what is torque?

I am a 15 year old trying to read a book on cars. The only thing is it doesn't explain what exact is horsepower, torque, and rpm. The show many dyno test that that the three information and i can't seem to undertand the tests. Can someone explain to me what these three words technically mean and how i would inturpet the information as i read the dyno test.

tourque is what for example a v8 is all about mostly. i mean tourque is what spins the tires down low.

you could have 400 hp, and 20 ft pnds of tourque, and untill the high revs, your car wouldnt pull.Horespower takes over int he higher rpms, it is what creates the high speed. wich is why most people tend to speak about it more than tourque.

rpm is revolutions per minuet, the speed at wich your engine is cranking.
at 1000 rpm, your car will do 1000 revolutions (the pistion will go up and down) 1000 times im a minuet. all cars have a redline at wich the car should not be reved passed.



other car guys, correct me if im wrong, ive had a couple beer and im kinda tired. but thats the jist of it.

"How Stuff Works" explains it very well http://science.howstuffworks.com/fpte3.htm

One ftlb of torque is like applying 1lb of pressure to the end of a 12" wrench. The bolt the wrench is attached to will feel 1ftlb ot torque. RPM is rotations per minute, 3000rpm mean the motor will turn 3000 times in 60 seconds. HP is a combination of the two and represents the actual power produced. Imagine being on a bike, you put 100lbs pressure (torque) on the petals, now multiply that pressure by how fast you pedal to get the power. If you pedal twice as fast you will make twice the power. If you hold the brakes at a dead stop and apply the 100lbs pressure you are making torque but not any HP.

Imagine putting a torque wrench on the crank and applying 100ftlbs torque. You just made 100ftlbs torque! Now try to do that AND turn that wrench at 3000rpm. That's a little tougher but that's exactly that the motor does. Torque x rpm is how you get HP, there is no magical shift from torque to HP as rpms rise. If a motor makes 300ftlbs tq @ 2000rpm and can still make 300ftlbs @ 4000rpm, it will be making exactly twice the HP at 4K that it did at 2K. Normally an engine makes peak torque at around 2000-4000, but peak HP at a higher rpm. Torque will drop off as rpm rises beyond that peak mark, but since it is in fact spinning faster it will actually be making more power. At some point about 2000rpm or so beyond peak tq, the tq will really drop off, at this point the tq will be so low that additional rpm will no longer be enough to make power. Zero x 7000 is still zero. So somewhere between 4k and 7k there is going to be a happy spot where the combination of tq and rpm will make the most HP. If you look at the power graphs you will see the pattern between tq, rpm and HP.

Hope I made some sense and didn't make things worse.

similarly 10kg on a 1 metre long spanner means the bolt feels 10kg/m of torque 10 Newtons (9.8N=1kg) on a 1 metre spanner means the bolt feels 10Nm of torque. Torque is the force combustion applies to the piston to force it downwards and rotate the crank.

it is actually LB-FT instead of FT-LB

it is actually LB-FT instead of FT-LB


They are used interchangably.

They are used interchangably.



using the wrench and bolt example
if I want to generate 30lb-ft of torque to the bolt, with a 1ft wrench
then I will have to apply 30lb of force to a 1ft wrech
but in the case of 30ft-lb,
then I need a 30ft wrech and apply 1 lb of force.
although in terms of math caculations,
the TORQUE would be the same
(torque = distance x force)
but it is actually two different things, just with the same results.

for the torque of an engine, we want to know,
the FORCE being generated through a DISTANCE of 1 ft,
rather than the DISTANCE when there is 1lb of FORCE
because torque defines power, and it is a twist of force
the force is what we really want to know
if it is ft-lb, then we know all cars generates 1lb of FORCE

In the English Unit,
lb-ft or lb-in are the units of torque

ft-lb is used as an unit of work
if it is 15ft-lb
then it means the work required to lift a 1 lb mass, 15ft vertically

In the Metric System
there are two common units of TORQUE
kg-m = kilogram meter
Nm = Newton meter
I don't think it would be right if we put it as m-kg or mN

Read the articles on the bottom of the page.

http://dynoperformance.com/article.php

Later,

One way I think of horsepower is as torque-rpm with engines that tap power through torque. Ignoring other parts and effects, the engine's crank height determines torque derived from that power. But I might we way off -- if so, don't tell me, because I don't want to be disturbed about this topic. Bliss... ;)

I also like to think of horsepower or Watts straight from a rocket nozzle. It's energy derived from fuel. Fuel into power. But, that is straight torque too. Torque becomes more relevant when using leverage. The rocket might blast the same rate all its life, but if we vary the nozzle or give it a working surface to push against, it's torque increases. Similarly, we can place the rocket on a lever or gear to vary it's torque higher or lower. Stating this, I'm trying to avoid discussion of Moment.

Does torque exist without motion? Can one have static torque? Static power?

Reading the other replies, I agree.

-edit-
Oh yeah, and why converting more fuel to the rocket increases power, and why higher RPM increase power, and why power is linear with RPM, ignoring inefficiencies.

hp = (lb-ft x rpm)/5252
likewise, torque = 5252XHP/RPM

Torque is the force that moves you, while h.p. speeds up the process that allows that force to move you.

horsepower is the measure of of how fast work can be done, not what can be done. That is Torque.

That is why high HP cars are so fast.
however, with proper gearing, even a low hp car car go very fast, it only needs enough power to overcome aerodynamic drag.

P = 1/2 x drag coefficient x density of air x velocity cubed x frontal area
(P stands for power)

so, given enough road, and very tall gears, a honda civic can go 180 mph!

I hope that helps.

You can't get horsepower without torque(simple as that). And there's even a formula,
Torque X RPM/5252=HP And 33,000 ft. lbs of work per minute=1 HP
Torque in essence is the twisting and turning force of the crankshaft.

damn you road racer, you beat me to it...lol

mustangs are faster than z28's.
Proven once again.

Only do to technicality.... :sly:

Torque is good for burnouts, hp is good for selling cars & winning races.

Torque is when your standing in front of the john and need to point your tool down, so you don't miss. In pushing it down it raises both feet off the ground, Thats torque. Jk

Some good answers.

One way I think of horsepower is as torque-rpm with engines that tap power through torque. Ignoring other parts and effects, the engine's crank height determines torque derived from that power. But I might we way off -- if so, don't tell me, because I don't want to be disturbed about this topic. Bliss... ;)

I also like to think of horsepower or Watts straight from a rocket nozzle. It's energy derived from fuel. Fuel into power. But, that is straight torque too. Torque becomes more relevant when using leverage. The rocket might blast the same rate all its life, but if we vary the nozzle or give it a working surface to push against, it's torque increases. Similarly, we can place the rocket on a lever or gear to vary it's torque higher or lower. Stating this, I'm trying to avoid discussion of Moment.

Does torque exist without motion? Can one have static torque? Static power?

Reading the other replies, I agree.

-edit-
Oh yeah, and why converting more fuel to the rocket increases power, and why higher RPM increase power, and why power is linear with RPM, ignoring inefficiencies.

Good thinking!
Many peaople thinks TQ happen at low rpm and Hp at high rpm.
Or , that Tq is a low rpm phanomenon. When in fact high rpm motors produce the best Tq numbers.
Allright, the car weights 3000p. The motor has a Tq of 500 fp. How fast will it do the quatermile?
I just said this with the static Tq in mind.
Goran Malmberg

FYI Pounds are expressed lb not P. P is pressure. anyways.
Im glad some people where smart enough to Explain why Torque isnt everything.

Torque- Defined in ft/lbs or lb/ft either eay it translates into the same amount of rotational force.
An engine's defined what work can be done. there is no alot ed ammount of time. Sure i have 500 lb/ft of torque but its at 500 RPM and im never going to get moving. (oh and torque can also be defined in Newton/meters or Kg/M. in reality it should be defined always as Newton's because a newton is a measuremnt of force, lb is a measurement of gravity pull and Kg is 1000grams, ie Mass or how much of a material is there. torque if force and there for SHOULD be defined as Newtons. but since we are living on earth with 1G Mass has weight and weight exerts force so....)

RPM- plain and simple is rotation per minute.

Horse Power: this is a hard one. THIS IS WHAT MATTERS WHEN THINKING OF ALL OUT PERFORMANCE, NOT EVERDAY DRIVEABILITY. the true formula is 33,000 lb/feet per min. but since you cant expect a horse to lift 33,000lbs 1ft or expect it to move 1lb 33,000 feet in one minute its more simply defined as Torque(RPM/5252). but that has already been said.
1HP=746w (i beleive)
1w=joule/sec.
A joule is a measurement of all out energy. what does this mean? Well alot of muscle car guys like to say its torque that gets you off the line. True, in a sence. its torque to the wheels that gets you off the line. so we have a good old american muscel V8 cranking out a flabergasting 500 ft/lbs of torque at a mere 2,000RPM. thats 190hp@2000RPM. now we have out European performance i-6 with 333hp@7,000 RPM. thats 250lb/ft@7000RPM. Which should launch faster? well lets assume in first gear the muscel car has a final drive of 16:1. 500*16=8,000 lb/ft of torque at 125 RPM. the euro sport car makes most of its power in the high high RPMS so it has a very short 1st gear. 32:1 8,000 lb/ft@218RPM this means that the euro sport car will take off faster because it has more torque at a higher RPM and therefor more HP. you se its all about gear ratio's. torque can be multiplied through gear ratio's HP is constant no matter what gear ratio you put it through.
so what does all this mean? well not only with the euro take off faster but because it has more over all energy it can go faster because in the end it takes HP (Kw) to brake through the air at high speeds, not just torque.
But let me ask you this. Which will be more comfertable for everyday driving? well the engine with 500lb/ft &2000RPM. why? well with that short of a 1st gear slow driving will waste gas and nobody wants to wind their engine up to 7000RPM everytime they need to pass somebody.
for the best all around engine an engine that makes decent torque in the lower RPM's but can hold a flat enough torque curve to make good power in the upper RPM's is perfect. if you are looking for good gas milage and a quite ride then lots of low end torque is your alley. if all you want to do is treat the road like your race trak then lots of HP is ideal.
And here is an idea to throw out at the muscle car people before they flame me for saying some euro POS will beat their cars off the line. 90% OF YOUR CARS WENT DESIGNED FOR STRAIGHTLINE PERFORMANCE. THEY ARE FULL SIZED SEDANS WITH TOO MUCH POWER FOR THEIR CHASIS MENT FOR GREAT EVERYDAY, LOW RPM DRIVING.
i love muscle cars such as the 426 Hemi, GTO, Stingray, GT500Kr, but all of these old family sedans (Bel Air's especially annoy me. they belong shoped and bagged, not raised in the rear and doing wheelies at the local 1/4 mile) built up to 400 lb/ft of torque and 350HP are stupid IMO.

Flymann, absolutley right so.
Then we might have a lever arm with a weight at the end hanging on it all day loong, creating Tq with no Hp. We may create ANY number of TQ with handcraft, say 10000fp, by using a lever loong enough. But it want give a 3000p car very much of a speed. Just one Hp or so.
But if we have 500 Hp we can tell a quatermile time for the 3000p heavy car, right. Tq is of no concern then, it should be as fast with any number.
It is the same phenomenon if the car accelerate at 1500 rpm at 25mph or 100 mph and 6000 rpm. Hp tells how fast the work is done in both examples.

Are you making speakers? Great I have been makint 1000ands of them!
You also like HEMIS:s? Even greater. I drive one myself.
Goran Malmberg

tricksaturn...the saying is actually 'horsepower sells cars, torque wins races"

Torque- Defined in ft/lbs or lb/ft either eay it translates into the same amount of rotational force.


Since torque is force times distances the units are more accurately written as lb-ft or ft-lb.

If you are an engineer lb-ft is torque and ft-lb is energy. You will hear us say them incorrectly often out of bad habit just like you will hear us talk about how much power our motor has when a motor is an electromechanical device and what we really mean to say is engine. Let me go ahead and get the General Motors and Ford Motor Compant out of the way. I knew that is what you where thinking of saying.

To add a bit to this, i'd like to mention the unimportance of a high peak torque, if it peaks too soon (also of course if horsepower doesn't pick up soon after torque starts to drop off). This is not to say that having a lot of torque is a bad thing. But people must understand that when you look at a dyno graph, what you want is a flat torque curve. It's the amount of area beneath the curve that counts, not how high the curve goes.

Torque is also a terrible, terrible movie.