This calculates the cubic feet per minute (cfm) of air that an engine will consume at its maximum rpm. This is a great tool for estimating carburetor or throttle body sizing to avoid going either too small or too big (which is a common mistake).

**Check out our quarter mile calculator

cubic inchesthe total displacement of the engine in cubic inches (see our cid calculator)
max rpmthe engines maximum rpm limit
volumetric efficiencythe volumetric efficiency is a measure of the efficiency of the engine moving the intake charge into the chamber and the exhaust out. Typical values are as follows:

2 valve head – 80%

4 valve head – 88%

it is not unusual however to have VE’s of 95% or more in correctly built race engines
cubic feet per minutethe total cubic feet per minute of air that the engine will consume
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