342 replies to this topic

[Canuck]

One of the current Dodge commercials running on the radio locally.

<Sam Elliot voiceover>
Torque....
Torque...Isn't complicated...
Torque is Power...
The new Dodge Ram <blah blah blah>

No wonder the general population is confused.

[Slumberer]

Are you sure he's not saying "Talk is power"
My wife would be inclined to agree...

[REN_AF1]

In general there are to types of people:
Those who ponder endlessly on "Horsepower VS. Torque".
And then there are those who adopted the metric system.. ;-)

R

[munks]

Well I married a marketing person. And let's just say this: it's better they work on commercials and advertisements than try their hand at science or engineering.

[gruntguru]

But a "Torque Curve" is as good as a "power Curve".

[saudoso]

They represent the same information and can be directly calculated one from the other, so I guess they are pretty much the same.

[hogits2]

But a "Torque Curve" is as good as a "power Curve".

Power curve - horse pulls plow over ridge of a hill.
Not much torque though.






thinks...flogging a dead one here.....

[Tony Matthews]

A seamless furrow though...

[cheapracer]

But a "Torque Curve" is as good as a "power Curve".

This is the Tech forum not a baseball forum.

[hogits2]

A seamless furrow though...

I see no gaps said the farmer.



He was outstanding in his field.

[Tony Matthews]

Quit hedging and stop the corn, hogits. That was an arable joke, really irrigating.

[John Brundage]

Quit hedging and stop the corn, hogits. That was an arable joke, really irrigating.

Beets me how yew can udder such manure.

[hogits2]

Man ure shirley awair they like their udders feeld in uddersfield.



I can feel me threads all coming adrift at the seams.

Edited by hogits2, 23 March 2012 - 17:57.

[malbear]

being a hazbeen farmer I love torque to plough with,
high rev hp is no good as it uses lots of fuel , give me a plodder that sits on 1000 rpm up hill down dale without changing
A high rev 2600 engine dies quickly and needs a powershift gearbox.

[bigleagueslider]

One of the current Dodge commercials running on the radio locally.

<Sam Elliot voiceover>
Torque....
Torque...Isn't complicated...
Torque is Power...
The new Dodge Ram <blah blah blah>

No wonder the general population is confused.

This is the kind of technical illiteracy that results when you put the Obama administration in charge of a car company.

[desmo]

Yes, the Obama administration is responsible for sure. I heard it was Kenyan born Muslim Marxist black magic that causes those trailer park tornadoes too. Yep.

[desmo]

Actually if you want to discuss politics I love to, just not in here. Join in this thread: http://forums.autosp...howtopic=106150 and we can go a couple rounds with the gloves off. Todd could definitely use a tag team partner for his wingnut Caliban Teaparty ranting. I might even do a little Obama bashing with you, but from a differing perspective. Just not in this forum.

[cheapracer]

He was outstanding in his field.

I raised barley a laugh and if it continues I'll cull the crops.

If I had my way I would barn you for giving me acres and payins.

Anyway I'm happy, just got my tickets to see Agnetha, Benny, Bjorn and Anni on the ABBAtoir.

[bigleagueslider]

They represent the same information and can be directly calculated one from the other, so I guess they are pretty much the same.

Torque and power are not the same information, and one cannot be determined from the other without knowing an additional variable, which is time.

Torque is a force applied at a radius about a shaft. Power is that torque applied over time.

The best explanation I have heard for engine torque and power is this: Torque is an engine's ability to do work. Power is the rate at which that work gets done.

[gruntguru]

But a "Torque Curve" is as good as a "power Curve".

They represent the same information and can be directly calculated one from the other, so I guess they are pretty much the same.

Slider last time time I checked torque and power curves both contain "time" information.

[saudoso]

Slider last time time I checked torque and power curves both contain "time" information.

Power =torque X rotational speed. Do the math.

Edited by saudoso, 24 March 2012 - 07:56.

[Magoo]

Slider last time time I checked torque and power curves both contain "time" information.

You and Slider are describing two different things. A torque curve contains time infomation only because the value is plotted x-y vs rpm. The torque value itself contains no time reference: 200 lb-ft. What he wrote was perfectly accurate. You just changed the subject. I see you went from zero to talking straight past people in 1.5 posts. Most impressive.

[Catalina Park]

My torque wrench doesn't have a stopwatch.

[Magoo]

Evidently, people are nostalgic for 15 pages of circular gibberish. They keep trying to restart it.

[saudoso]

You and Slider are describing two different things. A torque curve contains time infomation only because the value is plotted x-y vs rpm. The torque value itself contains no time reference: 200 lb-ft. What he wrote was perfectly accurate. You just changed the subject. I see you went from zero to talking straight past people in 1.5 posts. Most impressive.

Let's say Y is power and Y' is torque


Yes it cointains: Torque value Y' is achieved at X RPM. Not at X +100 RPM neither at X-100 RPM. So Y' is a function of X.

The toque curve(Y') is the first derivative of the power curve (Y) along time (X).

Serious, really, I just can't figure out why this **** is so complicated. People never learned calculus?

[saudoso]

My torque wrench doesn't have a stopwatch.

Your torque wrench will deliver torque in a static maner. A stopped engine delivers no torque, it will only deliver torque when it's spinning. And at NTP, at one given speed it will always deliver the same amount of torque.

[Canuck]

Evidently, people are nostalgic for 15 pages of circular gibberish. They keep trying to restart it.

I just like to light the fuse.

[saudoso]

Let's say anything to replace the tennis wall practice we had been watching lately.

[gruntguru]

You and Slider are describing two different things. A torque curve contains time infomation only because the value is plotted x-y vs rpm. The torque value itself contains no time reference: 200 lb-ft. What he wrote was perfectly accurate. You just changed the subject. I see you went from zero to talking straight past people in 1.5 posts. Most impressive.

Slider responded to consequtive posts by myself and Saudoso. If you take the time to view all three posts you will see that it was Slider who posted out of context. . . as you have now done in typical provocative style.

Edited by gruntguru, 24 March 2012 - 23:11.

[munks]

Agreed, gruntguru was talking about "torque curves" and "power curves", and saudoso's "they" referred to "torque curves" and "power curves", which obviously contain time information. bigleagueslider's response was talking about something else but appeared to be trying to contradict saudoso, which it did not. The comment was as useless and clueless as his other political one.

Edited by munks, 25 March 2012 - 01:41.

[Canuck]

Err...I read that (Magoo's) as "Slider and GG are describing two different things..." which is what you've just said. Isn't it?

[johnny yuma]

Going back to Chapter 1 in this never ending story,the thing I took away was you follow the powertrain back to the combustion chamber..spark plug fires...FORCE is produced.Then you need the conrod and crank to turn that into torque...then you need that to be repeated as often as possible to make power.Once you have force you can get torque,keep that coming for a period of time you have power.Are they the same thing ? Not really !

[saudoso]

The thing is, with an ICE if you don't have speed you don't have force/torque. It's a moving machine that needs speed to transform energy. And oddly enough, with throttles 100% open, for a given speed it will deliver always the same torque.

So you have a device that produces no force if it has no speed. And for each given speed it will always deliver the same given torque. How can you think of disregarding speed every time you mention torque?

Torque=f(s)
Power=f(s)*s


C'mon guys, it's not THAT complicated. Pretty much high school physics and calculus. First year college at most.

Edited by saudoso, 26 March 2012 - 02:13.

[gruntguru]

Going back to Chapter 1 in this never ending story,the thing I took away was you follow the powertrain back to the combustion chamber..spark plug fires...FORCE is produced.Then you need the conrod and crank to turn that into torque...then you need that to be repeated as often as possible to make power.Once you have force you can get torque,keep that coming for a period of time you have power.Are they the same thing ? Not really !

In a thermodynamic analysis you start even further back - with PRESSURE. As with force and torque, you don't get anything useful (work or mechanical energy) until something moves. So work is the integral of pressure wrt change in volume. Much the same as force wrt displacement and torque wrt angle.

Power of course is the rate of work production.

EDIT. There is an error that pops up pretty frequently on this forum - that torque and power are related by "time". It is actually "angular velocity", ("rate of change of angle" or rotation per unit time) that relates the two. To summarise:

Power = Pressure x "rate of change of volume"
Power = Force x "rate of change of displacement"
Power = Torque x "rate of change of angle".

Edited by gruntguru, 26 March 2012 - 03:37.

[johnny yuma]

In a thermodynamic analysis you start even further back - with PRESSURE. As with force and torque, you don't get anything useful (work or mechanical energy) until something moves. So work is the integral of pressure wrt change in volume. Much the same as force wrt displacement and torque wrt angle.

Power of course is the rate of work production.

EDIT. There is an error that pops up pretty frequently on this forum - that torque and power are related by "time". It is actually "angular velocity", ("rate of change of angle" or rotation per unit time) that relates the two. To summarise:

Power = Pressure x "rate of change of volume"
Power = Force x "rate of change of displacement"
Power = Torque x "rate of change of angle".

True enough,but in a cylinder the expanding gas force may indeed spread out over the piston crown as a certain pressure p.s.i. but comes together again in the conrod as a force ?

[gruntguru]

True enough,but in a cylinder the expanding gas force may indeed spread out over the piston crown as a certain pressure p.s.i. but comes together again in the conrod as a force ?

Exactly, the piston's purpose in life is to convert pressure into force. The work done by the expanding gas on the piston crown can only be expressed as the integral of P.dV however because some of this work is lost to friction on the cylinder walls. So work done by the piston on the conrod (Integral of F.dS) is less than the Integral of P.dV
(Having said that, force on the piston crown is of course P x Area of cylinder)

Edited by gruntguru, 26 March 2012 - 07:25.

[Magoo]

A stopped engine delivers no torque, it will only deliver torque when it's spinning.

Not so. You grab hold of the crank handle of the Model T with the engine stopped. Observe while I work the spark lever and break your arm for you.

Depending how you look at it, there is a little something in what you say. However, it only holds for some conditions and only for internal combustion engines. Other prime movers -- including electric motors, steam engines, and turbines -- develop torque and perform work at zero rpm. So what was your point about the universal properties of torque and power again? I suppose you will note that a piston engine must be free to operate in order to... umm, operate. Congratulations on the keen observation.

[saudoso]

1)Power = Pressure x "rate of change of volume"
2)Power = Force x "rate of change of displacement"
3)Power = Torque x "rate of change of angle".

in SI units:

1) Power = (kg/(m*s2))  *  (m3/s)  = (kg*m2)/s3
2) Power = (kg*(m/s2))  *  (m/s)   = (kg*m2)/s3
3) Power = ((kg*(m/s2))*m) * (1/s) = (kg*m2)/s3

[saudoso]

Not so. You grab hold of the crank handle of the Model T with the engine stopped. Observe while I work the spark lever and break your arm for you.

Depending how you look at it, there is a little something in what you say. However, it only holds for some conditions and only for internal combustion engines. Other prime movers -- including electric motors, steam engines, and turbines -- develop torque and perform work at zero rpm. So what was your point about the universal properties of torque and power again? I suppose you will note that a piston engine must be free to operate in order to... umm, operate. Congratulations on the keen observation.

You look ath the beggining of my post and you will read "The thing is, with an ICE...". And nothing produces work if there is no movement.

Work = Force *distance = (kg * m/s2) * (m) = kg * (m2/s2)

Back to school dude.

[Magoo]

You look ath the beggining of my post and you will read "The thing is, with an ICE...". And nothing produces work if there is no movement.

Work = Force *distance = (kg * m/s2) * (m) = kg * (m2/s2)

Back to school dude.

If your observation only applies to ICEs, then you aren't discussing the properties of torque and power. You are only discussing the properties of ICEs.

[saudoso]

Let me purpose an exercise:

GG and I said that the "Torque Curve" and the "Power Curve" of an ICE represent the one and same information.

Pay attention to the statements:

QUOTE (gruntguru @ Mar 23 2012, 09:32)
But a "Torque Curve" is as good as a "power Curve".
QUOTE (saudoso @ Mar 23 2012, 21:48)
They represent the same information and can be directly calculated one from the other, so I guess they are pretty much the same.

Now someone please tell me how you get an engine, attach it to a bench, run it and plot the torque and power curves?

If someone presents me a way to do it other than plotting the toqrue/RPM curve and then multipling it by the RPM to get the power/RPM curve I'll eat my socks.

[saudoso]

If your observation only applies to ICEs, then you aren't discussing the properties of torque and power. You are only discussing the properties of ICEs.

Power and torque curves of ICEs. Wasn't this the point being discussed?

You still let slip the fact that for any other deice you mentioned there is no work if there is no movement, so there is no work if there is not speed and then we can conclude that there is no work if there is no time variable included. There is only stactitc force. Like a beam or colum or a rusted door hinge can produce.

Edited by saudoso, 26 March 2012 - 10:31.

[Magoo]

You still let slip the fact that for any other deice you mentioned there is no work if there is no movement, so there is no work if there is not speed and then we can conclude that there is no work if there is no time variable included. There is only stactitc force. Like a beam or colum or a rusted door hinge can produce.

Your assertion is not true.

1. We can attach an electric motor to a shaft and, by manipulating the input, use it to stabilize varying and opposing loads on the shaft -- i.e. a trim tab. The shaft remains stationary and the motor remains at zero rpm yet it exerts torque, performs work, and produces power, which can be proven instrumentally with metaphysical certainty.

2. A tricycle is sitting on a ramp. I place my hand upon the circumference of the front wheel to prevent the tricycle from rolling downhill. I am producing torque, work, and power.

I'm sure you can think of many more examples yourself.

Personally, I find it confusing and awkward to have one set of physical terms, concepts, and laws that apply to internal combustion engines, another for external combustion engines, another for electric motors, yet another for tricycles on inclines, etc. It is my view that if we need more than the one set we already have, we are doing it wrong.

[kikiturbo2]

Let me purpose an exercise:

GG and I said that the "Torque Curve" and the "Power Curve" of an ICE represent the one and same information.

Pay attention to the statements:


Now someone please tell me how you get an engine, attach it to a bench, run it and plot the torque and power curves?

If someone presents me a way to do it other than plotting the toqrue/RPM curve and then multipling it by the RPM to get the power/RPM curve I'll eat my socks.

I can easily measure directly the engines power output on a dyno we have at my old university (by measuring the power coming out of a big generator used to apply load), but what is the point...really?

Also, all this torque vs power debate is utterly pointless since it is mostly subjective pub talk...

[saudoso]

Your assertion is not true.

1. We can attach an electric motor to a shaft and, by manipulating the input, use it to stabilize varying and opposing loads on the shaft -- i.e. a trim tab. The shaft remains stationary and the motor remains at zero rpm yet it exerts torque, performs work, and produces power, which can be proven instrumentally with metaphysical certainty.

2. A tricycle is sitting on a ramp. I place my hand upon the circumference of the front wheel to prevent the tricycle from rolling downhill. I am producing torque, work, and power.

I'm sure you can think of many more examples yourself.

Personally, I find it confusing and awkward to have one set of physical terms, concepts, and laws that apply to internal combustion engines, another for external combustion engines, another for electric motors, yet another for tricycles on inclines, etc. It is my view that if we need more than the one set we already have, we are doing it wrong.

1. Wrong. The motor will be probably acted on by a derivative integrative controller of the tab position, and it will require minimal, but still some movement for the force to be adjusted and the position re established.

2. You are confusing burning energy to produce force with producing work and power. You're only dissipating energy and contributing to the universe's entropy raise. If there is no movement there is not work and no power. You are being silly by burning your arm to accomplish what a wood wedge would do.

I'm not using separate concepts. Just stating the peculiar characteristis of two empiric diagrams (the torque and the power curves) when related to a specific kind of machine.

[NTSOS]

saudoso,

Is English your 2nd language?

If it is.....it just amazes me that there are so many people from different countries around the world that understand, write and converse in english.....*perfectly*!

As an example, I took two years of Spanish *One* in high school.....I think I flunked both years! lol!

Very impressive for all of you that have mastered two or more languages!

John

[saudoso]

Thank you!

But I guess the comparison is not fair. I did study English after school for I guess 5 years as a teenager, but I've been working with american companies/software and watching american movies all my life. Not counting how much I learn here or reading English in the Kindle. And there is always google spell checking with it's helping hand.

[gruntguru]

1. We can attach an electric motor to a shaft and, by manipulating the input, use it to stabilize varying and opposing loads on the shaft -- i.e. a trim tab. The shaft remains stationary and the motor remains at zero rpm yet it exerts torque, performs work, and produces power, which can be proven instrumentally with metaphysical certainty.

2. A tricycle is sitting on a ramp. I place my hand upon the circumference of the front wheel to prevent the tricycle from rolling downhill. I am producing torque, work, and power.

Your two examples suggest that work can be performed and power produced in a stationary shaft which of course is not true.

Power = torque x angular velocity
if angular velocity = zero then power = zero.

Work = torque x angular displacement
if angular displacement = zero then work = zero.

[gruntguru]

Whats better high power and higherngine speed or high torque and low engine speed? Assume both cars have optimum gear ratios

Don't go there.
Go here. http://forums.autosp...p;hl=v10 torque

[Greg Locock]

2. A tricycle is sitting on a ramp. I place my hand upon the circumference of the front wheel to prevent the tricycle from rolling downhill. I am producing torque, work, and power.


A book I was given at the age of 8 illustrated this in a pair of pictures. A clown on the left is attempting unsuccesfully to lift a chair that is nailed to floor, pulling upwards with all his might. A clown on the right lifts a feather from the floor. The caption, "which clown is doing more work?" At the time the answer seemed most unfair to the chap on the left, but the physics is indisputable. Semantics, on the other hand...