Calculate horsepower per liter, engine displacement, or horsepower from HP/kW and liters or cubic inches by entering any two values.
hp Per Liter Formula
The horsepower per liter value is engine output divided by engine displacement. The calculator can also rearrange the same relationship to solve for horsepower or displacement when you enter the other two values.
- HPL = horsepower per liter, usually shown as HP/L
- HP = engine horsepower
- L = engine displacement in liters
The calculator converts all entered values to base units before applying the formula. Horsepower is converted to HP, displacement is converted to liters, and power density is converted to HP/L. After the calculation, the result is converted back to the unit selected in the output field.
- To calculate HP per liter: enter horsepower and engine displacement.
- To calculate horsepower: enter engine displacement and HP per liter.
- To calculate displacement: enter horsepower and HP per liter.
The unit conversions used are:
Specific Output Examples
These hypothetical arithmetic examples are not typical engine-class ranges or ratings of reliability or efficiency. Here HP means mechanical horsepower, distinct from metric horsepower (PS).
| Power (mechanical hp) | Displacement (L) | Specific output (hp/L) |
|---|---|---|
| 100 | 2 | 50 |
| 200 | 2 | 100 |
| 300 | 3 | 100 |
Unit Conversion Reference
| Conversion | Factor |
|---|---|
| kW to HP | kW × 1.34102 |
| HP to kW | mechanical hp × 0.745699872 (approximately) |
| Cubic inches to liters | in³ × 0.016387064 |
| Liters to cubic inches | L × 61.0237 |
Example Problems
Example 1: Calculate horsepower per liter
You have a 2.0 liter engine that makes 250 HP.
The engine has a specific output of 125 HP/L.
Example 2: Calculate horsepower
You have a 3.5 liter engine with a power density of 90 HP/L.
The engine output is 315 HP.
FAQ
What does horsepower per liter mean?
Horsepower per liter measures how much power an engine makes for each liter of displacement. For example, a 2.0 liter engine making 200 HP has 100 HP/L. It is a way to compare engine output while accounting for engine size.
Is a higher HP per liter always better?
Not always. A higher HP/L value means the engine makes more power for its size, but it does not automatically mean the engine is better for every use. Reliability, torque, fuel economy, drivability, heat management, and maintenance requirements also matter.
Can I use kilowatts instead of horsepower?
Yes. If you enter power in kW, the calculator converts it to horsepower for the formula. If you choose kW/L for the result, it converts the final HP/L value back to kW/L.
