What is Wheel Power (WHP)?

Wheel Horsepower (WHP) represents the actual amount of power that reaches the ground through the vehicle's tires. While manufacturers usually advertise "Brake Horsepower" (BHP) or crank horsepower, this figure is measured directly at the engine's flywheel before the power undergoes losses through the drivetrain. In the real world, the power measured on a chassis dynamometer (dyno) is always lower than the engine's theoretical output.

Understanding Drivetrain Loss

Drivetrain loss is the energy consumed by the various mechanical components situated between the engine and the road. These components include the transmission, driveshaft, differential, axles, and even the weight and friction of the wheels and tires. Energy is primarily lost in the form of heat and friction.

Typical loss percentages vary based on the configuration of the vehicle:

• FWD (Front-Wheel Drive): Usually the most efficient, with losses ranging from 10% to 15%.
• RWD (Rear-Wheel Drive): Moderate efficiency with losses typically between 15% and 18%.
• AWD (All-Wheel Drive): The least efficient due to the complexity of multiple differentials and transfer cases, often losing 20% to 25%.

How to Use the Wheel Power Calculator

Using this calculator is simple. Follow these steps to estimate your car's true performance:

1. Enter the manufacturer's rated Horsepower (BHP) in the first field.
2. Select your vehicle's drivetrain layout (FWD, RWD, or AWD) to apply industry-standard loss averages.
3. If you have specific data or a high-performance custom build, select "Custom" to enter a specific loss percentage.
4. Click "Calculate" to see the estimated WHP.