Insulating exaust

[Ryland]

as I understand it, the hotter you can keep your exaust, the more easly it will flow, is this correct?
I was thinking that insulating your exaust would benifit mileage, they do this to a point on race cars to help squeaze out more power, right? but that is mostly with a glass fiber fabric wrap, and that would soak up water, and dirt and loose affectiveness in weather, something that is not alwas an issue in racing.
so my idea was this, find an insulation that can handle heat, and find a way to protect it.
polyisocyanurate can handle a bit of heat, at least when I've put a torch to it, it does not melt or burn, so how about putting an inch thick layer (around R6-7?) and then cover it with epoxy renforced carbon fiber to protect it from the weather, and damage, making some points that connect to the metal exaust pipe of course, so if over time the foam turns in to dust, you still have this shell to hold in the heat, it seems like it would work better the tin heat sheilding that is used, I'm going to look around and see how hot I can get stuff like this, as my catolitic converters heat sheild is rusting away, and they are suposed to stay hot.
it also seems like a way to save a little weight, replacing the metal heat sheilding with high temp "plastic".

[molecule]

the biggest problem with wraps, etc...is deterioration of the piping from moisture locked in...
coatings are more effective...because it gaurantees longevity of the system...
the pipes are cleaned and then coated in a short period of time in a controlled environment...
the heat performance of thermal coatings is up there as well...

now coated AND wrapped !!!
well not too many reports of all that...
cant say i've seen one...
just those that bicker about which is best

i dont know anything about this poly you speak of though...
i'd believe it to be seriously compromised by heat cycling
its claimed to have a heat rating only to 250-300°F
though it did do well in the fire test and created a "char-layer" rather than melting...

"ASTM E84, Standard Test Method for Surface Burning Characteristics of Building Materials, is a standard method to assess the spread of flame on the surface of a material. Often referred to as the " Tunnel Test," E84 involves installing a sample of material 20 inches wide and 25 feet long as the ceiling of a horizontal test chamber. The material is exposed to a gas flame on one end of the tunnel for a period of 10 minutes. The rate of flame front progression on the material is compared to selected standards and calculations made to produce a flame spread rating. Smoke from the fire in the tunnel is measured in the exhaust stack via a light beam to establish smoke developed ratings"

[JanGeo]

CAN YOU SPELL ENGINE FIRE? exhost temp over 1000 degrees if no cooling is present - reved my BMW a little one night for a minute and the headers got glowing red hot. I would only recommend a few layers of aluminum foil and a splash shield to keep water from splashing on the cat and pipes when driving in rain.