Venting of Lycoming 0-290 D Engine

[Phil]

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

[[email protected]]

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

[cavelamb himself[_4_]]

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

[Morgans[_2_]]

> 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

[stol]

> 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

[[email protected]]

On Apr 27, 11:22 pm, "Morgans" > wrote:
> > 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

No PCV because the aircraft engine runs at high manifold
pressures most of the time, so there's too little differential (read
"manifold vacuum" to suck a PCV valve open and adequately purge the
gases. On an auto, when the throttle is fairly open, the PCV valve
pretty much closes. The valve has to be there to stop flashback in
case the engine backfires; the flame would ignite the gases in the
crankcase. Boom, big ugly mess and a major CG shift. In the auto, the
gases will, at full throttle or nearly so, back up through the
crankcase intake filter and into the air cleaner and get cleaned up
that way. The filters act as flame arrestors. When the engine gets
old, there's too much blowby and lots of it exits this way, and its
moisture freezes up the crankcase intake filter in colder weather.
BTDT.
It could be done, with some different plumbing, which adds
weight, expense, and certification hassles. When the EPA or whoever
decides that airplanes need all the antipollution stuff that cars
have, we'll see it on airplanes and our useful loads will drop
considerably.

Dan

[[email protected]]

Dear Phil,

Your friend has the physics backwards.

Lycoming's use of a vent diameter of 5/8" should be taken as the
minimum needed to properly vent blow-by from the crankcase. Anything
attached to that outlet must then INCREASE in diameter according to
length... or be provided with some active means of pressure reduction
that is independent of throttle position. A venturi would work (and
has been used for this purpose in the past) but they tend to clog-up
or freeze. A metal funnel (!) has also been used on a small vent line
but slow speeds calls for a pretty big funnel (ie, about a 6" funnel
for a 1/2"x15' vent-line at about 60 mph) but it looks weird as
hell. If you have sufficient vertical height you can use a passive
oil separator... but keep in mind they make dandy condensers of water
as well as oil. Ditto for the active types, which generally use some
form of rotary motion to condense/capture the vapor, plus a scavenge
pump to get it back to the sump or oil tank.

Unstated -- but implied by the aircraft-type -- is the need to install
a flop-valve on the vent line to deal the occasional negative-g
maneuver. Without it, he's going to blow his oil overboard. If he
insists on using a small-diameter vent line, he'll probably blow his
seals at the same time.

-R.S.Hoover
-EAA 58400

PS -- There is also the tray type of oil separator/catchment that fits
under the firewall. It can hold a quart or more of oil which you
discretely drain between shows.

[Rich S.[_1_]]

"Morgans" > wrote in message
...

> 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.

Jim ...........

If you've ever seen the oil that collects in an oil/water separator, you
wouldn't want it back in an engine. I realize that some of the water in the
separator is condensation from the air coming back up the vent from the
outside after shutdown, but even so, the watery sludge in the reservoir is
really gross. Best to spend a few bucks and a couple of hours building a
simple firewall-mounted separator (plans available in old issues of Sport
Aviation when they had such things).

Wiping the bottom of a fuselage is kind of a Zen thing for me. Takes me back
to a simpler time.

Rich S.

[Capt. Geoffrey Thorpe]

"Morgans" > wrote in message
...
>
> > 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.


A) They don't have to.

B) PCV as found on automobiles won't work well at higher loads (no vacuum),
but new sytems for large diesel trucks are now coming onto the market to
meet emission standards - they have the same lack of vacuum...

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

[Morgans[_2_]]

"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

[stol]

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.

[Orval Fairbairn[_2_]]

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.

[stol]

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

[Orval Fairbairn[_2_]]

In article
>,
stol > wrote:

> 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....
>

The PCV valve was government mandated for pollution control only! It
makes no difference to the gov't if it harms your engine components, as
long as it meets THEIR requirements. It would be stupid to install one
on an aircraft.

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

[stol]

On Apr 29, 8:58*am, Orval Fairbairn >
wrote:
> In article
> >,
>
>
>
>
>
> *stol > wrote:
> > 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....
>
> The PCV valve was government mandated for pollution control only! It
> makes no difference to the gov't if it harms your engine components, as
> long as it meets THEIR requirements. It would be stupid to install one
> on an aircraft.
>
> --
> Remove _'s *from email address to talk to me.- Hide quoted text -
>
> - Show quoted text -

I don't want to get in a ****ing match with you. I am headed out to
fly my plane and I don't have time to waste. I can say I have been
working on engines most of my 53 years and I cannot say that even once
did I see corrosion, pitting, wear, etc or premature failure of any
component that the PVC valve related (bromic, sulfuric acid) theory
created.. In fact you don't have a clue on how a modern day engine is
plumbed. A PVC system dumps the (bromic, sulfuric acids), if they
really exist in any viable concentratiohat into the intake manifold
DOWNSTREAM of the carb or throttle body so your concept is BS. I
respect you as a fellow pilot, a person who has chosen to live in an
airpark, which in itself is a statement to you have a large commitment
to aviation and a fellow experimental aircraft owner. I would bet if a
lycoming had a PCV valve you would praising its function... Just my
opinion...

Tailwinds...

Ben
N801BH
EAA lifetime member.

[Morgans[_2_]]

"Orval Fairbairn" > wrote

> The PCV valve was government mandated for pollution control only! It
> makes no difference to the gov't if it harms your engine components, as
> long as it meets THEIR requirements. It would be stupid to install one
> on an aircraft.

While I believe your stand has merit, I think the truth is somewhere in the
middle. While some harm may be done, it is very little.

Otherwise, I don't think I would have gotten two of my last Detroit engines and
induction systems to over 200,000 miles. Added to that, the fact that these
engines had _no_ problem with their induction systems, at those miles.
--
Jim in NC

[Morgans[_2_]]

"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

[[email protected]]

On Apr 29, 5:53 pm, "Morgans" > wrote:
> "Orval Fairbairn" > wrote
>
> > The PCV valve was government mandated for pollution control only! It
> > makes no difference to the gov't if it harms your engine components, as
> > long as it meets THEIR requirements. It would be stupid to install one
> > on an aircraft.
>
> While I believe your stand has merit, I think the truth is somewhere in the
> middle. While some harm may be done, it is very little.
>
> Otherwise, I don't think I would have gotten two of my last Detroit engines and
> induction systems to over 200,000 miles. Added to that, the fact that these
> engines had _no_ problem with their induction systems, at those miles.
> --
> Jim in NC

Acids are formed in the crankcase, but mostly as a result of
condensation mixing with the oil and allowed to sit for some time.
Water breaks down and combines with elements in the oil to form those
acids, with the dissimilar metals acting as catalysts. The acids eat
bearings and cams and cylinders and pistons and such stuff.
The PCV system is better than a straight vent, where it can be
made to work. The intake manifold draws the blowby gases out of the
crankcase, those gases including water vapor, unburned hydrocarbons
and combustion byproducts. The volume of gases drawn out is larger
than the blowby gases, so filtered air is let into the case at some
other point. This purging keeps the case cleaner than with just an
overboard vent.
The PCV gases are reburned and blown out with the exhaust. They
do much less damage that way, both to the engine and the environment.

Dan

[stol]

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/partdetail.asp?autofilter=1&part=MOR%2D25900&N=700+400105+4294851516+115&autoview=sku

Ben

[et]

On Apr 29, 9:17*pm, stol > wrote:
> 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/partdetail.asp?autofilter=1&part=MOR%2D....
>
> Ben

Ben
Never knew these existed. Have you or anyone else tried it on a Lyc?
Probably need a couple of intakes on opposite valve covers?
Ed

[[email protected]]

On Apr 30, 9:34 am, et > wrote:

> Ben
> Never knew these existed. Have you or anyone else tried it on a Lyc?
> Probably need a couple of intakes on opposite valve covers?
> Ed

The valve rocker cavity vents through the 3/8" OD oil drain
tubes back to the case. Not very big at all. If you used the covers as
an air inlet, you might need all of them vented.

Dan

[et]

On Apr 30, 11:28*am, wrote:
> On Apr 30, 9:34 am, et > wrote:
>
> > Ben
> > Never knew these existed. *Have you or anyone else tried it on a Lyc?
> > Probably need a couple of intakes on opposite valve covers?
> > Ed
>
> * * * *The valve rocker cavity vents through the 3/8" OD oil drain
> tubes back to the case. Not very big at all. If you used the covers as
> an air inlet, you might need all of them vented.
>
> * * * * * *Dan

Is there any venting through the pushrod tubes? Maybe a side benefit
with four vents, head and valve cooling?
Great discussion!

Ed

[[email protected]]

On Apr 30, 3:57 pm, et > wrote:

> Is there any venting through the pushrod tubes? Maybe a side benefit
> with four vents, head and valve cooling?
> Great discussion!
>
> Ed

Nope. The pushrod tubes on a Lyc go only to the lifters. On a
Continental the tubes are on the bottom rather than the top, and the
oil drains through them so they also act as vents. Much bigger vents.


Dan

[Phil]

Thanks to ALL for the useful information , I think my friend has decided
against using a small tube for crankcase venting , your suggestions probably
saved him a lot of grief and possible danger , Thank You All Again , Phil
Lohiser EAA 12873
"Phil" > wrote in message
...
> 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
>

[[email protected]]

On May 3, 10:30 am, "Phil" > wrote:
> Thanks to ALL for the useful information , I think my friend has decided
> against using a small tube for crankcase venting , your suggestions probably
> saved him a lot of grief and possible danger , Thank You All Again , Phil
> Lohiser EAA 12873


Over the years (since 1972, EAA 89913) I have read of a few
accidents arising out of fuel tank venting issues. The "venting of Lyc
crankcase" reminds me that sometimes homebuilders don't have adequate
frame of reference when making changes to systems and end up getting
hurt or dead, or at least busting up a nice airplane.
A classic problem involves two or more fuel tanks, perhaps one in
each wing, or maybe a main and a header tank. For certified airplanes
having more than one tank, and the possibility of feeding from both
tanks simultaneously, certification requires that the tanks have a
common vent. They word it this way:

"Airspaces of tanks with interconnected outlets must be
interconnected." (FAR 23.975(4))

Howcome? Well, imagine a high-wing airplane with a tank in
each wing, with the fuel flowing from each tank through aluminum
tubing down through the fuselage to a tee where they join, then
through a shutoff valve, and from there to the strainer and carb.
Imagine, too that each tank has its own vent sticking out from under
its wing.
If there is any difference in pressure inside each tank, fuel
will flow faster from the tank with the higher pressure. If the
difference is high enough, the high tank will empty completely while
the low-pressure tank will not flow at all, or even worse, fuel from
the high tank will flow through the tee and into the low tank,
overfilling it and spilling from its vent. When the high tank is
empty, the engine gets nothing but air, and the flight is finished
even though there's still a full tank on board.
It's very easy to get uneven pressures from two separate
vents. Vent shape, angle of tip, any minor disturbance if the air
around it, will all affect its pressure. The Glastar had this separate-
vent system and uneven flow was the order of the day. Interconnecting
the top of the tanks of the one we had here fixed it. The Cessna 150
also has this system, but being certified, it has a single vent that
feeds both tanks. The 172 has a "Both" position on its selector, and
because of that it also has a single vent source.
Low-wing airplanes with two tanks do not normally have a "Both"
position because we're not relying on gravity flow, and if one tank
happened to run a little faster than the other (flying one-wing-low,
for example) the pump would be quite happy to suck air from the dry
tank rather than fuel from the one with fuel in it. The low-winger has
very little "head" between the tank outlets and the lowest point in
the system (maybe even no head at all) where the high-wing airplane
might have three feet or more. Sucking air from the tanks in the low-
wing airplane become a problem.
Vented fuel caps sometimes work well, sometimes don't. With wing
tanks, the low pressure atop the wing can reduce tank pressure
dangerously. Cessna uses check-vented caps in case of the main vent
plugging up with bugs or ice, but those caps have specially-designed
static ports on them to somehow reduce the suction. I flew an Aircoupe
that had a similar setup, without the check valves and without any
other tank vent, and fuel could be seen streaming off them when the
tanks were full. They also had those specially-designed non-sucking
cap vent ports but they obviously didn't work too well. Taylorcraft
used a cap with a forward-facing scoop to use ram pressure. The cap
could be installed backwards, though. Citabria has the single-vent two-
tank tee system like the 150, with totally unvented caps that *look*
like older auto or truck fuel caps, except that those older auto caps
were vented. I found one of those auto caps on a Citabria we bought,
and of course it had uneven fuel-flow issues. One cap was sucking, the
other not, and the low-pressure tank was a little slower. The
interconnected tank vent kept things from getting too far out of hand.
Parking an airplane with full tanks in a hangar can be asking
for trouble. If the day is cold, the fuel will be too, and it will
expand considerably in a heated hangar and run out of the vents,
creating an awesome fire hazard. If the airplane has the
interconnected outlets (or the selector is on "Both") and the hangar
floor is sloped and the vented wing is lower, fuel will cross-flow
through the system and run from the vent. As the higher tank drains,
the lower wing gets heavier and droops lower and the flow increases. I
get VERY annoyed when I find full tanks in our hangar, even after all
the prohibitions against it. We've had some very close calls with
fire.

Dan