I bought some sticky back cowl heat protector from Van's and used it on the bottom near exhaust and mufflers. I just coated the inside of the cowl with epoxy resin. Seems just fine after two years and 120 hours.

Roberta
 
I did as Roberta with sealing the cowl with thinned epoxy resin but I also painted the inside with engine block paint purchased in the aviation isle in my local Checker Autoparts store. Just used rattle cans. Used white paint to help locate any oil leaks. Then I applied the sticky-backed reflective foil that Van's sells in the areas where the exhaust pipes come close.


Regards,
 
painless said:
I did as Roberta with sealing the cowl with thinned epoxy resin but I also painted the inside with engine block paint purchased in the aviation isle in my local Checker Autoparts store. Just used rattle cans. Used white paint to help locate any oil leaks. Then I applied the sticky-backed reflective foil that Van's sells in the areas where the exhaust pipes come close.


Regards,
Click to expand...
Jeff - can I ask how much of the reflective foil you used? I have been meaning to do that to my lower cowl (I'll have to wait till it comes back from paint!), and don't want to order too little. Doesn't look very expensive (per foot), but I don't want to order a ridiculous excess either!

Paul
 
Inside Cowl Paint

I have Van's O-360-A1A (carbureted engine) cowl. As mentioned by a couple of others, I coated the inside of the cowl (top and bottom halves) with 2 coats of a thinned 1:1 epoxy resin. Makes a nice finish and seals the fiberglass.

Then to prevent cowl burn from the hottest areas, I used Van's heat shield material to cover the lower cowl vertical sides only (the lower protruding section nearest the exhaust stacks) and the main cowl bottom nearest the exhaust system. I hope that's a clear description.

I inspect the cowl every 25 hours when I remove it for oil changes/annual. The heat shield works great. I see no burn marks after 90 hours.

Van's material has a self-adhesive backing which is a pain to work with since you are dealing with a curved surface. It's a bit like thick aluminum foil. Don't worry about the inevitable wrinkles as no one will see them once the cowl is back on. I forget exactly how much I bought but I think 3 linear feet would be plenty for an RV-8.

Chris

P.S. I found another use for the stuff. When I was test flying my aircraft, I needed a way to temporarily add a tab to the rudder while trying to figure out how large a tab would be needed. This stuff was great for sticking on the tab and easy to remove as I adjusted the tab size.
 
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chrispratt said:
P.S. I found another use for the stuff. When I was test flying my aircraft, I needed a way to temporarily add a tab to the rudder while trying to figure out how large a tab would be needed. This stuff was great for sticking on the tab and easy to remove as I adjusted the tab size.
Click to expand...

Its also great for making temporary ramps to cover the fins on the front cylinders. I used a bit of this tape, adjusting the amount of coverage until the CHTs were even across all four cylinders. Then I make the 'real' ramps from 2024 and pop riveted them to my inlet floors.
 
Paul:

As I recall, I believe I ordered 3 feet of it. I just covered the corners where the carb inlet scoop meets up with the cowl. It really doesn't take too much.


Regards,
 
First, as a minimum seal the inside surface of your cowling to minimize the oil contamination. The cowl with my -8 was a little on the "dry" side (minimal resin) and tends to soak up oil and dirt.

I first used spray contact cement and aluminum foil. Lasted several years on the hotest areas of the cowling. Would have lasted several more on the moderately hot areas before I removed it.

My current solution is a home-brew mix of clear polyurethane resin and aluminum glitter. The trick came with finding which size glitter layed flay but was not so large that it couldn't be mixed and brushed on. Works pretty well and has been pretty durable. The resin sealed the surface and the glitter reflects a good bit of the radiant energy.

I had done some experimenting with a (conductive) insulating barrier under the radiant barrier, but have not worked on that plan in a while.

Bryan
 
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