Engine Airflow CFM Calculator
SI
Imp
Imperial
Inputs
View results
Displacement
(V_d)
Total engine displacement.
in³
Engine speed
(n)
Crankshaft speed.
rpm
Volumetric efficiency
(VE)
Cylinder filling efficiency.
%
Ambient pressure
(P_a)
Ambient absolute pressure.
psi
Boost gauge pressure
(P_b)
Manifold boost above ambient. Leave zero for naturally aspirated.
psi
Air density
(rho)
Air density used for mass flow.
lb/ft³
Results
Default result
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Engine airflow
(Q)
543.5
cfm
Pass
Also computed
Mass airflow
(m_dot)
41.56
lb/min
Pressure ratio
1.000
Method notes
2 notes
Uses the four-stroke airflow relation: displacement times RPM divided by two, adjusted by VE and pressure ratio.
This is a sizing screen. Real airflow depends on temperature, humidity, intercooler pressure drop, cam timing, compressor map and manifold losses.
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