Angier,
Lorn has a good point with the stainless Brillo pad solution. I took it a step further and had my exhaust mod guy weld several strips of stainless lengthwise down the exhaust.(see pic) I snipped the fins about 1/8" and bent them to try and get a better heat exchange. I shredded the Brillo pad inside and over the fins. The theory is the stainless does a better job of transferring heat and the Brillo slows down the air and also helps transfer heat.
I am comfy in shorts up to 22,500 ft. I don't use carb heat as I am injected but mine puts out all the heat I want whilst just cracking the heat knob open.
FWIW.

Randy Snarr
235/320

Lorn H Olsen <lorn@dynacomm.ws> wrote:

I packed my heat muff with stainless steel Brillo pads. I believe that this should help to absorb as much of the heat as can be from the exhaust pipe. I have also rapped the Heat muff (under the clamps) with asbestos equivalent tape. I keep the #1 exhaust gas probe away from the clamp with RTV. I have been running this setup for about 3 years without a problem.

Our heat rap is used for both the carb (if you have one) heat and the cabin heat. RVs use 2 heat muffs. I think that that would be a better setup. On my trip from Detroit to Norfolk yesterday I flew at 11,500 ft with a carb temp of -6. I could only raise the temp to +2. If my carb had iced, I could have had a problem.

If anyone knows, I would like to know what the temperature rise is on a production plane. I have had an A&P tell me that the temperature should go up by 20 or 30 degrees. I flew in a Tiger with a carb temp probe and only saw the temperature go up about 10 degrees. Can anyone out there tell me how far other carb temp gauges raise?

From: "Greenbacks, UnLtd." <N4ZQ@comcast.net>

My heat muff is held in place on the exhaust with 2 hose clamps but there are many possibilities for incoming air to escape into the lower cowl. Is high temp RTV suitable for closing up all possible air escape routes around the heat muff? Or is there a better solution.

Angier Ames

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Lorn H. 'Feathers' Olsen, MAA, DynaComm, Corp.

248-345-0500, mailto:lorn@dynacomm.ws

LNC2, FB90/92, O-320-D1F, 1,300 hrs, N31161, Y47, SE Michigan

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