Calculate horsepower per liter, engine displacement, or horsepower from HP/kW and liters or cubic inches by entering any two values.
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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 = HP / L
HP = HPL * L
L = HP / HPL
- 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:
1 kW = 1.34102 HP
1 in^3 = 0.0163871 L
1 kW/L = 1.34102 HP/L
Typical Horsepower Per Liter Ranges
These ranges are general references for comparing engine output per liter. Actual values vary by engine design, fuel, boost pressure, tuning, and measurement method.
| Engine type | Typical HP/L range | General interpretation |
|---|---|---|
| Older naturally aspirated economy engine | 40 to 70 HP/L | Low to moderate specific output |
| Modern naturally aspirated engine | 70 to 110 HP/L | Common range for many modern cars |
| High-performance naturally aspirated engine | 100 to 130+ HP/L | High revving or highly optimized engine |
| Turbocharged or supercharged engine | 100 to 200+ HP/L | Boosted engines often make more power per liter |
Unit Conversion Reference
| Conversion | Factor |
|---|---|
| kW to HP | kW × 1.34102 |
| HP to kW | HP × 0.746032 |
| Cubic inches to liters | in³ × 0.0163871 |
| 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.
HPL = 250 / 2.0 = 125 HP/L
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.
HP = 90 * 3.5 = 315 HP
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.
