Volumetric Efficiency Calculator
Calculate engine volumetric efficiency from displacement, RPM, and measured airflow. Supports MAF and MAP-based calculations.
What is Volumetric Efficiency?
Volumetric efficiency (VE) measures how well an engine fills its cylinders with air compared to their theoretical maximum capacity. A 100% VE means the cylinders are completely filling on every intake stroke.
Why It Matters
VE is one of the most important diagnostic values for understanding engine performance. It tells you whether the engine is breathing properly. Low VE can indicate intake restrictions, exhaust restrictions, cam timing issues, vacuum leaks, or head gasket problems.
- Naturally aspirated engines typically achieve 80–95% VE at peak torque RPM
- Well-tuned performance NA engines can reach 95–100%
- Boosted engines (turbo/supercharged) exceed 100% because forced induction pushes more air than the cylinders would naturally draw
MAF vs MAP Method
The MAF method uses the mass airflow sensor reading (in grams per second) to directly measure how much air is entering the engine. This is the most accurate method when a MAF sensor is present.
The MAP method uses manifold absolute pressure as an indirect estimate of airflow. It's a simplified calculation — useful for speed-density systems but less precise than direct MAF measurement.
The Formula
VE = (Actual Airflow / Theoretical Airflow) × 100
Where theoretical airflow = (Displacement × RPM × Air Density) / (2 × 60) for a 4-stroke engine. The division by 2 accounts for each cylinder filling only once every two crankshaft revolutions.