HP and Torque?
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Cruiser
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HP and Torque?
I'm in the process of hotting up the engine on my Fatboy, looking around at builds etc. Then I came to realize that I don't really know about HP and torque and what they really mean. From what I understand torque is how hard the bike will accelerate, and HP is more about top speed, and maybe not that important on a cruiser. Am I correct?
Road Warrior
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Road Warrior
Joined: Jan 2007
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From: Minnesota
RE: HP and Torque?
Torque is your power in lower RPMs but after 5252RPMs HP is where it's at. TQ and HP are always equall at 5252 RPMs by this time the TQ has already peaked and is going down and HP is still rising. Most of us on HD's spend our time in the 2000-4000 ranges. Obviously when passing RPM's go up and that is where your HP comes in handy.
I hope this is a good enough explanation.
I hope this is a good enough explanation.
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Cruiser
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RE: HP and Torque?
ORIGINAL: BigJfxdwg
Torque is your power in lower RPMs but after 5252RPMs HP is where it's at. TQ and HP are always equall at 5252 RPMs by this time the TQ has already peaked and is going down and HP is still rising. Most of us on HD's spend our time in the 2000-4000 ranges. Obviously when passing RPM's go up and that is where your HP comes in handy.
I hope this is a good enough explanation.
Torque is your power in lower RPMs but after 5252RPMs HP is where it's at. TQ and HP are always equall at 5252 RPMs by this time the TQ has already peaked and is going down and HP is still rising. Most of us on HD's spend our time in the 2000-4000 ranges. Obviously when passing RPM's go up and that is where your HP comes in handy.
I hope this is a good enough explanation.
Road Warrior
Joined: Jan 2007
Posts: 1,763
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From: Minnesota
RE: HP and Torque?
There you go. You learn quickly grasshopper.
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RE: HP and Torque?
It takes force to accelerate a motorcycle. A little force will accelerate a motorcycle slowly; a lot will do it faster. Force on a wheel is best measured by torque. With the right gearing, the little motor that opens and closes the plastic tray on your computer's CD-ROM drive can apply as much torque as you want ... it just can't do it very fast. That's where power comes in: how fast the motor can do the work of accelerating the motorcycle.
Torque all by itself is not terribly useful as a number for an engine's ability. There's this gearbox and final drive that changes the torque to whatever range is needed. In first gear, any given engine speed can produce a lot more toque at the rear wheel than in top gear ... but more slowly. We have gearboxes because piston engines have this annoyingly nonlinear torque curve: they're better at making torque at some RPMs than others, and they don't make any at zero RPM. So as long as the gearbox has the right ratios, I don't really care what the peak torque is. I want the engine to have a more-or-less linear torque curve.
Accelerating and maintaining top speed both require force and power. At speed, there's no more acceleration to be done, but you have to push all that air out of the way. So "Torque gets you moving, Horsepower = MPH" isn't true either.
Torque all by itself is not terribly useful as a number for an engine's ability. There's this gearbox and final drive that changes the torque to whatever range is needed. In first gear, any given engine speed can produce a lot more toque at the rear wheel than in top gear ... but more slowly. We have gearboxes because piston engines have this annoyingly nonlinear torque curve: they're better at making torque at some RPMs than others, and they don't make any at zero RPM. So as long as the gearbox has the right ratios, I don't really care what the peak torque is. I want the engine to have a more-or-less linear torque curve.
Accelerating and maintaining top speed both require force and power. At speed, there's no more acceleration to be done, but you have to push all that air out of the way. So "Torque gets you moving, Horsepower = MPH" isn't true either.
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Thread Starter
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Cruiser
Joined: Aug 2007
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From:
RE: HP and Torque?
ORIGINAL: BigJfxdwg
There you go. You learn quickly grasshopper.
There you go. You learn quickly grasshopper.
Road Warrior
Joined: Dec 2006
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From: Diamond Bar, California
RE: HP and Torque?
With your build, you will want a combonation of parts that will give you very broad torque form around 2K rpm to 5,500 rpm and a touch of HP to get you to 6K rpm!
Basicly a few cubic inches, a point or so of engine compresion and a minimal amount of head work to get you over the top!, and dont for get some cams and some sort of fuel management, SE race tuner or thundermax!
Basicly a few cubic inches, a point or so of engine compresion and a minimal amount of head work to get you over the top!, and dont for get some cams and some sort of fuel management, SE race tuner or thundermax!