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<DIV>Tim:</DIV>
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<DIV>Heat transfer from the cylinder's fins to the surrounding air flow is
maximized when the cowling is shaped around the cylinder such that the air
becomes turbulent. For this to occur, the space betwen the shroud and the engine
should be some minimal amount like 1/4" to 3/8". There are no cowls available in
even the most expensive models that offer such shapes. In fact, some of the more
popular models with the huge cowlings offer nothing more in terms of
cooling than large buckets up front where stagnant air collects, and it
matters little how large the exit opening is.</DIV>
<DIV> </DIV>
<DIV>I would add to what Ed has stated that proper ducting around an engine
will keep it happier. The inlet doesn't really need to be terribly large as
long as it smoothly transitions the air flow from inlet to cylinder/shroud. Then
turbulated air does its heat transfer most effectively. Exit area as Ed stated
earlier. </DIV>
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<DIV>Matt</DIV>
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<DIV> </DIV>
<DIV>In a message dated 2/13/2006 6:07:34 PM Eastern Standard Time,
ed_alt@hotmail.com writes:</DIV>
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<DIV><FONT face=Arial size=2>Tim:</FONT></DIV>
<DIV><FONT face=Arial size=2>Good question - I don't know for sure what the
best inlet size is. I always made an approximation that has about 2/3 to
3/4 the area of the cylinder behind the intake, then I apply the 2.5 or
greater rule of thumb for the outlet area. BTW, that is 2.5 x the total
intake, so if you have something taking in air for colling the crankcase, add
that in too. Not sure if this is optimal or not, but it has worked
for me so far.</FONT></DIV>
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<DIV><FONT face=Arial size=2>Ed</FONT></DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=mailto:TJS@mail.global-electronics.com
href="mailto:TJS@mail.global-electronics.com">Tim Of Global Electronics,
Ltd.</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=mailto:nsrca-discussion@lists.nsrca.org
href="mailto:nsrca-discussion@lists.nsrca.org">NSRCA Mailing List</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Monday, February 13, 2006 12:59
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [NSRCA-discussion] Cooling
inlet/out sizes???</DIV>
<DIV><BR></DIV>Thanks All!<BR><BR>But how do I calculate the minimum input
size?<BR><BR>Tim</BLOCKQUOTE></FONT></BLOCKQUOTE></DIV>
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