Enter your Engine RPM, Engine Displacement, Volumetric Efficiency, and Boost Pressure into the Engine Airflow Calculator to find out exactly how much air your engine is moving — output includes Airflow in CFM, lbs/min, and m³/min, plus a naturally aspirated CFM baseline so you can see exactly what boost is adding.
Airflow (CFM)
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Airflow (lbs/min)
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Airflow (m³/min)
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Natural Aspiration CFM
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CFM is calculated by multiplying engine displacement (cubic inches) by RPM, dividing by 3456, then multiplying by volumetric efficiency and boost pressure. This formula gives you the cubic feet per minute of air the engine consumes.
Volumetric efficiency measures how well an engine fills its cylinders with air compared to theoretical maximum. Naturally aspirated engines typically range from 75-100%, while forced induction engines can exceed 100%.
Boost pressure multiplies the airflow proportionally. 1 Bar equals atmospheric pressure (no boost), while 2 Bar doubles the airflow. Higher boost pressure requires larger turbochargers or superchargers to supply the needed air volume.
Knowing the engine's airflow requirements helps select the correct turbocharger size. An undersized turbo won't provide enough airflow, while an oversized one may have poor response and efficiency at lower RPMs.
CFM (cubic feet per minute) measures volume flow, lbs/min measures mass flow accounting for air density, and m³/min is the metric volume equivalent. Mass flow is more accurate for performance calculations as it accounts for air density changes.
Yes, this calculator works for both turbocharged and supercharged engines. Simply enter the boost pressure your supercharger produces, and the calculator will determine the required airflow for proper sizing.
The calculator automatically handles conversions. 1 liter equals 61.024 cubic inches, and 1 cubic inch equals 16.387 cubic centimeters. Select your preferred unit and enter the displacement value accordingly.
Volumetric efficiency is affected by cam timing, intake and exhaust flow, compression ratio, air temperature, and engine RPM. Modified engines with performance parts often achieve higher volumetric efficiency than stock engines.