Bore vs Stroke - What Makes More Power?

Summary by Krater

This video compares engine bore versus stroke, explaining how wider bore increases horsepower potential while longer stroke improves thermal efficiency and burn duration. The presenter analyzes cylinder dimensions, valve sizing, and surface-to-volume ratios to explain combustion behavior in internal combustion engines.

From the video

Answers: Does a wider bore or a longer stroke make an engine more powerful and efficient?

• engine bore vs stroke
• cylinder displacement
• engine horsepower and RPM limits
• valve size and airflow
• compression ratio and surface area
• combustion burn duration and turbulence

What it concludes

• Smaller strokes allow engines to rev higher, resulting in more power strokes per second and higher peak power.
• Larger bore sizes allow for larger valves, increasing intake and exhaust airflow area by about 35 percent at higher RPM.
• Longer stroke engines have lower surface-to-volume ratios at top dead center, reducing heat rejection and increasing thermal efficiency.
• Longer stroke engines accelerate combustion burn duration due to increased air-fuel turbulence from higher piston speeds, improving specific fuel consumption by 3 to 5 percent.