1. What is Bore to Stroke Ratio?

The bore to stroke ratio is the ratio of the cylinder bore (diameter) to the length of the piston stroke in an internal combustion engine. This ratio is a fundamental characteristic of engine design.

2. How Does the Calculator Work?

The calculator uses the simple formula:

Where:

• \( \text{bore} \) — Cylinder diameter in millimeters
• \( \text{stroke} \) — Piston travel distance in millimeters

Explanation: The ratio is calculated by dividing the bore measurement by the stroke measurement.

3. Importance of Bore to Stroke Ratio

Details: This ratio affects engine characteristics:

• Square or oversquare engines (ratio > 1) typically favor higher RPM operation
• Undersquare engines (ratio < 1) typically produce more torque at lower RPM
• Affects piston speed, engine balance, and thermal characteristics

4. Using the Calculator

Tips: Enter bore and stroke measurements in millimeters. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical bore to stroke ratio?
A: Most modern engines have ratios between 0.8 to 1.2, with performance engines often being oversquare (>1).

Q2: How does this ratio affect engine performance?
A: Higher ratios (oversquare) allow higher RPM operation while lower ratios (undersquare) favor torque production.

Q3: What's considered a "square" engine?
A: When bore equals stroke (ratio = 1.0), the engine is considered square.

Q4: Does this ratio affect engine reliability?
A: Yes, as it affects piston speed and thermal loading. Higher ratios may reduce piston speeds at given RPMs.

Q5: How does this relate to engine displacement?
A: Displacement is calculated using both bore and stroke, but the ratio indicates the engine's geometric characteristics.