Re: Engine KW's
The maximum speed and maximum power are at different rpm points (because as the torque curve drops away from its peak the increase in rpm means the power output keeps rising until the torque really begins to fall - hard to describe/picture I know). Therefore you can't calculate the maximum torque from the maximum power figure.
To get an idea of how "good" an engine is, the specific outputs (ie per litre) are a good guide, also how wide the "powerband" is - one way to get an idea of this is to see how far apart in rpm the peak torque and power figures are. Eg if peak torque is 6500rpm and peak power is 7500rpm the engine is likely to be quite peaky & not have much down low. However if the transmission etc can keep the engine in that peak operating band then it will still be quite quick (eg close ratio gearbox).
With newer engines the spread of torque is usually better than it was (especially compared to carburettor cars), with things like variable valve timing, inlet manifolds not to mention turbo engines. You will often hear people talk about a "flat" torque curve meaning the engine puts out high or close to maximum torque over a wide rpm range. So the bottom line is you can't just judge it on peak outputs (although they are certainly not unimportant), you can get a better idea from a power & torque graph buy looking at how much area is underneath the curves.