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Corvair conversion engines



 
 
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  #101  
Old February 5th 06, 09:38 PM posted to rec.aviation.homebuilt
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Default Corvair conversion engines

"UltraJohn" wrote in message
ink.net...
Morgans wrote:


It is a trick to see if you are overheating, with the typical VW or
Corvair instalation, since most have no way of monitoring CHT, or more
specifically, the valves, seats and guides.


Jim from what I've read (no personal experience!) it is not that difficult
to hook up a cht to a VW and they (whoever they are!) suggest attaching

the
sendor near the exhaust valve part of the head and limiting the cht to (I
think) 400 degrees or less. This is the part that limits VW's to less

than
40 -45 hp. Of course anything you can do to remove heat faster will let

you
run at a higher output. Such as proper baffling and external oil cooler

etc
etc. Nothing is wrong with using a VW or Corvair engine but you should be
knowledgable of their limitations!
John

As an aside, both a 1600 and a 2180 VW can put out 40hp continuous if
properly set up but the 2180 will be loafing while doing it at a lower rpm
which will let you use a bigger prop and limit you max rpm.
Life's all a big tradeoff! ;-)

There used to be, this is 35 year old info, a CHT sender that replaced the
copper spark plug gasket. At the time they were popluar with the Hot Rod
and SCCA crowd for both VW and Porsche engines. I have no idea whether they
are still available, nor there cost or level of accuracy.

As to the lower RPM option with a bigger prop on the VW 2180 conversion;
please promise that you will also install, and use, a manifold pressure
gauge. Two of the guys I know that broke VW cranks at less than 200 hours
were operating at what they believed was a conservative RPM--without
measuring manifold pressure...

Peter


Ads
  #102  
Old February 8th 06, 12:45 AM posted to rec.aviation.homebuilt
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Posts: n/a
Default Corvair conversion engines

On Sat, 4 Feb 2006 22:34:36 -0500, "Peter Dohm"
wrote:

"UltraJohn" wrote in message
hlink.net...
Morgans wrote:


"D.W. Taylor" wrote

I drove a harvesting machine that used hydrostatic drive and a VW

engine
for power. We ran it on a governer at 3950rpm 24x7 all summer. \\\

The fact that it ran with a governor means that it was not at full HP.

It
is admirable for it to run that many RPM's for that many hours, but

still,
there is no indication of how long it would run at true Wide Open
Throttle, making all the HP it could.

I suspect its life would have not been as long, if it were loaded to

it's
maximum output.


Jim
What airplane POH tells you to run your reciprocating engine at max/wot
throttle?
Most small airplanes run max hp for about 10 to 30 minutes for takeoff and
climb then throttle back to 75% for cruise. So expecting a VW/corvair to

go
max for hours on end and not break is unrealistic. I personally think
either engine is viable in the proper application and treated properly.

One
of the first things in your testing phase is to make sure your not
overheating the thing. It's quite well known a VW is not capable of
continuous operation at much more than 40 or 45 hp (let's see 75% of 65

(65
being about the highest you'll want to run a VW) is 49 hp) so your

probably
only going to cruise at about 65% power which is not bad because you still
have that extra reserve for takeoff and go arounds!
I don't know what the max continuous of a corvair is but the same applies,
run it at the right level and you'll probably have a sweet little smooth
engine! This is homebuilt/experimental right? ;-)
John

I don't know what the Corvair can really do either. But expect 40-50
percent more than an 1800cc (slightly overbored) VW. I really think I'd
cruise at more like 60 percent power, at most. I agree about that sweet
smooth little engine though, and the choice will have to depend on parts
availability and how fast I really think it has to fly when I get to that
point. 120-130 Kts should be readily feasible for the Corvair.
Peter

65hp continuous is no problem for a Corvair even 80 HP should be
reasonable.- it has significantly better head fin area than the VW.The
engine is designed as a 110 (or even 140) hp normally aspirated
engine, and in vehicle application, including the huge CorVan,
overheatiing was not a significant problem.

90HP at 3000 RPM is not a stretch at all, and at 2800 RPM cruise, even
if that was full throttle (max output for the RPM) we are talking 85
HP.
  #103  
Old February 8th 06, 12:50 AM posted to rec.aviation.homebuilt
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Default Corvair conversion engines

On Sat, 4 Feb 2006 21:00:11 -0500, "Peter Dohm"
wrote:

The fact that it ran with a governor means that it was not at full HP. It
is admirable for it to run that many RPM's for that many hours, but still,
there is no indication of how long it would run at true Wide Open

Throttle,
making all the HP it could.

I suspect its life would have not been as long, if it were loaded to it's
maximum output.
--
Jim in NC

I agree with your basic point. And also feel compelled to add that there is
probably no way for anyone to know how much power the VW engine produced in
the harvesting application--unless they metered torque, which would not be
reasonable. My supposition, just from reading the post, is that at least
half of the total fuel burned was applicable to pumping losses rather from
the work done.

However, also have problems with the wide open throttle scenario. I also
suspect that if we were to discuss the issue at length, we would find that
we are completely in agreement; but that we insist on using different
"phraseology."

We really don't operate our Lycomings and Continentals at their sea level
maximum output very much of the time. My best guess is that, flying with a
fixed pitch prop on a standard day, we can achieve nearly 90 percent just
off the runway and that drops gradually to less about 75 percent by around
3000 feet msl. (My recollection on exactly were this occurs is less than
perfect as I have not flown in a long time) And 75 percent, on the aircraft
engines with which I am familiar, ranges from about a low of about 0.355 to
0.357 HP per cubic inch of the low compression Lycoming O-235 engines
through 0.375 HP per cubic inch for the Continental O-200 and their new
O-240 FADEC engine, as well as Lycomings 160 HP O-326 and 180 HP O-360
engines, up to 0.420 HP per cubic inch on the 200 HP angle valve Lycoming
O-360. Those are all engines that really were designed to run that way, for
which the cooling intake and baffling requirements are well documented, and
even so many had "teething" problems which were solved long ago.

If we apply the same specific power output to a pure stock 1600cc VW as to
the smallest Lycomings, 75 percent power should equal 34 HP; which would
result in a theoretical 45 HP engine with a take-off rating that could be as
high as 60 HP, although 55 HP is more likely--based on a 52 inch diameter
prop turning about 3600 RPM. The slightly more agressive specific output of
the O-200 would give the 1600cc VW a rating of 48 HP which would equate to a
75 percent level of 36 HP.

My point in all this is that a relatively slippery aircraft fitted with a
climb prop, to conform to the ancient formula of 0.2 G static thrust
measured with a fish scale, should fly safely with an auto conversion. I
remain a fan of auto conversions, but my advocacy has its limits.

Peter



On the old Klaus combine the VW was rated at 40 HP. Actually, that is
on the later model units. The early ones were 35. (talking 1200cc).
The 1600 engine was rated at 60, IIRC.

  #104  
Old February 8th 06, 01:41 AM posted to rec.aviation.homebuilt
external usenet poster
 
Posts: n/a
Default Corvair conversion engines


clare at snyder.on.ca wrote in message
...
On Sat, 4 Feb 2006 21:00:11 -0500, "Peter Dohm"
wrote:

The fact that it ran with a governor means that it was not at full HP.

It
is admirable for it to run that many RPM's for that many hours, but

still,
there is no indication of how long it would run at true Wide Open

Throttle,
making all the HP it could.

I suspect its life would have not been as long, if it were loaded to

it's
maximum output.
--
Jim in NC

I agree with your basic point. And also feel compelled to add that there

is
probably no way for anyone to know how much power the VW engine produced

in
the harvesting application--unless they metered torque, which would not

be
reasonable. My supposition, just from reading the post, is that at least
half of the total fuel burned was applicable to pumping losses rather

from
the work done.

However, also have problems with the wide open throttle scenario. I also
suspect that if we were to discuss the issue at length, we would find

that
we are completely in agreement; but that we insist on using different
"phraseology."

We really don't operate our Lycomings and Continentals at their sea level
maximum output very much of the time. My best guess is that, flying with

a
fixed pitch prop on a standard day, we can achieve nearly 90 percent just
off the runway and that drops gradually to less about 75 percent by

around
3000 feet msl. (My recollection on exactly were this occurs is less than
perfect as I have not flown in a long time) And 75 percent, on the

aircraft
engines with which I am familiar, ranges from about a low of about 0.355

to
0.357 HP per cubic inch of the low compression Lycoming O-235 engines
through 0.375 HP per cubic inch for the Continental O-200 and their new
O-240 FADEC engine, as well as Lycomings 160 HP O-326 and 180 HP O-360
engines, up to 0.420 HP per cubic inch on the 200 HP angle valve Lycoming
O-360. Those are all engines that really were designed to run that way,

for
which the cooling intake and baffling requirements are well documented,

and
even so many had "teething" problems which were solved long ago.

If we apply the same specific power output to a pure stock 1600cc VW as

to
the smallest Lycomings, 75 percent power should equal 34 HP; which would
result in a theoretical 45 HP engine with a take-off rating that could be

as
high as 60 HP, although 55 HP is more likely--based on a 52 inch diameter
prop turning about 3600 RPM. The slightly more agressive specific output

of
the O-200 would give the 1600cc VW a rating of 48 HP which would equate

to a
75 percent level of 36 HP.

My point in all this is that a relatively slippery aircraft fitted with a
climb prop, to conform to the ancient formula of 0.2 G static thrust
measured with a fish scale, should fly safely with an auto conversion. I
remain a fan of auto conversions, but my advocacy has its limits.

Peter




On the old Klaus combine the VW was rated at 40 HP. Actually, that is
on the later model units. The early ones were 35. (talking 1200cc).
The 1600 engine was rated at 60, IIRC.


That really does put a little different light on the matter.

IIRC, the 40 HP (1200 cc) VW developed it's full power at 3600 rpm, and the
VW racers in SCCA placed the red line on their tachs at 4500, although no
beetle could hope to maintain 3600 rpm in top gear.

OTOH, I believe that Ken Rand claimed that the prototype KR-1 could wind up
to around 4000 rpm.

I believe that the "dual port" 1600 cc engines were rated at 65 HP at 4000
rpm. IIRC, they were used in the Super Beetles, Type-3s, and some of the
transporters. However, my recollection agrees with yours that the 1600 cc
engine used in a lot of the normal Beetles had siamesed intake ports (like
the 1200, 1300, and 1500 cc engines) and were rated at 60 HP; but I don't
know at what rpm.

None of this really is any dispute regarding the often quoted thermal limit
in aircraft, since the method of cooling is so different. The centrifugal
cooling fan used by VW was/is a *very* high pressure type!

Peter


  #105  
Old February 8th 06, 04:25 AM posted to rec.aviation.homebuilt
external usenet poster
 
Posts: n/a
Default Corvair conversion engines

On Tue, 7 Feb 2006 19:41:25 -0500, "Peter Dohm"
wrote:


clare at snyder.on.ca wrote in message
.. .
On Sat, 4 Feb 2006 21:00:11 -0500, "Peter Dohm"
wrote:

The fact that it ran with a governor means that it was not at full HP.

It
is admirable for it to run that many RPM's for that many hours, but

still,
there is no indication of how long it would run at true Wide Open
Throttle,
making all the HP it could.

I suspect its life would have not been as long, if it were loaded to

it's
maximum output.
--
Jim in NC

I agree with your basic point. And also feel compelled to add that there

is
probably no way for anyone to know how much power the VW engine produced

in
the harvesting application--unless they metered torque, which would not

be
reasonable. My supposition, just from reading the post, is that at least
half of the total fuel burned was applicable to pumping losses rather

from
the work done.

However, also have problems with the wide open throttle scenario. I also
suspect that if we were to discuss the issue at length, we would find

that
we are completely in agreement; but that we insist on using different
"phraseology."

We really don't operate our Lycomings and Continentals at their sea level
maximum output very much of the time. My best guess is that, flying with

a
fixed pitch prop on a standard day, we can achieve nearly 90 percent just
off the runway and that drops gradually to less about 75 percent by

around
3000 feet msl. (My recollection on exactly were this occurs is less than
perfect as I have not flown in a long time) And 75 percent, on the

aircraft
engines with which I am familiar, ranges from about a low of about 0.355

to
0.357 HP per cubic inch of the low compression Lycoming O-235 engines
through 0.375 HP per cubic inch for the Continental O-200 and their new
O-240 FADEC engine, as well as Lycomings 160 HP O-326 and 180 HP O-360
engines, up to 0.420 HP per cubic inch on the 200 HP angle valve Lycoming
O-360. Those are all engines that really were designed to run that way,

for
which the cooling intake and baffling requirements are well documented,

and
even so many had "teething" problems which were solved long ago.

If we apply the same specific power output to a pure stock 1600cc VW as

to
the smallest Lycomings, 75 percent power should equal 34 HP; which would
result in a theoretical 45 HP engine with a take-off rating that could be

as
high as 60 HP, although 55 HP is more likely--based on a 52 inch diameter
prop turning about 3600 RPM. The slightly more agressive specific output

of
the O-200 would give the 1600cc VW a rating of 48 HP which would equate

to a
75 percent level of 36 HP.

My point in all this is that a relatively slippery aircraft fitted with a
climb prop, to conform to the ancient formula of 0.2 G static thrust
measured with a fish scale, should fly safely with an auto conversion. I
remain a fan of auto conversions, but my advocacy has its limits.

Peter




On the old Klaus combine the VW was rated at 40 HP. Actually, that is
on the later model units. The early ones were 35. (talking 1200cc).
The 1600 engine was rated at 60, IIRC.


That really does put a little different light on the matter.

IIRC, the 40 HP (1200 cc) VW developed it's full power at 3600 rpm, and the
VW racers in SCCA placed the red line on their tachs at 4500, although no
beetle could hope to maintain 3600 rpm in top gear.

OTOH, I believe that Ken Rand claimed that the prototype KR-1 could wind up
to around 4000 rpm.

I believe that the "dual port" 1600 cc engines were rated at 65 HP at 4000
rpm. IIRC, they were used in the Super Beetles, Type-3s, and some of the
transporters. However, my recollection agrees with yours that the 1600 cc
engine used in a lot of the normal Beetles had siamesed intake ports (like
the 1200, 1300, and 1500 cc engines) and were rated at 60 HP; but I don't
know at what rpm.

None of this really is any dispute regarding the often quoted thermal limit
in aircraft, since the method of cooling is so different. The centrifugal
cooling fan used by VW was/is a *very* high pressure type!

Peter

In industrial use they were generally rated at 3600 RPM, and if run
at that speed required head jobs every 1000 hours or so. Often much
sooner than that, particularly if #3 cyl did not have the valve
clearance significantly increased (set cold). Air flow to #3 was
significantly impaired by the oil cooler. In many apps they were
governed to 2800 RPM, which detuned them. On the combines, keeping the
chaff out of the head fins was no trivial accomplishment.

As for cooling in an aircraft application, with a "pressure cowl" the
engine got better cooling than with the "box fan" provided by
Wolfsburg on the beetle. The "hang 'em out" style, cub style, was just
about as good as the beetle.
  #106  
Old December 1st 19, 02:23 AM posted to rec.aviation.homebuilt
[email protected]
external usenet poster
 
Posts: 1
Default Corvair conversion engines

On Wednesday, January 18, 2006 at 1:19:06 PM UTC-6, Cal Vanize wrote:
As my research continues, I have been investigating possible engines for
a 601XL. The Corvair engines looked like a good candidate. The reports
seemed very good and the engine was surprisingly inexpensive for initial
purchase and long-term maintenance.

The stated expected TBO is 1500 hours and the Corvair Authority website
documents the use of a Corvair engine in a 601XL.

Everything seemed OK until yesterday when I read the most recent updates
on their website. Seems that the "untreated" automotive cranks have
been cracking in a very short time. Nitriding seems like the only
solution. But with standard cranks cracking at under 100 hours, what
would be the expected life of a nitrided crank. Twice as long, four
times as long, eight times as long? This would still fall short of the
1500 hour TBO stated by the Corvair Authority.

Does anyone have any first hand experience with Corvair conversion
engines? Any info on their realistic life and reliability?

TIA,

CV


It seems that no one on this thread has heard of the 5th bearing. The factory crank is a forged steel crank. It is not cast. The 5th bearing has eliminated the broken crank. The broken crank usually only happened on engines that were not used as intended.
 




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