Air Intake Design Calculator

Usage Notes

Air Temperature - As measured before entering throttle body. If measurements are not available, typical values are 40-80 °C for a factory airbox/ducting, 20-30 °C for a cold air intake.

Air Pressure - Use atmospheric pressure (101.325 kPa) or appropriate ambient air pressure at your elevation. However, this value will neglect the pressure drop caused by the air filter.

Engine Speed - Enter engine speed for peak power, this is the point at which maximum air flow is required.

Volumetric Efficiency - If you don't know the volumetric efficiency, try different values until calculated Power matches your engine.

Tube Inside Diameter - The inside diameter of the intake tubing.

Air Flow Rate - This is the actual airflow rate calculated from the input entered. CFM is calculated for actual pressure drop.

Power - This is the engine power for your current configuration. If this calculation seems off, make sure you have entered the correct air temperature.

Pressure Drop - An indicator of how restrictive the throttle body is. Try to keep this under 1 kPa

Resonance Points - These are the resonant engine speeds for each reflected pressure wave. Intake resonance will increase air flow into the engine. The 1st resonant point is strongest and the 5th point is the weakest. Typically, the 1st resonant point will exceed the engine's redline RPM. In this case, design the intake tube so that the 2nd resonant point is close to peak power.