Most car and truck manufacturers advertise the amount of horsepower an engine provides and also the amount of torque it provides. But many people do not know what those numbers mean and how the two concepts are related. In this post, we want to explain the difference between the two and also some facts.
What is Horsepower?
Power is defined as the rate at which a work is done, and the power produced by an engine is called horsepower. In mathematical terms, horsepower is the power needed to move 550 pounds one foot in one second, or the power needed to move 33,000 pounds one foot in one minute. This accounts for three things: the amount of weight involved, the distance the object is being moved, and how long it takes to do it. Horsepower pushes, pulls, shoves or drags your rides through the friction-filled world. If you want to go faster, it takes more horsepower and if you want to go slower, it takes less horsepower. Horsepower gets the vehicle to move quickly down the track and that is why professional race engines are built to achieve maximum horsepower.
What is Torque?
Torque is a measurement of twisting or rotational force generated by the engine that results in motion. This force is transferred through the drive system into the wheels. Torque is what pushes you back in the seat when the accelerator is pushed down. Torque gets your car moving at lower speeds. So a car’s ability to jump off the line from a complete standstill depends on how much torque it has. However, once the vehicle gets moving it is important to have less torque and more horsepower to maintain a high speed. Torque is measured by the amount of force multiplied by the length of lever through which it acts. If you use a one-foot-long wrench to apply 10 pounds of force to a bolt head, you are generating 10-pound-feet torque. The torque of a vehicle is measured at various engine speeds, or revolutions per minute (RPM).
Torque vs Horsepower
Most people think that horsepower and torque are two separate and unrelated values. They are wrong, because horsepower is the product of torque and RPMs.
Horsepower = torque*rpm/5252
The torque and horsepower values illustrate what a truck or car can do. Torque gets you the required speed quickly, and horsepower keeps you in that speed. The horsepower basically picks up where torque leaves off. Below 5252 rpm, torque will always be more than horsepower, at 5252 rpm they will be equal, and above 5252 rpm torque will be less. The greater the torque figure, the faster the acceleration.
A car’s performance is tested with its torque, which is measured with a dynamometer and there is no machine to measure a car’s horsepower. The measure of an engine’s performance is torque, and the horsepower is an additional number attained by multiplying the torque by the RPMs. The unit of measure for torque is the pound-foot (lb-ft) and for work it is the foot-pound (ft-lb). Even with low-rpm setups, the engine that makes the most torque at equivalent rpm points will make more power and should be faster.
The gear system can affect the work that occurs within the engine. To understand this, consider a lightweight race car and a heavy truck. The race car develops a large amount of horsepower and the torque of the engine is used for producing high speed. A race car does not need a huge amount of work to push it forward. So, more power is left for speed. Whereas in a truck using the same size engine that produces the same amount of horsepower, torque is used for doing more work through gearing. Although a truck cannot reach high speeds, it can carry heavy weights.
When the question arises whether you need better torque or horsepower in your vehicle, the answer is dependent on your driving style. When you choose an engine with higher torque, you do not need to down shift quite so often when accelerating from lower speeds. The high torque gives you more access to power at lower revs and this makes driving more relaxed.
When your vehicle’s engine has little torque, you will have to change down a gear more often to explore the rev range to unleash the engine’s power. Engines with lower torque figures have to be worked harder to get up to speed. Although when an engine is built for torque, the horsepower will take care of itself, the end goal is to generate maximum power within the engine’s operating rpm range. One thing you should remember is you cannot have horsepower without torque, but you can have torque without horsepower. In racing when there is an accident, horsepower is how fast you hit the wall and torque is how far you move that wall.
Horsepower and torque are not exactly the same, but there is a close relationship between horsepower and torque, and they cannot work without each other.
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