What is Horsepower?

[Lakeside53]

Belgian:



It's all "torque"

 

[belgian]

Belgian:



It's all "torque"

LOLOLOL, Lake you've passed the stage of "correctionable" !

 

[Al Smith]

If taking the TQ-wrench idea out of the discussion helps prove your point, why do we seem to sweat more TQing the last say 1/8 of a turn then say the first 2 inches of a bolt?

The friction of a bolt is measuring the "Brake-horsepower" needed to TQ the bolt. Unless you have actualy ran the TQ on a few dozen "Torque to Yield " bolts, you would not understand the concept.

Screw fastening methods and proceedures differ greatly than a discussion of the internal combustion engine,in reference to torque.

In dealing with a bolt an old hard and fast rule applies.Righty tighty,lefty loosey.Tight is tight,too tight is broke.

 

[fuzzle]

That doesn't have anything to do with what we are discussing. With your wrench you apply a torque to the bolt by a lever and a force. They rotate together with the same speed. Hence the torque applied on the bolt by the wrench is the same as the torque applied on the wrench by the bolt.
This is however not true for combustion engines since you have gearboxes, flywheels etc. There you you can't say anything about the torque applied by the piston on the crank shaft without complete info about the whole system.
An enormous force on the piston won't help you if you don't have rpm's. Small force on piston, high rpm and a gear box will do the same thing - > What we refer to as engine torque" is of less interest.

What matters is what comes out (hp) of your black box.

What is the definition of horsepower Peter? The definition as James Watt defined it?

C'mon Peter! Are you afraid to say that

Or horsepower = (torque/time)

So Peter, everywhere that you have mentioned horsepower, we can substitute the term (torque/time)

Let's hear you say again that torque doesn't matter.

 

[ShoerFast]

Screw fastening methods and proceedures differ greatly than a discussion of the internal combustion engine,in reference to torque.

In dealing with a bolt an old hard and fast rule applies.Righty tighty,lefty loosey.Tight is tight,too tight is broke.

Al

Only hoping to defend the idea of TQ , and the use the TQ wrench as part of the discussion, as well as trying to steer the discussion into the term "brake-horsepower" as that seems to be were some took up sleeping in high-school.

Brake Horsepower , or Shaft horsepower is what pulls the chain, I see it as more of a kenitic-math. The post I was referring to wanted to remove the TQ wrench idea.

But in line with your bolt analogy, bolt TQ is the measurement of friction in an inclined plane (bolt threads) or "work" Torque to yield bolts measure the amount of friction change (work change) as the bolt stretches.

 

[NovaMan]

Work = force x distance
Torque = force x lever arm ("lever arm" is a distance, so what does that tell you?)
Power = work divided by time

Consider the chain. The saw has to apply enough force to the chain so that the cutters slice wood out of the cut. Pulling the cutters through the wood achieves distance - the cutter starts at one end of the cut and goes to the other. Here we have force and distance; multiply them and that's the amount of work your saw has done, and that same value is the torque which your saw must have. You also want this to happen in a fairly short period of time; divide the work you have to do by the time you want to do it in, and that's the power you need.
So, to recap: the saw has to supply sufficient torque so that the cutters slice and move, and the chain has to be moving fast enough so that the cut doesn't take forever, which takes power. You have no cut at all without torque, and you have no speed without power.

 

[SawTroll]

What really is important for cutting speed is chain speed, and the efficiency of the chain - but you need torque to keep the chain speed (and engine speed) up.....

Hp is a function of torque and engine speed, not chain speed - the size of the sprocket desides how those speeds relate, and how much torque you need to keep them up.

 

[NovaMan]

Hp is a function of torque and engine speed, not chain speed - the size of the sprocket desides how they relate.

Right. I was taking a different approach to the discussion by considering the chain and then relating that to the saw engine. You're right that the sprocket is between the two, but I was trying to keep things simple, especially since the sprocket turns at the same RPM as the saw engine.
Edit: this is the perfect example of what we're saying! You could have a huge sprocket so that your chain speed would be sky-high, but the force applied to the chain would probably not be enough to pull a cutter through wood... unless your saw had heaps and heaps of torque.

 

[ShoerFast]

What really is important for cutting speed is chain speed, and the efficiency of the chain - but you need torque to keep the chain speed (and engine speed) up.....

Hp is a function of torque and engine speed, not chain speed - the size of the sprocket desides how those speeds relate, and how much torque you need to keep them up.

Troll

Good point

The last saw I sold as a dealer was an 028 Super to my Dad, My Dad recently ran my Brother In-laws 044 and it brought back the days when having the sharpest chain was not as important as hanging on,,,,back in the old 2-man Mall days when you could count the cutters as they went by.

My Dad was very impressed with what you could get away with for chain sharpness, something I guess I have become accustom to from my ex-310 to my 361 , as the extra TQ will replace a slightly dull chain. I think the 361 is cheaper to operate as your not touching the chain up every-other fill.

 

[NovaMan]

Come to think of it, you could have a monstrously torquey engine which runs at low RPM and therefore has low HP (like a diesel or a big V8), but gear it and sprocket it so that you have good cutter speed. So maybe torque IS all that matters... for the engine. You just have to convert the engine torque into a good balance of chain speed and force applied to the chain.

 

[sperho]

Holy crap, stop wondering which is more important. Horsepower is some constant (550) time ft.lbs. per unit time (second). Expressed another way, torque per unit time or work per unit time, or power per unit time or watts per unit time, etc.

If you want to a lot of work with a small amount of torque per minute, your engine better be turning high RPMs to do so. Think chainsaw. If you want to run all day, day in, day out, you design an engine to run slowly, but make it generate tons of torque to get gobs of work done per unit time (think excavator or semi or farm tractor). Torque and horsepower are related to each other, pure and simple.

 

[Jim Mesthene]

horsepower = (torque/time)

As I said:
Horsepower is a calculation of torque applied over time. Different formulae give different numbers.

The R part of RPM is irrelevant, the M part is what counts.

 

[Al Smith]

But in line with your bolt analogy, bolt TQ is the measurement of friction in an inclined plane (bolt threads) or "work" Torque to yield bolts measure the amount of friction change (work change) as the bolt stretches.

I can't argue a bit on the bolt theory.FWIW this little portion of physics plays a big part in what I get paid to do.Do the words Atlas Copco or FEC ring a bell?

 

[ShoerFast]

Come to think of it, you could have a monstrously torquey engine which runs at low RPM and therefore has low HP (like a diesel or a big V8), but gear it and sprocket it so that you have good cutter speed. So maybe torque IS all that matters... for the engine. You just have to convert the engine torque into a good balance of chain speed and force applied to the chain.

Stalling the engine, or were the fun stops is all that is important, at a point before that, we are running engines at peak temperature, peak combustion pressure, peak VE (volumetric effeminacy) lower cooling fan drag, lower bar-chain drag and less adverse chain vibration,,,,, IOW= peak effeminacy or max power.

Using a pony brake system instead of "engineer HP" is dwelling in the real world, or making chips.

Stihl the best CS dyno is log and a stop watch, we can determine Best "H" setting, Best chain or chain angles, best DG setting, Best cutting technique, Best fuel or octane rating, Best mods, muffler , port or ignition timing changes and we don't need a engineer to argue the results with.

 

[fuzzle]

As I said:
Horsepower is a calculation of torque applied over time. Different formulae give different numbers.

The R part of RPM is irrelevant, the M part is what counts.

The R and the M in rpm are both relevant. If the equation could be made simpler, it already would be.
It makes a big difference whether the engine turns 5K rpm or 10K rpm.

 

[ShoerFast]

I can't argue a bit on the bolt theory.FWIW this little portion of physics plays a big part in what I get paid to do.Do the words Atlas Copco or FEC ring a bell?

It rings a bell, I have done work for a company called MTI* (mining technologies institute) were we did a lot of specialty equipment, have we meet?

*MTI bought out Clark EQ near I-25 and I-70 in Denver CO., and then was latter bought out by a Canadian company and moved to Sudesbury Canadia

 

[ShoerFast]

The R and the M in rpm are both relevant. If the equation could be made simpler, it already would be.
It makes a big difference whether the engine turns 5K rpm or 10K rpm.

Yes they are, just as important as V x A = Watts

 

[mountainlake]

Can any one tell me why Husky has come out with Xtra torque saws lately? I must not be the only one that likes a torquey saw. Steve

 

[Canyon Angler]

The amount of power required to lift 33,000# one foot vertically in one minute. So what?








I see everyone has carefully skirted the suckback controversy in this thread.

 

[spacemule]

I see everyone has carefully skirted the suckback controversy in this thread.

We'll deal with suckback after we've taken care of blowhard.