VWs

"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 :-(

On Jan 29, 5:54 am, " wrote:
On Jan 29, 2:29 am, "oilsardine" wrote:

compared to the '85 HP aircraft cylinder head' the VW head doesn't look so
bad after all...
---------------------------------------------------------------------

Looks can be deceiving.

The maximum output of the carburetted 1600cc VW engine was the 1971
model which could produce about 57bhp... for about ONE MINUTE.
Maximum SUSTAINED output (ie, CHT of 450F) was about 44bhp under
Standard Day conditions. At that level of output you could expect the
exhaust valves to drop out of spec after about 200 hours. NOMINAL
output of the 1600VW was about 15bhp, which allowed the exhaust valves
to survive for up to 1000 hours (although 600 t0 750 was more the
norm). After-market 'hot-rod' heads do even worse since they have
less fin area. Volkswagen dealers commonly swapped-out worn heads
without bothering to inform the owner, other than to list their
replacement in the 'OTHER SERVICE - AS REQUIRED' block on the work-
order.

To understand why the VW head does so poorly simply compare it to the
early 1500cc (85hp) Porsche heads. Then compare those to the Corvair.

-R.S.Hoover

PS -- Here in the States many VW owners insist their vehicle NEVER
required anything other than normal maintenance when in fact,
examination of its service records usually shows 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.

I'm building or should be building) a Hummel Bird, which
uses a half-VW conversion. What's your take on these things, seeing
that you have lots of VW experience? My experience with VWs is limited
to my first car, a '62 Beetle that I spent lots of time fixing, and a
friend's '59 van. Ditto. Scott Casler claims 37 HP from a 1037 CC two-
banger. Sounds high.
For those interested, here's the website: http://www.hummelengines.com/
Click on the "Hummer 2 Cylinder VW"

Dan

On Jan 29, 11:46 am, wrote:
half-VW conversion. What's your take on these things,

--------------------------------------------------------------------------------------------

Generally poor.

If I wanted a two-cylinder air cooled engine I'd go buy one, following
the lead of Leeon Davis.

If someone held a gun to my head and forced me to build a two-banger
using VW components, I'd do what Leonard Milholland has done.

But a cut-case half-VW doesn't make a lot of sense for several
reasons, most based on hard-ball engineering. For example, we've been
aware of the thermal limitations and lubrication problems of the VW
since the late 1950's and it would seem logical that if you're going
to modify the engine as extensively as is done with the typical half-
VW you would use that opportunity to increase the fin area of the
heads and provide for full-time top-end lubrication. But the guys
selling half-VW conversion plans didn't do that. Nor did they use
that opportunity to install a solid-state two-cylinder ignition
module, such as the Briggs & Stratton unit used on the AeroVee.

But the main reason for my generally poor opinion of two-bangers has
to do with how they FLY . Or rather, how they run. None of the
horizontally opposed two cylinder engines I've flown behind (3 of
them; Long, Wright-Moorehouse, and Aeronca) were very smooth and the
Aeronca was the only one you could call well engineered (Leslie Long's
engine was home-made using Harley-Davidson jugs).

Finally, given the alternatives, I can't see how anyone can justify
the cost of these converesions. To me, it simply doesn't make sense.

-R.S.Hoover

wrote:


I'm building or should be building) a Hummel Bird, which
uses a half-VW conversion. What's your take on these things, seeing
that you have lots of VW experience? My experience with VWs is limited
to my first car, a '62 Beetle that I spent lots of time fixing, and a
friend's '59 van. Ditto. Scott Casler claims 37 HP from a 1037 CC two-
banger. Sounds high.
For those interested, here's the website: http://www.hummelengines.com/
Click on the "Hummer 2 Cylinder VW"

Dan

In that case, I'm sure you've heard of Bruce King's Hummel project from
a few years back.

His is perhaps the "most successful" VW powered project - at least in
terms of miles traveled.

Bruce hung a full 1835 on his bird.
The weight difference is small - with no real issues other than weight
and balance.

But what a difference in performance.

Should be links somewhere of the Hummel forums.

Check it out before cutting the engine in half!

Richard

On Tue, 29 Jan 2008 11:46:17 -0800 (PST),
wrote:


I'm building or should be building) a Hummel Bird, which
uses a half-VW conversion. What's your take on these things, seeing
that you have lots of VW experience? My experience with VWs is limited
to my first car, a '62 Beetle that I spent lots of time fixing, and a
friend's '59 van. Ditto. Scott Casler claims 37 HP from a 1037 CC two-
banger. Sounds high.
For those interested, here's the website: http://www.hummelengines.com/
Click on the "Hummer 2 Cylinder VW"

Dan
Mabee 20 sustained and 35 peak. And I'm an optimist.

--
Posted via a free Usenet account from http://www.teranews.com

wrote:

To understand why the VW head does so poorly simply compare it to the
early 1500cc (85hp) Porsche heads. Then compare those to the Corvair.

-R.S.Hoover

Out of curiosity what is your opinion of the Corvair engine?

Tony

On Jan 29, 11:57 am, Anthony W wrote:

Out of curiosity what is your opinion of the Corvair engine?
______________________________________________-

Excellent.

It is a modern engine, with full-flow oil filtration, hydraulic cam
followers and a modern valve train. It also has more bearing area per
HP and a crankshaft that facilitates installation of a propeller.

I suggest you either leave the thing perfectly stock, including the
blower, as used by Bernard Pietenpol, or buy William Wynne's
conversion manual and follow it religiously.

-R.S.Hoover

On Tue, 29 Jan 2008 19:57:34 GMT, Anthony W
wrote:

wrote:

To understand why the VW head does so poorly simply compare it to the
early 1500cc (85hp) Porsche heads. Then compare those to the Corvair.

-R.S.Hoover

Out of curiosity what is your opinion of the Corvair engine?

Tony
The corvair has more fin area than an O200.

--
Posted via a free Usenet account from http://www.teranews.com

oilsardine wrote:
compared to the '85 HP aircraft cylinder head' the VW head doesn't look so
bad after all...


Really? When I look at the VW head image, I see two cylinder heads cast
together in a manner that reduces the total fin area and obstructs
cooling flow. I see a cylinder head with cylinder stud bosses that not
only reduce fin area, but are actually blocking cooling air just where
it is needed. Same with the studs themselves. I see a cylinder head
with a single pompadour cooling fin in the extremely critical area
between the valves and spark plug boss. If you could actually hold a
C-85 and VW both in your hand the differences would be even more striking.

Charles


"Charles Vincent" schrieb im Newsbeitrag
An 85 HP aircraft cylinder head:

http://www2.tech.purdue.edu/at/cours...arrel&head.jpg

A VW head:

http://www.allworldautomotive.com/ph...1817-15127.jpg


Charles

Really? *When I look at the VW head image, I see two cylinder heads cast
together in a manner that reduces the total fin area and obstructs
cooling flow. *I see a cylinder head with cylinder stud bosses that not
only reduce fin area, but are actually blocking cooling air just where
it is needed. *Same with the studs themselves. *I see a cylinder head
with a single pompadour cooling *fin in the extremely critical area
between the valves and spark plug boss. *If you could actually hold a
C-85 and VW both in your hand the differences would be even more striking.

Charles

Has anyone ever tried adapting aero head designs to the VW block and
cylinders?

Yes I know that would be a considerable effort. I guess no one has
otherwise we'd see references to it. If I were really good with CAD I
would consider giving it a shot. I know a guy who has the CNC
equipment and could probably machine aero style heads (although I
don't know what would be the right material).

An interesting experiment if you had cash and time on your hands. It
seems from what veeduber writes that this is a matter of cooling
efficiency for durability, rather than HP or torque per se.