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Corvair conversion engines



 
 
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  #1  
Old January 21st 06, 07:39 PM posted to rec.aviation.homebuilt
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Default Corvair conversion engines



clare wrote:
On Fri, 20 Jan 2006 08:06:33 -0600, Cal Vanize
wrote:



I don't think there's any dispute over the relative cost of engines.
This issue is longevity and whether one wants to fly an airplane with an
engine that might not make it to the next airport.



You mean like a Lycoming? or an old Franklin?


Can't speak for Franklins. But I've never had even a skip on Lycomings
with with over 400 hours flying PIC in plances with Lyc engines nor with
any Conti with over 500 hours PIC in those. These weren't in homebuilts.

  #2  
Old January 22nd 06, 04:46 AM posted to rec.aviation.homebuilt
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Default Corvair conversion engines -

clare at snyder.on.ca wrote:
On Fri, 20 Jan 2006 08:06:33 -0600, Cal Vanize
wrote:

I don't think there's any dispute over the relative cost of engines.
This issue is longevity and whether one wants to fly an airplane with an
engine that might not make it to the next airport.


You mean like a Lycoming? or an old Franklin?


Oh for Pete Sake...ok.

A couple of years back, I picked up an Aeronca Chief down in Florida and
flew it home. Real nice airplane, and a real bargain - because - the
engine wasn't all that great. Continental 85 with metal prop.

It had been "overhauled" by one of the club members (not A.P.) and
they (the sellers) were honest about it up front. It leaked (a bit).
And they were right reasonable on the price.
So a deal was offered, $1000 earnest money sent.
And Leo and I went down to see?/fetch?

We flew it around for a while and determined that the plane was rigged
nice and straight, stalled straight ahead, and with the 85 and a climb
prop, it could for sure and certain - climb!
The little engine ran strong.

Checking the oil level shortly after landing (yeah, I know) showed it
had indeed lost some oil, but we found it - all on the belly.

Oh well, I'm not going to have to clean it. Not part of the deal.

The seller offered to "wipe her down and top off the oil and gas".
(yeah, I know - now.)

So, next morning, oil and gas are full and we headed off for home.

It took 3 days to get home and about 12 hours flying.
Two hour legs left an hour fuel reserve for the Chief.
And the climb prop doesn't go anywhere in a hurry - except up.

This engine leaked so much oil it would embarrassed a Harley.
I mean really!

But something else was wrong.

The engine ran fine, but it felt a little sharper than normal
during climbs, but smooth out fine at cruise.

For the next three days (over swamps, timber, and once VFR on top,
I could actually hear/feel/taste it getting worse.

A little sharper at first. Then louder. Each takeoff.
Only while climbing.

On the last leg home I thought maybe an exhaust muff was opening
up maybe? And then thought - or a cracked mount?
But it smoothed out at cruise.

When we rolled out at home, I was glad to be there, because I had
decided that the engine was indeed failing and needed to be looked
over.
Very carefully.
BEFORE flying it again.

It still ran strong, but something was really major league wrong
somewhere during climb out.

When Bob (A.P.) tore it down he found the bad seals, sure, and some
other minor stuff, and one cylinder with a crack about 1/4 of the
circumference of the flange.

The crank and cam were ok. Mags ok.
A (as in one each - count it) new jug, bearings, seals, etc.
signed off major overhaul cost 4 grand.

Grandpa, the new owner, it totally tickled with his Chief.

He learned to fly in it.
Took his PPSEL check ride in it.
Took his _wife_ flying in it!
Someday his boys will have their chance to learn to fly in it.


So, what exactly is the point, you ask?

This issue is longevity and whether one wants to fly an airplane with
an engine that might not make it to the next airport.


Right
Hell if I know.
But it was a fun trip otherwise...

Richard
  #3  
Old January 20th 06, 07:17 PM posted to rec.aviation.homebuilt
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Default Corvair conversion engines

wrote)
I bought two 3.8L Ford V6's for $150 each, bought new pistons from Roush
racing, new rings, had the best block shot peened bored and honed, had the
best crank turned and nitrided, bought new bearings, new cam, new
distributer with two sensors installed for dual ignition, new pistons, new
timing gears and chain, planed the heads, had four new intake valves
installed and new guides installed as well, new valve springs, roller
rockers, new lifters, new carburetor, old style NWAero psru, ARP studs for
the crank bearings and cylinderheads, fabricated my own headers, and STILL
spent only about $6,000.



Why not fuel injected?

Also, is that two for $3K each?

What does that setup weigh?

Was matching a prop to your engine a problem? 3 bladed prop?

Curious...


Montblack

  #4  
Old January 20th 06, 09:04 PM posted to rec.aviation.homebuilt
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Default Corvair conversion engines

On Fri, 20 Jan 2006 13:17:48 -0600, "Montblack"
wrote:

wrote)
I bought two 3.8L Ford V6's for $150 each, bought new pistons from Roush
racing, new rings, had the best block shot peened bored and honed, had the
best crank turned and nitrided, bought new bearings, new cam, new
distributer with two sensors installed for dual ignition, new pistons, new
timing gears and chain, planed the heads, had four new intake valves
installed and new guides installed as well, new valve springs, roller
rockers, new lifters, new carburetor, old style NWAero psru, ARP studs for
the crank bearings and cylinderheads, fabricated my own headers, and STILL
spent only about $6,000.



Why not fuel injected?

Also, is that two for $3K each?

What does that setup weigh?

Was matching a prop to your engine a problem? 3 bladed prop?

Curious...


Montblack


I didn't go fuel injected for two reasons, simplicity and safety.
Carburetors don't need an electrical system to operate and are
basically pretty simple. If you are a mechanic, carburators are easy
to diagnose and repair. Fuel injection requires a relatively high
pressure fuel pump and of course, the injectors. Both of which are
likely electrically operated. The carburetor *may* use a fuel pump,
but it's of the 5 - 7 psi variety, and with a high wing airplane,
isn't absolutely necessary in order to get fuel to the carburetor. So
if the fuel pump fails, you likely will still be running.

Plus, my entire premise was to not reinvent the wheel. Using the auto
fuel injection requires the use of the car's computer. Using the
computer requires all the sensors and sometimes faking the sensors out
so that they give the proper information. It all seemed too arcane
and difficult for me.

Carburation does not produce less power than fuel injection, but it
might be slightly less efficient, depending on how the engine is
leaned, and how much the pilot pays attention to it.

I paid $150 for each engine, and built one engine, not two.

The weight of the setup is one of those "not sure's". It likely
weighed in excess of 400 lbs, but probably not by much. The block is
cast steel, but it's a thinwall design. The heads are aluminum, as is
the timing chain cover, and intake manifold. It was the lightest V-6
being built, and may still be in it's 4.2L form.

I also used the lightweight geared starter, rather than the routine
Ford beast. The NWAero psru is noted for it's relative light weight
compared to the Blanton version, which was it's genesis.

I also used a lightweight aluminum machined flywheel, rather than the
suggested Ford flexplate. Probably no gain or loss there.

As to the prop, I bought an IVO Magnum and ran it using that while I
tested the engine.

I added largish mufflers to the header system I fabricated (header
length and diameter suggested by "Headers by Ed". Ed sizes header
tubes scientifically to promote maximum flow at the power settings
most often used and altitude at which I would normally be flying. That
required relatively small diameter header pipes (1 3/8), which is
considerably smaller than the exhaust ports in the heads (1 3/4). The
length of the headers tubes was also specified to maximise torque,
which meant that they had to be 40" long and feed into 3" diameter
collector pipes, which had to be at least two feet long each.

When I first fired the engine up, all animals in the vicinity headed
for the hills. It seemed like I was standing next to two machine guns
blasting away. Of course, I was inside the shop at the time (with the
sliding door open).

I had to add two hefty mufflers to the exhaust system in order to run
it outside the house without being attacked by the neighbors, even
though I live in rural Vermont, with lots of trees between me and my
neighbors. They were big and unwieldy and I wasn't planning to use
them in the airplane. But I was unhappy with how noisy the engine was
and was concerned about being a good citizen when flying in the area.
I tried several inserts to try to quiet the barking down some, but
nothing but actual mufflers helped. With the mufflers, you basically
only heard the soft clicking of the lifters and the hiss of the
carburator, over the whopping of the prop. As I advanced the
throttle, the carburetor began moaning/roaring and the noise of that
big prop took over with a whapping blatting roar.

I literally had to chain the test stand/engine down securely or it
would have tipped over for sure.

I had built a test stand that was basically a fully instrumented
vehical on casters. It had a battery, radiator and fuel tank. I
could have strapped it into a flatbed pontoon boat and gone air
boating.

I had the engine up to around 3,500 or so for the last run before I
shut it down and sold it and the airplane. At that rpm, lots of air
was being blown back and things like rakes and shovels were flying off
the walls of the car port. The test stand was tied down to the car
port posts, which is why the air was blowing into the bays. It was
obvious I would have needed to back off on the prop pitch a bit to get
more rpm out of the engine, if I had continued.

Corky Scott
  #5  
Old January 20th 06, 10:12 PM posted to rec.aviation.homebuilt
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Default Corvair conversion engines

wrote)
[good report snipped]
I didn't go fuel injected for two reasons, simplicity and safety.



Thank you for the report.


Montblack
  #7  
Old January 20th 06, 03:19 PM posted to rec.aviation.homebuilt
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Default Corvair conversion engines

I just think hanging a prop on a crank directly is a non-starter in
the first place...especially on a crank and case not specifically
designed for this in the first palce. Maybe a good redrive and flywheel
would be a better way to go?


That is my opinion, also.
--

I partially agree.

I agree that hanging a prop directly on the end of an automotive crank, even
if you put it on the flywheel end, is a recipe for a short tbo even at low
power and for a high failure rate at high power. (If you only use it to
push an airboat around the local swamp, you can keep a couple of bottles of
skin-so-soft in your tackle box.)

However, switching to a traditional aircraft powerplant may not solve the
problem. You really only have the full value of testing, experience, and
service history when you mate an unmodified engine to an airworthy propeller
with which that engine was certified--and preferrably in a combination used
by a large number of aircraft in regular service for a reasonably long time.
Remember the crankshaft problems in some of the Cessna 172's soon after the
change from the Continental O-300 to the Lycoming O-320. (I think it was an
early 160HP version, but have long forgotter the dash number--and the
problem was promptly solved.) There have been other "teething" problems as
well on various engines...

In the special case of a KR-2, which was the subject of at lease two of the
Corvair engines torn down and inspected, the plane sits too low to swing a
70+ inch diameter propeller; and IIRC was originally designed for VW engines
swnging 52 inch diameter propellers. I have heard that the KR-2S sits
enough higher to accept a larger prop, possibly 60 inch diameter. That
seems to negate the reduction drives, although a shaft drive, similar to the
one Steve Whittman developed for his V8 powered Tailwind, could be
interesting. BTW, the plans are still available--I think Aircraft Spruce
still sells them. Also, Revmaster (and possibly others) offers an aircraft
engine based loosly on the VW dimensions and a Jabiru could work--especially
with a 3 blade prop...





  #8  
Old January 25th 06, 03:03 AM posted to rec.aviation.homebuilt
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Default Corvair conversion engines

On Thu, 19 Jan 2006 15:35:13 -0500, "Morgans"
wrote:


"Bret Ludwig" wrote in message
roups.com...

I just think hanging a prop on a crank directly is a non-starter in
the first place...especially on a crank and case not specifically
designed for this in the first palce. Maybe a good redrive and flywheel
would be a better way to go?


That is my opinion, also.


What isn't there can't break. That's my reson for a direct drive 'vair
insted of a geared Soob - same weight - same HP.
  #9  
Old January 25th 06, 03:19 AM posted to rec.aviation.homebuilt
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Default Corvair conversion engines


clare at snyder.on.ca wrote in message
...
What isn't there can't break. That's my reson for a direct drive 'vair
insted of a geared Soob - same weight - same HP.


Perhaps you missed the news flash, from the Corvair Authority, himself. The
'vair cranks are breaking on the new glass planes.
--
Jim in NC

  #10  
Old January 25th 06, 10:33 PM posted to rec.aviation.homebuilt
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Default Corvair conversion engines

On Tue, 24 Jan 2006 22:19:55 -0500, "Morgans"
wrote:


clare at snyder.on.ca wrote in message
.. .
What isn't there can't break. That's my reson for a direct drive 'vair
insted of a geared Soob - same weight - same HP.


Perhaps you missed the news flash, from the Corvair Authority, himself. The
'vair cranks are breaking on the new glass planes.

Yup, I'm aware. but the reduction box has more parts to fail. There
have been Rinker failures, and not much else in use. Lots of PSRU
failures on Soobs.
Mine's not fast, and not glass, and my crank is nitrided from the
factory.
 




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