wrote:


One BIG factor is being forgotten here. The diesel is turboed. This
makes it roughly equivalent to an 8 liter engine at about 6psi boost.
Any combustion engine produces power in proportion to the amount of
air consumed. On a diesel it does not necessarily "consume" all the
air that goes through it - but the maximum power output is definitely
limitted by how much air can be put through it. A turbo can eisily
double the amount of air an engine pumps through it at a given speed.

Running an engine at double the speed also increases the amount of air
going through the engine - not quite double due to reduced volumetric
efficiency at speed.

Double the CFM gives double the horsepower, before factoring in
frictional losses and / or pumping losses.

A naturally aspirated diesel engine generally produces less HP per
unit of displacement, but more torque at low RPMs due in part to less
pumping loss (no air throttle)

SOME diesels are turboed. Many are not. Some Diesels are normally
aspirated. Some are supercharged with geared chargers. Some are
turboed. It is by far an overgeneralization to claim that all Diesels
are supercharged, even more so to say they are all turbo-supercharged.