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Old 03-26-2017, 05:18 PM
Morgan444 Morgan444 is offline
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Originally Posted by NBA Jam View Post
The way I try to think about it:

Torque - What you need to move
Horsepower - How fast you use your torque

Consider two extremes:

- Imagine a massive truck trying to move a space shuttle. It moves very, very slow, but it can pull the shuttle. This is similar to something with high torque, low horsepower: its engine doesn't spin very fast, but it produces a lot of power for each revolution.

- Imagine a small car trying to move a space shuttle. The engine spins very fast, but it can never move the shuttle. This is similar to high horsepower, low torque: it can use the torque quicky, but because there's not enough of it, neither the car nor the shuttle go anywhere.

Torque is what does the work to move you, horsepower is how fast it does the work.

Of course these analogies aren't precisely how reality is, but it's a way to wrap your brain around it.
Fundamentally you are correct but . . . .

As I said in my post above, there is a very direct relationship between torque and horsepower. What this means generally speaking is that an engine developing high horsepower will not have low torque and conversely, high torque will not result in low horsepower.

And if your analogy with the massive truck is taken to the next step, no matter how much torque or horsepower the giant truck has, if it is not geared correctly it will not be able to do any work. E.g. if a heavy vehicle (say a Freightliner Argosy with 560hp, 1,850 lb-ft torque) tries to pull off in top gear, it will not get away, even with no load at all. The high gearing will simply not allow it. But in super low gear it is capable of moving well over 100 tons from stationary.

The useful expression is "Torque gets you up to speed, horsepower allows you to stay there"

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