WHP stands for wheel horsepower, which is the amount of power actually delivered to a car's wheels and measured on a dynamometer. It's the real-world power that propels the vehicle, making it a more accurate indicator of on-road performance than the engine's theoretical output.
The key difference lies in power loss. An engine generates brake horsepower (BHP), measured at the crankshaft before the power travels through the transmission, driveshaft, and other components. This journey through the drivetrain causes friction and mechanical losses. WHP is always lower than BHP because it accounts for this power loss. For most rear-wheel-drive and all-wheel-drive cars, this loss is typically 15-20%. In front-wheel-drive vehicles, it's often slightly less, around 10-15%, due to a simpler drivetrain.
This distinction is critical for performance tuning. When enthusiasts modify exhaust systems or engine control units (ECUs), they track gains in WHP, as it reflects the actual improvement in acceleration. Automotive journalists and professional tuners rely on WHP figures for accurate comparisons.
| Drivetrain Type | Typical Drivetrain Loss | Example: 300 BHP Engine = Approx. WHP |
|---|
| Rear-Wheel Drive (RWD) | 15% | 255 WHP |
| All-Wheel Drive (AWD) | 20% | 240 WHP |
| Front-Wheel Drive (FWD) | 12% | 264 WHP |
Ultimately, while BHP is a useful factory rating, WHP is the true measure of a car's performance capability on the pavement.
