Firstly, let us understand the difference between force and torque.

for linear propulsion, the formula is F = m*a where
F = Force exerted on the object
m = mass of object (also known as inertia, i.e. the tendency of a stationary object to resist motion in a straight line) and
a = acceleration

so for a given amount of mass, the higher Force applied, the higher acceleration you get, make sense?

Okay now let us move on Torque. Torque is basically turning force in layman's term with formula T = F*d where
T = Torque
F = Force
d = Distance between point of Force and pivot.

If this is difficult to understand, think of a door. It is easier to open a door when you push it from the knob compared to if you push it nearer to the hinge right? That's torque acting.

Torque is therefore the analog to Force when it comes to rotational propulsion. Car engines derive their power essentially through rotation therefore we rate engines (and electrical motors) based on their Torque, not Force.

The formula is then T = I*alpha where
T = Torque
I = moment of inertia (i.e. the tendency of a stationary shaft to resist rotation)\
alpha = angular acceleration

Therefore, it is clear to see that for a given moment of inertia, the higher the Torque to higher the angular acceleration. Makes sense so far? higher angular acceleration means higher straight line acceleration at the wheels.

Hope you find this useful, I am running short of time. Let's save the discussion of Power for another day lol. Cheers!

This post has been edited by onlyforthecars: Dec 7 2009, 06:42 PM

Lol. Until now still can't agree over Torque and Power?

In super layman terms, Torque is rotating force and power is how fast you take to do a certain amount of work.

A layman example would be, when you try and unscrew a bottle cap, torque is how much rotating force needed by your hands to unscrew it and power is just how fast you can unscrew it. (may not be 100% accurate but it gives a rough idea).

So for engines, Torque is the amount of rotating force the engine can provide to propel the car from standstill and Power is the how fast the engine can propel the car.

So higher Torque means the engine can propel the car to a given speed in a shorter time (Acceleration) and Power determines the maximum speed the car can achieve.

Power is derived from Torque.

The most super basic analogy i can think of is:

Power is how fast you can run.
Torque is how fast it takes you to get fast. (sorry might sound a lil cacat here haha but hope you get my drift).

Hope this helps.