Venting of Lycoming 0-290 D Engine

On Apr 27, 2:09 pm, "Phil" wrote:
Hello
I have been helping a young fellow EAA member with the restoration of a
EAA Biplane , he is using a rebuilt Lycoming 4cyl. , 125 H.P. 0-290 D engine
in this plane and has a 3/8 " O.D. aluminum tube running from the firewall
and exiting just ahead of the tailwheel , he wants' to keep the underside of
this fabric covered plane as clean as possible , the vent elbow that exits
the top forward area of the crankcase has an I.D. of approx. 5/8 " , he
plans to put a reducer to make the step from 5/8 " I.D. to approx 1/4 " I.D.
on the alum tube , this tube will go from the firewall to the tailwheel ,
the question is this , does the engine vent just relieve pressure and will
the long narrow tube cause any problem ?, am not an expert in the dynamics
of this of this area of the engine , any thoughts or help would be
appreciated .
Thanks
Phil Lohiser
EAA 12873

Unless that engine is really tight (pretty much zero ring
leakage) he'll end up with backpressure in the crankcase and will blow
the front crank seal out, losing oil at a good clip and maybe even
getting so much on the windscreen that he can't see where he's going.
If he flies long enough he'll run out of oil. And if by some miracle
it doesn't blow out, and then he flies in subfreezing weather, that
long tube is going to ice up immediately (water vapor condensing in
the tube, the vapor being an unavoidable byproduct of combustion) and
the sure thing will happen: blown seal and lost oil.
Cessna and Piper and Mooney and Beech and American Champion and
Taylorcraft and about a hundred others over the years have used
minimal lengths of 5/8" and 3/4" and 1" vent tubes for some very good
reasons, and those tubes often have a small hole well above the outlet
in case the outlet, being in the cold slipstream, ices up. A long tube
under the belly would ice up all along its entire length.
A slightly oily belly is much preferable to an engine failure.
It's pretty hard to improve on what the major manufacturers do with
their airplanes. They're concerned about oily bellies, too, but you
don't see long tubes under them. You can get the Airwolf oil/air
separator setup to supposedly extract the oil from the venting air,
and we have one on a 172, except that it doesn't work all that well.
Needs a vacuum pump on the system, too, to get the pressure to drive
the oil back from the separator to the case.

Dan

wrote:
On Apr 27, 2:09 pm, "Phil" wrote:

Hello
I have been helping a young fellow EAA member with the restoration of a
EAA Biplane , he is using a rebuilt Lycoming 4cyl. , 125 H.P. 0-290 D engine
in this plane and has a 3/8 " O.D. aluminum tube running from the firewall
and exiting just ahead of the tailwheel , he wants' to keep the underside of
this fabric covered plane as clean as possible , the vent elbow that exits
the top forward area of the crankcase has an I.D. of approx. 5/8 " , he
plans to put a reducer to make the step from 5/8 " I.D. to approx 1/4 " I.D.
on the alum tube , this tube will go from the firewall to the tailwheel ,
the question is this , does the engine vent just relieve pressure and will
the long narrow tube cause any problem ?, am not an expert in the dynamics
of this of this area of the engine , any thoughts or help would be
appreciated .
Thanks
Phil Lohiser
EAA 12873


Unless that engine is really tight (pretty much zero ring
leakage) he'll end up with backpressure in the crankcase and will blow
the front crank seal out, losing oil at a good clip and maybe even
getting so much on the windscreen that he can't see where he's going.
If he flies long enough he'll run out of oil. And if by some miracle
it doesn't blow out, and then he flies in subfreezing weather, that
long tube is going to ice up immediately (water vapor condensing in
the tube, the vapor being an unavoidable byproduct of combustion) and
the sure thing will happen: blown seal and lost oil.
Cessna and Piper and Mooney and Beech and American Champion and
Taylorcraft and about a hundred others over the years have used
minimal lengths of 5/8" and 3/4" and 1" vent tubes for some very good
reasons, and those tubes often have a small hole well above the outlet
in case the outlet, being in the cold slipstream, ices up. A long tube
under the belly would ice up all along its entire length.
A slightly oily belly is much preferable to an engine failure.
It's pretty hard to improve on what the major manufacturers do with
their airplanes. They're concerned about oily bellies, too, but you
don't see long tubes under them. You can get the Airwolf oil/air
separator setup to supposedly extract the oil from the venting air,
and we have one on a 172, except that it doesn't work all that well.
Needs a vacuum pump on the system, too, to get the pressure to drive
the oil back from the separator to the case.

Dan

I wanted to check the Pitts plans.
There is a breather tube shown on the plans running just
below thr left side stringer.
I _think_ it's 1" od aluminum tube.

If anyone has the Pitts plans handy???

Richard
--
(remove the X to email)

Now just why the HELL do I have to press 1 for English?
John Wayne

wrote

Unless that engine is really tight (pretty much zero ring
leakage) he'll end up with backpressure in the crankcase and will blow
the front crank seal out, losing oil at a good clip

I agree.

How come airplane engines don't have PCV valves, plumbed back into the intake
manifold, like cars? You could even use an oil separator, before the gas enters
the manifold, if too much oil was worried to be a problem.

An arrangement like that would solve the oily discharge on the belly, I would
think.

Might even keep the intake valves lubricated a little bit! g

I wonder what the answer is, and why that solution would be a problem. I'm sure
it has been tried, since it seems there is truly nothing new under the sun, when
it comes to airplanes.
--
Jim in NC

I wonder what the answer is, and why that solution would be a problem. *I'm sure
it has been tried, since it seems there is truly nothing new under the sun, when
it comes to airplanes.
--
Jim in NC

You have hurt my feelings again....... :((

cryin lil ben

"stol" wrote in message
...

I wonder what the answer is, and why that solution would be a problem. I'm
sure
it has been tried, since it seems there is truly nothing new under the sun,
when
it comes to airplanes.
--
Jim in NC

You have hurt my feelings again....... :((

Whoops!

Sorry.

That should have read "nothing new under the sun, when it comes to the _old_
designed air cooled opposed aircraft engines.

Or something like that! ;-)

Speaking of auto engine aircraft, how do you handle the crankcase ventilation
issue? Vent overboard, or recirculate?
--
Jim in NC

On Apr 28, 5:36*pm, "Morgans" wrote:
"stol" wrote in message

...

I wonder what the answer is, and why that solution would be a problem. I'm
sure
it has been tried, since it seems there is truly nothing new under the sun,
when
it comes to airplanes.
--
Jim in NC

*You have hurt my feelings again....... :((

Whoops!

Sorry.

That should have read "nothing new under the sun, when it comes to the _old_
designed air cooled opposed aircraft engines.

Or something like that! ;-)

Speaking of auto engine aircraft, how do you handle the crankcase ventilation
issue? *Vent overboard, or recirculate?
--
Jim in NC

I have tried three ways. The first was to recirculate using a PCV
valve. At the time it seems to be the most logical. The motor was
still fresh and has a slight amount of blowby. That system made it
real twitchy to try to lean, but is was doable. my second concept was
the racing vacuum system used in dragsters, That did work great but I
am now on my third design of the exhaust pipes. those don't have the
fittings welded in them for the vacuum so I dump the stuff overboard,
what little blowby there is. This is like developing software.
Version 1.0,,, 1.2,,,, 2.0,,, 2.3... Yada Yada yada... On the final
engines that will go out the door they will incorporate the Moroso
vacuum system. Hands down,, the more power you make the greater the
suction. Just what a aircraft engine needs.

In article
,
stol wrote:

On Apr 28, 5:36*pm, "Morgans" wrote:
"stol" wrote in message

...

I wonder what the answer is, and why that solution would be a problem.
I'm
sure
it has been tried, since it seems there is truly nothing new under the
sun,
when
it comes to airplanes.
--
Jim in NC

*You have hurt my feelings again....... :((

Whoops!

Sorry.

That should have read "nothing new under the sun, when it comes to the
_old_
designed air cooled opposed aircraft engines.

Or something like that! ;-)

Speaking of auto engine aircraft, how do you handle the crankcase
ventilation
issue? *Vent overboard, or recirculate?
--
Jim in NC

I have tried three ways. The first was to recirculate using a PCV
valve. At the time it seems to be the most logical. The motor was
still fresh and has a slight amount of blowby. That system made it
real twitchy to try to lean, but is was doable. my second concept was
the racing vacuum system used in dragsters, That did work great but I
am now on my third design of the exhaust pipes. those don't have the
fittings welded in them for the vacuum so I dump the stuff overboard,
what little blowby there is. This is like developing software.
Version 1.0,,, 1.2,,,, 2.0,,, 2.3... Yada Yada yada... On the final
engines that will go out the door they will incorporate the Moroso
vacuum system. Hands down,, the more power you make the greater the
suction. Just what a aircraft engine needs.

Actually, it is not a good idea to ingest crankcase fumes into the
induction system, as those fumes contain acids (bromic, sulfuric acids)
that corrode carburetors, valves, throttle bodies, etc.

It is best just to vent the crankcase overboard, to ambient air.

--
Remove _'s from email address to talk to me.

On Apr 28, 9:00*pm, Orval Fairbairn
wrote:
In article
,





*stol wrote:
On Apr 28, 5:36*pm, "Morgans" wrote:
"stol" wrote in message

....

I wonder what the answer is, and why that solution would be a problem.
I'm
sure
it has been tried, since it seems there is truly nothing new under the
sun,
when
it comes to airplanes.
--
Jim in NC

*You have hurt my feelings again....... :((

Whoops!

Sorry.

That should have read "nothing new under the sun, when it comes to the
_old_
designed air cooled opposed aircraft engines.

Or something like that! ;-)

Speaking of auto engine aircraft, how do you handle the crankcase
ventilation
issue? *Vent overboard, or recirculate?
--
Jim in NC

I have tried *three ways. The first was to recirculate using a PCV
valve. At the time it seems to be the most logical. The motor was
still fresh and has a slight amount of blowby. That system made it
real twitchy to try to lean, but is was doable. my second concept was
the racing vacuum system used in dragsters, That did work great but I
am now on my third design of the exhaust pipes. those don't have the
fittings welded in them for the vacuum so I dump the stuff overboard,
what little blowby there is. This is like developing software.
Version 1.0,,, 1.2,,,, 2.0,,, 2.3... Yada Yada yada... On the final
engines that will go out the door they will incorporate the Moroso
vacuum system. Hands down,, the more power you make the greater the
suction. Just what a aircraft engine needs.

Actually, it is not a good idea to ingest crankcase fumes into the
induction system, as those fumes contain acids (bromic, sulfuric acids)
that corrode carburetors, valves, throttle bodies, etc.

It is best just to vent the crankcase overboard, to ambient air.

--
Remove _'s *from email address to talk to me.- Hide quoted text -

- Show quoted text -

Interesting,, I will call Detroit this morning to warn them that the
PCV valve, in operation since the late 60's is clearly defective....

:).

Ben

"stol" wrote

my second concept was
the racing vacuum system used in dragsters, That did work great but I
am now on my third design of the exhaust pipes.

What do dragsters and such use in their pipes for vacuum? Some type of venture,
or something?
--
Jim in NC

On Apr 29, 5:56*pm, "Morgans" wrote:
"stol" wrote

*my second concept was
the racing vacuum system used in dragsters, That did work great but I
am now on my third design of the exhaust pipes.

What do dragsters and such use in their pipes for vacuum? *Some type of venture,
or something?
--
Jim in NC

Jim, It is a rather easy device. It acts just like those air nozzles
with a small hose attached at an angle that one can use to spray
solvent on a part to clean it. As the air passes across the side
opening it creates a vacuum. Here is a link to Moroso's kit. The kit
comes with two 3/8" pipes about 3" long, you weld on a bung at about a
45 degree angle to the tailpipe and screw in the pipe. The kit has a
check valve to prevent backfires from entering the valve covers. On my
application I made my own set up, ( imagine that)... I used just one
on the right tailpipe and I had way too much suction so I had to
restrict it. Kinda like the old joke " she could suck a golf ball
through a garden hose".. This was when my motor had 10 hours on it or
so and the rings had not completely seated. I took that version off
because the motor is now so sealed up I have practically no blowby and
saved a couple of lbs... YMMV.

http://store.summitracing.com/partde...5&autoview=sku

Ben