Date:         Fri, 28 Sep 2001 03:42:01 EDT
Reply-To:     FrankGRUN@AOL.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Frank Grunthaner <FrankGRUN@AOL.COM>
Subject:      On the Lower Perceived Lifetime of Diesel Vanagons ACT VW Diesels
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Again faulty wisdom has raised its nefarious head!

This topic was enjoined by the anecdotal observation that Diesel Vanagons
died the death of the internals faster (in terms of total distance traversed!
- I understand the apparent oxymoron generated upon using diesel and forms of
fast, faster and fastest in the same sentence) than do similar engines
mounted in G/J/D/Q/A frames. Even more odious, the suggestion was made that
the problem was related to gearing differences. So it is with a heavy sigh I
offer the comment (with further documentation addressed in the archives):

Its not the number of spins (revolutions) but rather the work done! Not the
length of walk, but the weight of the pack! Not the ... Oh well another tack:

The Vanagon diesel is plagued by two serious shortcomings. 1). A lifetime at
full load, and 2). Mere disinterested users who disregard maintenance. As for
point two, I shall not expound. For point the first, however, I would note
that the diesel vanagon generally yields a maximum fuel economy of 25 to 28
miles to the US gallon. This is in contrast to normal VW N/A diesel economy
of 35 to 45 mpg. Miles per gallon in the long statistical aggregate can be
taken as related directly to the amount of work expended per unit distance.
These "data" suggest that the average Vanagon diesel is putting out between a
minimum of 25% to a maximum of 80% more work over its lifespan that other VW
applications. So a vanagon engine lifetime of 110,000 miles translates to
about 200,000 miles in rabbit units. Seems OK to me!

Engine longevity is directly proportional to mean brake specific pressure per
unit time. Temperature issue, rpm and load cycling and excess fuel wash of
cylinders are further perturbations as is lubricity and oil acidity, but
these are secondary. Lower gearing (more spins per mile), lower load, then
longer life.

Guys (and others), if the engine is properly designed and operated within its
design limits, 3000 rpm at 60 or 4000 at 60, 4000 rpm for these small low
torque engines probably has more durability (mean time to failure) as
compared to the 3000 case. Negligibly more fuel burned. Just louder!

Frank Grunthaner