VWs

wrote:

Luckily for me RS Hoover has taken the time to actually be helpful. He
sounds like he's been building VWs and messing with them in airplanes
for many years. It looks like Dale Alexander has had a lot of
experience with VWs too. I can't tell yet who else responding to this
thread actually has built or used VWs in airplanes. Those are the
people I'm interested in hearing from and whose opinions I'd like to
hear.

VeeDubber is an excellent writer - and I believe he IS building a plane.

But I don't think he has yet finished and flown one.

(Correct me if I'm wrong on that Robert?)


Does "cavelamb himself" have any experience building VWs? Flown them
in aircraft? I don't know. I can't tell.


I have - several.

And helped on others.

But from tone alone, I doubt you are willing to listen.

Richard

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


An answer to my own question (in addition to the Limbach link):

http://www.jpx.fr/Jpx/english/pg_4tx75E.htm

Looks kind of like Jabiru cylinder/heads.

"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, 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

Here you go...
Some assembly required.

http://www.aeroconversions.com/aero_vee_2002.html


wrote in message
...
I had posted a link to a vid of a 701 weaving through the trees over
on .piloting.

At some point down the line I expressed interest in a VW powered 701.

One guy said he figured a VW would melt down in an aircraft cowling
when producing no more that 50HP.

He provided a link to Bob Hoover's blog, which had an entry "The
Christmas Engine", in which he states pretty flatly that:

1) No way to get 80 (let alone 100) HP out of an aircooled VW for any
extended period of time.
2) No way to cool an engine at those HP values if you could get them,
so you either get meltdown or very low time between overhauls.

Bob's blog looks as though he's talking direct drive. That pretty much
lines up with what I've read on the Great Plains website. GP says you
can only get higher HP from the VW by PSRU. That I can believe, on the
general principle that any engine has higher HP at higher RPM. Since
the VW wasn't designed to spin propellers, well, the best HP values vs
RPM don't align nicely for a direct drive VW and a propeller, do they?
That stands to reason.

So I'm asking this: for you VW people builders, what about cooling,
and is there some dyno data available from VWs spinning props with
PSRUs and direct drive available? Something somebody has been willing
to publish?

What about meltdowns? Because if what Bob Hoover says is true then it
seems to me there's no way Great Plains should be making a living --
unless their customers never have checked the numbers they GP claims.
GP has a lot of customers. You'd think they'd be screaming bloody
murder if they couldn't at least get close to 80 for takeoff.

I'm more concerned with thrust and cooling, though, than some HP
number.

What gives? What's "the truth"?

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

wrote

I thought this was the first "shot"

"You would have to replace the jug and head to match the aero design.
And
then why? So that you could mate you're new heads to a cylinder block
that has been known to crack just sitting on a shelf waiting to be
installed?"

I didn't think that was offered in the spirit of answering an honest
question, but to be aggressive and insulting.

That is where we part ways, with the spirit of the answer.

That, to me, was an important answer concerning the problems of using the VW
engine, pointing out that there were not only problems with heat and the
head, but that the case was another added problem. It was an honest attempt
to inform about yet another reason why the VW had problems. Nothing
personal, to me.
--
Jim in NC

And here we have a prime example of why humans communicating via text
rather than voice isn't always the best choice for communicating. It's
convenient, but... One can't pick up subtle clues as to intent via
facial expression or voice inflections, etc. The choice of a word can
be interpreted in more than one way by the receiver.

Scott
http://corbenflyer.tripod.com/
Gotta Fly or Gonna Die
Building RV-4 (Super Slow Build Version)

wrote:



I thought this was the first "shot"

"You would have to replace the jug and head to match the aero design.
And
then why? So that you could mate you're new heads to a cylinder block
that has been known to crack just sitting on a shelf waiting to be
installed?"

I didn't think that was offered in the spirit of answering an honest
question, but to be aggressive and insulting.

--

Craig wrote:

Careful, lest we end up juandering in the forest..

Craig

copy that...



Ok, so...



What we have here is a cute little motor that LOOKS a lot like an
aircraft engine. And it has been use that way for ages - with varying
degrees of success.

We've sorta discussed the problems cooling the heads. This is one of
the major limitations for a happy motor. But not the only one.

There are a few tricks that may help keeping your cool - but it takes
careful attention to detail. And I'm not promising anything!

one - increase the airflow through the heads. Dremel and file out the
cooling passageways. But note that they run vertically through the heads.
That's because in a car the engine has a shroud and a fan to
push air through. But the fan and sheet metal are big, heavy, and
awkward to cowl around.

Depending on whether the heads air exposed to the airflow or buried
inside a cowl, getting air through the cooling passage ways can be
fairly simple - or a real grumpy bear.

Exposed heads almost (ALMOST) take care of themselves. It will help to
add a set of eyebrows on top of the cylinder/head to push air down between
the jugs and through the heads. But pay attention to what's
UNDER the cylinders too.

Air does not like to be pushed around.

An inadvertent high pressure area under the cylinders (like a gap in the
cowl?)
can ruin the whole plan. Yarn and tape and check to see that the air is
really
going into the eyebrows and not simply going around.

For a full cowling, a plenums is IMHO worth the weight, cost and
complexity.
But you have to learn how to design a working plenums
for it to work well (or at all?)


All air cooled engines are really oil cooled. So cooling the oil
makes good sense and pays off in reduced temperatures.

But - don't try to hang an oil cooler remotely and run a bunch of
oil lines back and forth. The wall drag in the tubes can be counter
productive.

Besides the weight. (get used to hearing that because it's a lot more
important than beginners (and many experienced builders)
think/remember/admit.

The VW has a top mounted oil cooler. A small block of aluminum can be
carved into an adapter to mount the stock oil cooler on top of the motor
- laid over 90 degrees (flat across the top).

But for it to work you much convince the air to go through it.
Easier said than done some times.

I had a pretty big hole in the nose end of my cowling. It just HAD
to be pressurizing the inside of the cowl - so the cooler should get
plenty of air. Wrong. Temps hit 210 in only a few minutes climb
and would not come down when throttled back.

Well, yes, I had a nice lip at the aft bottom of the cowl to help
extract the hot air - but...

Short story is I had to add an inlet and duct to the oil cooler because
the exit lip worked REAL well. Air was not going over the top of the
engine.

Next major problem with the VW is that it is a slow turning auto engine
but a real fast spinning airplane motor. It has to turn up RPMs to make
horsepower - but the high RPM means a very short and horrible inefficient
propeller.

Works out sorta ok for light fast planes like the KR but sucks bags
for low and slow baby buggies.

My approach last time was to max out the engine displacement (2180cc!)
and over prop the thing with a 62 inch Tennessee prop. Full power
static RPM was around 2800 and came up to 3200 in flight. But I could
cruise at 2400 and climb well.

Beat the heck out of my first 1600 VW. I had to "step climb" that one.

Takes all the fun out of having fun!


PSRU - Prop Speed Reduction Units

While it looks good on paper, I've not seen many that really lived up
to expectation on the VW. Yes, you can make more power and swing
a bigger prop. But the heads are going to limit that.
And it is more weight...


Now, if you can work within all these limits and still fly the plane
a VW can work very well for you.

It can provide years of fairly dependable service.

But try to hot rod it and you may (or may not) live to regret it.

For what it's worth...

YMMV


Richard

"cavalamb himself" wrote in message
...
| Craig wrote:
SNIP

| All air cooled engines are really oil cooled. So cooling the oil
| makes good sense and pays off in reduced temperatures.
|
| But - don't try to hang an oil cooler remotely and run a bunch of
| oil lines back and forth. The wall drag in the tubes can be counter
| productive.

SNIP

| Richard

Your post is the only one addressing the real problem with VW engines as
being oil temperature. As a test bed I had a '73 VW van 2000cc type IV
carbureted engine rebuilt using German jugs and new heads. Cylinder head
temperature and oil temperature sensors were installed and monitored. A
two hour drive with OAT in the 90's brought the oil temperature up to
250°F and a mandatory long wait for it to cool down. The Cylinder head
temperatures were around 325°F.

Since the type IV has an oil filter I ordered a remote filter kit with
180°F bypass to a Cessna 150 flat plate oil cooler. The stock oil cooler
was left in place and the C-150 cooler was installed in the rear quarter
panel where air from the intake above would pass through the cooler. An
extra fan was not installed or needed.

Several long 70 mph trips were made in western Kansas and eastern
Colorado during 106°F weather. The oil temperature never went above
210°F with this setup. The cylinder head temperatures stayed around
300°F except for the #3 cylinder which sometimes reached 325°. No doubt
due to the placement of the internal cooler.

At a time when most van owners were lucky to get 45K miles out of their
engines I had 89K on it when I sold the van to a teenager. He managed to
destroy the clutch twice and the transaxle once before he sold it and
moved off to college. The engine was still running strong.

--
Anyolmouse


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