What is Horsepower?

[chowdozer]

so how does the acceleration of the RPM to its' peak effect how you calculate HP? Not all engines accelerate at the same rate even if they turn the same RPM and same HP rating.

If the engine is accelerating, then the torque is accelerating the engine not the horsepower. If two engines have the same hp and the same rpm, the engine with the higher torque in the rpm area of interest will accelerate faster. I don't know if I answered the question.

 

[klickitatsacket]

If the engine is accelerating, then the torque is accelerating the engine not the horsepower. If two engines have the same hp and the same rpm, the engine with the higher torque in the rpm area of interest will accelerate faster. I don't know if I answered the question.

you did, I was just making a point about torque.

 

[Peacock]

If the engine is accelerating, then the torque is accelerating the engine not the horsepower. If two engines have the same hp and the same rpm, the engine with the higher torque in the rpm area of interest will accelerate faster. I don't know if I answered the question.

You nailed it.:rockn:

 

[ShoerFast]

Horsepower is when you wake up in the morning with a piss hard on, when pressing down your heels raise off the floor

I call that TQ, as in "every inch is a pound"

 

[RiverRat2]

Cmon Chowdozer,,,,

There's the correct answer. Horsepower is only the application of torque over a period of time.

Are you saying that HP and torque have to work together?????


Say it ain't so!!!!!!!!

Its a sad day,,, I think you've left your common folk brethern behind and actually crossed over into the prestigious realm of the "Scientific Chainsaw Community" (SCC) and don't even realize it,,,,

Chow I hate to say it but you're in,,,,,,, D E KN I A L,,,, Don't, Even, Know, I, Am, Lying!!!!!

Next thing ya know youll be buyin a 50 cc husky or Dolmar with a 13 inch bar and moving to your new residence,,,,,, Under A bridge,,,,,,,,,with your pocket pal full of gizmos and a calculator........ :notrolls2:

It's never too late to call for help dude,,,,

We're gonna miss ya!!!!! :monkey:

 

[RiverRat2]

Careful there Dean,,,,

you did, I was just making a point about torque.

You may be skating on thin ice!!!!!!!

 

[klickitatsacket]

You may be skating on thin ice!!!!!!!

:biggrinbounce2: You can not have one with out the other. However you can lean towards one over the other. Personal feeling here is that when you lean towards the torque end of the equation you will get a much wider ability to tune your bar length, raker hight, chain style and sprocket size. With a saw built towards the RPM end of the equation everything else has to be tailored to the RPM of the saw and is a lot less utilitarian.

 

[chowdozer]

Next thing ya know youll be buyin a 50 cc husky or Dolmar with a 13 inch bar and moving to your new residence,,,,,, Under A bridge,,,,,,,,,with your pocket pal full of gizmos and a calculator........ :notrolls2:

I don't think so!!! :deadhorse:

 

[RiverRat2]

Ha ha hah,,haaa!!!!

I don't think so!!! :deadhorse:

That a boy,,,,,are we having fun yet?????

 

[chowdozer]

:biggrinbounce2: You can not have one with out the other. However you can lean towards one over the other. Personal feeling here is that when you lean towards the torque end of the equation you will get a much wider ability to tune your bar length, raker hight, chain style and sprocket size. With a saw built towards the RPM end of the equation everything else has to be tailored to the RPM of the saw and is a lot less utilitarian.

I'll make a modification to your statement.

In an internal combustion engine, neither horsepower nor torque cannot exist without the other.

An example:

Ever spin a torque wrench? Then you know you can apply torque (twisting force) to a bolt and not move it. With the physics equation WRW quoted, we would generate zero horsepower no matter how much torque we applied as long as the bolt does not turn.

(Torque x bolt rpm) / 5,252 = Horsepower
so, (100 ft/lbs x 0)/5252 = Horsepower
then, 0=0 but we still applied torque - we just didn't make any horsepower.

If we plug in zero for torque
(0 ft/lbs x 0 rpm)/5252 = horsepower
0=0 it's a multiplication by zero.
There's no way we can make horsepower with the above equation because we can't accelerate from zero rpm. We can't apply a "twisting force" if torque = 0.

Now we know that horsepower is dependent on torque, but torque is not dependent on horsepower.

Sometimes it is said that the characteristics of the torque curve define how high the horsepower curve goes. Obviously, if the torque peak is low in the rpm range, top rpm will be limited but if we can move the torque curve up the rpm scale, we can generate more horsepower simply because we have more powerstrokes per minute.

So let's look at an example of a piston driven engine such as a chainsaw. The piston goes up and down. So, when ignition happens in a chainsaw, the piston and rod exhibit a torque on the crankshaft throw and the piston accelerates downward. Past mid stroke, it begins to decelerate, then the piston stops, reverses direction and accelerates to TDC. The torque applied to the crankshaft in the powerstroke establishes momentum in the crankshaft that carries the piston back to TDC.
We can now imagine that the rpm's of the saw can reach a point where the torque is unable to accelerate the piston any faster in the powerstroke. Peak rpm. But if we had a little more torque, we could spin more rpms thus creating more horsepower. Simple, eh?

It's the shape of the torque curve that defines how many rpm's your saw is going to turn and how much horsepower it's going to make.

 

[drmiller100]

horsepower is work over time.

I can lift 10,000 pounds a foot off the ground. It takes me about a day.

A 1000 horsepower engine can do that well under a second.

Horsepower can be converted into acceleration. Get a G meter gizmo that plugs into your cigarette lighter, type in the weight, and it can tell you the horsepower of the engine.

Hook up an inertial dyno to a car and it can directly measure horsepower. Hook up the RPM signal and it can COMPUTE torque.

Horsepower causes acceleration, or it can be converted to heat, or it can be converted into changing a solid log into little chips.

The term "torque" in the real world is a parody of the mechanical definition of torque. Torque in the real world really means a wide, flat horsepower curve that is very usable. It isn't finicky.

If you have a 7 pin sprocket, and want to increase your effective torque, just convert to a 6 pin sprocket.

You will cut wood a lot slower, but your "torque" will increase.

 

[Drive_1305]

I may be wrong but !!!!

I've had several college level classes in an "engineering science" program. The classes were similar to mechanical engineering- some may have even used the same books. So I think I know what Im talking about, but then again I may be wrong. The average "new" Mechanical Engineering graduate doesn't know how to apply "engineering" to real word applications and explain correctly "whats going on" good enough to engineer their way out of a wet paper bag! Even some "old" engineers don't. So when somebody says " Im a Mechanical Engineer"- that may not mean much.

The average Mechanical Engineering graduate knows how to go to class, take notes, read some "text book" problems, punch in some numbers in a calculator and come up with a "number answer" then check it in the back of the book to see if its correct! Or at least thats the way I did it and a lot of other students I know did it too.

The average Mechanical Engineer student knows mathematics- algebra, calculus, and how to "plug and chug" numbers in a formula. Most really don't know true engineering concepts that well.

 

[belgian]

I've had several college level classes in an "engineering science" program. The classes were similar to mechanical engineering- some may have even used the same books. So I think I know what Im talking about, but then again I may be wrong. The average "new" Mechanical Engineering graduate doesn't know how to apply "engineering" to real word applications and explain correctly "whats going on" good enough to engineer their way out of a wet paper bag! Even some "old" engineers don't. So when somebody says " Im a Mechanical Engineer"- that may not mean much.

The average Mechanical Engineering graduate knows how to go to class, take notes, read some "text book" problems, punch in some numbers in a calculator and come up with a "number answer" then check it in the back of the book to see if its correct! Or at least thats the way I did it and a lot of other students I know did it too.

The average Mechanical Engineer student knows mathematics- algebra, calculus, and how to "plug and chug" numbers in a formula. Most really don't know true engineering concepts that well.

I have no intention to look at your profile but I may assume you are not an engineer. :jester: And your arguments are plain stupid also, maybe you should talk to some engineers how they think about what is needed to graduate.

 

[mountainlake]

:biggrinbounce2: You can not have one with out the other. However you can lean towards one over the other. Personal feeling here is that when you lean towards the torque end of the equation you will get a much wider ability to tune your bar length, raker hight, chain style and sprocket size. With a saw built towards the RPM end of the equation everything else has to be tailored to the RPM of the saw and is a lot less utilitarian.

Well said!!! Steve

 

[RiverRat2]

Nice piece of trolling there,,,

I have no intention to look at your profile but I may assume you are not an engineer. :jester: And your arguments are plain stupid also, maybe you should talk to some engineers how they think about what is needed to graduate.

Hey Simon,,,, See what you started!!!!!!! :bang:

 

[Woodie]

No. Torque doesn't matter at all. If anyone is interested to go deep in this
discussion, read:

http://www.arboristsite.com/showthread.php?t=41214

The thread where you got owned?

 

[peter399]

The thread where you got owned?

I think the conclusions in this thread are the same as what I said in "my" thread. Seems like people did learn something after all since it took less posts this time.

 

[Woodie]

I think the conclusions in this thread are the same as what I said in "my" thread. Seems like people did learn something after all since it took less posts this time.

Maybe they did...there are certainly fewer posts, so far, in this thread.

But notice how most of them think you are wrong?

While there are many people in the current thread who have it correct, Chowdozer explains it in terms even you should understand.

 

[CylinderService]

Hydraulic Horsepower

Just to add to this mess:

We use these formulas to figure Hp.
PSI x GPM divided by 1714 gives theoretical Hp in a hydraulic system (you have to reduce the result by your efficiency loss to get a "real" number.)

For hydraulic motors we use in-lbs of Torque x RPM divided by 63025 = Hp

These can both be worked back to Watt's definition of 550 ft-lb/sec, but are easier for us to use in these forms.


Don the Hydraulics Guy

 

[peter399]

Since you wrote , then go ahead and put ZERO for torque in this physics equation WRW posted and tell me how much horsepower you have.

(Torque x Engine speed) / 5,252 = Horsepower

You're arguing physics of which there are thousands of textbooks written.

Torque has zero importance on cutting speed - does not equal - the torque is zero.

What I say is pretty much exactly what you can read in your textbooks.
POWER is the physical unit that does the work, cuts the wood during a certain time. The higher power (kW, hp), the more wood you can cut during this given time. Torque in this discussion is just derived from power and rpm.