Analyze engine airflow capacity using volumetric efficiency, displacement, and RPM per SAE J1723 methods.
Input Parameters
Results
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Airflow
CFM
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Mass Flow
lb/min
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Est. Horsepower
hp
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Intake Velocity
ft/s
Note: A 4-stroke engine only ingests air every other revolution. Peak volumetric efficiency typically occurs near peak torque RPM. SAE J1723 covers airflow measurement.
Reference
CFM = (Disp_CI × RPM × VE) / (2 × 1728)
Mass Flow = CFM × Air_density / 60
Air Density ≈ 2.7 × (519.67 / T_Rankine) lb/ft³
Est. HP ≈ Mass_flow × 60 × 0.5 (rule of thumb)
4-stroke: divide by 2 for intake every other rev