[Gerrit Loubser]

Engine torque is what gets things going and keeps them going, and engine power is merely a consequence of the engine's ability to generate torque at speed.

High power can be generated at very low engine speeds if a lot of torque is available (e.g. in a ship's diesel engine) or the same power can be generated at very high engine speeds with a lot less torque (e.g. in a Formula 1 engine).

The main reason why diesel engines have more torque is that they have much higher compression ratios. A higher compression ratio simply means the piston has to travel further from bottom dead center to top dead center in a diesel than in a petrol of comparable capacity, i.e. the stroke must be longer. A longer stroke requires a larger crank throw, which means more torque, even if the mean effective pressure on the piston is the same, because the lever arm is longer. By the way, the diesels normally run at slightly higher mean effective pressures as well.

[Ejay]

Kw's is the rate at which an engine develops its torque.

Therefore obviously the more Kw's you have the better the rate at which the torque is developed.

eg. Assume Pierre Spies and Os Du Randt are both only capable of pulling a maximum load of 100Kg up a hill, Pierre with slightly more power (Kw) may not be able to pull a heavier load up the hill but he can pull the 100Kg's up the hill slightly faster than Os.

Ejay