I do not understand why Paul McBride is so against diesels as all new diesels are virtually vibration free (Diesel engines and GA: A good combination? June 23 issue).
The new Jaguar built V-6 DOHC diesel being placed in Jaguars, Peugeots, Saabs, etc., has the least — and certainly cannot be felt “vibrating.” It is, in fact, “silky smooth” and is said to be able to stand a dime on it while running — as are now quite a few different makes.
What you seem to be referring to are the crankshaft “impulse” effects on propellers and reduction transmissions that the FAA requires testing on.
The impulses produced by diesels (not vibrations) are far greater than a gas engine due to the greater torque that a diesel produces due to the far greater power that kerosene and diesel fuel produces over gas. However the computer-controlled multistaged injectors are all but eliminating that problem.
Today’s modern diesel is absolutely nothing like a diesel from just 10 years ago. Even the weight issue is being reduced, and with about 30% less fuel consumption, and TBOs being about double and beyond that of a gas engine means that you carry less weight in fuel (due to that lower fuel consumption), but still go farther — and have far fewer problems than you could ever realize with a new gas-powered Lycoming.
A new Thielert 350 hp V-8 diesel will power a Malibu Mirage to well over 230 kts at altitude due to a lower lapse rate than a gas Lycoming and will also go beyond 3,000 hours before replacement with no top ends or anything else other than filter and oil changes which, by the way, are far fewer between than a gas engine running on sludge-producing 100LL. (A full synthetic oil will not suspend and hold lead sludge).
As for Harley vibrations — even Harley has removed a good percentage from its new engines.
I do not understand why you are so against diesels.