No subject
Sun Mar 9 12:52:58 CDT 2008
Turbo Cirrus TIO-550N (turbo-normalized by Tornado Alley for Cirrus). They
run their oil breather line into an exhaust pipe nipple that enters the pipe
at right angles and appears to be cut off flush on the inside. There is
about two feet of pipe past the nipple to the outside end of the exhaust
stack.
My inclination at the moment is to copy the Cirrus approach.
Chuck - our first plan was to use an air-oil separator, but we've gone away
from it because of stories of the condensed water vapor returning to the
crankcase with the condensed oil, and the internal corrosion problems that
may be caused by the water. When you say your oil analysis has been good
over the years, have you noticed any problems that may have been caused by
the returned water?
Thanks for the help!
Bob
_____
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Chuck
Sent: Wednesday, April 23, 2008 2:26 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Oil Breather Nipple Into Exhaust Pipe
Bob, have you considered an air-oil separator? The turbo's will create
higher cylinder pressures (temps) and thus more blow-by through the rings.
This will send more oil/water vapor out the breather and into the
exhaust/atmosphere. Anytime you weld an exhaust pipe, your adding a stress
riser which can crack and fail. If you do it, you might want to have it
normalized (heat treated) afterwards.
I've had a separator for years and it works well. I'm also finishing my
add-on turbo and plan to keep the same system. I get very little oil through
the separator discharge tube and my oil analysis has been fine.
Chuck H
Bob,
A simpler though less aesthetic solution would be to clamp a short length of
pipe to the leeward side of the current exhaust pipe and exiting the cowl
through the same opening that you have currently. You could attach the oil
breather tube to this pipe. If the exit end of the pipe is cut diagonally
as your exhaust pipe may be, I believe that will give the slight negative
pressure that you are looking for. This solution also may mitigate the
freezing over of the breather line.
Kirk
> From: bobj at computer.org
> To: reflector at tvbf.org
> Date: Tue, 22 Apr 2008 22:04:35 -0500
> CC: bobj at JaxTechLLC.com
> Subject: REFLECTOR: Oil Breather Nipple Into Exhaust Pipe
>
> Does anyone have experience or ideas for the best way to weld a nipple
into
> the exhaust pipe for the oil breather hose?
>
> We want to weld a nipple for our oil breather hose into the short exhaust
> outlet pipe of one of the turbochargers (we've custom-added to our
IO-550N).
> We are aware of several issues and concerns. One issue is how far the
> nipple is extended and/or is angled into the exhaust gas stream. If for
> example on the inside of the pipe, the nipple is extended and angled away
> from the turbocharger, it might create a small Venturi effect and help
draw
> moisture and oil 'fumes' out of the crankcase. But if angled away too
much,
> this Venturi might be strong enough to excessively de-pressurize the
> crankcase and cause problems.
>
> Or, if the nipple were angled a little too much back into the direction of
> the turbo exhaust, it could positively pressurize the crankcase and cause
> engine seal problems.
>
> Hopefully, there is an angle of the nipple that creates no positive
> crankcase pressure, and with just the proper, small amount of negative
> pressure to help draw out the oil fumes slightly.
>
> Another issue we're concerned about is that this short stub of a breather
> nipple on the inside of the turbo exhaust pipe could eventually burn
through
> or break off and strike the prop. This has apparently happened in the past
> with some certified aircraft (not bang into the prop, just break off).
>
> Finally, we've also heard that if the nipple enters the exhaust pipe at
> right angles and is flush cut with the wall of the exhaust pipe, not
> extending into the inside of the breather nipple, it may be slightly
> pressurized and can become completely clogged with 'soot' over a period of
> time.
>
> If anyone has experience or suggestions for how far in to extend the oil
> breather nipple into the exhaust pipe, and which way to angle it, we would
> appreciate the help.
>
> Or alternatively, if someone has a (TCM or Lycoming) engine with a factory
> installed oil breather nipple, maybe they could look to see how far the
> nipple extends into the exhaust pipe, and at what angle.
>
> Thanks,
> Bob Jackson
> N2XF -- Ten years and still working!
>
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<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>Chuck, Kirk, Brian & All =
–
thanks for all the ideas and suggestions on routing the oil breather =
into the
exhaust pipe.<o:p></o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>Thinking more about it based on =
Brian’s
astute observation that although there may be fairly high (in our case =
~108 ft/sec
exhaust gas <u>velocities</u> per side at WOT since ours is a twin turbo
design) doesn’t necessarily mean high exhaust gas <u>pressures</u> =
at a
oil breather nipple if it’s located only about a foot from the =
exhaust
pipe outlet (our case). If I did my math right, I figured the 108 =
ft/sec
exhaust gas velocity from our ~225 cfm per side air flow rates through =
2.5 inch
diameter exhaust pipes. I’m also now thinking that although =
our <u>intake</u>
air rate may be ~450 cfm total, the <u>exhaust</u> gas rate will =
probably be considerably
higher than that due to the combustion of the fuel too, =
correct?<o:p></o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>What Brian says makes good sense to =
me –
how can you have high pressures that close to ambient pressure when =
it’s only
a foot away through a 2.5” tube? But my EE background is not =
strong
enough in flow dynamics to figure it out exactly. I’m =
probably
splitting hairs, as Brian says! Does anyone have the theoretical
background to confirm that oil breather back pressure (or Venturi =
‘vacuum’
affects) should not be an issue, depending on the angle of the nipple =
into the exhaust
gas flow?<o:p></o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>From the practical side, I did get =
a
chance to look fairly closely at a new Turbo Cirrus TIO-550N =
(turbo-normalized
by Tornado Alley for Cirrus). They run their oil breather line =
into an
exhaust pipe nipple that enters the pipe at right angles and appears to =
be cut
off flush on the inside. There is about two feet of pipe past the =
nipple
to the outside end of the exhaust =
stack…<o:p></o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>My inclination at the moment is to =
copy
the Cirrus approach. <o:p></o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>Chuck – our first plan was to =
use an
air-oil separator, but we’ve gone away from it because of stories =
of the
condensed water vapor returning to the crankcase with the condensed oil, =
and
the internal corrosion problems that may be caused by the water. =
When you
say your oil analysis has been good over the years, have you noticed any
problems that may have been caused by the returned =
water?<o:p></o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>Thanks for the =
help!<o:p></o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>Bob<o:p></o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<div>
<div class=3DMsoNormal align=3Dcenter style=3D'text-align:center'><font =
size=3D3
face=3D"Times New Roman"><span style=3D'font-size:12.0pt'>
<hr size=3D2 width=3D"100%" align=3Dcenter tabindex=3D-1>
</span></font></div>
<p class=3DMsoNormal><b><font size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font =
size=3D2
face=3DTahoma><span style=3D'font-size:10.0pt;font-family:Tahoma'>
reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] <b><span
style=3D'font-weight:bold'>On Behalf Of </span></b>Chuck<br>
<b><span style=3D'font-weight:bold'>Sent:</span></b> Wednesday, April =
23, 2008
2:26 PM<br>
<b><span style=3D'font-weight:bold'>To:</span></b> <st1:PersonName =
w:st=3D"on">Velocity
Aircraft Owners and Builders list</st1:PersonName><br>
<b><span style=3D'font-weight:bold'>Subject:</span></b> Re: REFLECTOR: =
Oil
Breather Nipple Into Exhaust Pipe</span></font><o:p></o:p></p>
</div>
<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'><o:p> </o:p></span></font></p>
<div>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Bob, have you considered an air-oil separator? The =
turbo's
will create higher cylinder pressures (temps) and thus more blow-by
through the rings. This will send more oil/water vapor out the breather =
and
into the exhaust/atmosphere. Anytime you weld an exhaust pipe, your =
adding a
stress riser which can crack and fail. If you do it, you might want to =
have it
normalized (heat treated) afterwards.</span></font><font size=3D2
face=3DTahoma><span =
style=3D'font-size:10.0pt;font-family:Tahoma'><o:p></o:p></span></font></=
p>
</div>
<div>
<p class=3DMsoNormal><font size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;
font-family:Tahoma'> <o:p></o:p></span></font></p>
</div>
<div>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>I've had a separator for years and it works well. I'm =
also
finishing my add-on turbo and plan to keep the same system. I get very =
little
oil through the separator discharge tube and my oil analysis has been =
fine.</span></font><font
size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;font-family:Tahoma'><o:p></o:p></span></font></=
p>
</div>
<div>
<p class=3DMsoNormal><font size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;
font-family:Tahoma'> <o:p></o:p></span></font></p>
</div>
<div>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Chuck H</span></font><font size=3D2 =
face=3DTahoma><span
style=3D'font-size:10.0pt;font-family:Tahoma'><o:p></o:p></span></font></=
p>
</div>
<blockquote style=3D'border:none;border-left:solid black =
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margin-left:3.75pt;margin-top:5.0pt;margin-right:0in;margin-bottom:5.0pt'=
>
<div>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><br>
<o:p></o:p></span></font></p>
</div>
<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'><br>
Bob,<br>
<br>
A simpler though less aesthetic solution would be to clamp a short =
length of
pipe to the leeward side of the current exhaust pipe and exiting the =
cowl
through the same opening that you have currently. You could attach the =
oil
breather tube to this pipe. If the exit end of the pipe is cut =
diagonally
as your exhaust pipe may be, I believe that will give the slight =
negative
pressure that you are looking for. This solution also may mitigate the =
freezing
over of the breather line.<br>
<br>
<br>
Kirk<br>
<br>
<br>
> From: bobj at computer.org<br>
> To: reflector at tvbf.org<br>
> Date: Tue, 22 Apr 2008 22:04:35 -0500<br>
> CC: <st1:PersonName =
w:st=3D"on">bobj at JaxTechLLC.com</st1:PersonName><br>
> Subject: REFLECTOR: Oil Breather Nipple Into Exhaust Pipe<br>
> <br>
> Does anyone have experience or ideas for the best way to weld a =
nipple
into<br>
> the exhaust pipe for the oil breather hose?<br>
> <br>
> We want to weld a nipple for our oil breather hose into the short =
exhaust<br>
> outlet pipe of one of the turbochargers (we've custom-added to our
IO-550N).<br>
> We are aware of several issues and concerns. One issue is how far =
the<br>
> nipple is extended and/or is angled into the exhaust gas stream. If =
for<br>
> example on the inside of the pipe, the nipple is extended and =
angled away<br>
> from the turbocharger, it might create a small Venturi effect and =
help
draw<br>
> moisture and oil 'fumes' out of the crankcase. But if angled away =
too
much,<br>
> this Venturi might be strong enough to excessively de-pressurize =
the<br>
> crankcase and cause problems.<br>
> <br>
> Or, if the nipple were angled a little too much back into the =
direction of<br>
> the turbo exhaust, it could positively pressurize the crankcase and =
cause<br>
> engine seal problems.<br>
> <br>
> Hopefully, there is an angle of the nipple that creates no =
positive<br>
> crankcase pressure, and with just the proper, small amount of =
negative<br>
> pressure to help draw out the oil fumes slightly.<br>
> <br>
> Another issue we're concerned about is that this short stub of a =
breather<br>
> nipple on the inside of the turbo exhaust pipe could eventually =
burn
through<br>
> or break off and strike the prop. This has apparently happened in =
the past<br>
> with some certified aircraft (not bang into the prop, just break =
off).<br>
> <br>
> Finally, we've also heard that if the nipple enters the exhaust =
pipe at<br>
> right angles and is flush cut with the wall of the exhaust pipe, =
not<br>
> extending into the inside of the breather nipple, it may be =
slightly<br>
> pressurized and can become completely clogged with 'soot' over a =
period of<br>
> time.<br>
> <br>
> If anyone has experience or suggestions for how far in to extend =
the oil<br>
> breather nipple into the exhaust pipe, and which way to angle it, =
we would<br>
> appreciate the help.<br>
> <br>
> Or alternatively, if someone has a (TCM or Lycoming) engine with a =
factory<br>
> installed oil breather nipple, maybe they could look to see how far =
the<br>
> nipple extends into the exhaust pipe, and at what angle.<br>
> <br>
> Thanks,<br>
> Bob Jackson<br>
> N2XF -- Ten years and still working!<br>
> <br>
<br>
<o:p></o:p></span></font></p>
</blockquote>
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