Engine Horsepower Calculator
Advanced engine performance calculator for determining horsepower, torque curves, volumetric efficiency, and comprehensive engine analysis for automotive and racing applications.
Engine Specifications
Performance Data
Engine Presets
Engine Analysis
💡 Performance Insights:
- • Low specific output - potential for improvement
- • Low BMEP suggests room for optimization
How to Use the Engine Horsepower Calculator
To perform comprehensive engine analysis:
- Select your engine type (naturally aspirated, turbocharged, etc.)
- Enter basic engine specifications (displacement, cylinders, compression ratio)
- Input bore and stroke measurements for detailed analysis
- Add performance data (peak horsepower, torque, and RPM values)
- For forced induction engines, specify boost pressure and intercooler efficiency
- Review comprehensive performance metrics and analysis
- Use engine presets to quickly analyze popular engine configurations
Advanced Engine Calculations
Brake Mean Effective Pressure (BMEP)
Formula: BMEP = (Torque × 4π) / Displacement
BMEP indicates engine efficiency and stress levels. Higher BMEP means more power per displacement.
Mean Piston Speed
Formula: MPS = (2 × Stroke × RPM) / 60
Critical for engine durability. Most engines limit MPS to 20-25 m/s for reliability.
Volumetric Efficiency
Formula: VE = (Actual Airflow) / (Theoretical Airflow)
Measures how effectively the engine breathes. Naturally aspirated engines typically achieve 80-95% VE.
Specific Power Output
Formula: SPO = Horsepower / Displacement
Indicates power density. Modern engines achieve 60-120+ HP/L depending on technology.
Example: LS3 V8 Engine Analysis
Engine Specifications:
- Displacement: 6.2L (376 ci)
- Configuration: V8, naturally aspirated
- Bore × Stroke: 103.25 × 92.0 mm
- Compression Ratio: 10.7:1
- Peak Power: 430 HP @ 5900 RPM
- Peak Torque: 424 lb-ft @ 4600 RPM
Calculated Metrics:
- HP per Liter: 430 ÷ 6.2 = 69.4 HP/L
- BMEP: (424 × 4π) ÷ 6.2 = 858 bar
- Bore/Stroke Ratio: 103.25 ÷ 92.0 = 1.12 (slightly oversquare)
- Mean Piston Speed @ 5900 RPM: 18.1 m/s
Frequently Asked Questions
What is BMEP and why is it important?
Brake Mean Effective Pressure measures the average pressure in the cylinders during the power stroke. It's a key indicator of engine efficiency and stress levels, independent of engine size.
How does bore/stroke ratio affect engine characteristics?
Oversquare engines (bore > stroke) typically rev higher and produce more horsepower, while undersquare engines (stroke > bore) generate more torque at lower RPMs and are often more fuel efficient.
What's considered high specific power output?
Naturally aspirated engines achieving 80+ HP/L are considered high-performance, while forced induction engines can exceed 150+ HP/L. Formula 1 engines achieve over 300 HP/L.