The Orphaned Engine, Part Two

Having referred to an 'orphaned' engine shortly after being diagnosed
with an incurable form of cancer lead to a gross misunderstanding as
to the immediacy of my demise, with me being carried out the door, X's
for eyes with a wrench still clutched in my hand. Last June I was
diagnosed with Multiple Myeloma. Although there is no cure, it IS a
treatable form of cancer and I'm doing everything I can to stave off
the inevitable.

The misunderstanding arose from my mention of an ORPHANED engine.

An orphaned engine is one that is no longer supported by it's
manufacturer, such as the twenty MILLION or so air-cooled
Volkswagens. And even then, the term isn't very accurate, for while
Volkswagen of Germany no longer supports the air-cooled engine,
Volkswagen of Mexico continues to manufacture air-cooled crate
engines.

But the worst part of this misunderstanding has to do with a
particular configuration of an air cooled Volkswagen engine that has
been converted for use in a light plane. The purpose of this message
is to try and clarify that particular misunderstanding.

When someone mentions a VW engine converted for flight a majority of
people assume you are speaking of a big-bore stroker. And a big-bore
stroker can be an expensive proposition. Why so expensive? Mostly
because of all the machining needed. Which may not make much sense
until you realize they are talking about BIG bore strokers -- engines
of 140cid and up. (What's the biggest of the big bore strokers?
Probably the full-trick aluminum-cased Type IV's with a set of 101mm
jugs on top of a forged 90mm crankshaft. That's 175 cubic inches.
And a lot of machining.

But that's not what I was referring to when I mentioned 'orphaned'
engines. I was referring to the often overlooked method of increasing
the displacement without having to do any machining at all. That is,
to simply install a crankshaft having a longer throw. Auto-makers
regularly design-in this method of displacement growth to sustain
interest in their product-line.

This method of increasing the displacement of the VW engine should be
of particular interest to homebuilders because there are a number of
single-place designs that fly perfectly well behind a VW conversion of
stock displacement... and fly even better when using an 1834cc
engine. But the 1834 can be an expensive proposition, requiring
machining of the case and heads to accept 92mm jugs. By comparison, a
1700cc engine -- the result of running STOCK jugs over a 74mm
crankshaft -- requires NO machining at all. An added plus would be to
use longer connecting rods, taking advantage of the greater dwell at
TDC to enhance the engine's low-end torque, making it more suitable
for bolting to a propeller than to a box of gears.

-R.S.Hoover