Fastime Performance Carb CFM Calculator
Estimate recommended carb size using: CFM = (CID × RPM × VE) ÷ 3456
Recommended Carb Size
Target CFM 473 CFM Based on your CID, RPM & VE
CFM Range 426–521 CFM Approx. -10% / +10% tuning window
Assumed VE 85 % Higher VE = more airflow required
Formula (4-stroke engines): CFM = (CID × Max RPM × VE%) ÷ 3456
Example: 350 cid × 6000 rpm × 0.85 ÷ 3456 ≈ 517 CFM → a 600 CFM carb is a common choice.