CC to HP Converter
Estimate engine horsepower from cubic centimeters
Understanding the CC to HP Conversion
In the world of internal combustion engines, displacement (measured in cubic centimeters or CC) and horsepower (HP) are related but not identical metrics. CC measures the physical volume of the cylinders, while horsepower measures the rate at which work is performed. Because engine efficiency, cooling systems, and fuel injection technology vary, there is no fixed mathematical constant that applies to every engine.
How the Calculation Works
This calculator uses industry-standard approximation ratios for small to mid-sized engines. While modern engineering can push these limits, the general rules of thumb are:
- 4-Stroke Engines: Generally produce 1 HP for every 15 to 17 CC.
- 2-Stroke Engines: More powerful for their size, typically producing 1 HP for every 10 to 12 CC.
- Small Utility Engines: Often found in lawnmowers or tillers, these are tuned for longevity over power, averaging 1 HP per 20 CC.
CC to HP Conversion Examples
| Engine Size (CC) | Typical HP (4-Stroke) | Typical HP (2-Stroke) |
|---|---|---|
| 50cc | ~3.3 HP | ~4.5 HP |
| 125cc | ~8.3 HP | ~11.4 HP |
| 250cc | ~16.7 HP | ~22.7 HP |
| 600cc | ~40.0 HP | ~54.5 HP |
Factors That Affect Horsepower
Displacement is only one part of the equation. Two engines with the same CC rating can have wildly different horsepower outputs based on:
- RPM (Revolutions Per Minute): Horsepower is calculated as (Torque x RPM) / 5252. Engines that rev higher generally produce more horsepower.
- Aspiration: Turbocharged or supercharged engines force more air into the cylinders, significantly increasing HP without changing CC.
- Fuel Delivery: Electronic Fuel Injection (EFI) is typically more efficient than carbureted systems.
- Valve Timing: Technologies like VVT allow an engine to breathe better across different speed ranges.