Just thought I’d share this - got a ramair crossover to install and decided to try an experiment:
Wrapped with corrugated aluminum heat shielding and metal zip ties. Inside the bottom half I tucked in a layer of Pyrogel XTE high temp insulation to provide extra shielding from the exhaust manifold.
The Pyrogel is basically mineral wool with embedded silica aerogel microbeads (yes, the NASA developed stuff) good to 1200F, which should handle anything under the engine bay including the catalyst. 5mm is roughly the equivalent of the 3/8” (9mm) black foam pipe insulation in effectiveness (about R1.2). Found someone selling cuts of it on ebay. Seems to be the real stuff. Reasonably affordable at least in smaller pieces.
Unfortunately I don’t have any temperature data for comparison, but if this works I’m considering making an add-on shield to stack on the exhaust manifold and/or cat. (Probably with stainless shielding riveted together which will handle higher heat instead than aluminum at the expense of being a slightly less effective reflective surface)
Caveats working with this stuff - it is extremely dusty when cutting, so wear at least an N95 and use gloves because it will dessicate your skin if you get it on you and unspeakable things to your lungs if you breathe the dust. I tried to make sure it is completely contained inside the aluminum shield. Hopefully it doesn’t dust all over my engine bay or into my cabin air vents…