To calculate the theoretical (not actual) CFM of an engine, divide the displacement by 2 - - - -(216/2=108). Multiply half the displacement by the RPM (108 X 3000=324,000) and divide by 1728 (cubic inches in a cubic foot). 324000/1728 = 187.5 CFM. That's assuming 100% volumetric efficiency, which is impossible. A more realistic CFM for a 216 at 3000 RPM would be about 85%- - - - - -159.4 CFM. The above formula works for ANY 4-stroke engine, regardless of cubic inch displacement or the number of cylinders. Even racing engines with major modifications to intake and exhaust systems have a hard time getting more than 90% volumetric efficiency.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
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