The torque's non existing influence on cutting speed.

[ShoerFast]

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.

Jim

Yes

Even automatic transmissions are a crude HP estimator. Taking governor pressure (from flyweights on the out put) , Engine load (from the vacuum modulator) , and Throttle position (from the kick-down linkage) And with that set the shift points.

In another example, if there were a machine that could measure how far a horse could lift a , for a say, say #550 pound weight , with a Sharpe attached to it, and it drew a line on a foot wide roll of paper. If the roll of paper moved at one foot in one second, the line would be at 45 deg. for one horse.

 

[peter399]

Peter is correct. Power is torque times speed. Power is the rate of doing work.

The more powerful saw can drive the chain faster at a given load (torque), or it can drive a higher load at the same speed. Either way the more powerful saw will cut faster. The greater power can be matched to the job by the "gear ratio" (number of sproket teeth), the pitch of the chain or the depth of the cut.

Couldn't have said it better myself. Congratulations beweller!

- Peter

 

[peter399]

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. .

Wrong. For getting through the knot, work has to be done. And the more powerful saw can do that work faster because of higher (chain)speed at the
same torque (applied to drive sprocket by the knot!)

No he's not, and neither are you. .

Yes I am. Yes he is.

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.
.

No. Therein lies the POWERcurve. The integral of the power curve by rpm that you use in the cut should be as big as possible. I must say I find your numbers a bit wide. Do you operate at 2500? For me idle power is not important. Chainsaws should be operated throttle wide open.

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.

I'm glad you feel better, although your knowledge is false and that you haven't schooled us.

I think we can sum up and close this thread now. It's up to each one to either accept facts or you can use a 3000 lbs steam machine that also makes 3hp but a lot of torque, put on a 1:100 gearbox, drive sprocket, bar and chain and be happy with it. As long as everyone is happy, that's fine. You don't have to be a rocket scientist to operate a chainsaw which I think you all do very well since you spend time on AS. The idea was to bring the topic into the light, which I must say succeeded although the outcome could have been better.

/Peter

 

[chowdozer]

I think we can sum up and close this thread now. It's up to each one to either accept facts or you can use a 3000 lbs steam machine that also makes 3hp but a lot of torque, put on a 1:100 gearbox, drive sprocket, bar and chain and be happy with it. As long as everyone is happy, that's fine. You don't have to be a rocket scientist to operate a chainsaw which I think you all do very well since you spend time on AS. The idea was to bring the topic into the light, which I must say succeeded although the outcome could have been better.

/Peter

Not so fast to abandon the thread there, sugar.

The title of the thread you started is "The torque's non existing influence on cutting speed. "

Now you want to leave this thread by saying:

It's up to each one to either accept facts or you can use a 3000 lbs steam machine that also makes 3hp but a lot of torque, put on a 1:100 gearbox, drive sprocket, bar and chain and be happy with it. /Peter

Uh-oh. Trapped by your own words. I hate when that happens.

One of your above statements is false. See, if torque doesn't have an influence on cutting speed as you stated in your thread title, then it would be irrelevant as to how much torque the steam engine could generate in your example, wouldn't it? But the fact is, the more torque you can generate, the higher gear you can run, and the faster you can cut.

That's ok, we all knew the truth but it was a good review session. We were just waiting for you to catch on.

 

[RiverRat2]

opcorn: opcorn: opcorn: opcorn:
Here we go again!!!!!!!!!

Peter, have you ever run a saw thats bigger than your 262 XPG???????

 

[peter399]

Not so fast to abandon the thread there, sugar.

The title of the thread you started is "The torque's non existing influence on cutting speed. "

Now you want to leave this thread by saying:


Uh-oh. Trapped by your own words. I hate when that happens.

One of your above statements is false. See, if torque doesn't have an influence on cutting speed as you stated in your thread title, then it would be irrelevant as to how much torque the steam engine could generate in your example, wouldn't it? But the fact is, the more torque you can generate, the higher gear you can run, and the faster you can cut.

That's ok, we all knew the truth but it was a good review session. We were just waiting for you to catch on.

Why should I be trapped with my own words? The steam machine has the same power as the normal chain saw engine (3hp), and a "massive" torque compared to the chain saw in your guy's eyes, ok? oh my god... here we go again.... this is the last time ok??

1. Both engines have the same power, both can do the same work in the same time. That's the definition of power, work per time unit.

2. From post #1 : Torque on the outgoing shaft = Torque on crank shaft * (angular velocity on crank shaft / angular velocity on outgoing shaft) = Engine power / angular velocity on outgoing shaft.

Set angular velocity on outgoing shaft constant (chain speed). This gives us:

The torque on the outgoing shaft (that will pull the chain through wood) = constant * engine power (1)

The massive torque of the steam machine is gone in the gear box that would be needed for reaching chain speed! Funny isn't it? Ever wondered why they don't even mention torque in the spec on the chain saw manufacturers websites?

Answer: Because of equation 1. The gear box (rim sprocket) is what it is, so what of importance remains ???

Now please don't make me explain that again. Read Bewellers post, he put in perfect english language also.

BR, Peter

 

[Gologit]

Why should I be trapped with my own words? The steam machine has the same power as the normal chain saw engine (3hp), and a "massive" torque compared to the chain saw in your guy's eyes, ok? oh my god... here we go again.... this is the last time ok??

1. Both engines have the same power, both can do the same work in the same time. That's the definition of power, work per time unit.

2. From post #1 : Torque on the outgoing shaft = Torque on crank shaft * (angular velocity on crank shaft / angular velocity on outgoing shaft) = Engine power / angular velocity on outgoing shaft.

Set angular velocity on outgoing shaft constant (chain speed). This gives us:

The torque on the outgoing shaft (that will pull the chain through wood) = constant * engine power (1)

The massive torque of the steam machine is gone in the gear box that would be needed for reaching chain speed! Funny isn't it? Ever wondered why they don't even mention torque in the spec on the chain saw manufacturers websites?

Answer: Because of equation 1. The gear box (rim sprocket) is what it is, so what of importance remains ???

Now please don't make me explain that again. Read Bewellers post, he put in perfect english language also.

BR, Peter

Yup...this guy has made up his mind. The rest of you...quit confusing him with your logic and reason. And fact. And common sense. And experience.:bang:

 

[chowdozer]

Why should I be trapped with my own words? The steam machine has the same power as the normal chain saw engine (3hp), and a "massive" torque compared to the chain saw in your guy's eyes, ok? oh my god... here we go again.... this is the last time ok??

1. Both engines have the same power, both can do the same work in the same time. That's the definition of power, work per time unit.

2. From post #1 : Torque on the outgoing shaft = Torque on crank shaft * (angular velocity on crank shaft / angular velocity on outgoing shaft) = Engine power / angular velocity on outgoing shaft.

Set angular velocity on outgoing shaft constant (chain speed). This gives us:

The torque on the outgoing shaft (that will pull the chain through wood) = constant * engine power (1)

The massive torque of the steam machine is gone in the gear box that would be needed for reaching chain speed! Funny isn't it? Ever wondered why they don't even mention torque in the spec on the chain saw manufacturers websites?

Answer: Because of equation 1. The gear box (rim sprocket) is what it is, so what of importance remains ???

Now please don't make me explain that again. Read Bewellers post, he put in perfect english language also.

BR, Peter

Do you understand what you have written above contradicts your thread title?

 

[ShoerFast]

Yup...this guy has made up his mind. The rest of you...quit confusing him with your logic and reason. And fact. And common sense. And experience.:bang:

You mean not to ask him if a Tommy Fells Jr < s p chain, with 6" cutters on his steem-saw wouldent out cut the saw in his thread title??

 

[Tzed250]

think about it

torque is what gets the chain to cutting speed in the first place. torque is what maintains the cutting speed. torque is what returns the chain to cutting speed when it falls below. Sounds to me like torque has a LARGE INFLUENCE ON CUTTING SPEED.

 

[Deadman]

Torque does all the work, because look at heavy machinery.....they often only have 200 HP, but make like 600 LB Feet of torque.

If the HP did the work, then they'd run dump trucks with Honda Civic engines in them. :biggrinbounce2:

 

[drmiller100]

interesting thread.

a few fallacies presented. One factoid was that horsepower was a derived measurement, and dynos measure torque and calculate horsepower.
Actually, almost all modern dynos measure horsepower, and calculate torque. As an example, look at ANY of the chassis or wheel dynos where you drive your mustang on and strap it down, and accelerate a drum. they are measuring the acceleration of the drum, which measures horsepower. if they know the rpm of the engine, they then calculate torque. Look it up.

Another fallacy. A higher torque equals the ability to do more work. Not true. Horsepower, by definitino, is the abiliity to do work quickly.

Torque by its mathematical definition is pretty much useless to about everything. However, the word "torque" has morphed. The better engine builders all think of the word "torque" as really meaning "horsepower over a wide, friendly, RPM range." they maybe use different words for this, but the final effects can be described by these examples.

a "torque" engine, or engine with wide friendly power band
Is not jetting picky
is not air temperature picky
is comfortable to run
still produces decent power at 90 percent of optimal rpm. So, if peak power occurs at 12k rpm, it makes 90 percent of peak power at 10,500 rpm.

best example was the Knot. You are cutting, hit a knot. a "torquey" saw will power on through it. a peaky saw the operator has to work to keep it cutting fast. The smart, experienced engine builders I bet work for the "torquey" saw as it makes you a LOT more productive over the day vs the saw that makes 10 percent more peak power, but causes you to work your buns off all the time to keep it operating at max.

i used to fight this battle, eventually figured out my mathematics and physics definitions of torque aren't really what the old timers are talking about.

 

[drmiller100]

volumetric efficiency.

big words. What is it???? who cares????

An engine has a fixed displacmeent. My dolmar is 79cc's. For each stroke fo the piston, how much air does my engine displace??? 79cc's. but how thick is that air it is pumping? that is VE.

In a perfect world, the answer would alwasy be 100 percent of ambient air, right? Well, no. At part throttle, we only want part efficiiency. Even at full throttle, the engine will be more "efficient" at some rpm's then others. For instance, at idle, but full throttle, the harmonics of it all causes the engine to not run at 100 percent effiiency.

Sooner or later, you will reach the highest efficiency RPM. Here's a brain teaser. The rpm of highest VE by definition is also Peak Torque RPM, using the mathematic definition. It probably is also the most efficient for mileage, if you ignore a bunch of stuff like friction.

anyway, now that we have hit peak VE, why spin it higher? becuase horsepower is torque times RPM, and if we can keep our VE somewhat reasonable, and just spin it faster, we get "free" horsepower. So going a little further, the old time engine builders are after VE over a wide rpm range. Which by the way is NOT trivial to do.

So a friendly trap for Timberwolf. What is the max possible VE for a naturally aspirated engine????

edited cuz of typo!!

 

[drmiller100]

Torque does all the work, because look at heavy machinery.....they often only have 200 HP, but make like 600 LB Feet of torque.

If the HP did the work, then they'd run dump trucks with Honda Civic engines in them. :biggrinbounce2:

but if torque did all the work, then they'd run diesel engines in funny cars at the race track.

maybe truck drivers are just lazy and don't like swapping engines out all the time and shifting gears even more then they already do.

 

[ShoerFast]

but if torque did all the work, then they'd run diesel engines in funny cars at the race track.

maybe truck drivers are just lazy and don't like swapping engines out all the time and shifting gears even more then they already do.

"C" engines need a lot more beef to get the "T" remember when GM put diesel heads on the 350 and called it a diesel? Right at about the same time there was a Windy's carmercial asking "were's the beef?"

Diesels are too heavy, for a timed event, Jets are too fast, only a few of the smaller versions are allowed.

If you could make a lighter diesel block, that dog would hunt!

But take a look at what a lot of the weekend warriors are running, the more competive , consistant setups are using a lot more "RV" or Torque pulling cams then the triditional cams snow-caped mountan peaks. Traiding the 4:56 and 4:11's in for a few 3:75 and 3:55 diffys and competing againced 10K rpm engines with the same ET's.

 

[chowdozer]

Actually, almost all modern dynos measure horsepower, and calculate torque.

Ummm, no. Horsepower, by it's very definition is a linear force. 33,000 lbs 1 foot/min. or any factor thereof. 'Splain how you directly measure a linear force on a dyno.

As an example, look at ANY of the chassis or wheel dynos where you drive your mustang on and strap it down, and accelerate a drum. they are measuring the acceleration of the drum, which measures horsepower. if they know the rpm of the engine, they then calculate torque. Look it up.

Ummm, no. See above. If you are accelerating a drum, that's a rotational force and we measure rotational forces with torque.

Horsepower is nothing more than a quantity of torque. A dyno only measures an application of torque for a measured unit of time.

 

[Jim Mesthene]

volumetric efficiency.

big words. What is it???? who cares????
?

You're reading too many Hot Rod magazines, and not enough about the science of measurement.
Try this:

Torque = Force
Horsepower=Power

Power is the ability to do Work.
Work takes time.

So.....Power is Force, applied for a period of time that is long enough to do the Work.


Dynos measure force while running a clock.

 

[Gologit]

You mean not to ask him if a Tommy Fells Jr < s p chain, with 6" cutters on his steem-saw wouldent out cut the saw in his thread title??

Yup!

 

[ShoerFast]

So a friendly trap for Timberwolf. What is the max possible VE for a non aspirated engine????

If I may ask, what is a "non aspirated" engine?

 

[Canyon Angler]

Dynos measure force while running a clock.

You forgot the "distance" (number of rotations) factor.

A dyno measures/counts the # of rotations completed in a given amount of time against a certain amount of resistance measured in foot-pounds of torque.