Horsepower Calculator

An engine horsepower calculator makes it really easy to find out the horsepower in your car. All you need is the weight of your car and how fast you drive a quarter mile.

By using this calculator, you get a quantifiable number on your vehicle's performance. The more horsepower and the less weight, the better it will perform.

This ratio also gives you the ability to compare different cars performance. This is how you distinguish high-performance sports cars from those that are not.

You may not have as much horsepower as the Koenigsegg Regera. But knowing how much you do have will help you know the performance abilities of your car.

Horsepower units measure the rate that work gets done, also called power. The sought-after speed formula is the right amount of torque and horsepower.

The Beginning

In 1781 an engineer named James Watt wanted to compare steam engine power output to draft horse power. He hoped to convince skeptics to convert to steam engines for their work.

He measured a horse's walking distance pulling a grindstone at the mill. Then he multiplied the distance by the horse's 180-pound pulling force.

The resulting number was then divided by the time it took. The final number was horsepower.

He managed to prove that the output of an engine did the work of 35 horses. This is about the same amount of horsepower as a riding lawn mower today.

There are many different equtions to calculate horsepower, depending on the information you have on hand and the type of measurements you're utilizing.

Using Foot Pound Measurements

Horsepower is a calculation of torque multiplied by RPMs and then divided by 5252. The value 5252 is a rounded value of (33,000 sq ft lbf/min)/(2 degrees rad/rev).

Horsepower= (Torque x RPM)/ 5252

If torque is in an inch-pound measurement use the below formula.

Using Inch Pound Measurements

If your torque and RPMs are in SI units your formula is simple.

Horsepower= (Torque x RPM)/ 63,025

You multiply the torque by RPM and divide by the above number to get horsepower.

The ET Method

The elapsed time (ET) method uses the vehicle weight and time it takes to finish a quarter mile.

Estimated Horsepower= Weight/ (ET/5.825)3

You input your vehicle's weight and how long it takes to complete a quarter mile. If you're using our calculator, be sure to select a unit of measurement for both.

Trap Speed Method

Finally, this equation differs slightly from above.

Horsepower= Weight x (Speed/234)3

The Trap-Speed method uses the vehicle weight and speed when you finish the quarter mile. These numbers are then multiplied together.

Horsepower

The horsepower of a car is what keeps the car going at a certain speed. It is also what keeps the engine or motor running smoothly once it is up to speed.

Horsepower is measured in foot-pounds per second.

Torque

Torque is what gets the car up to speed. Torque is the force used to rotate an object.

Torque is a measurement said as pound-feet.

Differences

Low 0-60 numbers are thanks to a large amount of torque. Then a large amount of horsepower gives you a smooth ride at the fast speed.

An engine that makes more torque has more potential for work. Additionally, an engine that produces more horsepower can make more torque.

Example

Race cars put a high amount of torque through their system to go fast because they are light. A tractor is heavy so a high amount of torque gets used to push and pull things.

The same high horsepower engine lets one go fast and the other be a workhorse. The weight of the vehicle is what contributes to the use of the horsepower and torque.

Equation for Torque

The torque equation is Force multiplied by Distance.

T = F * D

The bigger the distance, the greater the torque will be.

Fast or high-performance cars have a lot of horsepower and a low amount of weight. To put this into perspective we will compare a Ferrari and a Ford Escort.

The Ferrari creates 350 foot-pounds of horsepower while weighing 3,000 pounds. The Ford Escort has 110 horsepower for 2,500 pounds.

The power to weight ratio for the Ferrari is 0.126. While the Escort's ratio is much lower at 0.045.

The Ferrari can do 0-60 in 5 seconds while it takes the Escort 10. The Escort would need a lot more horspower or a lot less weight to compete with the Ferrari.

The next time you have a debate over horsepower, you will know there is more to it than one number. Hopefully, this guide has shown you that torque also plays a big part in the performance of your car.