ft-lb, hp...please help
Hey guys...I'm looking to add a second scoot to the stable but don't know what to choose. i want something bigger but I don't want the weight to eat up too much power.
I'm not someone that rides fast but I like sharp acceleration (being quick), fast off the line...
I've looked at the Blackline and the Nightrod, even the XR1200X.
The Fat Bob seems to have a lot of power 100ft-lb.
Please can someone explain the relationship between torque and HP?
Thanks guys
I'm not someone that rides fast but I like sharp acceleration (being quick), fast off the line...
I've looked at the Blackline and the Nightrod, even the XR1200X.
The Fat Bob seems to have a lot of power 100ft-lb.
Please can someone explain the relationship between torque and HP?
Thanks guys
Elite HDF Member
Joined: Jul 2010
Posts: 4,828
Likes: 8
There's your answer then, sounds like a Fat Bob is for you. The performance of the bikes is close enough that it really is not gonna matter all that much, more a rider issue than the bike. Harleys are not really performance minded anyway, they are more about the ride. If you wanted to maximize performance, you probably would be looking into a 'Busa or something of that nature. Just test ride a number of Harleys and see what model fits you best. Good luck with your choice, but you are going to get a Harley, so 90% of the decision is already behind you. You will enjoy it regardless of which model you chose, I'm sure.
Road Master
Joined: Dec 2005
Posts: 1,078
Likes: 5
From: Hickory, NC
Didn't really want to start this discussion again but torque is what you feel in the seat of your pants. You can NOT feel horsepower.
Horsepower as a unit of measure was determined by James Watt in 1782. By experimentation he determined that a horse could turn a mill wheel 144 times in an hour. Watts developed the horsepower as a unit of measure to use as a marketing tool to sell more steam engines (in a time when horses were still used to perform the majority of work).
Bottom line is - torque is directly measurable, horsepower is not. Horsepower is a mathematically determined number that represents the rate of performing work. As someone already pointed out, it is calculated based on torque. So, when you go to the dyno, the dyno is actually measuring the torque your bike produces and displays that directly. The horsepower curve is calculated by the aforementioned forumla and displayed on the graph.
Sorry, as part of my job I used to teach this crap and I sometimes tend to ramble about it.
Horsepower as a unit of measure was determined by James Watt in 1782. By experimentation he determined that a horse could turn a mill wheel 144 times in an hour. Watts developed the horsepower as a unit of measure to use as a marketing tool to sell more steam engines (in a time when horses were still used to perform the majority of work).
Bottom line is - torque is directly measurable, horsepower is not. Horsepower is a mathematically determined number that represents the rate of performing work. As someone already pointed out, it is calculated based on torque. So, when you go to the dyno, the dyno is actually measuring the torque your bike produces and displays that directly. The horsepower curve is calculated by the aforementioned forumla and displayed on the graph.
Sorry, as part of my job I used to teach this crap and I sometimes tend to ramble about it.
Cruiser
Joined: May 2010
Posts: 128
Likes: 0
The slipper clutches on modern sportbikes don't slip on acceleration, only when you down shift a gear too much and the rear wheel tries to overdrive the engine. The have one way dogs on them that won't allow any slippage when the engine is driving the rear wheel. Considering that a good rider can put one of the better liter bikes or a Busa or KX 1400 with 175+ rear wheel horsepower into the 9s in the quarter, I'd say they get along just fine without any slip other than the rear tire.
Cruiser
Joined: May 2010
Posts: 128
Likes: 0
Didn't really want to start this discussion again but torque is what you feel in the seat of your pants. You can NOT feel horsepower.
Horsepower as a unit of measure was determined by James Watt in 1782. By experimentation he determined that a horse could turn a mill wheel 144 times in an hour. Watts developed the horsepower as a unit of measure to use as a marketing tool to sell more steam engines (in a time when horses were still used to perform the majority of work).
Bottom line is - torque is directly measurable, horsepower is not. Horsepower is a mathematically determined number that represents the rate of performing work. As someone already pointed out, it is calculated based on torque. So, when you go to the dyno, the dyno is actually measuring the torque your bike produces and displays that directly. The horsepower curve is calculated by the aforementioned forumla and displayed on the graph.
Sorry, as part of my job I used to teach this crap and I sometimes tend to ramble about it.
Horsepower as a unit of measure was determined by James Watt in 1782. By experimentation he determined that a horse could turn a mill wheel 144 times in an hour. Watts developed the horsepower as a unit of measure to use as a marketing tool to sell more steam engines (in a time when horses were still used to perform the majority of work).
Bottom line is - torque is directly measurable, horsepower is not. Horsepower is a mathematically determined number that represents the rate of performing work. As someone already pointed out, it is calculated based on torque. So, when you go to the dyno, the dyno is actually measuring the torque your bike produces and displays that directly. The horsepower curve is calculated by the aforementioned forumla and displayed on the graph.
Sorry, as part of my job I used to teach this crap and I sometimes tend to ramble about it.
Elite HDF Member
Joined: Apr 2009
Posts: 4,082
Likes: 11
From: Long Island, NY
The 100 ft-lb found on the Fat Bob spec sheet is no more than what is listed for the WG or similar 103" motors.
When you compare numbers, you should be aware that the HD is measuring the tq at the crank, and not the rear wheel. There is a big difference.
When you compare numbers, you should be aware that the HD is measuring the tq at the crank, and not the rear wheel. There is a big difference.
http://www.harley-davidson.com/en_US....html#/c/specs
Performance
Engine Torque Testing MethodJ1349
Engine Torque 4100 ft-lb
Engine Torque (rpm)3,500
Lean Angle, Right (deg.)30
Lean Angle, Left (deg.)31
Fuel Economy: Combined City/Hwy 642 mpg
Performance
Engine Torque Testing MethodJ1349
Engine Torque 4100 ft-lb
Engine Torque (rpm)3,500
Lean Angle, Right (deg.)30
Lean Angle, Left (deg.)31
Fuel Economy: Combined City/Hwy 642 mpg
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Road Warrior
Joined: Aug 2010
Posts: 1,268
Likes: 8
From: Detroit, the asshole of America
Bottom line is - torque is directly measurable, horsepower is not. Horsepower is a mathematically determined number that represents the rate of performing work. As someone already pointed out, it is calculated based on torque. So, when you go to the dyno, the dyno is actually measuring the torque your bike produces and displays that directly. The horsepower curve is calculated by the aforementioned forumla and displayed on the graph.
Big Kahuna HDF Member
Joined: Nov 2008
Posts: 35,506
Likes: 27
From: Calgary eh
Look at the equation that sportster bob posted. It clearly shows that HP is proportional to rmp. As rpm increases the HP will increase. So to achieve maximum power you need maximum RPM.
Maximum HP is always at or very near the red line.
On the other hand Maximum torque usually occurs at mid RPM. Torque is not RPM dependent.
Torque is what you feel when you roll the throttle on at a lower RPM.
Maximum HP is always at or very near the red line.
On the other hand Maximum torque usually occurs at mid RPM. Torque is not RPM dependent.
Torque is what you feel when you roll the throttle on at a lower RPM.