Wallace Racing
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These formulas are from A. Graham Bell’s Performance Tuning in Theory and Practice
or Philip A Smith's Scientific Design of Exhaust and Intake Systems.
The following calculator can be used to calculate the header dimensions best suited to your combination. The input terms are below:
Displacement is given in inches (CID).
Exhaust Valve Opening Point is given in degrees before bottom dead center (BBDC). Entered values should be greater than 0.
Engine Speed or Peak Power RPM For a street engine, the RPM used should be the peak torque RPM. For a race engine, the peak hp RPM should be used. .