1. What is Bore to Stroke Ratio?

The bore to stroke ratio is a fundamental measurement in engine design that compares the diameter of the cylinder (bore) to the length of the piston travel (stroke). This ratio significantly influences engine characteristics including power output, torque, and efficiency.

2. How Does the Calculator Work?

The calculator uses a simple formula:

Where:

• \( Bore \) — Cylinder diameter in millimeters
• \( Stroke \) — Piston travel length in millimeters

Explanation: The formula calculates the ratio by dividing the bore measurement by the stroke measurement. A ratio greater than 1 indicates an oversquare engine, while a ratio less than 1 indicates an undersquare engine.

3. Importance of Bore to Stroke Ratio

Details: The bore to stroke ratio is crucial in engine design as it affects engine performance characteristics. Oversquare engines (ratio > 1) typically produce higher RPMs and horsepower, while undersquare engines (ratio < 1) typically produce more torque at lower RPMs.

4. Using the Calculator

Tips: Enter both bore and stroke measurements in millimeters. Ensure values are greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is considered a good bore to stroke ratio?
A: There's no single "good" ratio as it depends on the engine's intended purpose. High-performance engines often have ratios around 1.1-1.2, while torque-focused engines might have ratios around 0.8-0.9.

Q2: How does bore to stroke ratio affect engine performance?
A: Larger bore relative to stroke allows for larger valves and better breathing at high RPM, favoring horsepower. Longer stroke relative to bore creates more leverage on the crankshaft, favoring torque.

Q3: Can I change the bore to stroke ratio of an existing engine?
A: Yes, through engine modifications like boring cylinders or changing the crankshaft, but these are significant modifications that require professional expertise.

Q4: What's the difference between oversquare, square, and undersquare engines?
A: Oversquare: bore > stroke; Square: bore = stroke; Undersquare: bore < stroke. Most modern engines are slightly oversquare.

Q5: Does bore to stroke ratio affect fuel efficiency?
A: Yes, generally undersquare engines can be more fuel efficient at lower RPMs due to better combustion efficiency, while oversquare engines may be more efficient at higher RPMs.