Drivetrain horsepower loss guestimator

Input Values

Results

Understanding the different parameters

Horsepower

The power value you want to convert, which can be measured either at the crankshaft (engine output) or at the wheels (what reaches the ground). Crankshaft horsepower is always higher than wheel horsepower due to power losses through the drivetrain.

Measurement Location

• At Crankshaft: Also known as brake horsepower (BHP) or engine horsepower. This is what manufacturers typically advertise and what engine dynos measure directly from the engine.
• At Wheels: Also called wheel horsepower (WHP). This is what chassis dynos measure and represents the actual power delivered to the ground after drivetrain losses.

Drivetrain Type

• Front Wheel Drive (FWD): Generally has the lowest power loss (around 10% base) due to the engine and transmission being integrated into one unit (transaxle) and a shorter driveline.
• Rear Wheel Drive (RWD): Slightly higher losses (around 13% base) due to having a longer driveshaft and separate transmission and differential.
• All Wheel Drive (AWD): Highest power loss (around 18% base) due to the complex drivetrain system including transfer cases, additional differentials, and more rotating mass.
• Four Wheel Drive (4WD): Highest power loss (around 20% base) due to the robust transfer case, typically for off-road use with selectable 4WD modes and often mechanical engagement.

Transmission Type

Each transmission type adds different levels of power loss to the base drivetrain loss:

• Manual: Lowest additional loss (+2%) due to its mechanical simplicity.
• Automatic:Higher losses (+3%) due to the torque converter and more complex internals.
• Dual Clutch (DCT): Moderate losses (+2.5%) combining some benefits of both manual and automatic designs
• Continuously Variable (CVT): Highest transmission loss (+3.5%) due to the belt/chain drive system.

Note that these values are approximations and actual losses can vary based on:

• Transmission and differential condition
• Drivetrain maintenance
• Modifications and upgrades
• Operating temperature
• Vehicle age and mileage