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<DIV><FONT face=Arial size=2>Jeff,</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I generally break in every 2C engine on a muffler
before adding the pipe. There is not a specific answer to your question -
it depends on many variables, such as the timing of the engine, the design of
the muffler, the design of the tuned pipe, how aggressively the tuned pipe is
tuned, etc.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I do not know of a readily available muffler for
the big 2Cs in the US at this time. The Bolly 480 and 590s were among the
best, as is a muffler I picked up from Jerry Budd from Stefan Fink years
ago (very light alum, I believe it was made by Graeber in Germany).</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>If you were to look at a common pattern 2C like the
OS140RX running mild/moderate fuel and compression at say 8000 RPM, adding a
pipe could add no RPM (but substantially more torque from maybe 3000-4000 and
up), or maybe as much as 400 RPM on the top end (and more unload in the
air). The real trick is matching up engine timing (porting), pipe design,
and tune length for the RPM range you want to run in. You can
certainly gain more than 400 RPM with the addition of a pipe, but
realistically for pattern, you won't see much more than 200-400 RPM (or 1" of
pitch or 1" of diameter at the same RPM) without compromising torque, throttle
response, and consistency over varied weather conditions.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Regards,</FONT></DIV><FONT face=Arial size=2>
<DIV><BR>Dave Lockhart</DIV>
<DIV><A href="mailto:DaveL322@comcast.net">DaveL322@comcast.net</A></DIV>
<DIV></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV>----- Original Message ----- </DIV>
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<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=jeffghughes@comcast.net
href="mailto:jeffghughes@comcast.net">jeffghughes@comcast.net</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=nsrca-discussion@lists.nsrca.org
href="mailto:nsrca-discussion@lists.nsrca.org">NSRCA Mailing List</A> ; <A
title=nsrca-discussion@lists.nsrca.org
href="mailto:nsrca-discussion@lists.nsrca.org">nsrca-discussion@lists.nsrca.org</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Cc:</B> <A title=Rcmaster199@aol.com
href="mailto:Rcmaster199@aol.com">Rcmaster199@aol.com</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Monday, March 06, 2006 8:59
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [NSRCA-discussion] 2C Pipe
vs Muffler</DIV>
<DIV><BR></DIV>
<DIV>So you are saying you have tried a comparison of a tuned pipe vs a
muffler back to back? Any data?</DIV>
<DIV> </DIV>
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Original message -------------- <BR>From: <A
href="mailto:Rcmaster199@aol.com">Rcmaster199@aol.com</A> <BR>
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<DIV>
<DIV>In a message dated 3/6/2006 6:57:30 PM Eastern Standard Time, <A
href="mailto:jeffghughes@comcast.net">jeffghughes@comcast.net</A>
writes:</DIV>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px solid"><FONT
style="BACKGROUND-COLOR: transparent" face=Arial color=#000000 size=2>was
going through the data on Ed Hartley's 2 stroke page and noted that there
is virtually no difference between a piped OS1.40 and a muffled OS1.40 for
the prop sizes being used. I assume that is because to get a nice
linear throttle curve on a pipe, the pipe is deliberately set too long for
peak horsepower. My question is why run a tuned pipe at all if you are
going to set it too long for peak power?. Has anyone run back to back
tests with same engine and plane with a pipe vs a muffler to see if
there is truly a difference in power or feel?</FONT></BLOCKQUOTE></DIV>
<DIV> </DIV>
<DIV>Yes and there is</DIV>
<DIV> </DIV>
<DIV>MattK</DIV></FONT></BLOCKQUOTE>
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