The torque's non existing influence on cutting speed.

[SRT-Tech]

now we're talking leverage more please

 

[ciscoguy01]

Question???

one horsePOWER is the ability put out work at the rate needed to lift 33,000 pounds one foot vertically IN ONE MINUTE.

with the proper gearbox, and given enough time, a 2-ounce albino mouse could lift 33,000 pounds one foot vertically. but it couldn't be considered a one-horsepower mouse unless it could do that amount of work within one minute.

Ok, I pretty much understand that, butttttt, and here's the big BUT... I don't understand how the hp equates to torque. Reason being, think of a diesel. They'll push like 250/300 hp but put out like 900lbs/ft of torque while a car that's 300hp will only produce say 280lbs/ft of torque. How does the torque match up to hp in saws??? I.e. everyone knows huskys are dogs when it comes to torque, you lean on them a little bit and they cry like little school girl and puke out. A Stihl, least the old ones, would just keep churning away. So in other words, your gear box theory wouldn't be correct. You'd have more torque which would mean fewer teeth on your gears which would raise the 33,000lbs quicker than a saw that wouldn't have the turning torque... Get where I'm coming from? Anyone explain this clear to me???

 

[Woodie]

Wood newbie: So what happens when you hit the knot?

Easy. My chainspeed falls as well, but since I have a broader torque curve, thus producing the same moment at a given rate of speed, I have the ability to "recover" better, and my engine doesn't bog like yours does. Mine falls, but not as far, and I power through the knot without lifting. You, on the other hand, have to lift, and therefore I beat you like a rented mule.

Peter is right.

No he's not, and neither are you.

You are completely ignoring the other factor in the equation, which is chain speed. Torque is measured on a continuum; force measured at different speeds. You, on the other hand, are talking peak horsepower numbers. A number that exists ONLY at a given speed. It is abstraction past the point of usability. (Which is why I called you a Keynesian.) (He was an economist, dolt.) (And a bad one.) Because a 2-stroke chainsaw engine must run at speeds varying from approximately 2,500 - 14,000 RPM, you have a range of 11,500 RPM you must account for. Therein lies the torque curve.

Funny, they say you never understand a concept completely until you have to teach it.

Having schooled you, I feel even better about my knowledge now.

 

[ciscoguy01]

Yip

Easy. My chainspeed falls as well, but since I have a broader torque curve, thus producing the same moment at a given rate of speed, I have the ability to "recover" better, and my engine doesn't bog like yours does. Mine falls, but not as far, and I power through the knot without lifting. You, on the other hand, have to lift, and therefore I beat you like a rented mule.



No he's not, and neither are you.

You are completely ignoring the other factor in the equation, which is chain speed. Torque is measured on a continuum; force measured at different speeds. You, on the other hand, are talking peak horsepower numbers. A number that exists ONLY at a given speed. It is abstraction past the point of usability. (Which is why I called you a Keynesian.) (He was an economist, dolt.) (And a bad one.) Because a 2-stroke chainsaw engine must run at speeds varying from approximately 2,500 - 14,000 RPM, you have a range of 11,500 RPM you must account for. Therein lies the torque curve.

Funny, they say you never understand a concept completely until you have to teach it.

Having schooled you, I feel even better about my knowledge now.

It's nice to know the dolmars have figgered out how to put the torque in the whole range... lmao... :jester:

 

[Ekka]

Ok, I pretty much understand that, butttttt, and here's the big BUT... I don't understand how the hp equates to torque. Reason being, think of a diesel. They'll push like 250/300 hp but put out like 900lbs/ft of torque while a car that's 300hp will only produce say 280lbs/ft of torque. How does the torque match up to hp in saws???

HP=TORQUE * RPM / 5252

So large diesel truck engines dont rev out as much plus diesel has more compression and combustion .... imagine trying to stop the crankshaft turning on a big truck engine? Heck, some of them you can hardly even stall they got that much torque.

Then you get a car engine, you can stop it easier as it's petrol driven and lower compression and usually shorter stroked so revs out more.

The first few pages had some links I put in to how it's calculated. Basically they fit a brake assembly to the output shaft of the engine have it run flat chat and apply the brake. The amount of braking force is recorded alongs with the revs ... more brake applied revs drop and so on.

Eventually the engine stops and you got a graph of the torque curve at given rpm's ... then the formula is applied.

I think the 57cc Shindaiwa saw (577) I had which was rated 3KW may have had a longer stroke and more torque than the equivalent Husky as it didn't rev out much and I think it was only around 10,500rpm ... some of the saw guys might be able to get the bore/stroke specs and HP vs Torque specs. I bet the Husky has more HP though.

That would be a good comparison 557 Shindaiwa vs 57cc Husky in specs.

 

[RiverRat2]

Yep u R right

Lots!!! I notice it works better with a long bottle opener as opposed to a short one.

Longer handle/longerstroke produces more torque, a nice Heinie will do
But miller lite or Bud will tooo!!!!!!!!!!!!!!!

 

[amdburner]

I'll even take a Lone Star at this point. Got used to drinkin' those as I have been to Texas a few times.

Another analogy for this whole argument:
Long srew driver or short screw driver to back out a stubborn screw? For some reason I always have better luck with the long driver.

 

[ciscoguy01]

Deere

That's like the John Deere Tractors dude. I don't know if they are building the Timberjacks with 2 cylinders now, but everyone know about the that dang 8" piston with like a 16" stroke on it, lmfao. Those babies put out some serious torque eh??? opcorn:

 

[amdburner]

Damn straight cisco! My father in law has a Johnny B that is quite the torque monster.

 

[Sprig]

Ok, I pretty much understand that, butttttt, and here's the big BUT... I don't understand how the hp equates to torque. Reason being, think of a diesel. They'll push like 250/300 hp but put out like 900lbs/ft of torque while a car that's 300hp will only produce say 280lbs/ft of torque. How does the torque match up to hp in saws??? I.e. everyone knows huskys are dogs when it comes to torque, you lean on them a little bit and they cry like little school girl and puke out. A Stihl, least the old ones, would just keep churning away. So in other words, your gear box theory wouldn't be correct. You'd have more torque which would mean fewer teeth on your gears which would raise the 33,000lbs quicker than a saw that wouldn't have the turning torque... Get where I'm coming from? Anyone explain this clear to me???

Yesh, a mice on steroids and amylnitrate will have more torque that a mice without, but the heart bearings burn out faster.



opcorn: opcorn:

 

[Jim Mesthene]

.... a Keynesian.) (He was an economist, dolt.) (And a bad one.)

Funny, they say you never understand a concept completely until you have to teach it.

So, it's clear that you don't teach economics.

 

[Beweller]

Wood newbie: I'm not sure what knowledge of Keynes has to do with the characteristics of IC engines. In any event, it seems unlikely that Keynes was responsible for the Great Depression, but quite likely that he had a hand in determining its duration.


Remember, Keynes did get one thing right: that in the long run we are all dead.

 

[Woodie]

So, it's clear that you don't teach economics.

Virtually all of Keynes has been discredited. He is a relic of a bygone era...the era where FDR listened to his theories, thus keeping the US mired in the Great Depression, as Beweller correctly points out.

 

[Woodie]

Wood newbie: I'm not sure what knowledge of Keynes has to do with the characteristics of IC engines. In any event, it seems unlikely that Keynes was responsible for the Great Depression, but quite likely that he had a hand in determining its duration.

Remember, Keynes did get one thing right: that in the long run we are all dead.

My point was that taking into account only peak HP numbers was ignoring too many factors, in particular chain speed. Keynes was famous for oversimplifying things, and in doing so ignoring the effects that one change had on other factors. PLUS he ran dull chain.

BTW, my post last night, admittedly alcohol-induced, was overly snarky, and I'll apologize to you for the tone of it. It was uncalled for.

 

[Jim Mesthene]

If you laid all the economists in the world end-to-end, they still wouldn't reach a conclusion.
I really don't have a problem with Keynes being considered "wrong", so long as it's acknowledged that no economist has ever been shown to be "right".

 

[Woodie]

If you laid all the economists in the world end-to-end, they still wouldn't reach a conclusion.

I like Dorothy Parker's version better: "If all the girls who attended the Yale prom were laid end to end, I wouldn't be a bit surprised."

 

[Drive_1305]

I'll be the first to admit I don't fully understand the concepts of tourque, horsepower and how they relate to cutting wood, powering a kart or whatever. After reading some of peter399's and other's post, I realize they don't either. Here's a link to some good Kart Dyno and other tech articles that help explain the subject. http://www.foxvalleykart.com/articleindex.html

Here's a good qoute from the article ..."I heard it said once that, if you could spin it fast enough, you could get 100 horsepower out of electric pencil sharpener. But remember, without a significant amount of torque, you can't drive anything of any mass. In other words, YOU DRIVE YOUR KART WITH TORQUE, NOT HORSEPOWER."

 

[stihltech]

twist

All we need is a saw with the torque of an 090 and the speed of a 460.

 

[RiverRat2]

cool!!!!!!!!!

That ought to just about be close to your 66 hot saw then Huh????

 

[Jim Mesthene]

I've run Dynos. They don't, and can't measure horsepower, they measure torque. Then the operator (or built in electronics), uses one of several competing mathematical formulas to come up with a horsepower number.
Horsepower is torque applied for a specified time.
Torque curves are a whole different thing. Ideally we'd have steam powered saws; 100% torque at all RPMs, including zero.