Bore & Stroke Calculator
Calculate bore diameter or stroke length from displacement and determine if an engine is oversquare or undersquare.
How It Works
Enter target displacement, number of cylinders, and either bore or stroke. The calculator solves for the missing dimension and determines the bore/stroke ratio.
Formula
Bore = sqrt(Displacement x 4 / (Pi x Stroke x Cylinders x 0.001))
Frequently Asked Questions
What is bore-to-stroke ratio?
Bore-to-stroke ratio compares cylinder width to piston travel. Oversquare engines (ratio > 1) rev higher and produce peak power at high RPM. Undersquare engines produce more torque at lower RPM.
What does "square" engine mean?
A square engine has equal bore and stroke dimensions (ratio = 1). This provides a balance between high-RPM power and low-RPM torque.