Carburetor CFM Calculator

Find the carburetor airflow an engine needs.

Required CFM (cfm) 516.49

Formula: CFM = (CID · rpm · VE) ÷ 3456

Step-by-step with your numbers:

1. Values used:

2. Engine displacement = 350 CID

3. Max RPM = 6,000 rpm

4. Volumetric efficiency = 85 %

6. Required CFM = 516.49cfm

Did we solve your problem today?

Sizing a carburetor means matching its airflow (CFM) to the engine's appetite.

The math behind it

CFM = (CID × rpm × VE) ÷ 3456. The 3456 converts cubic inches per two revolutions to cubic feet per minute.

350 CID at 6000 rpm, 85% VE → about 516 CFM.

Bigger CFM is better?

Not always — an oversized carb hurts low-rpm response and economy.