not exactly.... when you said the turbo diesel truck does not spin enough RPM's to spool up a turbo...

you have to remember that the big truck has a piston the size of a 5 gallon bucket. (well not really but you get my point) but a car engine has a piston the size of a a coke can. (also not exactly, but you get my point)

Turbos work off of exhaust pressure, the coke can may spin faster, then the 5 gallon bucket can still push just as much if not more air trough the turbo.

how did this subject get on turbos, instead of bore and stroke like nitro had first asked about?

anyways, just thought i would throw that one in.