Horsepower Versus Torque: Understanding Key Engine Performance Terms

If you’re looking to buy a new car, chances are good that you want to know how much horsepower it has, and how much torque it produces. If you’re looking at the latest hot rod, the same things apply. We throw those numbers around a lot, but many people get them confused. What’s the difference between horsepower and torque? Is one more important than the other? How do they actually impact vehicle performance? We’ll answer those questions and more below.

What Is Torque?

Torque is nothing more than a rating of force as applied from a distance and rated in pound-feet (or lb.-ft.). For instance, the force applied by a piston to a crankshaft in order to make the shaft turn.

What Is Horsepower?

Horsepower, usually abbreviated as HP, is actually a measure of torque multiplied by the engine’s revolutions per minute, or RPM.

What Do Those Things Mean?

Left on their own, the definitions of horsepower and torque provided above really don’t offer much in the way of information. However, we can put them into more easily understood contexts.

Horsepower:

Horsepower is easiest to understand in terms of speed and acceleration. The more horsepower an engine has, the faster it can go, and the quicker it can reach top speed. In other words, it is a measure of the amount of work the engine can do over a specific period of time, such as getting the car up to speed within a quarter-mile.

Torque:

Torque is nothing more than the ability to do work. The more torque an engine and transmission produce, the more work it can do. Note that this does not necessarily equate to speed – it’s about power, instead. For instance, a vehicle with high torque is going to be better at towing heavy loads than one with high horsepower but lower torque.

Which Matters Most?

Really, neither torque nor horsepower is more important in all situations. It all depends on what you want. Looking for something that will let you tackle the track on the weekend? If you’re going for a traditional race, you need power off the start (torque), but also the ability to get up to a high rate of speed (horsepower). However, if you’re going to take your boat up to the lake for some quality family time on the water, horsepower is going to matter a lot less than the torque of your vehicle.

You get more pulling power from an engine that creates greater torque at lower RPM than you do from one that hits peak performance at a high RPM. Yes, horsepower and torque increase as speed increases, but that is not the best solution for all situations. Again, look at towing – trying to pull a trailer with a car that puts out 148 pound-feet of torque at 4,600 RPM isn’t going to work out all that well.

Conclusion

In the both horsepower and torque are important, but they refer to very different things and neither trumps the other in all situations.