Torque vs. Horsepower Explained

Torque vs. Horsepower Explained

The terms torque and horsepower are probably familiar to most car enthusiasts, but they aren't necessarily that well understood.
In this video, I’ll take you through a simplified explanation, and we will explore the relationship between the two, and how they interact in the real world.

If you want to support the channel, and get a ton of extra content, you can find on Patreon.

Sources:

Footage:

As ever, the end title music is courtesy of Saint Valentine Music:

[martinhilvers]

Torque = moment = distance x force, Newton x metre (Nm), or ft x lbs, never ft/lbs.

[Marco-vndb]

I swear, out of all the videos that explain power and torque (which have many more views than this video) this one is the most clearly explained and complete. This video was really helpful. I'm glad I came across this video.

[GreatPotato]

I was expecting millions of views with the quality of this video, keep up the good work bro!

[MathiasBacher]

I've been looking for a good explanation for a long time and this is the best I've seen so far!

[ipeaceful]

Wow! Thanks for the rundown on the physics behind torque and horsepower. I'm watching more videos about cars and how they work, but have definitely been lacking on combining this new knowledge with my limited knowledge of mechanics. Thanks for helping me begin to bridge the gap. And I loved the info on electric engines, too!

[Jay_Wolfe]

I have watched more videos explaining this subject than I care to admit, and finally, this is the video where it finally made sense.
Thank you so, so, so much for this!

[ThePiquedPigeon]

This is the video that FINALLY, I repeat _FINALLY_ taught me where engine torque actually comes from. The example of loosening a bolt with a wrench to define what torque is has been done by countless "what's torque" videos, and I understood what torque is alright, but I just couldn't transfer the concept to vehicles. My thought was "Ok, but when a car is moving, it's the other way around: you turn the wheels' center so that the wheel can rotate and the vehicle can move, you are not acting on the wheels like you'd do with the wrench". Those videos, at least the ones I've watched, missed the part at 2:35 - it all starts with the pistons being pushed by the working fluid (air-gas mixture, air-diesel mixture, steam...), and the pistons in turn push or pull their crankpins in the crankshaft, making the latter rotate. The pistons pushing the crankpins and rotating the 'shaft are like our jands pushing on the wrench to loosen (rotate) the bolt. It's then relatively easy to work your way to the wheels from this point!! Thanks for the video and the explanation!!!

[diegocwu]

This video cleared my confusion of torque and hp inside a combustion engine, I was so lost. Thank you very much.

[nelloreryderzclub]

There are lot of videos on internet, but you made it really easy... I'm comparing with big channels like Donute Media.. your articulation is too good!

[Sherman]

Great explanation.

Torque is an expression of twisting force with NO REGARD FOR SPEED. It could be at 0 rpm or 10, 000 rpm.
Horsepower is a more complete expression of performance, taking both torque and speed into account.

As is common when speaking of car engines, torque is usually noted AT a particular speed. This is in fact all we need to compute HP, but the math is simply not completed. We could just as easily say that X engine makes 360 hp at 3500 rpm (its torque peak) and 500 hp at 6250 rpm (its hp peak). Graphing this curve really tells us a lot.

We can double HP by either doubling torque OR by doubling the rpm at which the same torque is produced. Or more realistically, by increasing BOTH factors to a lesser degree.

Assuming proper gearing, the engine with more horsepower will ultimately do work more quickly. OTOH, most of us don't operate street cars at their HP peak very often. It is unpleasant (to police at least) and hard on the engine. Low rpm and part throttle torque is useful in everyday cars because they spend so much of their time in that range.

[josiahbomford]

Best explanation I've heard so far thanks!

[Ganserndorf]

It is a common misconception to believe that a longer stroke generates higher torque. The complete physics and thermodynamics of it all are quite complex, but in general terms, for a given displacement, the longer stroke is offset by the smaller piston area on which the combustion gases apply pressure, which results in less force being applied. Truck engine make more torque because they are big: there is no substitute for displacement.

Also, a 300hp engine will be able to move the same heavy load up a hill at the exact same speed, be it a 8000rpm sports car engine or a big diesel truck engine, it's all in the gearing. Truck engines are "tuned for torque" simply for durability and fuel economy reasons. By being able to generate the desired power levels at low RPM, they can last way longer and consume less fuel in the process.

[TheTruthseeker]

Great info. It is a little clearer indeed

[JECHOE]

Great work done here video quality is 11/10

[s.jackson]

Incredible. Wish i could buy u a drink. Thanks. Torque and its formula is as eady as 2+2, but understanding it related to the engine gave me problems. 10 vids in, I found the answer thanks so much

[tomaspaimans]

Great explanation now i finaly understand !

[mayur]

Best video on torque and horsepower on YouTube

[grimftl]

Good use of graphs to explain that hp and torque aren't constant when it comes to motors.

[arun_vadakkath]

That’s the best explanation I’ve ever come across. The Narration and the visual aid provided a great way of understanding the whole process. Thank you very much.

[rotorblade]

Power is how fast you (or the engine) generate chunks of energy and torque is sort of how big are the chunks. The piston strokes are “stronger” with more torque. That’s half of the problem. The next problem is why small chunks at high rate is equivalent to high chunks at low rate. You can try on a bicycle, to go on a slope you can either use lower gear and low torque or high gear and push hard with the bicycle going the same speed in both cases. So with high torque you will use a high gear ratio. But what about high torque and low gear ratio. That can be done and the rpm will go up quickly so you will need to be capable of high rpm but high rpm and high torque simply means a lot more power so in that case you have a more powerful engine.
Another problem is trying to analyze the power curve. You can have high torque from low rpm. That also means high power not only torque at that low rpm and that makes the car relatively fast without needing to push the rpm high.