Carburetor CFM Calculator
Estimate four-stroke engine intake flow from displacement, RPM and volumetric efficiency.
Formula
CFM = displacement (in³) × RPM × VE/100 / 3456
Total displacement: 350 in³ · Estimated airflow (CFM) ≈ (350 in³ × 0.016387064 L/in³)×(6,000)×((85)÷100)÷(2×28.316846592)
How to use
- Enter total engine displacement.
- Enter target RPM and volumetric efficiency.
- Read estimated airflow in cubic feet per minute.
Examples
- A 2 L engine at 6000 RPM and 85% VE needs about 180.105 CFM.
Frequently asked questions
Why divide by 3456?
Four-stroke intake takes two revolutions; one cubic foot is 1728 cubic inches.
Is 85% efficiency universal?
No. Enter the engine’s estimated volumetric efficiency at the chosen RPM.
Does the result choose a carburetor?
It is a starting estimate, not a guaranteed size. Rating pressure, engine tuning and drivability matter.
Sources
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