I just got the insulation. glue. and tape. from J.C Wittney it seems ok but the directions say up to 700 Degrees dosent exhaust manafolds get a lot hotter than this, can this stuff catch fire or melt
Jim ACOC 3172
Exhaust manifolds commonly reach 1500 + degrees on their surface.They can reach a dull red color on a long steep summer time pull.There have been materials mentioned in the past that will withstand this much heat.Bear in mind that aluminum melts at 2000+ degrees.So a heat shield of that material would work. the problem is finding a glue or bonding agent that will stand those temperatures.
I've read all the comments all over this great website, and ordered the hi-temp aluminum faced fiber backed insulation from JC Whitney. When it arrived I was disappointed to find the backing material was not non-flammable. I gave it a Bernz-o-Matic torch test on the aluminum side from a distance of 6" from the end of the flame. The aluminum is thinner than heavy duty Reynolds Wrap, and burned away in a few seconds. The fiber backing (about 1/2 inch) started to burn immediatly. It must be treated with a flame retardant as the flame did not spread, but it did burn. I was nervous about the area close to the headers burning away. My solution was to get a roll of 2" paper backed fiberglass insulation at Home Depot, strip off the paper and 1/2" of insulation to get to a 1 1/2 " thick layer that would fit into the available space. Using 3M high temp spray adhesive, glue the insulation to the inside of the doghouse (after removing the old insulation), then glue several layers of heavy duty Reynolds Wrap aluminum foil in an overlapping pattern on top of the fiberglass insulation, pressing the layers into the shape of the inside of the doghouse. Works great ! Total time about 5 hours to complete. My doghouse inside the cab is totally room temp !! I have 8 hours of run time on this setup, and it still holding up. Improvements to this would be only 1" insulation. Hope this helps.
I have the insulation installed in my dog house. No sign of burning or discoloration. I wouldn't fret.