OS1.40 Pipe > Couplers

[Brian Young]

I remedied the difference in size this weekend w/ a
new pipe that matches the header diameter. 

The previous muffler was for a 1.20-1.40 size engine
but used a 3/4" inlet, headers available happened to
be 7/8". 

Anyway, new pipe is lighter and more power just hope
its not too loud. Couplers will probably survive
better with same size pipe and header.

--- "Karl G. Mueller" <kgamueller at rogers.com> wrote:
> 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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> 
=== message truncated ===


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