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What's the difference between horsepower and torque?

Nick Psaros
Automotive Expert
Nick Psaros is an Automotive Expert working to encourage people to become car enthusiasts and share useful automotive content with people around the world. He has spent the past six years building an online following and community dedicated to automotive excellence. He has a follower base of over 10,000 YouTube subscribers and has garnered over 1 million views on his channel.

Nick Psaros

Automotive Expert

Expert Answer

Horsepower is a measure of the engine's ability to do work overtime, often associated with a vehicle's top speed and overall performance. Conversely, Torque represents the rotational force produced by the engine, providing the feeling of acceleration. While horsepower influences a vehicle's top speed, torque plays a crucial role in its acceleration and towing capabilities. In essence, torque is the force that propels the vehicle forward, and horsepower determines how quickly it can maintain that force over time. Contrary to common perception, modern turbo engines generate significantly more torque than naturally aspirated ones. This heightened torque delivery improves performance within the RPM ranges commonly encountered in your daily driving.

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How can I calculate horsepower from a motor?

Community Answer

Multiply the voltage, current and efficiency; then divide the result by 746. For example, the horsepower of a 230 volt motor pulling four amps and having 82 percent efficiency would equal one horsepower. Convert the efficiency into a decimal before calculating.

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Question

What is the horsepower for a centrifugal pump?

Community Answer

A pump is not a drive. It will be driven by another source or prime mover such as an engine, motor or natural kinetics. Only the drivers have horsepower, not the pump.

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Question

How do I calculate the horse power of a motor?

Community Answer

Multiply the voltage, current and efficiency; then divide the result by 746. For example, the horsepower of a 230 volt motor pulling four amps and having 82 percent efficiency would equal one horsepower. Convert the efficiency into a decimal before calculating.

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Question

How do I increase the horsepower of any engine?

Community Answer

If you're looking to improve your cars performance (assuming your using a petrol driven car), a good way would be to invest in a cold air intake. It makes the air intake more dense, allowing the car to burn more fuel and power the crankshaft even further.

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Question

What is horsepower?

Community Answer

Horsepower is the power needed to raise/move 550 pounds a distance of one foot in one second.

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Question

How do I find the amperage if I know the horsepower?

Community Answer

HP is a unit for power, as it can be measured by W (watt). First we need to convert the horsepower to watts. 1HP=746 watts. So, if the motor is 2HP, 2HP=1492 watts. The formula for calculating power in electrical circuits is P=VI. We derive the formula for amperage from that to be I=P/V. I=1492/240 (for single phase), which means I=6.21A.

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Question

What is the difference between BHP and HP?

Community Answer

HP is measured with all the accessories attached to the engine to determine its maximum rate and speed. BHP, on the other hand, is more of a theoretical calculation, which is made under lab-controlled conditions and without having anything attached to the engine.

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Question

How many watts are in 1 horsepower?

Community Answer

As stated above, one horsepower is equal to 746 watts. You divide your calculated watts by this number to get your equivalent horsepower.

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Question

How do I calculate the horsepower of a pump?

Community Answer

HP = (GMP × PSI) / (1713 × efficiency of pump) GMP = gallons per minute PSI = pounds per square inch (pressure)

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Question

I don't understand why you multiply weight and (.454). What is (.454)?

Jose Guerrero

Community Answer

It is a conversion factor. He had a reading in lbs. Ex: 10lbs x (1 Kg/2.2lbs) = 10lbs x (.454kg/lbs) = 4.54Kg. So, 10lbs= 4.45Kg.

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Question

Why was it multiplied by 0.454 for weight and 0.3048 for height?

Community Answer

Since you are using the SI unit in the equation, but your height is in British units. Thus, you need to convert feet into meters; 1 foot = 0.3048 meters. Similarly, 1 pound = 0.454 kg.

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Question

How do I convert cc into HP?

Community Answer

You don't. HP is a measurement of power, cc is a measurement of volume.

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Question

Why do I use the 746 figure when calculating horse power?

Community Answer

To convert from W to HP. 1 HP = 746 W. So if you have 2000 W ---> HP = 2000/746 = 2.681 HP.

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Question

How do I calculate horsepower and the watts of a motor?

Community Answer

Multiply the voltage by the current by the % efficiency, then divide the product by 746 (1 HP = 746 watts).

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Question

How can I find engine horsepower, RPM and torque?

Community Answer

The use of a vehicle Rolling road or vehicle Dynamometer is the best way when the engine is in a vehicle. The dynamometer will measure torque over a given engine RPM and from this will calculate the BHP.

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Question

Can one horsepower lift over a ton?

Community Answer

Yes; however, it would take a long time, as HP is a measure of work over time. 1 HP can lift a small amount of weight in a short time or lift a heavy load over a long time.

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Question

Why do I need to multiply by .3048?

Community Answer

Because you are using the SI unit in the equation, but your height is in British units. You need to convert feet into meters, and 1 ft.= 0.3048.

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Question

What unit is being used for torque in a gas engine?

Community Answer

For IS, torque uses N.m (Newton.meter). In the English system, it is (Pound.foot).

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Question

How do you calculate human horsepower running on flat ground?

Tom Johnson

Community Answer

Easy! It is zero according to the most straightforward methods of calculating power. But we could measure all the heat which the person gives off to the surroundings. The resulting quantity of heat, usually given in America as British Thermal Units (BTU) per hour, can be (improperly) expressed as horsepower; to do so would be improper because heat flow and power are not the same quantity. In fact, careful calculations routinely subtract heat flow (loss of useful energy) from practical outputs as we account for energy out from a machine being equal to energy into the machine. A car engine's horsepower is a small fraction of the energy flowing into it over time as it consumes fuel.

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Question

What is the mathematical equation of output mechanical power?

Community Answer

S x T = P. Speed multiplied by Torque is Power. Speed is measured in rpm (rotations per minute). Torque is measured in ft-lbs.(foot-pounds).

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