Enter your Horsepower, then select your Power Source, Drivetrain Type, and Transmission Type to convert between Flywheel HP and Wheel HP — the calculator breaks down your Drivetrain Loss, Power Lost, and Drivetrain Efficiency so you know exactly how much grunt actually hits the pavement.
Converted Power
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Drivetrain Loss
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Power Lost
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Drivetrain Efficiency
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Flywheel horsepower is the power measured at the engine's crankshaft, while wheel horsepower is the power that actually reaches the wheels after drivetrain losses. Wheel HP is always lower due to friction and mechanical losses in the transmission, differential, and driveshafts.
Typical drivetrain losses range from 10-25% depending on the configuration. Front-wheel drive vehicles typically lose 10-15%, rear-wheel drive loses 15-20%, and all-wheel drive systems can lose 20-25% or more due to additional components.
Automatic transmissions use a torque converter and hydraulic systems that create more internal friction and parasitic losses compared to the direct mechanical connection in manual transmissions. This typically results in 2-5% additional power loss.
Wheel horsepower is more accurate for real-world performance because it represents the actual power available to move the vehicle. However, flywheel HP is commonly used by manufacturers because it shows higher numbers and represents the engine's theoretical maximum output.
AWD systems have the highest losses due to transfer cases, additional differentials, and more driveshafts. RWD has moderate losses from the transmission, driveshaft, and rear differential. FWD has the lowest losses with the shortest power path from engine to wheels.
Yes, but keep in mind that heavily modified drivetrains, aftermarket transmissions, or performance differentials may have different loss characteristics than stock configurations. The calculator provides estimates based on typical factory drivetrain losses.
Factors that increase losses include worn components, thick gear oil, tight differentials, heavy wheels/tires, and additional accessories like power steering pumps or air conditioning compressors that are driven by the engine.