"Dale Alexander" wrote in message
...
Hear! Hear!

Back in my miss-spent youth, I worked in a VW independent repair shop in
San Mateo, Ca. A place called Father Noel's. I rebuilt three engines a
week and saw it all. The same 47 reasons why the air-cooled VW needed
"periodic replacement of heads, carb, distributor, clutch and oil pump
with rebuilt units, all for a nominal charge, when the vehicle was brought
in for service."

Here is a partial list of what WILL go wrong with your fan drive up front
WITH A STOCK TYPE ENGINE ( for those about to flame me, please read that
last statement several times least you look foolish):

Exhaust valve stems stretch to the point of the valve heads breaking off
and trashing engine. You'll know when this is about to happen when your
engine won't hold a valve adjustment.
Cylinder heads crack between seats.
Cylinder heads crack to spark plug hole. You'll know this when the spark
plug seizes when being removed because of accumulated carbon in the
threads.
And then the spark plugs blow out...
Valve guides that wear out as soon as engine starts (a lot like old
Triumph motorcycle engines)
Cylinder head sealing surface leaks due to case studs stripping threads
out of the case. You'll know this when your brand new muffler sounds like
it is falling off under acceleration.
Ever present oil leaks from the case crack developing in the number 3
cylinder area behind the flywheel (ok...prop drive).
Loss of oil pressure at low rpm due to case separating at the center main
bearing area.
Flat cams and worn lifters due to great German metallurgy.
New version of air-cooling when rod escapes confines of case.
And on...and on...and on...

Granted, all of these things can be fixed with a generous infusion of
money, maybe two shoe-boxes full of 20's will do the trick. But the basic
idea is that this engine isn't adequate to push around a 1500 pound car at
part throttle let alone an aircraft. And by the time it is capable, it is
more a Lycoming (no great accomplishment in itself) than a VW i.e. a
horizontally opposed four cylinder engine in the same vein as a
water-cooled chevy based aircraft engine is no more a chevy than a Nascar
prepped race engine with origins in a dozen speed part catalogs.

A common statement by some of the longer haired VW owners ( this was the
70's) was that VW's were great because they were easy to work on to which
I would reply that is fortunate as one works on them a lot. We made a lot
of money off those types. Now today, would the owner of a present day
vehicle, with all of the subsequent technology advances, put up with that
repair frequency? Oh wait! They do! They are called Volvo, Mercedes and
BMW owners.

If you are going to rely on a VW or other small displacement engine to
keep your aircraft an aircraft and not a smoking hole full of parts, build
it with the best parts possible with the best information available and
don't skimp.

By the way, I'm have not been immune from thinking poorly or emotionally.
In the 80's, I raced a Ducati bevel-drive twin in AMA Twins. It developed
enough horsepower to break cases every two races. I welded a chain to it
and took it fishing once. When I was done fishing, I cut the anchor chain
and went home.

Gotta realize when you have gone down a road too far...

Ready for flames now...

Dale Alexander

I appologise for reading this thread a little belatedly; but this is quite
interesting, and my own rather limited experience with the earlier 1200cc VW
engines suggests that there is much more than a grain or two of truth in it.
Actually, I do suspect that a lot of owners may have shortened their times
between service by shifting to the next higher gear in the belief that they
were saving fuel and extending their engine life--in much the same way that
many homebuilders opt for a more coarsely pitched prop in the belief that it
is easier on the engine and will also save fuel. However, we did have far
more trouble than might have been expected after putting in one of the "big
bore" kits, which raised the displacement to a little less than 1400cc, when
rebuilding one of our 1200cc VW engines.

In any case, although I greatly respect Bob Hoover, I had been about to
dispute his horsepower figures--simply on the basis that around 3200, or
even 3400, RPM seems like a reasonable speed for a prop small enough for the
torque of a 1600cc direct drive engine. A large part of that was because of
my own affection for relatively "slippery" designs, and is really not
applicable to any of the slower designs, such as most of the biplanes and
parasols. Just as an example, a carefully built KR-2 should really only
need about 30 HP or so to maintain a 100 to 105 knot cruising speed, and a
1600cc engine should be able to do that--with enough excess torque available
for the takeoff and climb. Not an extreme performer; but, at least on its
face, seemingly a reasonable goal.

However, given your additional experience to suggest that my own was not an
isolated case, it may indeed be more reasonable to think of the 1200cc VW as
a 25 HP engine--as it was considered for the old Jodel D-9 and several other
aircraft of that period. That would conveniently scale up to about 37 HP
for a 1600cc engine--and a little more rpm would add more horsepower at the
expense of a little thrust at low speeds and a very strict time limit on the
use of high power. But that was only the bad news--the worse news is that
all of this suggests that the cruising power limit for the 1600cc VW might
only be 70 to 75% of 37 HP--and that is about 26 to 28 HP, which is really
only enough for some of the single seaters!

Obviously, larger displacement and some of the purpose built kits and parts
should help; but I have no idea how much.

Peter :-(