Volumetric Efficiency Calculator - Calculate Engine VE
Volumetric Efficiency Calculator
Calculate your engine's volumetric efficiency using CFM, metric volume, or mass airflow methods. Compare different RPM points and tune changes.
Volumetric efficiency (VE) is the ratio between the actual air an engine inducts and the theoretical volume it could induct. Use any method below. Values over 100% can occur with tuned intakes or forced induction.
Read the complete guide →Engine Configuration
Controls the cycle factor used in the calculation
The exact RPM of your measurement point
VE = (Q × k) ÷ (Vd × N)
Q in m³/s, Vd in m³, N in rev/s, k depends on engine type
For reference: classic imperial form is VE = (CFM × 3456) ÷ (ci × RPM)
From dyno or airflow meter
Total engine capacity
Understanding the Calculation
VE is dimensionless. 100% means the engine inducts one displacement volume of air per cycle. The core relation is VE = (Q × k) ÷ (Vd × N). Here, Q is volumetric flow in m³/s, Vd is total displacement in m³, N is rev/s, and k depends on the engine cycle. We convert whatever you enter to these base units, then evaluate once to avoid hidden unit errors.
CFM-based
Best when you have a calibrated CFM figure. Internally we convert to m³/s. The familiar 3456 constant comes from 1728 cu-in/ft³ × 2 rev/cycle.
Metric Volume
If you already have m³/s from a flowmeter or dyno, this is the most direct route.
Mass-airflow
Use MAP at the manifold and IAT after the compressor and cooler. If you only know boost gauge pressure, pick Boost and enter barometric or elevation.