Torque and horsepower: what they mean and why they matter

You may have heard it before: “Horsepower sells cars; Torque races won.” But what is torque and why does it matter? We’re not engineers here, even when we run them on YouTube, so we’re going to give you a non-engineer explanation and try our best not to make you feel like the head of photography in a Zen-ed math class. Dive into it.


Mechanically, torque is how you get things done. Bending a knot, opening a valve, working a lever – the everyday application of this concept. In essence, it is a measure of the amount of work done by something. Or, more precisely (and unscientifically), it is a measure of leverage.

Your general physics teacher will probably demonstrate the concept with some common levers, but that’s it Autoblog, West Crestfield Senior is not high, so let’s use the car thing, what shall we do? The best way to easily imagine torque is not with the engine components, but with a log wrench.

Why a log wrench? Because torque is a qualitative measure of the energy supplied at a given distance. So the automotive engine torque is expressed in pounds-feet; You are applying a force (in pounds) to a distance (in feet).

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Scenario: You moved into a parking lot with a flat tire. You’ve got a properly inflated spare, a jack and a simple log wrench For the purpose of this example, suppose the handle of a log wrench is one foot (12 ”) long. You line up the jack at the right point and you are ready to loosen those nuts before you put the wheel in the air. You attach the log wrench and give it a good, firm push counterclockwise… and nothing happens.

What do you do Go ahead, shout and answer if you know it. If you say “get a long log wrench,” you’re right. “Yankee Harder” would also be correct, because either increasing the distance (length of the handle of the wrench) or increasing the force (hardening yanking) will increase the amount of torque you are applying to that log nut.

But you can only shake so hard, and the more you try, the more tired you will become. You can replace yourself with a bigger, more powerful man (try using Diesel Turkey; Vine) or you can get a better tool. But there are no log wrench shops nearby (what, you don’t have a log wrench shop?), Just a one-window hardware store, a wine joint and a few hair and nail salons. So, you walk around the hardware store and ask the clerk if they carry a log wrench.

They don’t. Just your luck! But now that you understand how torque works, you know that all you need is something that will lengthen the handle of your log wrench, like a piece of pipe that will fit over the grip. So you buy a 4-foot-long metal pipe, walk outside, and just close those suckers, because now you’re applying four times the force of that one-foot wrench handle.


Now that you understand torque, it is much easier to understand the difference between it and horsepower. The beauty of the torque is that it’s a very simple “can it be done?” Formula You need to remove something that requires X ball and you have Y foot-pound leverage to apply. If Y is greater than or equal to X, you can move it. So why should we worry about horsepower?

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Horsepower is a more complex measure because it calculates the time, mathematically referred to as the rate. In other words, if torque tells you if you can do anything at all, horsepower tells you how fast you can accomplish it. To calculate this, you multiply the torque (in pounds-feet) by the speed (in RPM, in the case of a car) and divide the total by 5,252. Why 5,252? Because it’s a mathematical constant, like “Why are you constantly asking us questions we don’t want to answer?”

Let’s get back to that flat tire scene. Let’s say the hardware store was new to something you could use to lengthen your log wrench, and Vin Diesel haunted your InstaChat. So while you may not be able to strengthen yourself, you may be able to find ways to increase the power you are applying at the end of the wrench. For example, say, using a hammer.

With that hammer, you can apply more force to the end of the wrench handle, but you’re not going to help it just to shake it, are you? You’re going to hit things. Each of these instantaneous blasting energies is greater than the constant amount you can apply to the handle by shaking it, and of course, each impact lug starts to loosen the nut.

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Frog. Frog. Frog. Finally, it is loose enough that you can use the wrench (and finally your fingers) to do the rest. No, you didn’t apply as much torque as you could with a long wrench, so it took a little longer. The rate at which you get the job done decreases, but you get it done in the end. This is the same basic premise behind a handheld impact gun. You’re repeatedly delivering fast, powerful torque explosions to apply increasing leverage.

So, yes, if you have a big enough impact gun, you can use it to turn the crankshaft in your car and take it down the road, but even an imaginary monster impact gun won’t be able to move a lot – a thousand pound car gets off the road very quickly. In other words, it has leverage (torque) to turn it on, but not too fast (horsepower).

Basically, this is how an internal combustion engine works, only you have multiple wrenches (your connecting rods) that apply torque to your nut (crankshaft) hundreds of times per second. And to take that analogy further, the crankshaft in turn (sorry) turns into a huge wrench you’re using to rotate your flywheel.

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This is the point at which the torque output of an engine is actually measured. Each part of your powertrain at the bottom of the crankshaft is another wrench that bends another component and using this analogy, your transmission is basically a box of different sized wrench, allowing you to choose the best one for the job you are trying to perform. . Ranches. Wrenches everywhere.

So which is better?

There is a saying in racing: to finish first, you have to finish first. Torque, represented by the large red Ford pickup truck above this article, is this “can it be done?” Figure, so it is the most important measure of the potential of an engine. But if you’re in a race where the little red Ferrari F1 is represented by a car, wheel-to-wheel or clockwise, “How fast?” An incredibly relevant question. Neither torque nor horsepower tells the whole story. There are many reasons for the choice of tires, aerodynamics, suspension design and (arguably the most critical) gearing. But it is a matter for another time.

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