What's the difference between torque and power?

Simply put: Torque is the how much a motor can pull, and horsepower is how fast it can do it.

Nicely put Chewbaka, but 'when I were a lad' - well 20 odd years ago a Volvo FL10 produced 320 hp + 990 lbs ft torque from 10 litres, but an ERF EC10 with a 10 litre Cummins Celect produced 350 hp + 1250 ft lbs of torque & it was that extra grunt that made the difference on hills 9 and some). Both engines produced the max torque around 1200 - 1500 rpm. But that is irrelevant to the question. A steam engine produces massive torque from the start & relatively little hp until running normally. So torque for the initial start & once the revs build so does the horse power or Ps as our European masters have decreed

Difference Between Torque And Horsepower

Torque is what can pull the greatest load.

BHP is what can accelerate a load fastest.

You can see this if you drive a long hill in top on gentle acceleration. Speed will drop off until it stabilises at an engine speed of about 2900 rpm. This is the point of max torque.

Next try accelerating in top from about 30mph to whatever is legal [or you can get away with] Have a passenger mark with a stop watch as you pass 35, 40, 45, 50, 55, 60, 65, 70 etc. The shortest period of time thus recorded is the point of maximum acceleration.

I guarantee that the RPM at that speed will be about 6000. That is the point of maximum BHP.

By the way 3500 is a bit high to find max torque except in a specialised engine. You obviously have a highly tuned lump

Torque is the measure of rotational force. In your application torque would be the amount of turning force the crankshaft has. Torque and engine speed have a direct impact on horsepower. There is an equation to calculate the conversion. It is basically using rotational speed and torque to calculate horsepower:

Power (hp) = [torque(lb.ft.) x angular speed (rpm)] / 5252

As for your acceleration question. You will get your best acceleration keeping the engine speed between the peak torque rpm and the peak horsepower rpm. Acceleration is best in this range; which is different for almost every engine.

It reads as follows from the Wikipedia:

Conversion to other units

For different units of power, torque, or angular speed, a conversion factor must be inserted into the equation. For example, if the angular speed is measured in revolutions instead of radians, a conversion factor of 2π must be added because there are 2π radians in a revolution:

, where rotational speed is in revolutions per unit time.

Some people (e.g. American automotive engineers) use horsepower (imperial mechanical) for power, foot-pounds (lbf·ft) for torque and rpm's (revolutions per minute) for angular speed. This results in the formula changing to:

This conversion factor is approximate because the transcendental number π appears in it; a more precise value is 5252.113 122 032 55... It also changes with the definition of the horsepower, of course; for example, using the metric horsepower, it becomes ~5180.

Use of other units (e.g. BTU/h for power) would require a different custom conversion factor.

My spelling may be off on a few words but the information is correct.

Torque is a measure of the force that the engine can exert. Horsepower is a measure of the speed with which the engine can delivered that torque.

In the electrical world, you have amperage. If you know that a circuit can deliver 10 amps, that's useful information, but it's not enough. If you know that a circuit can deliver 120 volts, that good information, but it's not enough. Knowing both, you can say that the circuit can deliver 1200 watts (watts = volts x amps). If you need 1200 watts of power at 220 volts, you can build a transformer to change the voltage.

It the same with an engine. 400 lbs/ft of torque is really good. But, if the engine can only deliver that at 1000 rpm, you'll need a transmission with a lot of gears for it to be useful. If it can deliver it at 4000 rpm, you'll need fewer gears to exploit the engine.

To finish the comparison ...

volts = rpm

amps = torque

watts = horsepower

Thus, torque is a measure of force. RPM is a measure of speed, and horsepower is a expression of how quickly the engine can deliver the torque.

(BTW, in Europe, engines are rated in kilowatts. )

this it a long and technical answer. torque is the twisting force. a 1 foot long wrench on a bolt with a 1 pound weight on the other is 1 foot pounds of torque. torque is the true measurement of a engines power not horsepower. horsepower is the ability to use that torque, the more HP, the faster the torque can be used. to get the best MPG its best to run your Eng at max peak torque, which is a specific RPM for that Eng. running at max peak torque uses the most torque available and not wasting fuel. you ll need to get a spec sheet for your vehicle that shows torque specs. run the Eng at that rpm . email me if needed

If you walk 2 miles in a circle, and walk 2 miles in a straight line; then you have walked a total of 4 miles. The distance your feet have traveled is the same each time. In this way power is similar torque. The distance may be the same but the forces exerted on you are different; angular velocity vs. linear velocity and angular acceleration vs. linear acceleration.

Torque = Force X radius [T=Fr]

Torque = mass X acceleration X radius [T=Fmar]

a = acceleration in feet per second per second

F = foot pounds per second per second per second

m = mass in slugs (which is foot pounds per second).

r = radius in feet

T = Torque in foot-pounds per minute per minute

V = Velocity = linear velocity in feet per minute,

Horse Power = Force X Velocity/33,000 = 2 (pie) rN/12 OR

Horse Power = NT/63,00

hp = foot pounds of work per minute

N = angular velocity in revolutions per minute

By definition 1 hp = 33,000 foot pounds of work per minute OR

746 watts of power (metric system).

Converting Torque (rotational energy) to linear movement is done by the tires. Since the average automobile is only 40% efficient a lot of energy is lost in the conversion.

If the math and all the conversion of units are troublesome, then don’t feel alone. If you have trouble doing the math then talk with a professional car guy.

I cannot give you an answer to your last question since I don’t know m (the weight of your spinning flywheel) and its angular velocity. To find this you need to either dissemble your transmission or find it in a mechanics repair manual for your car. Again, talk with a professional car guy.

the easy explanation would like to have a clidesdale horse pulling your heavy wagon or a quarter horse. the clidesdale has a lot of pulling power but not much speed. (torque) the quarter horse has lots of speed but very little pulling power. (horsepower)

i see torque as the thing that gets you to the maximum power, so the more torque the faster you get to max BHP....