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<DIV>John,</DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>Most of the 2C sport engines to be used with a
muffler are timed</FONT></DIV>
<DIV><FONT size=2 face=Arial>at about 145-148º exhaust down time.</FONT></DIV>
<DIV><FONT size=2 face=Arial>On most of the .60 to 1.60 size, to get the benefit
of the supercharging</FONT></DIV>
<DIV><FONT size=2 face=Arial>effect from the pipe, I increase the exhaust
downtime to 155-158º, without</FONT></DIV>
<DIV><FONT size=2 face=Arial>changing </FONT><FONT size=2 face=Arial>the intake
timing, except for some directional porting for better </FONT></DIV>
<DIV><FONT size=2 face=Arial>scavenging </FONT><FONT size=2 face=Arial>effect.
This all will not decrease a reliable idle.</FONT></DIV>
<DIV><FONT size=2 face=Arial>I believe that the pylon engines are ported to 170º
exhaust down time and </FONT></DIV>
<DIV><FONT size=2 face=Arial>on those you are not looking for a reliable low
idle. </FONT></DIV>
<DIV><FONT size=2 face=Arial>Never tried any work on 4 strokes. To get any
benefit from a pipe on those</FONT></DIV>
<DIV><FONT size=2 face=Arial>you would have to have overlapping valve timing,
which none of our model</FONT></DIV>
<DIV><FONT size=2 face=Arial>4 stroke </FONT><FONT size=2 face=Arial>engines
have.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Regards,</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Karl G. Mueller<BR><A
href="mailto:kgamueller@rogers.com">kgamueller@rogers.com</A><BR></FONT></DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=jpavlick@idseng.com href="mailto:jpavlick@idseng.com">John
Pavlick</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-discussion@lists.nsrca.org</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Thursday, November 06, 2008 5:02
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [NSRCA-discussion] Engine tuning
info</DIV>
<DIV><BR></DIV>
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<DIV>Has anyone taken the time to measure the port timing of
various model airplane 2C engines? Specifically the OS140 and 160? Also,
if anyone has cam profiles + index info for the YS 160 and
170 4C motors I'd be interested in that as well.</DIV>
<DIV> </DIV>
<DIV>John Pavlick</DIV></TD></TR></TBODY></TABLE>
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