How to Use the Carburetor CFM Calculator

To estimate the required carburetor CFM for your engine, input the engine displacement, maximum RPM, and volumetric efficiency. Select the appropriate unit for each parameter.

The formula used is:

CFM = (CID × Max RPM × Efficiency) / 3456

Here's an example:

Let's say we have a 340 cubic inch engine with a 5,600 max RPM, working at 80% efficiency. With our engine CFM calculator:

Step 1: Calculate the total volume

Volume = CID × Max RPM

Volume = 340 × 5,600 = 1,904,000 cubic inches

Step 2: Adjust for efficiency

Since the engine is 80% efficient, multiply the volume by 0.80:

1,904,000 × 0.80 = 1,523,200 cubic inches

Step 3: Convert to CFM

Convert the volume from cubic inches to cubic feet per minute (CFM) by dividing by 3,456:

1,523,200 / 3,456 = 440.74 CFM

That's how our carburetor CFM calculator works!

Results can also be converted to:

• Gallons per minute (US gal/min)
• Cubic feet per second (ft³/s)
• Cubic meters per second (m³/s)
• Cubic meters per minute (m³/min)
• Liters per minute (L/min)