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 distance the piston travels (stroke). This ratio significantly influences engine characteristics including power delivery, torque, and efficiency.

2. How Does the Calculator Work?

The calculator uses a simple formula:

Where:

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

Explanation: The ratio is calculated 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: This ratio is crucial for understanding engine behavior. Oversquare engines (ratio > 1) typically favor higher RPM operation and horsepower, while undersquare engines (ratio < 1) generally produce more torque at lower RPMs. Square engines (ratio = 1) offer a balance between these characteristics.

4. Using the Calculator

Tips: Enter both bore and stroke measurements in millimeters. Ensure values are accurate and greater than zero for proper 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 engine purpose. Sports cars often have higher ratios (>1.1) for high-RPM power, while trucks typically have lower ratios (<0.9) for low-end torque.

Q2: How does bore to stroke ratio affect engine performance?
A: Higher ratios allow for larger valves and better breathing at high RPM, favoring horsepower. Lower ratios create better cylinder filling at low RPM, favoring torque.

Q3: Can I change my engine's bore to stroke ratio?
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 and undersquare engines?
A: Oversquare engines have a larger bore than stroke, favoring high-RPM performance. Undersquare engines have a longer stroke than bore, favoring low-RPM torque.

Q5: Do modern engines tend to be oversquare or undersquare?
A: Modern engines increasingly use oversquare designs to achieve higher specific output and better efficiency, though many diesel and truck engines remain undersquare for torque production.