how come car makers brag about how much power its got rather then how much torque its got, isn't torque more important then power? i'm just asking this out of curiosty cause i always thought is was only torque that had everything to do with the acceleration performence

kW Give you the power to have top speed

Torque Pushes you there

i think...

They are both connected. Power is a function of torque multiplied by rpm

kW is amount of power, Torque is rate of power increase. No point having a car that can go up to 200Km/h if it takes 5 minutes to reach because it has hardly any torque.

kW is amount of power, Torque is rate of power increase. No point having a car that can go up to 200Km/h if it takes 5 minutes to reach because it has hardly any torque.

Yeah and allot of deisels can pull a house, but they can't pull it fast :P

nodz the way i thought it was similar to the relationship between velocity and acceleration

acceleration is the multiplier that gets you to your velocity quicker

torque is the multiplier that gets you to your power quicker

this has always confused the crap out of me. torque is measured in newtons applied to a point an amount of metres from a pivot. so 100N at 10m is 1000Nm, and could be countered by 200N at 5m from the pivot on the other side. the thing i don't get is the speed of revolution would be determined by how much force is countering the torque of the engine, so where does power come into it? seems to me kW is just a measure of how high in the rev range the torque remains strong, but i know theres something i'm missing. if anyone wants to fill me in i'd greatly appreciate it.

Power (kW) = Torque (Nm) × rpm / 9550

Torque = Force X Radius

Imagine 2 engines with equal power. One high in torque, one low in torque but revs faster. Both are connected to a winch/pully that are pulling up load of equal mass.

The engine with more torque will pull a heavier mass up. The engine with less torque will pull less mass up but at a higher speed.

In the world of cars, torque will shove you your butt firmly in the seat when accelerating. Power will allow you to have a higher top end. Performance comes from both. Whats the point of having lots of torque but using all that to get to 30km/h. And Whats the point of having huge power when it takes you a minute to get to 300km/h or beyond.

Autospeed (http://www.autospeed.com/) wrote a two part article back in 2000 exploring the relationship between power and torque and their effects on performance. It's worth a read. Anyhow, here's the article's conclusion which I've shamlessly pinched.


So power is the critical determining factor for maximum acceleration, and torque is necessary for driveability. This can quite clearly be seen in looking at the types of engines used for certain applications. Trucks and industrial vehicles use engines with large amounts of torque with a fairly flat torque curve, but relatively little power. Racing and sporting vehicles use high revving engines, with high power and relatively little torque in comparison to their power outputs. That is why you have F1 having engines revving to over 18000 rpm. And there's no use doing that if to maximise acceleration all you needed to do was maximise the amount of torque you had!
Articles themselves are here (http://www.autospeed.com/cms/A_0744/article.html) and here (http://www.autospeed.com/cms/A_0755/article.html).

When ever a question like this needs answering this (http://www.howstuffworks.com) is the best place to look. In regards to torque... (http://science.howstuffworks.com/fpte4.htm)

if you have a look at WRC rally cars they have way more tourqe then power cos there off and on the throttle in corners

its hard to do its either well this is the way i have always seen it bucket loads of power no torque or vice versus

Power (kW) = Torque (Nm) × rpm / 9550

Torque = Force X Radius

Imagine 2 engines with equal power. One high in torque, one low in torque but revs faster. Both are connected to a winch/pully that are pulling up load of equal mass.

The engine with more torque will pull a heavier mass up. The engine with less torque will pull less mass up but at a higher speed.

In the world of cars, torque will shove you your butt firmly in the seat when accelerating. Power will allow you to have a higher top end. Performance comes from both. Whats the point of having lots of torque but using all that to get to 30km/h. And Whats the point of having huge power when it takes you a minute to get to 300km/h or beyond.

To be honest though.. I'd be pretty happy if my car got to 300km/h in a minute :bowrofl:

I like to use the analagy that power is the ability to do work and torque is the rate at which work can be done.

Yes I know its not supa accurate but it gets the idea across :D

and talk is what u do with ur mates...:P :bowrofl: :bowrofl:

I like to use the analagy that power is the ability to do work and torque is the rate at which work can be done.

Yes I know its not supa accurate but it gets the idea across :D


noice :bowrofl: :bowrofl: but at the same time :redface:

if you have a look at WRC rally cars they have way more tourqe then power cos there off and on the throttle in corners
That's because they have restrictor plates to restrict the inlet airflow and have a power limitation.

I like to use the analagy that power is the ability to do work and torque is the rate at which work can be done.

Yes I know its not supa accurate but it gets the idea across :D

I think you have the two mixed around, torque it the abillity to do work, and power is the rate at witch you can do it. :P

With women torque is how far they twist yur nuts and power is what it gives em :bowrofl:

With women torque is how far they twist yur nuts and power is what it gives em :bowrofl:


classic :bowrofl: i think this might be my next sig

That's because they have restrictor plates to restrict the inlet airflow and have a power limitation.


yer and there only allowed a cetain turbo wheel size aswel

Torque is twisting force. I.e. twisting a crank shaft, tail shaft etc. Power is the amount of work done at any given time the twisting force is applied. This abviously increases with rpm until additional torque cannot be generated due to mechanical or other restrictions on the motor.


Example: A donkey turns a windmill 2x times in a minute and crushes 10kg of wheat. The same donkey feels energetic and gets 4 laps done in a minute, crushing 20kg of wheat. The 'donkey' motor achieved the same torque at 2rpm as it did at 4rpm, but got much more work done at 4rpm than at 2rpm.

Turbos and Superchargers are generally tuned to produce the highest torque figure from as low in the rpm as possible and keep the torque output as linear (geometric anyway) as possible until mechanical restrictions apply. In a street/road car it is best to have a motor that pulls (applies torque) hard in a large band thru the rev range, rather than a motor that has little torque thru much of the range and a peak of torque at say high rpm. Such a motor would be best suited to the F1 circuit rather than a street racer.