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<DIV><SPAN class=373165321-29112004><FONT face=Arial color=#0000ff size=2>That's
hangin' my head out the window like a happy dog ...</FONT></SPAN></DIV>
<DIV> </DIV>
<P><FONT face="Times New Roman">Dean Pappas</FONT> <BR><FONT
face="Times New Roman">Sr. Design Engineer</FONT> <BR><FONT
face="Times New Roman">Kodeos Communications</FONT> <BR><FONT
face="Times New Roman">111 Corporate Blvd.</FONT> <BR><FONT
face="Times New Roman">South Plainfield, N.J. 07080</FONT> <BR><FONT
face="Times New Roman">(908) 222-7817 phone</FONT> <BR><FONT
face="Times New Roman">(908) 222-2392 fax</FONT> <BR><FONT
face="Times New Roman">d.pappas@kodeos.com</FONT> </P>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B> discussion-request@nsrca.org
[mailto:discussion-request@nsrca.org]<B>On Behalf Of </B>Dean
Pappas<BR><B>Sent:</B> Monday, November 29, 2004 4:53 PM<BR><B>To:</B>
discussion@nsrca.org<BR><B>Subject:</B> RE: to tune the
pipe<BR><BR></FONT></DIV>
<DIV><SPAN class=331204221-29112004><FONT face=Arial color=#0000ff size=2>So
Bill,</FONT></SPAN></DIV>
<DIV><SPAN class=331204221-29112004><FONT face=Arial color=#0000ff size=2>You
would have loved watching this bit ...</FONT></SPAN></DIV>
<DIV><SPAN class=331204221-29112004><FONT face=Arial color=#0000ff size=2>Baby
Brother was driving the then 12.0 second street-legal '69 Camaro down
Interstate 80, with me driving alongside the rear tire, with my head out the
window (think happy dod) listening for the "mellow sound"
that indicated the RPM at which our left-to-right bank header
crossover pipe was tuned. As you, no doubt, know, this pipe if placed
correctly cancels the first anti-resonance of the headre, and improves the
leave and short or 60-foot time. We got good at hand signals for, "now
drive at 3000 RPM" and the like. We moved and re-welded that pipe twice to get
it in the right spot.</FONT></SPAN></DIV>
<DIV><SPAN class=331204221-29112004><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=331204221-29112004><FONT face=Arial color=#0000ff size=2>Oh
yeah, the burn spot trick! By my estimate, things worked best when you cut the
pipe at 40% of a diameter longer than the burn spot.</FONT></SPAN></DIV>
<DIV><SPAN class=331204221-29112004><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=331204221-29112004><FONT face=Arial color=#0000ff size=2>Cool
stuff, eh?</FONT></SPAN></DIV>
<DIV> </DIV>
<P><FONT face="Times New Roman">Dean Pappas</FONT> <BR><FONT
face="Times New Roman">Sr. Design Engineer</FONT> <BR><FONT
face="Times New Roman">Kodeos Communications</FONT> <BR><FONT
face="Times New Roman">111 Corporate Blvd.</FONT> <BR><FONT
face="Times New Roman">South Plainfield, N.J. 07080</FONT> <BR><FONT
face="Times New Roman">(908) 222-7817 phone</FONT> <BR><FONT
face="Times New Roman">(908) 222-2392 fax</FONT> <BR><FONT
face="Times New Roman">d.pappas@kodeos.com</FONT> </P>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B>
discussion-request@nsrca.org [mailto:discussion-request@nsrca.org]<B>On
Behalf Of </B>Bill Glaze<BR><B>Sent:</B> Monday, November 29, 2004 4:41
PM<BR><B>To:</B> discussion@nsrca.org<BR><B>Subject:</B> Re: to tune the
pipe<BR><BR></FONT></DIV>Dean:<BR>Absolutely correct. As outlined
below, this is a well known principle. When I was running, and
building, engines for drag racing, we definitely noticed h.p. differences
both on the dyno, and on the race course, after tuning headers.
However, because of the size of the exhaust collectors, (4" diameter) we
could look in the collector and clearly see the "lean burn" ring.
Without going through the mechanics, suffice to say we were able to "tune"
the exhaust to add a few h.p.<BR>Bill Glaze<BR><BR>Dean Pappas wrote:
<BLOCKQUOTE cite=midEE17DCCB005C1B4EBCE4863113BB25D703E9B2@kcnt4.kodeos.com
type="cite">
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<DIV><SPAN class=147295914-29112004><FONT face=Arial color=#0000ff
size=2>Hello Dean ... Dean here.</FONT></SPAN></DIV>
<DIV><SPAN class=147295914-29112004><FONT face=Arial color=#0000ff
size=2>Echo ... echo ... echo ...</FONT></SPAN></DIV>
<DIV><SPAN class=147295914-29112004></SPAN> </DIV>
<DIV><SPAN class=147295914-29112004><FONT face=Arial color=#0000ff
size=2>The short answer is that no tuning is necessary.
</FONT></SPAN></DIV>
<DIV><SPAN class=147295914-29112004><FONT face=Arial color=#0000ff
size=2>4-cycle exhausts do indeed tune. This tuning is not at all
crirtical, and produces only a marginal horsepower
improvement.</FONT></SPAN></DIV>
<DIV><SPAN class=147295914-29112004></SPAN> </DIV>
<DIV><SPAN class=147295914-29112004><FONT face=Arial color=#0000ff
size=2>What happens is that as the exhaust wave front makes its way down
the long header it reaches the muffler can,</FONT></SPAN></DIV>
<DIV><SPAN class=147295914-29112004><FONT face=Arial color=#0000ff
size=2>or the expanding cone part of the muffler. In the case of a race
car, it reaches the open atmosphere. In all of these
cases,</FONT></SPAN></DIV>
<DIV><SPAN class=147295914-29112004><FONT face=Arial color=#0000ff
size=2>the gasses expand rapidly, causing a "reflected" vacuum wave to
travel back to the exhaust valve. If the length of the
</FONT></SPAN></DIV>
<DIV><SPAN class=147295914-29112004><FONT face=Arial color=#0000ff
size=2>header is correct, then the reflected wave will return to the
engine at the right time to help pull the exhaust
out,</FONT></SPAN></DIV>
<DIV><SPAN class=147295914-29112004><FONT face=Arial color=#0000ff
size=2>and fresh intake mixture into the combustion chamber, behind
it. This happens because of the valve-overlap. T</FONT></SPAN><SPAN
class=147295914-29112004><FONT face=Arial color=#0000ff size=2>he intake
valve</FONT></SPAN></DIV>
<DIV><SPAN class=147295914-29112004></SPAN><SPAN
class=147295914-29112004><FONT face=Arial color=#0000ff size=2>is
already open </FONT></SPAN><SPAN class=147295914-29112004><FONT
face=Arial color=#0000ff size=2>during the last 60 or 70
</FONT></SPAN><SPAN class=147295914-29112004><FONT face=Arial
color=#0000ff size=2>degrees of the exhaust valve
opening</FONT></SPAN><SPAN class=147295914-29112004><FONT face=Arial
color=#0000ff size=2>. This is desireable, even with supercharged
engines.</FONT></SPAN></DIV>
<DIV><SPAN class=147295914-29112004></SPAN> </DIV>
<DIV><SPAN class=147295914-29112004><FONT face=Arial color=#0000ff
size=2>As I said, this tuning is very non-critical. A good figure for the
length, from exhaust valve to place where gasses may
expand,</FONT></SPAN></DIV>
<DIV><SPAN class=147295914-29112004><FONT face=Arial color=#0000ff
size=2>is anywhere from 12inches to 16 inches, for our RPM range.
Back when I ran my YS 120-ACs at under 7,500 RPM (16-13 N
prop)</FONT></SPAN></DIV>
<DIV><SPAN class=147295914-29112004><FONT face=Arial color=#0000ff
size=2>I did run slightly longer headers.</FONT></SPAN></DIV>
<DIV><SPAN class=147295914-29112004></SPAN> </DIV>
<DIV><SPAN class=147295914-29112004><FONT face=Arial color=#0000ff
size=2>Regards,</FONT></SPAN></DIV>
<DIV> </DIV>
<P><FONT face="Times New Roman">Dean Pappas</FONT> <BR><FONT
face="Times New Roman">Sr. Design Engineer</FONT> <BR><FONT
face="Times New Roman">Kodeos Communications</FONT> <BR><FONT
face="Times New Roman">111 Corporate Blvd.</FONT> <BR><FONT
face="Times New Roman">South Plainfield, N.J. 07080</FONT> <BR><FONT
face="Times New Roman">(908) 222-7817 phone</FONT> <BR><FONT
face="Times New Roman">(908) 222-2392 fax</FONT> <BR><FONT
face="Times New Roman"><A class=moz-txt-link-abbreviated
href="mailto:d.pappas@kodeos.com">d.pappas@kodeos.com</A></FONT> </P>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B> <A
class=moz-txt-link-abbreviated
href="mailto:discussion-request@nsrca.org">discussion-request@nsrca.org</A>
[<A class=moz-txt-link-freetext
href="mailto:discussion-request@nsrca.org">mailto:discussion-request@nsrca.org</A>]<B>On
Behalf Of </B>Dean & Melissa Williams<BR><B>Sent:</B> Thursday,
November 25, 2004 12:20 AM<BR><B>To:</B> <A
class=moz-txt-link-abbreviated
href="mailto:discussion@nsrca.org">discussion@nsrca.org</A><BR><B>Subject:</B>
to tune the pipe <BR><BR></FONT></DIV>
<DIV><FONT face=Arial size=2>
<DIV><FONT face=Arial size=2>Hi</FONT></DIV>
<DIV><FONT face=Arial size=2>Could you please tell me if I have to tune
the pipe length for a CD mkII system for the YS FZ91 , I purchased
this system several years ago and have just set it
up.</FONT></DIV>
<DIV><FONT face=Arial size=2>If I do have to tune the length how do I do
it and at what length ?</FONT></DIV>
<DIV><FONT face=Arial size=2>I have the Cd mkII pipe +CD header +
CDflexible header + CDmounting system.</FONT></DIV>
<DIV>I am running 20/20 fuel an a 14 x 10 apc prop with a Hyde
mount.</DIV>
<DIV>The YS idles at 1950 to 2000 and seems to max out at 8900 to 9000
rpm still seems rich (lots of oil out of the exhaust ) and the high end
needle seems insensitive until you go too lean and start dropping
rpm.</DIV>
<DIV>Any assistance is greatly appreciated.</DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>Thanking you</FONT></DIV>
<DIV><FONT face=Arial
size=2>
Dean</FONT> </DIV></FONT></DIV></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BODY></HTML>