OS1.40 Pipe > Couplers

[Karl G. Mueller]

Brian,

If you are using a larger dia. header than your pipe inlet you're
restricting the flow of the spent gases into the pipe. What is
happening is that you're pushing fresh gases mixed with a certain
amount of exhaust gases back into the combustion chamber. This creates
additional heat and less performance. A better combination would be
same size header or smaller diameter than the pipe inlet. What you
want to achieve is a high velocity (more important than volume) in the
header.
Judging by the size of the pipe inlet you must be using a 10cc pipe
which might be a little on the small side in volume.

Karl G. Mueller
kgamueller at rogers.com




----- Original Message ----- 
From: "Brian Young" <b4598070 at yahoo.com>
To: <discussion at nsrca.org>
Sent: Monday, March 01, 2004 10:24 AM
Subject: RE: OS1.40 Pipe > Couplers


> Interesting to see all the solutions to this. Are
> these on planes that have exposed or enclosed tunnels?
> Same size pipe inlet and header, or different?
>
> Im particularly interested in the teflon that lasts
> for 1000 flights. I think im getting about 50-100
> flights per silicone coupler on a 7/8 diameter header
> and 3/4 diameter pipe inlet.
>
> Thanks,
>
>
> --- "Henderson,Eric" <Eric.Henderson at gartner.com>
> wrote:
> > One of the pilots that I support with OS 1.40's has
> > run the cut header set up for three seasons with no
> > failures. Also he was breaking headers until he
> > changed over to the two-coupler set up.
> >
> > It is interesting how we get opposing views on what
> > appears to be the same situation. I suspect that the
> > choice of coupler material and cooling has a lot to
> > do with the result. BTW I have had great success
> > with 1/16" walled 500F+ Teflon tubing where non
> > flexible, but directional, needs occurred.
> >
> > Regards,
> >
> > Eric.
> >
> >
> > -----Original Message-----
> > From: discussion-request at nsrca.org
> > [mailto:discussion-request at nsrca.org]On Behalf Of
> > David Lockhart
> > Sent: Monday, March 01, 2004 9:56 AM
> > To: discussion at nsrca.org
> > Subject: Re: OS1.40 Pipe
> >
> >
> > Same experience here.  I've got 2 2.25" rise MAC
> > headers that were bent slightly and then cut about
> > 1.5" after 2.25" rise.  Both have over 1,000 flights
> > and no problems with breakage or burning up
> > couplers.  Currently using Teflon couplers w/ the
> > constant tension spring clamps (Central has them).
> >
> > Dave
> >
> > ----- Original Message ----- 
> > From: mike mueller <mailto:mups1953 at yahoo.com>
> > To: discussion at nsrca.org
> > Sent: Monday, March 01, 2004 8:48 AM
> > Subject: Re: OS1.40 Pipe
> >
> >  Lance, I have the same problem with the couplers
> > burning out when they are too close to the engine
> > and I don't have a problem with bending my headers
> > the same way Lance does it. Mike
> >
> > Lance Van Nostrand < patterndude at comcast.net> wrote:
> >
> >
> > I'm not so sure Eric. I've seen people try to cut
> > the header in the rise
> > and the couplers used kept burning out. the exhaust
> > temps are very hot
> > there, but cool quickly. You really don't want a
> > coupler within 8" of the
> > exhaust outlet.
> > My suggestion, the solution I've used for years with
> > Macs headers, is to
> > use an appropriately sized forstner bit (e.g. 7/8")
> > and drill a hole in the
> > end of a 2x4. Slide in the header and use the 2x4 as
> > a bending arm. The
> > hole supports the header and the 2x4 gives you
> > leverage. Oh, don't leave
> > the header bolted to the engine!! Bolt it to
> > something else.
> > --Lance
> >
> > ----- Original Message ----- 
> > From: "Henderson,Eric"
> > To:
> > Sent: Sunday, February 29, 2004 7:21 PM
> > Subject: RE: OS1.40 Pipe
> >
> >
> > They are hard to bend without kinking. I usually
> > cant the engine to the side
> > to line up the header.
> >
> > If it is a MAC, one piece header - no exhaust stub
> > and o-rings - it is
> > advisable to cut the header half way up the header
> > rise, and fit a second
> > coupler. This will allow you to rotate the tubing
> > and also provide
> > protection from header fractures.
> >
> > Regards,
> >
> > Eric.
> >
> > -----Original Message-----
> > From: discussion-request at nsrca.org
> > [mailto:discussion-request at nsrca.org]On Behalf Of
> > Jeff Hughes
> > Sent: Sunday, February 29, 2004 7:28 PM
> > To: discussion at nsrca.org
> > Subject: OS1.40 Pipe
> >
> >
> > Now that I have my OS1.40 mounted in my new focus, I
> > find that the pipe hits
> > the side of the pipe tunnel due to the right thrust.
> > Can I just bend the
> > pipe, or should I heat it first?
> >
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