Can someone explain horsepower ratings to me? Other than my spyder i have two bikes: a triumph sprint and a triumph tiger. Each has the same 1050 cc engine but the sprint is 125 hp and the tiger 115 hp. ( they call it bhp not sure what the "b" stands for). And they talk about torque which i suppose tells more about the speed of the bike than horsepower does? Is weight of the bike factored into any power descriptors? What is spyder horse power, being almost 1000 cc bike it should be similar to the triumphs?
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Horsepower
- Thread starter tnfleming
- Start date
bone crusher
Alignment Specialist
Torque takes you from 0-60 and what takes you from there tends to be the hp...this is the easy way to remember the difference...torque will also create a lot of problems when it's wet out and you're driving a sports car...(wheel spin)...
There are cruisers with 1800cc and only 105 hp! Go figure...the cc doesn't translate directly into any hp numbers...
You'll get more technical answers here but I have learned not to link the two...the fastest sports bikes have around 190hp but the cubic centimeter displacement of the engine is not more than 1800 in most cases...
The bhp (brake horsepower) is the hp rating of your engine by itself. For example your bhp and rear wheel hp ratings would be different because you lose hp in the drive train.
Torque is the power delivery to the drive wheels. More torque gives you better acceleration or pulling power.
ataDude
Mod Maniac
Firefly
Active member
Simply put, when an engines energy output is rated on a dynomometer, foot pounds of torque is the measurement obtained. Horsepower is only a calculation obtained from measured torque and RPM. Torque is the acceleration you feel, horsepower isn't. Here is a Spyder dyno run posted last fall
If you look at the torque curve, you'll see that the Rotax makes the best power between 5200-7200RPM. Although the horsepower continues to climb, the rate of acceleration actually slows because torque is falling off. So not only is the peak torque number important, the "shape" of the torque curve is equally important. When torque rises quickly to a peak, and stays in a longer, 'flatter' line, the engine will maintain acceleration longer in the RPM band....
The reason the same engine may have different ratings in another application can be varied. Different heads, pistons, compression ratios, valves, cams, throttle bodies, exhaust systems, transmission and final drive ratios, etc. will all have an effect on measured rear wheel torque
Those numbers seem low compared to what BRP advertises - 77 T and 106 HP. They really should do that chart with colors that don't look so much alike - man if that Blue line was the torque---- that would ROCK.
mike3069
New member
I had a discusion with the Rotax liason to BRP, Marcus Zimmerman at the Homecoming event last summer. He has been working with this basic motor since before it was first released as the Apprillia Milli, for both street and GP raceing. He told me that in the Mille street version the motor rates at ~145 hp, and in the full race version ~185 hp.
In these versions the hp and torque curves would show much sharper peaks and a much shorter overlap, most likly higher in the RPM range.
This would result in a more explosive burst of power over a smaller range of RPM.
Having raced high performance shifterkarts for a number of years, I speak from some personal experiance when I say that the sharper and shorter the peaks and overlap, the harder the vehicle is to keep under control (driveability).
The changes made to the powerband in our :spyder2: version result in a VERY large RPM range of USABLE powerband, resulting in a motor that is very easy to drive without being hard to control.
My personal opinion, witch I told to Mr. Zimmerman, is that ROTAX has absolutely nailed the power curves on this motor version and have given us a very comfortable and USABLE (driveable) setup.
In these versions the hp and torque curves would show much sharper peaks and a much shorter overlap, most likly higher in the RPM range.
This would result in a more explosive burst of power over a smaller range of RPM.
Having raced high performance shifterkarts for a number of years, I speak from some personal experiance when I say that the sharper and shorter the peaks and overlap, the harder the vehicle is to keep under control (driveability).
The changes made to the powerband in our :spyder2: version result in a VERY large RPM range of USABLE powerband, resulting in a motor that is very easy to drive without being hard to control.
My personal opinion, witch I told to Mr. Zimmerman, is that ROTAX has absolutely nailed the power curves on this motor version and have given us a very comfortable and USABLE (driveable) setup.
NancysToy
Motorbike Professor
Think of horsepower as the bragging rights (or the advertising) and the torque as what you feel in the seat of your pants.
:agree: They did very well!
-Scotty
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