Here is an interesting idea.
the spring keeps the heat shield spaced out
from the tangential muffler and allows air to
flow through for cooling.

Paul Lamar

To my mind, all that spring is doing is increasing the
rate of heat transfer from the muffler to the heat shield.
Sort of defeats the whole purpose of the shield.
Charlie Kuss

I think that the questionable word is 'all.' That's a very
common technique used in standard a/c engine exhaust heat
muffs for both carb heat & cabin heat. The exhaust pipe is
stainless, the shroud is al. Air flow through the system
carries the heat away from the springs & the al does not
suffer. If all the heat from the exhaust did transfer to the
the al, it would quickly melt or fail from the fatigue of
thermal cycling. A requirement of the a/c engine muffs is
that airflow be maintained through the muffs at all times,
either to the carb/cabin or into the cowl.

Does this help?

Charlie

Lycosaur powered RV-4

No cabin heat out of this. One of the advantages of a liquid cooled engine
is you don't have to use exhaust heat to heat the cabin so no possibility
of exhaust leaks feeding carbon monoxide into the cabin.

Perry Mick has a heater core under his seat in his Longez. He said it was
very comfortable on the way down from Oregon yesterday in very cold conditions.

BTW Perry is on his way home. The weather is great in CA but he will
have to avoid this freezing rain when he gets to Oregon later today.

Paul Lamar

I was trying to address Charlie Kuss' concern about heat
transfer through the springs to the shield. Carb/cabin heat
examples were mentioned only to show that it's been done
with no ill effects& will probably work as intended.

Charlie England

Pardon me.

Paul Lamar
 
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