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Engine Airflow CFM Calculator — result sheet
Estimate theoretical engine airflow from displacement, engine speed, volumetric efficiency, and engine cycle.
Inputs used
Results
Visual chart
Breakdown
Calculation steps
Returned data table
Formula and methodology
Formula: CFM = displacement × RPM × VE/100 ÷ 3456 for a four-stroke engine; the two-stroke denominator is 1728.
The estimate turns swept volume and intake events into a theoretical cubic-feet-per-minute flow, then applies the entered volumetric-efficiency assumption.
This result follows the calculator's declared inputs, precision, validation boundaries, and model limits.
Input contract
- Engine displacement — in³; minimum 1.0E-6; maximum 1000000
- Engine speed — RPM; minimum 1.0E-6; maximum 1000000
- Volumetric efficiency — %; minimum 1.0E-6; maximum 300
- Engine cycle — 2 choices
Worked example
| Input | Value |
|---|---|
| Engine displacement | 350 |
| Engine speed | 3000 |
| Volumetric efficiency | 85 |
| Engine cycle | four |
Estimated airflow is about 258.4 CFM.
Assumptions and limits
- Displacement is total engine displacement in cubic inches and RPM is crankshaft speed.
- Volumetric efficiency is entered as a percentage and may exceed 100% for boosted or tuned cases.
- Pressure drop, manifold design, air density, fuel mixture, altitude, and actual carburetor selection are not modeled.
Calculator note
Source and methodology
Use the official WorldCalculate methodology policy for the source, formula, precision, and boundary standards behind this calculator.
Planning estimate, not financial, medical, legal, or professional advice. © WorldCalculate — reuse with attribution. Built and curated by Hassan ALRowaie.
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