Paul,
          I give up, just how are you intending to fasten
the muffler to the manifold slip joint ??  Any solution
I think up adds a lot of weight.  The design is actually
impressive, simple and as light as p[ossible.,
  I can only get 316 stainless here, but the simplicity
means that I can make two with one as a spare.
             Neil.

Two small vertical tabs and a horzontal link with a couple
of six mm SS bolts and SS nuts. One tab on the muffler and the
other on the flange stub. Another way its been done
is a small spring but I suspect the temper will go away
sooner rather than later. Even several loops of heavy
safety wire will work.


   _     _
  |o|   |o|
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     |

This is SOP in aviation.

The link with bolts is the best.

The slip joints allow a bit of expansion and
contraction due to differences in temperature.

One link at the center exhaust port will work
but I would put three on there in case one failed.

BTW there is an old book still for sale by
the EAA called "Fire Wall Forward" by Tony Bingelis.
It is sort of the bible for piston engine AC installations.
Well worth it. Here is a graphic from it.


Paul Lamar

Looking at the graphic, it seems that a better
seal or containment of the exhaust gasses would
result if the flow direction was reversed.

Joel

I agree but who am I to argue with Tony Bingelis :)

Paul Lamar


At first It occurred to me too that reversed flow would be better.
On second look it becomes apparent that it does not matter as it is the
same situation for either direction.
The two pipes are butting up against each other while the outer muff is
just covering it up.
The escaping gas flow exiting on the left will have the same supply
source and pressure no matter which direction the gas flows.
The escaping gas must find its way past the butt joint and then out
between the muff and the pipe OD.

In general I find it a good and simple design.

Rolf

For an exhaust pipe connection where is is not feasible to weld,
I prefer a flanged connection with a gasket.  Butt flanges and
gaskets are readily available.  If you need a connection that
needs a little flexibility,  The GM type connection with a donut
gasket is a tried and true method that has been used for years.

If you need coil springs as shown in Tony's design, you might
try the springs used in the GM connection.  I've never seen one
that has collapsed due to heat although the Mazda does run
considerably hotter.  If higher temperature resistant coil
springs are needed,  Super Alloy wound wire coils such as
Inconel 718 have been shown to maintain their strength at
temperatures of 1000 degrees F, although I would guess they
are a bit expensive.

As far as extra weight is concerned,  I believe in the saying:
Don't screw with mother nature and Carbon Monoxide.

Joel
Over the Hill Materials Engr