SO WHAT MAKES AN ENGINE POWERFUL IS HIGH TORQUE AT HIGH RPM.
Totally agree. The higher up the rev range the torque is produced, the more horsepower an engine will develop. Power only starts to trail off when the torque curve falls faster than the rpm's increase.
The problem with diesel engines is, the torque is created from a long stroke , this will lead to a very high compression ratio which is necessary to ignite the diesel, in turn will make the maximum engine speed very limited hence not a lot of power.
Again, I totally agree. The long stroke of the diesel engine limits the rev range of the engine, so regardless of the amount of torque an engine produces it will only be as powerful as the rev range allows.
I don't think I've ever said horsepower is not important. All I've tried to get across is that a massive bhp isn't the only factor in creating a fast car and people should not assume that a low power figure means a slow car (in the case of a diesel).
That is reflected by comparing the in gear times of my PD150 with, for example, a Civic type R. That has a third as much power more than mine, but as its engine's output (torque) is produced much hgher up the rev range, all this power is produced 6000rpm+ So, how does that translate to its in-gear times? It doesn't see which way I go!
To summarise, Power is a figure that reflects an engines capability to repeat its output (torque) over time (rpms). Due to the requirements of diesel iginiting (as you said) my engine is not capable of reproducing that output over such a long period of time (rpms). that doesn't mean diesel cars are slow, it just means we can't take advantage of that output over such a long rev-range, we just need to grab another gear!
If we agree on all that, then I don't see what we're arguing about either!
