REFLECTOR:POWER & EXHAUST
KeithHallsten
reflector@tvbf.org
Thu, 31 Jul 2003 16:57:28 -0700
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Tom,
It's extremely difficult to quantify the differences in performance due =
to exhaust system style. Generally speaking, I believe the differences =
would be very slight, as long as the dimensions were appropriate (e.g., =
the collector pipe has about double the cross-sectional area of the =
individual pipes in a header-type system). The biggest concerns in =
exhaust system selection are:
1. Structural integrity and resistance to vibration - you don't want =
the system to fail and throw metal into your prop or start a fire.
2. Cooling. Too much glowing pipe in the cowl is a heater that you =
won't be able to overcome!
3. Outlet far enough forward to avoid baking your prop blades.
The collector system that meets criteria 2 can NOT be a tuned exhaust, =
so you won't get any benefit of scavenging the exhaust from other =
cylinders. You can see what a tuned exhaust for an IO-360 looks like by =
looking at Powerflow exhausts. Unfortunately for us pusher pilots, that =
system would likely violate ALL of the "prime directives"! =20
After due consideration, I selected a 3-into-1 collector-type exhaust =
system (Custom Aircraft Parts) due to its structural integrity, light =
weight, and minimal hot pipe area in the cowl.
Keith Hallsten, XLFG, waiting for my IO-540 so I can install the =
headers! =20
----- Original Message -----=20
From: Tom Martino=20
To: reflector@www.tvbf.org=20
Sent: Thursday, July 31, 2003 3:51 PM
Subject: REFLECTOR:POWER & EXHAUST
There are a few choices for exhaust systems and other than cosmetics I =
want to know if one over the other will make a difference in power.
=20
Choices:
=20
-Six individual pipes directed through the bottom of the cowling.
=20
-Three into one directed through the bottom of the cowling.
=20
-Three into one directed straight back (then turn down at the end to =
avoid prop).
=20
I would hate to lose a few horsepower simply for not using the proper =
exhaust. Some say straight pipes are the only way to go. Others say =
the pulsing of three into one do not create back-pressure and actually =
can create a vacuum. Others contend that three short pipes directed to =
a pipe that goes straight backwards is "too restrictive".
=20
Any feedback?=20
=20
=20
=20
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<DIV><FONT face=3DArial size=3D2>Tom,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>It's extremely difficult to quantify =
the=20
differences in performance due to exhaust system style. Generally=20
speaking, I believe the differences would be very slight, as long as the =
dimensions were appropriate (e.g., the collector pipe has about double =
the=20
cross-sectional area of the individual pipes in a header-type =
system). The=20
biggest concerns in exhaust system selection are:</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>1. Structural integrity and =
resistance to=20
vibration - you don't want the system to fail and throw metal into your =
prop or=20
start a fire.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>2. Cooling. Too much =
glowing pipe in=20
the cowl is a heater that you won't be able to overcome!</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>3. Outlet far enough forward to =
avoid baking=20
your prop blades.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>The collector system that meets =
criteria 2 can NOT=20
be a tuned exhaust, so you won't get any benefit of scavenging the =
exhaust from=20
other cylinders. You can see what a tuned exhaust for an IO-360 =
looks like=20
by looking at Powerflow exhausts. Unfortunately for us pusher =
pilots, that=20
system would likely violate ALL of the "prime directives"! =
</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>After due consideration, I selected a =
3-into-1=20
collector-type exhaust system (Custom Aircraft Parts) due to its =
structural=20
integrity, light weight, and minimal hot pipe area in the =
cowl.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Keith Hallsten, XLFG, waiting for my =
IO-540 so I=20
can install the headers! </FONT></DIV>
<BLOCKQUOTE dir=3Dltr=20
style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV=20
style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>=20
<A title=3Dtmartino@troubleshooter.com=20
href=3D"mailto:tmartino@troubleshooter.com">Tom Martino</A> </DIV>
<DIV style=3D"FONT: 10pt arial"><B>To:</B> <A =
title=3Dreflector@www.tvbf.org=20
href=3D"mailto:reflector@www.tvbf.org">reflector@www.tvbf.org</A> =
</DIV>
<DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Thursday, July 31, 2003 =
3:51=20
PM</DIV>
<DIV style=3D"FONT: 10pt arial"><B>Subject:</B> REFLECTOR:POWER &=20
EXHAUST</DIV>
<DIV><BR></DIV>
<DIV class=3DSection1>
<P class=3DMsoNormal><FONT face=3DArial size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; FONT-FAMILY: Arial">There are a few choices =
for=20
exhaust systems and other than cosmetics I want to know if one over =
the other=20
will make a difference in power.<o:p></o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; FONT-FAMILY: =
Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; FONT-FAMILY: =
Arial">Choices:<o:p></o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; FONT-FAMILY: =
Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; FONT-FAMILY: Arial">-Six individual pipes =
directed=20
through the bottom of the cowling.<o:p></o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; FONT-FAMILY: =
Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; FONT-FAMILY: Arial">-Three into one directed =
through=20
the bottom of the cowling.<o:p></o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; FONT-FAMILY: =
Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; FONT-FAMILY: Arial">-Three into one directed =
straight=20
back (then turn down at the end to avoid =
prop).<o:p></o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; FONT-FAMILY: =
Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; FONT-FAMILY: Arial">I would hate to lose a =
few=20
horsepower simply for not using the proper exhaust.<SPAN=20
style=3D"mso-spacerun: yes"> </SPAN>Some say straight pipes are =
the only=20
way to go.<SPAN style=3D"mso-spacerun: yes"> </SPAN>Others say =
the pulsing=20
of three into one do not create back-pressure and actually can create =
a=20
vacuum.<SPAN style=3D"mso-spacerun: yes"> </SPAN>Others contend =
that three=20
short pipes directed to a pipe that goes straight backwards is =93too=20
restrictive=94.<o:p></o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; FONT-FAMILY: =
Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; FONT-FAMILY: Arial">Any feedback?=20
<o:p></o:p></SPAN></FONT></P>
<P class=3DMsoNormal><FONT face=3DArial size=3D2><SPAN=20
style=3D"FONT-SIZE: 10pt; FONT-FAMILY: =
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yes"> </SPAN><o:p></o:p></FONT></P>
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