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<DIV>I have used the OS160 as a test bed for such comparison, in the air. Ground
running doesn't show much of a difference; just a couple hundred.
Eventhough it is very mildly timed for tuned pipe use, the device definitely
adds HP. Of course it can be set too long to have a useful boost in output and I
had it set there initially. As it was shortened to a more typical setting for
large 2C engines, not only was the output improved (again, in the air), the
engine became sweeter running with improved response.</DIV>
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<DIV>Don't ask for RPM's, I couldn't care less. It improved the capability
of the airplane and that's about all that counts.</DIV>
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<DIV>MattK</DIV>
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<DIV>In a message dated 3/6/2006 9:01:40 PM Eastern Standard Time,
jeffghughes@comcast.net writes:</DIV>
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<DIV>So you are saying you have tried a comparison of a tuned pipe vs a
muffler back to back? Any data?</DIV>
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Original message -------------- <BR>From: Rcmaster199@aol.com <BR>
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<DIV>In a message dated 3/6/2006 6:57:30 PM Eastern Standard Time,
jeffghughes@comcast.net 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>
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<DIV>Yes and there is</DIV>
<DIV> </DIV>
<DIV>MattK</DIV></FONT></BLOCKQUOTE></FONT></BLOCKQUOTE></DIV>
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