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Discussion Starter · #1 ·
Hi!

I've been reading around on this forum for a while and have a question since you guys probably are educated in the matter.

My question concerns torque versus horsepower. I read somewhere that "torque wins races, hp sells cars", is that true? I've heard many different opinions on the matter.
 

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Life is what you make it
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Well I read somewhere that Horsepower Is an illusory Mathematical equation
Torque Is the source of all Good things in the world. To me Torque is what you feel in the seat of the pants. Hp is a number you can brag about to your buddies. Depending on where the torque kicks in it can be a nice rush. :D
JMO for what it's worth.
 

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It seems to be trendy to discount hp and claim torque is everything. Hp is the measure of how much work an engine can do in a set amount of time. 1000 ft. lbs. of torque at 1 rpm won't get much done.
The Yamaha that makes 144 hp from 37 cubic inches dosen't have much torque but sure hauls ass. Of course the 17,500 rpm redline helps.
Big torque makes an engine a delight to operate. Big hp makes a vehicle fast.
 

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Horsepower is an indicator of how much work is performed but it is mathmatically derived from Torque and RPM. HP=(Torque X RPM)/5252. High HP figures are only useful if they fall into an RPM range that the rider uses. High HP at 6000 RPM is meaningless if you ried at 2500 RPM.
 

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Torque determines how hard a vehicle will accelerate - up to a certain engine speed (rpm) where either the torque falls off, or redline is reached.

HP indicates how long the vehicle can continue to accelerate at that rate before you have to shift, again, due to either redline being reached or the peak of the torque curve being reached.

So an engine that makes torque at a higher rpm will have more hp than an engine that makes the same torque, but at a lower rpm.

John
 

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Milehog said:
It seems to be trendy to discount hp and claim torque is everything. Hp is the measure of how much work an engine can do in a set amount of time. 1000 ft. lbs. of torque at 1 rpm won't get much done.
The Yamaha that makes 144 hp from 37 cubic inches dosen't have much torque but sure hauls ass. Of course the 17,500 rpm redline helps.
Big torque makes an engine a delight to operate. Big hp makes a vehicle fast.
I could be wrong and sure would like to debate this but I think TQ will get you there quicker. It is that off the line feeling. I'm thinking like hp would be great on the salt flats and tq would be nice on the street
 

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Discussion Starter · #7 ·
Milehog said:
It seems to be trendy to discount hp and claim torque is everything. Hp is the measure of how much work an engine can do in a set amount of time. 1000 ft. lbs. of torque at 1 rpm won't get much done.
The Yamaha that makes 144 hp from 37 cubic inches dosen't have much torque but sure hauls ass. Of course the 17,500 rpm redline helps.
Big torque makes an engine a delight to operate. Big hp makes a vehicle fast.
Yeah, it seems as if the maximum torque number of a bike doesn't really say anything at all about its performance. There are these 600cc bikes with like half the torque of a Harley and half the weight but still much stronger acceleration. It has to be the hp that plays a major role.
 

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For this old fart and my style of riding I'll take Torque any day. To me thats why you see the rice rockets going 150 mph all the time is they dont have no torque. Ive seen dyno charts at the shop for some of them and until you reach some scary rpm and dont make anything. maybe I am just to old but I want to live a little longer, not have to go 150 for the hp and tq to kick in?
 

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Milehog said:
It seems to be trendy to discount hp and claim torque is everything. Hp is the measure of how much work an engine can do in a set amount of time. 1000 ft. lbs. of torque at 1 rpm won't get much done.
The Yamaha that makes 144 hp from 37 cubic inches dosen't have much torque but sure hauls ass. Of course the 17,500 rpm redline helps.
Big torque makes an engine a delight to operate. Big hp makes a vehicle fast.
It's really a matter of balance. To use your example:
1000 ft. lbs of torque and 1RPM = .19 HP
1000 RPM and 1ft. LB. of torque = .19 HP

In a perfect world, you would want an engine to develop a ton of torque at low RPM and maintain it to redline.
 

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Speaking as an old mechanical engineer...given a choice between a high torque engine and a high horsepower one, I would choose torque every time. Notice I said choice. If I could have both, that would be even better.
When you twist the throttle and you feel the bike accelerating, what you are feeling is torque. If the engine can deliver that torque at a higher rpm, then horsepower comes into play, since horsepower is just torque multiplied by rpm. If my engine had 80 foot pounds of torque at 2000 rpm and yours had 80 foot pounds as well, but not at 2000 rpm, not until say 3000 rpm, then I would feel more acceleration that you would...at 2000 rpm. At 3000 rpm you would feel the same acceleration, but unless you were geared down, you would be going faster. At 3000 rpm my high torque setup would probably be producing less torque than at 2000 rpm, I would on the declining part of the rpm/torque curve, and you would accelerate better than I would.
Torque is what you feel when you twist the throttle. Horsepower is what you get when you get that torque at higher rpms.
High torque is a real pleasure riding around town, and this is where the big Harley engines really shine.
 

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I don't know how it works out scientifically/technically. Here's what I do know from seat of pants. On my fat assed Road Glide with my fat 300lb ass on it, torque is what pulls you out of a tight swichback with authority and no downshifting, you can feel it, it's like a tractor, get all the way down to 2000rpm's getting in, just roll on the throttle and it pulls you out like a John Deere pulling you outta the mud(on a built motor). HP is what gets you there faster and especially when yer really getting on it, keeps you accelerating beyond where the TQ starts to drop off. I tested these principals very thougholy yesterday as I am still evaluating my new build and haven't had many dry days to really let her rip. With a few hundred miles on her, been letting her out a little and hammering her a little just to know the capabilities(all in the name of safety of course...).
I also know that a stock/stage1 twinkie has no real usable tq below at least 3200 and gives up before the magic 5252. At least my big beast haulling my fat ass did. Don't believe me? Take your stock/stage1 out in the hills, try to pull yourself out of a hard uphill switchback when you've let the r's get down to 2k without downshifting. Careful she doesn't stall on you! Pretty sure that's TQ......

Maybe i'm FOS, who knows....
 

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Discussion Starter · #14 ·
meanbean said:
Great article!

Some really interesting things there. That Kawasaki has more grunt from 55mph and up in 6th gear than the modified Harley in 5th gear from the same speed. The Harley revs 2300rpm at 55mph and the Kawasaki revs 3300rpm. Not that much of a difference. The Kawasaki probably feels stronger in daily driving than the Harley. I didn't expect that considering the Harley's big v-twin. Even though the Harley and the Kawasaki has the same maximum torque in the engine the Kawasaki has much more torque on the wheel.

This kinda punctures the statement in my original post ("Torque wins races, hp sells cars"). The quote is correct if we refer to the torque at the wheel though.

Torque is kinda hard to grasp. If you only looked at the specified torque in the engines you wouldn't have thought that the Kawasaki had that much more torque than the Harley on the wheel.
 

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Discussion Starter · #15 ·
Tommy Meisel said:
If my engine had 80 foot pounds of torque at 2000 rpm and yours had 80 foot pounds as well, but not at 2000 rpm, not until say 3000 rpm, then I would feel more acceleration that you would...at 2000 rpm. At 3000 rpm you would feel the same acceleration, but unless you were geared down, you would be going faster.
I think I've got it. That 3000rpm engine will have more power, and if it was geared down so that it was equally as fast as the 2000rpm engine in every gear, the 3000rpm engine would accelerate harder in every gear because the lower gearing gives it more torque on the wheel, right?

It seems power is what is needed to accelerate fast. You can get that power by massive torque at low rpms or low torque at high rpms or a combination, it doesn't matter. As long as the horsepower figure is high and given the appropriate gearing you have good performance. A Harley has good torque but it is delivered at too low rpms to give high power, which is why they aren't fast.
 

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Torque gets you there, Horsepower keeps you there.
 

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Fredda said:
I think I've got it. That 3000rpm engine will have more power, and if it was geared down so that it was equally as fast as the 2000rpm engine in every gear, the 3000rpm engine would accelerate harder in every gear because the lower gearing gives it more torque on the wheel, right?

It seems power is what is needed to accelerate fast. You can get that power by massive torque at low rpms or low torque at high rpms or a combination, it doesn't matter. As long as the horsepower figure is high and given the appropriate gearing you have good performance. A Harley has good torque but it is delivered at too low rpms to give high power, which is why they aren't fast.
You have to be careful when you add gearing into the mix. You can take a small engine with very little torque and a lot of RPMs and using a high gear ratio give it stump pulling power. On the other hand you can take a real torque monster running at a low RPM and overdrive it into a real speedster.
 

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Discussion Starter · #18 ·
Rubrto said:
Torque gets you there, Horsepower keeps you there.
That's twice in this thread. Do you have anything to back up those claims?

Have you read the article meanbean posted? I don't see anything supporting that theory there.
 

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Discussion Starter · #19 ·
DesertRat said:
You have to be careful when you add gearing into the mix. You can take a small engine with very little torque and a lot of RPMs and using a high gear ratio give it stump pulling power. On the other hand you can take a real torque monster running at a low RPM and overdrive it into a real speedster.
You meant LOW gear ratio on that small engine, right?

Other than that I'm with you. Assuming both have equal power they can be geared to perform equally. Of course the gearing will be very different between these engines.
 
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