Originally posted by CGrieves
EDIT: Come to think of it, another reason is that diesels inherently produce their peak power typically much lower in the rev range (i.e. more torque... remember torque is simply power output per revolution)
SOrry to correct you but power doesnt exist.
Its simple a value to qutify the rate torque is applies... or work done.
1bhp is (PooP mind blank
its late) IIRC 33,000 lbft/min
The diesel produces ace torque figures but as it only up to about 4.5 k the rate it can applie work is much lower than a revving petrol. hence the lower power figure.
Imagine a tight nut on a car wheel, if you had all the torque in the world, great?..... no not if no revolutions of the wheel brace is occuring, work is not being done only a force applied
The Deisel engine is like that strong, but cant work fast enough to create good power.
Honda Vtec on the other hand has medicre torque but applies it so fast with the revolutions of the fast spinning engine that work done is very high and hence the high power output.
Diesels have a compression ratio, circa 20:1 this requires strong compoinents and a robust block, hence the heavy weight, the engine cant rotate fast with all that mass and it doesnt particularly help that you cant optimise ignition points
Hope this is slightly conherant, im drunk and its late
Jonny