V Rod engine
Sorry, but it sounds like a couple of you haven't thought the "torque" thing all the way through. There are common misunderstandings about torque, horsepower, and what moves a vehicle down the road.
Let's take a 103" with 92 torque at 3000 rpm, and compare it to a V-Rod with 83 torque at 6750 rpm.
Since the V-Rod is turning roughly twice the rpm at it's torque peak, you can have twice the gear reduction between the engine and the rear wheel at the same vehicle speed. Twice the gear reduction means that the rear-wheel torque is doubled. The amount of rear-wheel torque is what's responsible for accelerating the bike, all other things being equal, and that's why a bike accelerates much faster in 1st gear than it does in 3rd. 1st has a larger gear reduction.
So the bottom line is that a bike with the V-Rod engine will deliver about twice as much torque to the rear wheel, compared to the 103, if both bikes are going down the road at the same speed, and both engines are running at their peak-torque rpm.
Engine torque by itself doesn't mean much, until you factor in the rpm where it makes that torque. Once you do that, by jimminy , you're suddenly talking about horsepower. That's why horsepower is the common measure of how much "work" an engine can do, and why a tiny engine with very low torque, screaming at 15000 rpm, can leave a Harley in the dust, even if both bikes weighed the same.
To put it a different way: If an engine made peak torque at 10 rpm, it would need 27,600 foot pounds of torque to make the same power as the Harley 103 does at it's 3000 rpm torque peak.
Let's take a 103" with 92 torque at 3000 rpm, and compare it to a V-Rod with 83 torque at 6750 rpm.
Since the V-Rod is turning roughly twice the rpm at it's torque peak, you can have twice the gear reduction between the engine and the rear wheel at the same vehicle speed. Twice the gear reduction means that the rear-wheel torque is doubled. The amount of rear-wheel torque is what's responsible for accelerating the bike, all other things being equal, and that's why a bike accelerates much faster in 1st gear than it does in 3rd. 1st has a larger gear reduction.
So the bottom line is that a bike with the V-Rod engine will deliver about twice as much torque to the rear wheel, compared to the 103, if both bikes are going down the road at the same speed, and both engines are running at their peak-torque rpm.
Engine torque by itself doesn't mean much, until you factor in the rpm where it makes that torque. Once you do that, by jimminy , you're suddenly talking about horsepower. That's why horsepower is the common measure of how much "work" an engine can do, and why a tiny engine with very low torque, screaming at 15000 rpm, can leave a Harley in the dust, even if both bikes weighed the same.
To put it a different way: If an engine made peak torque at 10 rpm, it would need 27,600 foot pounds of torque to make the same power as the Harley 103 does at it's 3000 rpm torque peak.
As I wrote in the previous post, if you change the gear ratio enough to produce the equal amount of torque, you would need some extra transmission gears to drive at normal speeds. This extra gears, would counteract the original gear reduction. What you are talking about is similar to those big rig trucks that shift gears five or six times just to get to the end of the block.
Besides that, gear reductions rob power, so you wouldn't get the full advantage anyway,
Now, back to the regularly scheduled program. V-Rod engine in a Dyna.
Performance would be cool, but it wouldn't look very good. The motor is just too long front to back.
Outstanding HDF Member
Joined: Aug 2012
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From: Detroit
No, as an engineer, I understand torque quite well.
As I wrote in the previous post, if you change the gear ratio enough to produce the equal amount of torque, you would need some extra transmission gears to drive at normal speeds. This extra gears, would counteract the original gear reduction. What you are talking about is similar to those big rig trucks that shift gears five or six times just to get to the end of the block.
As I wrote in the previous post, if you change the gear ratio enough to produce the equal amount of torque, you would need some extra transmission gears to drive at normal speeds. This extra gears, would counteract the original gear reduction. What you are talking about is similar to those big rig trucks that shift gears five or six times just to get to the end of the block.
Big rig trucks have 13-plus speed transmissions because the engine is designed to operate in a very narrow power band, like between 1900 and 2300 rpm. V-Rod engines have a much broader power band.
So do gear overdrives. No current Harley has a 1:1 final drive ratio anyway, so that's kind of a moot point.
Last edited by Warp Factor; Dec 7, 2013 at 12:48 PM.
Sorry, but you are mistaken. Twice the rpm, at twice the gear reduction, equals the same speed.
Big rig trucks have 13-plus speed transmissions because the engine is designed to operate in a very narrow power band, like between 1900 and 2300 rpm. V-Rod engines have a much broader power band.
Big rig trucks have 13-plus speed transmissions because the engine is designed to operate in a very narrow power band, like between 1900 and 2300 rpm. V-Rod engines have a much broader power band.
Believe what you want, but cutting your gear ratios in half so you can ride around at 6700 RPM to double your peak torque is impractical at best. Secondly, cutting the ratios means reducing the speed capability of the bike in any particular gear. Thus, you would need more gears to reach normal top speeds. And finally, the additional gears would negate the ratio change in the upper gears.
Last edited by SLV; Dec 7, 2013 at 12:52 PM.
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Joined: Aug 2012
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From: Detroit
Whatever. I'm not going to get sucked into one of your famous forum debates. This will be my last post in this thread.
Believe what you want, but cutting your gear ratios in half so you can ride around at 6700 RPM to double your peak torque is impractical at best. Secondly, cutting the ratios means reducing the speed capability of the bike in any particular gear. Thus, you would need more gears to reach normal top speeds. And finally, the additional gears would negate the ratio change in the upper gears.
Believe what you want, but cutting your gear ratios in half so you can ride around at 6700 RPM to double your peak torque is impractical at best. Secondly, cutting the ratios means reducing the speed capability of the bike in any particular gear. Thus, you would need more gears to reach normal top speeds. And finally, the additional gears would negate the ratio change in the upper gears.
Last edited by Warp Factor; Dec 7, 2013 at 01:02 PM.
Road Captain
Joined: Aug 2012
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From: +^
Whatever. I'm not going to get sucked into one of your famous forum debates. This will be my last post in this thread.
Believe what you want, but cutting your gear ratios in half so you can ride around at 6700 RPM to double your peak torque is impractical at best. Secondly, cutting the ratios means reducing the speed capability of the bike in any particular gear. Thus, you would need more gears to reach normal top speeds. And finally, the additional gears would negate the ratio change in the upper gears.
Believe what you want, but cutting your gear ratios in half so you can ride around at 6700 RPM to double your peak torque is impractical at best. Secondly, cutting the ratios means reducing the speed capability of the bike in any particular gear. Thus, you would need more gears to reach normal top speeds. And finally, the additional gears would negate the ratio change in the upper gears.
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Joined: Aug 2012
Posts: 3,217
Likes: 90
From: Detroit
I can understand if it's tough for some people to get on board with things like "the earth isn't really flat", and "Christmas presents aren't really delivered by Santa Clause coming down the chimney", but I'm satisfied that it's their problem more than mine.
Nevertheless, I feel kinda bad for little kids who cry when they find out that Santa Clause isn't real.
Last edited by Warp Factor; Dec 7, 2013 at 03:22 PM.
ou don't have to be insulting, why don't you **** off.
Tourer
Joined: Oct 2013
Posts: 344
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From: WMass
Regardless, y'all can argue the tongue thing all day.
All that matters is, with it's lower torque numbers, the Vrod still walks all over Big Twins, without even breaking a sweat.
While I love numbers, and math, there is MUCH more to the picture than specific torque output.
Street Rod in motion.... More betterer than a regular Vrod.
Sorry for the link, trying to do this from an iPad, and quite haven't figured it out yet....
Chase
All that matters is, with it's lower torque numbers, the Vrod still walks all over Big Twins, without even breaking a sweat.
While I love numbers, and math, there is MUCH more to the picture than specific torque output.
Street Rod in motion.... More betterer than a regular Vrod.
Sorry for the link, trying to do this from an iPad, and quite haven't figured it out yet....
Chase
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Tourer
Joined: Nov 2012
Posts: 496
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From: Columbia sc
Same old arguments about the "lack of torque" every time this subject comes up concerning the vrod engine. It's a good thing I put over 30000 miles on one myself to realize that's much more of a perception than a reality out on the road. The horsepower and rpm capability of that engine cancel that argument out with ease. I weigh in at 350+ and never had any problem from a "lack of torque" riding at any speed, slow or fast with it. Put it in the right gear and it's smooth and powerful, just what I want.
And no, I'm not going to debate the issue either.
And no, I'm not going to debate the issue either.