Massive Torque

[tinbender0]

Ok ...I always hear the Harley guys talking about their "massive amounts of torque"... I've also noticed on a Harley that the rear sprocket is about twice the size my Busas' stock sprocket or larger..Does the size of the spocket play a role in the torque reading on the dyno? Is the torque is derived from the rear wheel, or does the Dyno take sprocket size in consideration for the final reading giving net engine torque? My question is IF you go to a larger sprocket on the rear does the torque increase also? If so, is that why Harley's have "high torque" or is it from inertia from engine parts? I'm confused,, forgive my ignorance on the subject...please enlighten

 

[CrashBomb]

This comes up a lot in conversation. Horsepower and torque are pretty universal terms but it's surprising how few people actually understand what they mean and how they relate to each other.

http://www.nrhsperformance.com/tech_power.shtml

Here's a link to an excellent article that does a great job of explaining how the numbers work together.

As to your question, I don't think there are any dynos that record actual numerical measurement torque at the rear wheel. As the article explains it's actually "engine torque as measured at the rear wheel" derived by the computer calculating the relationship between how fast the engine is spinning and how fast the rear wheel is spinning.

I think the only reason the Harley guys talk about "massive amounts of torque" is because they've never ridden anything fast. It's simply a way in their eyes to save face. "Yeah, your bike is a lot faster than mine but I've got MASSIVE amounts of torque. So *phhhbbbbbbttttttt*."

Some other certified "experts" can chime in here, this has just been my experience, so someone with some credentials help back me up here (or tell me if I'm wrong)

 

[blue83camaro]

They really don't have high torque when compared to a busa. In fact most HDs make less torque than the busa. The diff on a HD is the torque peak is at 2000 rpm or something like that (I believe busa is around 6000), so HDs go as soon as u hit the throttle making them feel "fast". They get their high torque at low rpm from a long stroke on the crankshaft. In answer to the gearing question if there is a bigger spocket on the back the rear tire will see more real torque, but I don't know if it will affect dyno results because they figure engine rpm into it.

 

[Haelo]

They're bragging point is the low RPM at which they get a useable amount of torque.

But have you ever jammed on the throttle and thought, "Man, 'busas are slow until you build the revs!"

Didn't think so.

 

[Mr Brown]

Horsepower is a theoretical mathematical extrapolation of torque. Torque is measured force, horsepower is calculated using that measurement, and some other formula that I can't remember. A dyno measures the force at the wheel, and calclates hp using rpm. A sprocket isn't gonna make a difference on the amount of torque generated, it just affects how quickly it is used. HD's make torque because of their relatively large displacement, but lack hp due to a longer stroke and sh!tty valvetrain design which limits rpm.
The Busa is a tq monster in sportbike world, there aren't too many bikes that put out more.

 

[tinbender0]

I do know the busa has more torque but I still have questions..So ,,the dyno DOES calculate the differences and measures engine torque. Why are the Harleys rear pulleys so big in diameter? If they had the same sprocket size as the busa it probably be like a Mo-ped out of the hole!! What happenend to their" Massive amounts "of torque then??Then their torque has to be a result of gearing I would think,,, not engine torque?

......?

?

???

 

[tinbender0]

UH he said "extrapolation" uh, huh,uh, huh, huh

 

[CrashBomb]

(tinbender0 @ Oct. 19 2006,16:49) Then their torque has to be a result of gearing I would think,,, not engine torque?

......?

?

???

Exactly right.
Read through the article on NHRS' site and pay attention to the part about the electric drill motor. You can make any kind of torque you want as long as you don't care how fast you turn, and you can turn as fast as you want as long as you don't care how much torque you're making. Torque at the crankshaft is much different from torque at the rear wheel.

 

[Mr Brown]

(CrashBomb @ Oct. 19 2006,15:53)

(tinbender0 @ Oct. 19 2006,16:49) Then their torque has to be a result of gearing I would think,,, not engine torque?

......?

?

???

Exactly right.
Read through the article on NHRS' site and pay attention to the part about the electric drill motor. You can make any kind of torque you want as long as you don't care how fast you turn, and you can turn as fast as you want as long as you don't care how much torque you're making. Torque at the crankshaft is much different from torque at the rear wheel.

But the torque applied (Wheel) is still an application of the torque available (Crank) right? If you put a sprocket four miles in diameter on the back of a bike, it will still only have as much force pushing the sprocket as it does with a tiny one, right?

 

[tinbender0]

oh noooooooooooo

 

[Mr Brown]

(tinbender0 @ Oct. 19 2006,16:01) oh noooooooooooo

??

 

[tinbender0]

Ok here's what i'm going to do...I'm going out to ride, if another harley dude starts talkin about torque,,,I'm gonna bust him in the mouf

.....just kidding

,,,just going to laugh a little...

 

[CrashBomb]

(Mr Brown @ Oct. 19 2006,16:58) But the torque applied (Wheel) is still an application of the torque available (Crank) right? If you put a sprocket four miles in diameter on the back of a bike, it will still only have as much force pushing the sprocket as it does with a tiny one, right?

On the dyno, yes I believe you are correct. The numbers would be the same. (Which is why the dyno readings don't change with sprocket changes).

But the dynomometer isn't measuring the amount of rear wheel torque, it's a measurement of engine torque that just happens to be taken at the rear wheel. I don't know of a system out there that actually measures the foot pounds of force put down to the ground by the wheel with gear reduction taken into account. That's why the dyno doesn't measure torque unless you plug in the tach pickup, because it needs to be able to compute the relationship between how fast the engine is turning and how fast the wheel is turning to come up with engine torque figures.

 

[tinbender0]

(Mr Brown @ Oct. 19 2006,14:02)

(tinbender0 @ Oct. 19 2006,16:01) oh noooooooooooo

??

just still confused...i think the harley/warrior guys are too..that make us even......but mine is still faster..lol

 

[tinbender0]

(CrashBomb @ Oct. 19 2006,14:05)

(Mr Brown @ Oct. 19 2006,16:58) But the torque applied (Wheel) is still an application of the torque available (Crank) right? If you put a sprocket four miles in diameter on the back of a bike, it will still only have as much force pushing the sprocket as it does with a tiny one, right?

On the dyno, yes I believe you are correct. The numbers would be the same. (Which is why the dyno readings don't change with sprocket changes).

But the dynomometer isn't measuring the amount of rear wheel torque, it's a measurement of engine torque that just happens to be taken at the rear wheel.  I don't know of a system out there that actually measures the foot pounds of force put down to the ground by the wheel with gear reduction taken into account. That's why the dyno doesn't measure torque unless you plug in the tach pickup, because it needs to be able to compute the relationship between how fast the engine is turning and how fast the wheel is turning to come up with engine torque figures.

Now that I understand

But just for kicks would like to see the differences in each gear 'torque" at the rear wheel on the different bikes....

 

[Mr Brown]

(CrashBomb @ Oct. 19 2006,16:05)

(Mr Brown @ Oct. 19 2006,16:58) But the torque applied (Wheel) is still an application of the torque available (Crank) right? If you put a sprocket four miles in diameter on the back of a bike, it will still only have as much force pushing the sprocket as it does with a tiny one, right?

On the dyno, yes I believe you are correct. The numbers would be the same. (Which is why the dyno readings don't change with sprocket changes).

But the dynomometer isn't measuring the amount of rear wheel torque, it's a measurement of engine torque that just happens to be taken at the rear wheel.  I don't know of a system out there that actually measures the foot pounds of force put down to the ground by the wheel with gear reduction taken into account. That's why the dyno doesn't measure torque unless you plug in the tach pickup, because it needs to be able to compute the relationship between how fast the engine is turning and how fast the wheel is turning to come up with engine torque figures.

I see what you are saying.

 

[Mr Brown]

(tinbender0 @ Oct. 19 2006,16:04) Ok here's what i'm going to do...I'm going out to ride, if another harley dude starts talkin about torque,,,I'm gonna bust him in the mouf  

.....just kidding

 ,,,just going to laugh a little...

Just inform him that your bike puts out 100 lb/ft, see how they like that........

 

[tinbender0]

whew ,, glad that's straight

 

[tinbender0]

(Mr Brown @ Oct. 19 2006,14:11)

(tinbender0 @ Oct. 19 2006,16:04) Ok here's what i'm going to do...I'm going out to ride, if another harley dude starts talkin about torque,,,I'm gonna bust him in the mouf  

.....just kidding

 ,,,just going to laugh a little...

Just inform him that your bike puts out 100 lb/ft, see how they like that........

10-4

 

[Johnnycheese]

gearing DOES make a differance

and you have to look at curve. any Vtwin is a long flat line (hardly no curve)
so the torque is low and constant