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Randy writes: "I wrapped my entire exhaust system with hot rod exhaust wrap."
Bad idea for turbocharged engines. The attached photos show a crossover balance tube that was wrapped with exhaust tape. The tube was 0.045 wall 321 stainless. Note where heat caused the tube to bulge in a helical pattern, matching the wrap of the tape. Had I not caught this during a routine engine inspection, when it failed it most likely would have resulted in an in-flight engine fire.
How do you spot an exhaust crack with a wrapped system? Wait for it to fall off?
Ceramic coatings are also a bad idea on turbocharged engines upstream of the turbocharger(s). The longevity of the exhaust system is a function of the temperature of the tube. The tube temperature is a function of the differential temperatures and the relative heat transfer between the gas on the inside and the inside wall and the gas on the outside and the outside wall. Insulation has TWO elements. One is the ability of heat to travel through the material and the other is the ability for heat to cross the interface between the materials. Adding a thin coating may not add much bulk insulation but it does add the insulation provided by the interface. Just like dressing in layers keeps you warm in winter, dressing your exhaust pipe with a layer will keep it hotter, and hotter is bad.
Regards
Brent Regan
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