I was talking with my boyfriend Rob #940 last night. I asked him to give me a definition of "torque" and he could not. I got an explaination but not a true definition. Can any of you give one, without the aid of Websters?
Hey Rob, I like your wet little....pug. Yes, pug. Give Mr. Fredricks #91 a shout and a big kiss for for me! ;D
You can feel torque.
HP you can't.
So, when you're buzzing in a car around the neighbor hood and you accelerate hard and it kind of gets going quicker....that's more of a torque feeling. Car that has more of that feeling? More torque...or it weighs less in comparison to a similar amount of torque generated by the engine.
That help?
Easiest way I explain it to g/f:
Torque is how hard you can twist
Hp is how fast you can twist it
and of course, the two are related in a mathematical and physics equation based upon rpm
(more definition view: Torque is the amount of work you can perform, HP is the amount of work over a given time)
a squid movie ???
:P
Yep, torque is the immediate force applied. HP basically is how many times you can apply that force.
Taken from allpar.com/eek:
QuoteBoth torque and power can be observed "directly". Think of slowing a free-spinning tire with your hand. Feel the tug on your palm and the tension in your arm? That's a measure of torque, the torque the tire experiences as a result of your palm slowing it down. Feel the heat build up from friction? That's a measure of power.
Lets say you have a motor that makes 50 ftlbs of torque at 4000 RPM, and another that makes 30 ftlbs of torque at 8000 RPM.
The one that makes the most power, and accelerates the fastest (Given the same chassis and motor weights, etc, the only variable being the power curve) will be the one that makes 30 ft lbs at 8000.
Torque is immediate, but power is really how often that torque can be used. That 30 ft lbs is used 8000 times/minute, compared to the 50 being used only 4000.
Motors with High RPM and no torque may make the same HP as a motor with the other extreme. (Think crappy dremel tool compared to rotissere (sp) motor) They might both make the same HP, but the motor with hardly any rpm, but TONS of torque (the rotisserie) could turn a bigger load. (Like a chicken) So, although they both make the same power, the dremel would never be able to start the chicken moving, whereas the rotissere motor would.
So, torque has importance.
Does this help the overall understanding at all?
Torque is defined as the product of a force by a moment arm: T=F x L where T is Torque, F is force and L is the moment arm.
Torque and horsepower are related by the following equation:
(hp x 5250)/rpm = torque
when torque is measured in foot-pounds
That is why the hp and torque curves always cross at 5250 rpm on a dyno chart.
QuoteSo, when you're buzzing in a car around the neighbor hood and you accelerate hard and it kind of gets going quicker....that's more of a torque feeling. Car that has more of that feeling? More torque...or it weighs less in comparison to a similar amount of torque generated by the engine.
Hmm, when I drove my dad-in-law's tractor (~45 HP, ~200 ft-lbs plus the torque amplification of crazy-low gear ratios) it didn't feel like my car buzzing around the neighborhood...
Torque is simply force times distance. So if I turn my rear axle with a certain torque (not the same as the engine torque due to the mutiplication of the tranny) and multiply that by the radius of the wheel the will give the force one the ground and I can calculate the acceleration using F=ma (in a perfect world with no friction in a vacuum).
If I had a bike with only one gear, the engines torque curve and the weight of the bike and rider would determine the acceleration curve, while the horsepower and drag would determine top speed. Include drag in the acceleration curve and it gets pretty complicated.
Give me a gearbox, and now I can turn a high HP low torque engine into large wheel torque with a low first gear. Hence why a 600 in-line 4 can out accelerate a cruiser that has 4 times the torque, the 600 just has to shift a lot.
Then we can go itno the shape of the torque curve, the resulting HP curve, and the effect on ridability... ::)
-z.
QuoteSo, although they both make the same power, the dremel would never be able to start the chicken moving, whereas the rotissere motor would.
Although I could hook the dremel tool up to a 5000:1 gearbox and turn the rotissere. It might have some stall current issues getting the thing started though...might need a torque converter.
Which brings up the intresting point of electric motorcycles. An electric motor makes maximum torque at stall (0 rpm) and the torque decreases as the rpm goes up. Hence why if you turn on a drill it only goes so fast. The free running speed is where the motor has only enough torque to cancel out the back EMF (the generator effect of the spinning motor)
;D
-z.
A machinist I grew up around defined torque as "the ability to spin a rod". If that clears anything up for you...
QuoteThen we can go itno the shape of the torque curve, the resulting HP curve, and the effect on ridability... ::)
-z.
I was wondering how long it would take the mechanical engineer to chime in on this... ::)
there are a lot of detailed explinations on the web such as:
http://www.revsearch.com/dynamometer/torque_vs_horsepower.html
Dyno of an electric Ford Ranger:
http://www.mindbent.org/evranger/dyno/
its really interesting to see how the gasoline and electric compare on the graph. The real world application of an electric motor charts out different than would be expected from a motor only charting. The most interesting thing to me was the sustained peak horsepower on the electric motor in this application.
All very interesting explanations.
On a race bike, torque and hp mean nothing without the proper transmission gear ratios and the chassis geometry to get the motive force to the ground. And bear in mind that once you are going a constant speed you don't need the same amount of torque or hp to maintain that speed - think variable displacement engines. Two stroke bike are good for this. On my TZ I could go into a corner with the clutch all the way in (no motive force to the ground)and wouldn't lose much of my current velocity.
Basically, I just want to add the motor is part of a large system that cannot be separated without considering some important relationships.
The way I had it explained to me years ago was that torque told you how much you could move, hp told you how fast you could get it moving.
Torque is force x distance and has the units of lbf-ft or N-m. Torque is an expression of work or energy. In other words, the amount of energy you imparted on an engine while torquing cylinder head bolts (stored as preload in the head bolts and lost as friction) may be the same as the amount of energy you expended while pushing a boulder up a hill. It's all about force and distance.
Power can be seen in several ways, depending on your available variables. It could be seen as force x velocity (as in how fast you can push a fairing through air or how fast you can run under water), or it can be seen as the time rate of change of energy (how fast a given volume of water will boil, or how quickly an object's kinetic energy can be increased). Power is work (energy, torque, lb-ft) over time (sec).
Horsepower is an arbitrary value that dates back to the early 19th century. It represents the average amount of power that a horse can produce. Specifically, one horsepower is 550 lb-ft per second, meaning that a horse can lift a 550 lb weight one foot in one second. Notice the units here: feet, pounds and seconds.
So where does 5252 come from? It's an approximation of 550 (from 550 lb-ft/sec) multiplied by 60 (sec/min) divided by 2pi (radians/revolution), used when calculating the instantaneous horsepower value of an engine that's producing a given amount of torque at a given engine speed.
Why the terms 'low-end torque' and 'high-end power' have evolved culturally into the implication that torque is exclusively a low-engine-speed phenomenon is a mystery to me. Torque and horsepower and not independent variables. They are both present all the time, but power just happens to include an engine speed component.
I'm still faster than you guys.... :P
Few people experience "HP". Maybe at Daytona. But torque you can feel. Do you guys recognize the difference? I don't teach schools with equations. It has no feel.
I'll chime in, Torque is the force behind one repetition, horsepower is torque X rpm. So if an engine makes 1/2 the power each time it rotates than another engine but it revs to more than twice the RPM then it will make more horsepower. The problem is the power created until it gets into the high revs. In the end, assuming you can keep the revs up on a machine, only HP matters. But if you can't then some lower HP engines may be using more HP at a given time than a higher HP engine if the higher one is lower in RPM at the time. After all, you don't use the power an engine is capable of, use use what it is putting out at the time.
HP is work,
Torque is force.
The answer to WHY
is why not
Now everyone lets define Irony
:D X
You're all missing the most important detail. Rob has a girlfriend? Is her name Louise? ;)
QuoteYou're all missing the most important detail. Rob has a girlfriend? Is her name Louise? ;)
LOL!!!!
;D
This thread is getting esoteric enough that I'm getting the desire to read "Zen and the art of Motorcycle Maintenance", again...
QuoteI was talking with my boyfriend Rob #940 last night. I asked him to give me a definition of "torque" and he could not. I got an explaination but not a true definition. Can any of you give one, without the aid of Websters?
Hey Rob, I like your wet little....pug. Yes, pug. Give Mr. Fredricks #91 a shout and a big kiss for for me! ;D
Rob is your boy freind?! Run for the hills girl! :o ;D ;)
QuoteHP is work,
Torque is force.
The answer to WHY
is why not
Now everyone lets define Irony
The only irony here is that HP is power := d(work)/dt, torque is work and work is the cross-product of the force vector and the distance vector. Get it right.
QuoteFew people experience "HP". Maybe at Daytona. But torque you can feel. Do you guys recognize the difference? I don't teach schools with equations. It has no feel.
And Dave, I still don't see your point about feeling torque and not feeling power. They are inseparable, so if you're feeling one, you're feeling both. Sorry, but I went to school to get a feeling for equations. Knowing which equations are governing my environment helps me to better understand my environment.
All I know is my Buell has tons of torque and I can get off the line faster than most anybody, once rolling most anybody is faster. ;D
Wheres that confused smilie? :-/ ;D
That was the most real and results way I could think of to describe the difference Torque is the grunt that gets it going, Hp is what gets it going faster once it's going. Sorry, I wasn't too clear either. At least you know I'm not an engineer.
Torque is the machine's ability to put the hp to the ground.
Torque is a Powerstroke diesel. I do not disagree with Mr. Chin on the two, hp and torque, being inseperable, but the "feel" difference of torque exploding from the wheels of a TurboDiesel vs the HP of a Shelby is looking at kiwi and apples.
Ahhhh, the sound of red-winged blackbirds in a Minnesota marsh is calling.....
Alright, finally something fun to talk about. (besides being a physicist I teach college physics for a living)
Torque can be best described as a twist. It is the rotational version of force. It is a force times a lever arm (actually a cross product for you vectorally inclined). It has the same units as energy, but it is not energy. In the metric system, N-m and J are the same (1 N-m = 1 J), but N-m is used for torque and J is used for energy and work.
Power is the rate at which work is done. Power is what is important when it comes to acceleration, the more power, the quicker your acceleration, all else being the same.
Power and torque are related as stated previously, change one and you change the other. It really doesn't make much sense to say you can feel one but not feel the other. People see acceleration and feel force. Force causes your head to snap back when someone steps on the gas. This force can be described from the point of view of torque or power. When I lower my gearing (such as larger rear sprocket), do I gain acceleration because I increased torque or because I am making more power for a given speed?
Equations are like a picture, they express much more than words ever can. Avoiding them can be a disservice to the audience. Equations are the key to truely understanding the subject of physics. Math is to physics, like a motorcycle is to a racer.
To answer the question, for an engine, torque is the twisting (rotational force) of the crankshaft at a given rpm. Power is the torque times the rate the crank is rotating. In some sense they are really 2 different ways of measuring the same thing.
Whew, my dribble actually almost agreed with the Professor's answer! Why couldn't that have happened back in school when it counted?
And now for some trivia: How can two properties have the same units and not be the same? Why is torque not energy? Obviously, torque is work, otherwise it couldn't become power when multiplied by RPM and a constant, and work defines the increase or decrease in the energy state of an object... Please help a lowly layman fit the pieces together.
QuoteHP is work,
Torque is force.
The answer to WHY
is why not
Now everyone lets define Irony
:D X
irony- n. 1. a method of humorous or sarcastic expression in which the intended meaning of the words used is their direct opposite of their usual sense: as, the speaker was using irony when he said that the stupid plan was "very clever." 2. an instance of this. 3. a combination of circumstances or a result that is the opposite of what might be expected or considered appropriate: as, it was an irony of fate that the fireboat burned and sank 4. the feigning of ignorance in argument: more frequently Socratic irony (after Socrates, who uses this device in Plato's Dialogues).
QuoteWhew, my dribble actually almost agreed with the Professor's answer! Why couldn't that have happened back in school when it counted?
Because then you would not have the humbling experience that is being a student.
QuoteAnd now for some trivia: How can two properties have the same units and not be the same? Why is torque not energy? Obviously, torque is work, otherwise it couldn't become power when multiplied by RPM and a constant, and work defines the increase or decrease in the energy state of an object... Please help a lowly layman fit the pieces together.
First, torque is not work. One way to tell is that torque is a vector quantity and work is a scalar quantity, so torque cannot be work.
Rotational work is the dot product of torque and angular displacement (tau times theta). Torque has units (N-m, ft-lb, etc) but angles do not have units. We measure angles in degrees, radians and on rare occations gradians. These are not units, they are labels. Don't like that? Look at the formula (see formulas do come in handy) for arc length. Arclength (s) = radius (r) * angle (theta, measured in radians). Rearrange the formula solving for the angle : angle = arclength/radius. Radius and arclength are both lengths, a length divided by a length will have no units, therefore the angle has no units.
So since angles have no units, torque, work and energy have the same units. Some in the engineering community will argue that the units are not the same. Engineers tend to use lb-ft for torque and ft-lb for work and energy, then tell you that these are not the same units. It would be much easier if everyone used the much better metric system in which torque is measured in N-m, and work and energy are J (Joules).
Power is work divided by time, so it is (torque * angle)/time, but due to commutivity and associativity in math this can be re-written as torque*(angle/time). Angle/time is rotational speed (omega), rpm is one of the units of rotational speed. The formulas show how it works out, multiplying torque times rpm converts the torque to work (the angle) and divides by time.
W = T * theta
P = T * omega
omega = theta/t
P = w/t
where
W = work
P = power
theta = angle
omega = angular velocity
t = time
Why do people consider low rpm engines torquey and high rpm motors to not be torquey?
Power (hp) = [torque (ft-lbs) * RPM]/5252
Low rpm engines, such as a diesel or a HD twin, "feel" torquey. These engines also make more power at low rpm. If you have 2 engines at the same rpm, the one with more torque is making more power. So I could just say that the "feel" of an engine depends upon how the power is delivered. More power at low rpm will make the vehicle feel more lively. This is what most people call a torquey engine.
So can you "feel" torque and not "feel" power?
One of the problems with refering to the torque, depends upon where you measure the torque. Torque can be changed by gearing (up or down). The amount of engine torque, the useful rpm range and the gearing all contribute to the "feel" of the engine. An engine with low rpm torque may be easier to tow with, but it doesn't have to be able to tow more. Towing capacities have more to do with gearing and frame strength than engine type. I have driven plenty of 40,000 lb straight trucks with gasoline engines that worked fine.
I guess I figure more HP to generally = more wheelspin. More torque to = more forward movement. So, I guess I can "feel" torque in a forward rush of movement. I hear hp in spinning wheels, but then we enter the realm of inertial forces, clutches, and my brain's constipation. Anyway, let's put this in perspective we all understand a little better.
Two bikes that each have 80 hp. Both machines are four strokes with engine size that is equivalent.(Oooh man, this can get messy.) One has a torque rating of 75 ft/lbs and the other is rated at 67 ft/lbs. Using the same rider for speed and lap times which machine has faster lap and 1/4 times?
Mr. Mc Laughlin, are you the "Science Guy" Rick refers to? If so thanks for your time at the track. Now, back to the Minnesota marshes/Montana/church of quality book. Merry Christmas everyone. ;)
QuoteÊI guess I figure more HP to generally = more wheelspin. More torque to = more forward movement. So, I guess I can "feel" torque in a forward rush of movement. I hear hp in spinning wheels, but then we enter the realm of inertial forces, clutches, and my brain's constipation.
If you have more power then you also have more torque. Wheelspin can explained interms of torque or power. How the power is delivered is as important as the amount of power. Things like heavier cranks help to control wheelspin.
QuoteAnyway, let's put this in perspective we all understand a little better.
Ê Two bikes that each have 80 hp. Both machines are four strokes with engine size that is equivalent.(Oooh man, this can get messy.) One has a torque rating of 75 ft/lbs and the other is rated at 67 ft/lbs. Using the same rider for speed and lap times which machine has faster lap and 1/4 times?
Really can't say. Too many undefined variables. The engine with higher torque will probably have the power peak and torque peak at lower rpm. The shape of the curves are what is most important. The shape tells how power and torque are delivered, the width of the power band. Generally all else being equal, a more rider friendly powerband will make for an easier to ride bike (although not necessarily faster, at least under ideal conditions), especially when tires are worn or in the rain. I don't like to see big dips or steep increses when I look at a power/torque graph. For an engine power and torque are not seperable. Any description in terms of torque can be made in terms of power.
Wheelspin - too much torque, abrupt power increase.
QuoteÊ Mr. Mc Laughlin, are you the "Science Guy" Rick refers to? If so thanks for your time at the track. Now, back to the Minnesota marshes/Montana/church of quality book. Merry Christmas everyone. ;) Ê Ê Ê Ê
Yes I am. You are welcome. Remember we are here to help.
I had this discussion with an engineer a few years ago. It took awhile to understand it, especially when you look at how one horsepower is measured - in relation to a actual horse doing work. It was confusing, at first, to look at a 1,000 lb horse as having only 1 hp. Then I realized the torque behind that horse and how slow it is compared to a 10,000 rpm motor. You can probably gear the horse and get a ton more hp out of one horse with all that torque.
Only one problem, power is unaffected by gearing. Power output cannot exceed power input for any machine. A gearbox is a form of machine. Torque can be increased by a gearbox, but at the expense of rotational speed (output shaft slower than input shaft). Double torque, cut rotational speed in half. Cut torque in half, double rotational speed.
Quote You can probably gear the horse and get a ton more hp out of one horse with all that torque.
:D ;D :D ;D :D
;D ;) ;D
Just make the horse work faster then. Like a 1000cc single cylinder engine doing 15,000 rpm. :D
btw - why do engines have peaks at certain rpms? Does this have something to do with 'floating valves?' iow - what does my R6 lose at 12,500? Compression or something?
Think of torque as the effort required to break loose a stuck nut (or bottle cap).
Think of horsepower as how fast you can unscrew it.
Peaks and dips in a power curve are caused by harmonic backpressure pulses.
In a typical 4 cylinder four stroke this usually affects power around 7000 rpm.