Calculate Primary Header Tube Length and Diameter

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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:

Input either Inches or Millimeters. Also has Exhaust Port length input for better accuracy.

Enter your information below and select "Calculate"

Stroke:   MM     Inches 
Bore:   MM     Inches 
Exhaust Valve Diameter:   MM     Inches 
Exhaust Port Length:*   MM     Inches 
Exhaust Valve Opening Point: (Degrees )
Exhaust Valve Duration: (Advertised Deg.)
Exhaust Valve Centerline: (Degrees)
Peak Power RPM:
Number of Cylinders:
Volumetric Efficiency:
Calculated information appears below