what is torque?

[vietxxxtasy]

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.

[Jm93]

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.

[Volvord 784VC]

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

[chevota]

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.

[AE92 Drift Corolla]

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.

[MioCLK]

it is actually LB-FT instead of FT-LB

[P10DET]

Originally Posted by MioCLK

it is actually LB-FT instead of FT-LB

They are used interchangably.

[MioCLK]

Originally Posted by P10DET

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

[KC Ron Carter]

Read the articles on the bottom of the page.

http://dynoperformance.com/article.php

Later,

[jhillyer]

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.

[MustangRoadRacer]

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.

[-Josh-]

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.

[-Josh-]

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

[MustangRoadRacer]

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

[-Josh-]

Only do to technicality....