Need to be schooled-HP

[DaveOTZ]

So was lookin around the HD dealer and talked about the Buel Ullyses also the XR1200... Asked about the test ride... The guy knew that I had an FZ6 at 98HP and he said that just jumping on a XR1200 was going to be a lot different... this was also after discussing the low end torque of a V-Twin... He said the 88HP put out by the XR1200 was a lot of bike to handle and wasn't easy to tame...
OK I get the torque issue really I do Ive been riding for years, but I would tend to think that riding a 98HP bike would prepare me for most bikes, this "beast" included...
Is this guy just a douche???

 

[Wavex]

I don't think he's a douche. Better safe then sorry

I don't think you'll have issues though... just don't WOT it without being prepared for it. The difference with a lot of torque (at equivalent HP) is that the peak power -or most of it- comes right away, without the smooth ramp up of an I4. That's all.

 

[DaveOTZ]

I don't think he's a douche. Better safe then sorry

I don't think you'll have issues though... just don't WOT it without being prepared for it. The difference with a lot of torque (at equivalent HP) is that the peak power -or most of it- comes right away, without the smooth ramp up of an I4. That's all.

So apart from when the power hits the bike will ultimately not be this rocket from hell as compared to my FZ right?? He kind of made it seem like I was driving there on a Vespa.

 

[jtarkany]

I doubt he's a douche, more likely he knows less about the FZ6 than you do about the 1200.

 

[MRGM]

Horsepower is going to usually come at a higher RPM because HP is a measure of power over time. Torque is the ability to turn something about an axis. Our bikes make good HP at a high rpm, but this is at the expense of low end torque. It's hard to get both.

 

[macem29]

anyone who has a chance to see a dyno in operation should spare some time
and do it, very educational...torque and HP are the same thing, sort of, torque
is twisting effort, HP is twisting effort expressed over time, ie: peak torque is
usually not at maximum governed speed, but peak HP always is, because that
increased RPM allows more work to be done in a given time frame, torque curve
is a more meaningful topic in that it shows graphically how an engine builds
torque through acceleration... have a look at this chart, you can see a dead
spot in the curve from around 5-7K, does this match what you feel? and peak
torque is at 10K, but the engine pulls strong after that....that's the work over
time thingy (HP)....also on the chart in an SV650-Vtwin, more linear -straight
torque curve up to around 8K, then it falls off sharply, nearing redline the torque
curve has dropped off the map, but the FZ6 is still twisting pretty well, and with
a 2K higher redline, it's got got more twisting over time in it, that's why you'll
blow away a Vtwin at high speeds, higher torque and HP at speed

I know this has nothing directly to do with your 1200 question,
but I like to talk about this stuff

edit: looks like we were typing at the same time

 

[RJ2112]

The XR1200 is considerably heavier than the FZ6, isn't it? Longer wheelbase, too. Slower steering, etc, etc.

The oomph just comes on at a lower RPM and goes away about where the FZ wakes up. All in all, I'd think the XR is a pokier bike with a more friendly power band. If you don't want to wrap a motor out to get the ponies, it's probably a really good steed.

 

[youngy]

bhp = (rpm x lbft)/5252

So the faster you can spin the motor (without it going pop), the more bhp you can get.

But the more torque you have in the first place means you can generate the same bhp at lower revs.

More displacement = more torque.

 

[Wavex]

So apart from when the power hits the bike will ultimately not be this rocket from hell as compared to my FZ right?? He kind of made it seem like I was driving there on a Vespa.

FZ6 max "pull" is at 10.5k, with 45ft/lb of torque...

XR1200 has more torque than that below 4k......... and keeps giving...

Now the bike is heavier has less overall HP, so again the actual "feel" on the bike is difficult to predict accurately... it should be quite a lot of fun though.... My Buell's torque is almost flat across the power band... which means I have access to most the power at any rpm.

 

[afpreppie04]

Sort of going off-topic here, but Wavex, was there much of an insurance hike when you went from the FZ6 to something with twice the displacement, or did you just tell them to think of it as a Harley?

 

[The Toecutter]

The word horsepower was introduced by James Watt, the inventor of the steam engine in about 1775. Watt learned that "a strong horse could lift 150 pounds a height of 220 feet in 1 minute." One horsepower is also commonly expressed as 550 pounds one foot in one second or 33,000 pounds one foot in one minute. These are just different ways of saying the same thing. Notice these definitions includes force (pounds), distance (feet), and time, (minute, second). A horse could hold weight in a static position but this would not be considered horsepower, it would be similar to what we call torque. Adding time and distance to a static force (or to torque) results in horsepower. RPM, revolutions (distance) per minute (time), is today's equivalent of time and distance. Back to horses, imagine a horse raising coal out of a coal mine. A horse exerting one horsepower could raise 550 pounds of coal one foot every second.

Here is an example of another way horsepower could be directly measured. Say you have a horse hitched to a plow. In the hitch is a spring scale (like a fish scale). The horse pulls the plow one foot every second and you see 550 pounds on the scale. That horse would be generating one horsepower.

We see horsepower can be directly measured. However there is a problem directly measuring horsepower of modern day internal combustion engines because they produce rotary motion not linear motion, and unless the engine is geared down, the speed at which they do work (time and distance or RPM) is too great for practical direct measurement of horsepower. It seems logical then that the solution was to directly measure torque (rotational force eventually expressed in pounds at one foot radius) and RPM (time and distance, i.e. distance in circumference at the one foot radius) and from these calculate horsepower. Torque and RPM are easily measured directly. Early dynamometers used a brake device to load the engine. A torque arm was attached to this brake's stator. The brake's rotor was coupled to the engine's crankshaft. A spring scale or other measuring device connected the torque arm to the stationary fixture holding the engine and brake. During a test the brake's application loaded the engine. Torque and engine rpm were observed and recorded. Click here for a description of how this happens on our dyno.

On modern day dynamometers horsepower is a calculated value. It's important to remember the dyno measures torque and rpm and then from these calculates horsepower. On the dyno it takes more water flow to the water brake to increase the load on the engine being tested. As the test engine's torque rises more water flow is needed. As the test engine's torque drops less water flow is needed. The dyno's water brake does not respond to Horsepower. Major adjustments to water flow are needed as an engine crosses its torque peak but none are needed as it crosses its horsepower peak. In other words the water flow to the brake during a dyno test follows the engines torque curve and not its horsepower curve. Torque is what twists the tire, prop, or pump. Horsepower helps us understand an amount or quantity of torque. (Torque + time and distance)

Now if we are measuring torque and RPM how can we calculate horsepower? Where does the equation HP=TORQUE X RPM / 5252 come from? We will use Watts observation of one horsepower as 150 pounds, 220 feet in one minute. First we need express 150 pounds of force as foot pounds torque.

(The * symbol means multiply in the explanations below.)

Pretend the force of 150 pounds is "applied" tangentially to a one foot radius circle. This would be 150 foot pounds torque.
Next we need to express 220 feet in one minute as RPM.

The circumference of a one foot radius circle is 6.283186 feet. ft. (Pi * diameter; 3.141593 * 2 feet)
The distance of 220 feet, divided by 6.283185 feet, gives us a RPM of 35.014.
We are then talking about 150 pounds of force (150 foot pounds torque), 35 RPM, and one horsepower.

Constant (X) = 150 ft.lbs. * 35.014 RPM / 1hp

35.014 * 150 / 1 = 5252.1

5252 is the constant.

So then hp = torque * RPM / 5252


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Here is another way; Remember we know 150 foot pounds and 35.014 RPM = one horsepower

1hp is to 150 ft.lbs. * 35.014 RPM as X hp is to observed ft.lbs.torque * observed RPM

Example; We dyno test and observe 400 ft.lbs. torque at 5000 RPM

1 hp is to 150 ft.lbs. * 35.014 RPM as X hp is to 400 ft.lbs. * 5000 RPM

When we cross multiply X hp * (150 ft.lbs. * 35.014 RPM) = 1hp * (400 ft.lbs. * 5000 RPM)

X hp * (5252 ft.lbs. RPM) = 1 hp * (2,000,000 ft.lbs. RPM)

Divide both sides by 5252 ft.lbs. RPM

X hp = 1 hp * 380.80

X hp = 380.80 hp

Horsepower = torque X rpm / 5252

:rockon::rockon:

 

[Cali rider]

The word horsepower....SNIPPED:rockon::rockon:

If you are going to copy and paste from another site, just post the link directly. :ban:
RevSearch Engine Dyno; Torque vs Horsepower

 

[The Toecutter]

If you are going to copy and paste from another site, just post the link directly. :ban:
RevSearch Engine Dyno; Torque vs Horsepower

It would have been easier but I cut out the useless stuff this way!!