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Stroke to Bore Ratio Formula:
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The stroke to bore ratio is a fundamental parameter in engine design that compares the length of the piston stroke to the diameter of the cylinder bore. It significantly influences engine characteristics including torque, power, and efficiency.
The calculator uses the simple formula:
Where:
Explanation: This ratio helps determine whether an engine is "undersquare" (ratio > 1), "square" (ratio = 1), or "oversquare" (ratio < 1), each with different performance characteristics.
Details: The stroke to bore ratio affects engine torque curve, maximum RPM, piston speed, and overall engine dimensions. It's a critical factor in engine design for specific applications like racing, economy, or towing.
Tips: Enter stroke and bore measurements in inches. Both values must be positive numbers greater than zero for accurate calculation.
Q1: What is considered a good stroke to bore ratio?
A: It depends on the application. High-performance engines often use oversquare designs (ratio < 1) for higher RPM, while torque-focused engines use undersquare designs (ratio > 1).
Q2: How does stroke to bore ratio affect engine performance?
A: Higher ratios typically produce more torque at lower RPM, while lower ratios allow higher RPM and potentially more horsepower.
Q3: Can I use metric measurements with this calculator?
A: The calculator requires inches, but you can convert metric measurements (1 inch = 25.4 mm) before entering values.
Q4: What are typical stroke to bore ratios for different engine types?
A: Diesel engines often have ratios around 1.0-1.2, performance gasoline engines around 0.8-1.0, and high-revving motorcycle engines can be as low as 0.6.
Q5: Does stroke to bore ratio affect fuel economy?
A: Yes, undersquare engines (higher ratio) often have better low-RPM efficiency, while oversquare designs may have advantages at higher RPM ranges.