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[Richard230]

Here is a link to an interesting article regarding dynamometers and horsepower:

https://rideapart.com/articles/dynamometers-horsepower-doctor-moto-rideapart

[PhreaK]

"Engine “torque” is the twisting force at the crankshaft, which comes from explosions in the combustion chamber(s) pushing the piston(s) down, which push the connecting rod(s) and rotate the engine's crankshaft. This rotating motion is transferred through a clutch, transmission, and finally by chain, belt or gears to the drive wheel before moving the motorcycle."

Well, not quite...

[Killroy]

Article mentions "metric horsepower", which is really not part of the metric system, so it is really a bastardization of the metric system, just like metric "tonne". 

People always argue "No, torque is better"  "No, horsepower is more important"

The answer is both, but with torque you want quality and horsepower you want QUANTITY.

You can always gear a engine/motor to have more torque or thrust at the ground, but if you reach the speed limit of the engine, it does not matter.  So for torque you want a predictable and practical torque curve.  This is when people talk about a flat torque curve.  Peaky torque curves are bad.

Horsepower is basically torque X RPM, so if you spin a small torque fast enough, you will have a large horsepower.

[Killroy]

"Engine “torque” is the twisting force at the crankshaft, which comes from explosions in the combustion chamber(s) pushing the piston(s) down, which push the connecting rod(s) and rotate the engine's crankshaft. This rotating motion is transferred through a clutch, transmission, and finally by chain, belt or gears to the drive wheel before moving the motorcycle."

We'll, not quite...

There is something to be said about not wasting power through water pumps, oil pumps, cams, transmission, vibration, clutch.

One thing to note is that a chain is more efficient than a belt, but listening to a chain on a electric motorcycle would be annoying.

[KrazyEd]

When I had my speed shop, I would tell people that
Horsepower is how fast you hit the wall.
Torque is how far you move it when you do.
Speed costs money, how fast can you afford to go.

[Doug S]

We'll, not quite...

That was pretty much my reaction to the whole article....yeah, almost, but not really. Kinda had me cringing a little bit, actually.

I like to make an analogy to pushing kids on an old, rusty merry-go-round. A big, muscular, strong man could get them up to speed quickly because his sheer strength provides lots of force -- that's torque. But he's too big and massive to move very quickly, so once up to speed, someone like a boxer can move his hands quicker and get the kids up to a higher top speed -- being able to deliver energy to the system even when it's already moving quickly. Delivering energy to a system is power. It's not an exact analogy but it gets the idea across. You need torque to accelerate quickly, especially from a dead stop, but you need power to get to high speed.

[Semper Why]

A long time ago when I was much younger and was part of the Mustang GT scene, there was much discussion of torque, horsepower, gearing, dynos, imports, domestics and those wacky AWD people. I'll spare you the details as they weren't always pretty. No, seriously. There were mullets involved.

Anyhow, the best essay explaining torque & horsepower was this one: Torque and Horsepower - A Primer.

[MostlyBonkers]

Semper is Latin for always, so 'Always Why' is your handle?  It's as good as any I suppose and would indicate that you're a philosopher of sorts. Am I warm?

Thanks for posting that article, I found it very helpful.

[Frank]

Not a bad article overall, but they mis-stated the definition of horsepower: it's 550 ft-lb of WORK per second, not torque...

[Semper Why]

Semper is Latin for always, so 'Always Why' is your handle?  It's as good as any I suppose and would indicate that you're a philosopher of sorts. Am I warm?

Not really. It's a pun off of the motto of the US Marine Corps, "Semper Fi" (always faithful). I am not a Marine, but I have several friends who are and this is a little joke for them. I translate it very loosely as "Always Question". I failed Latin when I took it many years ago.

The best part about it is that pretty much nobody will have registered it on any other forum. 

I am not a philosopher. I have too many expensive hobbies and a degree/job in philosophy doesn't pay well enough to support them.