The wheels/real axle converts the rotational form of power back to a linear form of power by moving the car forward. When the car accelerates through the quarter mile in a given amount of time you have a measure on horsepower.

The engine's horsepower is used up in four ways.

1. By accelerating the car over a distance in a given amount of time.
2. Aerodynamic drag on the vehicle.
3. Rolling friction loss. Some of the energy is dissipated as heat in the gears, torque converter, wheel bearing, and tires.
4. Inertial losses. It takes energy to speed up a mass. Internal components in the vehicle drivetrain that undergo acceleration draw energy. These components include the pistons/connecting rods changing direction, pulleys, flywheel, transmission shafts, drive shaft, axles, and wheels. The mass of the pistons/connecting rods and valves/springs are always a draw on horsepower. The mass of the rotating components only draw horsepower when the engine increases RPM. Lightening up all of these components will reduce inertial losses. On the plus side, these inertial components, once up to speed, will make your car coast further and can help mileage on the highway. But they kill acceleration so buy aluminum or magnesium rims.

The rest of the fuels energy is lost due to the thermodynamic inefficiency of the otto cycle process (four cycle gas engine). Usually about 60% of the fuels energy is converted to work. The remaining 40% is dissipated as heat. A higher compression ratio will capture more of the fuel energy and make the engine more efficient.

The last two losses, rolling friction and drivetrain inertial losses, can be approximated with a straight percentage loss from the fly wheel back, 15% for manual transmissions, 20% for automatic transmissions.

 Here are two simple equations for calculating horsepower from the quarter mile. I usually average the two.

The charts can be used for your vette or any other car if the weight of you and the car add to 3600 lbs. 15% has been added for manual tranys.

The above equations are simple and only somewhat accurate. For flywheel HP you should add either 15% or 20% depending on your transmission type. The charts are shown for a manual transmission.