Wheel Horsepower Calculator
Calculate wheel horsepower (WHP) and brake horsepower (BHP) instantly. Estimate drivetrain losses and engine efficiency for accurate vehicle performance analysis.
wheel horsepower calculator:
The Wheel Horsepower Calculator helps you determine how much real power your car delivers to the ground. By entering either WHP or BHP and the drivetrain loss percentage, you can instantly calculate the other value. It’s an essential tool for comparing dyno results, tuning efficiency, and understanding performance differences between engine and wheel power.
Wheel Horsepower tool Formula:
The Wheel Horsepower Calculator estimates the actual power delivered to the wheels (WHP) or converts it to engine power (BHP) by accounting for drivetrain losses. Wheel horsepower represents the usable power that propels the vehicle, while brake horsepower measures the total power output at the engine before losses.
Using the formula:
\[ BHP = \frac{WHP}{1 - (\textrm{Drivetrain Loss% / 100})} \]
and conversely,
\[ WHP = BHP \times (1- \textrm{Drivetrain Loss % / 100}) \]
This calculator is useful for car tuners, racers, and automotive engineers to analyze performance after modifications or dyno testing. It supports front-wheel, rear-wheel, and all-wheel-drive systems with customizable drivetrain loss settings.
Work & Installation — Input to Output Summary
Inputs:
- Brake Horsepower (BHP) or Wheel Horsepower (WHP)
- Drivetrain Loss (%)
- Drive Type (FWD, RWD, AWD)
Process:
- Select input type: BHP → WHP or WHP → BHP.
- Apply drivetrain loss conversion using the chosen formula.
- Display accurate power output in both HP and kW.
Outputs:
- Wheel Horsepower (WHP)
- Brake Horsepower (BHP)
- Power loss in HP and %
Typical drivetrain losses:
- FWD: 10–15%
- RWD: 15–20%
- AWD: 20–25%
Testing and Final Adjustments
To verify calculator accuracy, compare results with dynamometer (dyno) test data. Measure wheel horsepower using a chassis dyno and engine horsepower via an engine dyno if available. Adjust drivetrain loss percentages based on actual drivetrain type, transmission condition, and tire friction. Real-world driving conditions may cause small variations due to rolling resistance, tire pressure, and temperature. Regularly calibrate dyno equipment to ensure measurement accuracy. These checks help maintain reliable WHP to BHP conversions and optimize vehicle tuning for maximum efficiency and performance.
Frequently Asked Questions - Wheel Horsepower Calculator:
What is Wheel Horsepower (WHP)?
WHP is the power actually delivered to a vehicle’s wheels after drivetrain losses.
How do I calculate WHP from BHP?
Use WHP = BHP × (1 - Drivetrain Loss% / 100).
How do I calculate BHP from WHP?
Use BHP = WHP / (1 - Drivetrain Loss% / 100).
What are typical drivetrain losses?
FWD: 10–15%, RWD: 15–20%, AWD: 20–25%.
Why is WHP lower than BHP?
Power is lost due to friction and mechanical resistance in the drivetrain.
Can I use this calculator for electric cars?
Yes, but drivetrain losses are much lower in EVs (5–10%).
What unit does the calculator use?
Results are given in horsepower (HP) and kilowatts (kW).
What causes drivetrain loss variations?
Transmission type, gear oil, tire condition, and wheel size affect losses.
Is dyno testing more accurate?
Yes, dynos directly measure WHP under controlled load conditions.
Why is this calculator useful?
It helps estimate real-world vehicle performance and compare power outputs.
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