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Hp number vs torque number on the pto

tundra

tundra

TY 4 Stroke Junkie
Joined
May 11, 2003
Messages
737
Location
Saguenay , Quebec
what is the real hp number from our stock sled.

Is the reduction gear raise the power output to the driveline. I assume he does on torque number. If so, we have some kind of 100 lbs/ft of torque at his max.

It's is true or i'm dreaming :?: 8)

where is the truth between 130 and 145hp .

i has take some drag(nothing serious) with almost and most powerful mountain sled,(semi-hard snow) and when i'm not taking the lead, i'm so close behind. Many people said that RX-1 isn't that much powerful, somewhat like 130 hp, i hope this is wrong because the drag result of many of our. :?
 

You also have to remember that a dyno done at say 6000' is not the same as one done at sea level. More HP at sea level because higher oxygen density.
 
Here's the lowdown on horsepower vs torque:

Horsepower is independant of rotating speed. 1 horsepower is defined as the ability to LIFT ONE POUND ONE FOOT IN ONE MINUTE. 100 hp can lift 100 pounds one foot in one minute.

Torque is defined as the torsional force produced by a rotating shaft. It is measured at a particular distance out from the center of the shaft in the direction perpendicular to the line out from the shaft.

Gear reduction affects torque, but not horsepower. If you reduce the gearing to 50% based on rpms, the torque is exactly DOUBLED. At the same time, horsepower is NOT affected.

Theoretically, with infinite gear reduction, you can achieve infinite torque.

Torque can be calculated with the knowledge of TWO things; 1) Horsepower, 2) RPM.


PTO SHAFT TORQUE IS IRRELEVANT!!! The only measurable torque on a sled that IS relevant is the DRIVESHAFT torque.

As the clutches shift into a higher gear, the torque at the driveshaft diminishes. At peak speed, the driveshaft torque is exactly equal to the force of friction.






Next lesson: How to spell your name in BINARY.
 
LB, is that how AC measures horsepower :shock: ??? For a Yamaha and the rest of the world the formula is : 1 horsepower = 550 ft. lb. / second. :oops: Roadrunner is my name, fast Mopars are my game.
 
Machinery Handbook say that also 550lbf-ft by sec

When you Dyno sled, the power is where ... at the track , at the output of the driveline, or at the pto of the motor.

Youre not taking apart the motor ? is the hp figure claim by yamaha was motor on table directly on pto or something else.

I dont know many thing on motor, all i know is somekind of theory that you learn at school(university and CEgep)

Like, we cannot just take the peak in consideration, because 4stroke has much power under the curve than 2 stroke. Kind of mathematical application, Integral of the powercurve. I'm very in quest of knowledge about motor, not how to repair them, but how they really work :?: :lol:
 
Roadrunner said:
LB, is that how AC measures horsepower :shock: ??? For a Yamaha and the rest of the world the formula is : 1 horsepower = 550 ft. lb. / second. :oops: Roadrunner is my name, fast Mopars are my game.
Click to expand...

That is the same definition of horsepower, written differently. Think about it like this:

Acceleration (gravity) = Distance / Time^2
Force (gravity) = Mass (subject to gravity) * Acceleration (gravity)
Power = Force * Time

Therefore:
Power = Mass * Distance / Time
Notice that FOOT = Distance, POUND = Mass, SECOND = time.
 
Great posts LB. It seems there is a little confusion on the issue of horsepower=1ft lb/s or 550ft lb/s. In a way both are correct.

Simply put Horsepower=torque*rpm/5252. If you don't believe this look at any dyno graph and you'll see that at 5252 rpms the torqe curve and hp curve cross. From what I understand, a dynameter determines torque and hp is just calculated.

Now for more info on horsepower. Way back when an engineer name James Watt came to the conclusion that 1 horse could lift 33,000 lbs of coal 1 ft in 1 minute. Or 550 lbs 1 ft in 1 sec (33,000/60=550), hence the definition of horsepower. Now your crankshaft doesn't do much coal lifting. Your crank is twisting and 1 horsepower is the force it takes to support a one pound weight one foot from the fulcrum (assuming a weightless bar). Now if you rotate that 1 full turn you have moved that 1lb mass 6.2832 ft (2*pi*radius). (NOTE: If you remove 1lb of rotating mass, you have 1 more hp not wasted that can go to your track. Also if you remove 6.28lbs of mass you have an extra pony to move you.) Now if we moved that 1lb mass 6.28 ft we have done 6.28ft lbs of work in one revolution. Now divide 33,000 ft lb/min by 6.2832 ft lbs/revolution you get 5252 revolutions/minute or RPMs. In otherwords 1 ft lb of torque at 5252 RPMs = 1 horsepower (33,000 ft lb/min).

Now throw in gearing and a CVT and you complicate things more.

Hope this helps rather than confuse everyone :? .
 
Tundra, to answer your question, the HP figures quoted by Yamaha and all the other sled mfgs. are measured at the engine output shaft (not the track, or jackshaft).
 
I knew I should remember those physics lectures.
Force = MxA, Hp =(T x RPM)/5252 ............. This is what makes this site GREAT, we have people with both practical and theoretical info, and even apply it and report successess and failures. On so many other sites it is only, "my sled is faster.........YOU stink etc" Thanks, its fun to think with you guys.
I have way to much time on my hands.......It needs to snow!!!! Yamadoo
 
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