does not mean that is your Actual CR.