As I have posted on this list before; doing some relatively simple heat
transfer calculations will tell you that putting these coatings on the
outside surface of the exhaust can reduce the temps by less than 1%.
Coating the inside will make a larger difference initially because of the
lower emissivity; possible as much as 5%, but after some buildup of exhaust
products, the difference will be about the same as coating the outside.
Anyone telling you it will reduce the temp by 65% is blowing smoke, and
hasn't the faintest idea of reality.

The coatings make the exhaust look nice, and will inhibit corrosion on
carbon steel systems, especially on the inside; but on SS system they are
pretty much a waste of money.

Ok; it's just my opinion.

Al G

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of Mike Wills
Sent: Monday, July 27, 2009 8:45 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Intake filter box & Jet Hot Exhaust Coating

My exhaust is coated in and out with a 2000 degree coating. Its holding up
OK, but I wouldnt rely on it to keep the heat off of nearby components. I
have a stainless heatshield around a large portion of the exhaust and I have

a self adhesive fiberglass heat shielding material applied in various places

like the inside of the cowl. In places not protected by the heatshield, the
adhesive has gotten hot enough to release. I also have a couple of painted
parts fairly close to the exhaust that have gotten hot enough for the paint
to burn.

Mike Wills
RV-4 N144MW
----- Original Message -----
From: "Ben Schneider" <plumberben@yahoo.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Monday, July 27, 2009 4:54 AM
Subject: [FlyRotary] Intake filter box & Jet Hot Exhaust Coating


>
> Thanks for the kind words. Let me answer some of the questions. The intake

> filter box has a K&N filter inside, and a butterfly valve for ram air that

> bypasses through the center of the filter. It also has a spring loaded
> door that would suck open in the event of the opening being plugged. That
> is why the odd shaped top.
>  The pictures of the exhaust are pretty old. In the one picture, the
> exhaust had not yet been sent to the coater. I guess I should also add
> that the coating is not actually Jet Hot coating as I have been calling
> it, (common trade name) It was actually done by High Performance Coatings
> (www.hpcoatings.com) It is their equivalent to the Jet Hot. Supposed to be

> good up to 2000 degrees, and supposedly reduces surface temperatures as
> much as 65%. I am wondering if that is true or just sales propaganda?
> Guess I'll find out.
>   The muffler is an Aeroturbine muffler, all stainless, 2 1/2" inlet and
> outlet. Don't have any idea if it will blow apart, quite the thing, or
> just increase drag. Yet another unknown. Ahh, the life of an
> experimenter....
>
> ;)
>
> Will be off line for a few days, headed to OSH. Hope to see some of you
> there.
>
> Ben
>
> --
> Homepage:  http://www.flyrotary.com/
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>



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