[Healeys] exhaust manifold tape

[Bob Spidell]

I'm using tape on the downpipes of my BJ8. The tape works well at keeping heat in, no question. My car's exhaust is pistol hot at the tail pipes (that's heat that isn't being dissipated in the engine bay). I believe the engine runs a bit cooler for it. 

I posed this question to the List and some said the tape traps moisture but that made no sense to me because any moisture (e.g. rain) on hot exhaust parts get evaporated immediately (plus, I sprayed high-temp silicone sealant on the tape and it appears to make it waterproof). I read an explanation in hot rod magazines that seems more logical to me: the heat retained in the manifold or pipes is more than mild steel or cast iron can endure and the parts disintegrate from the inside out (the hot rodders call the effect on headers "mummification"--probably not doing much good for my glasspack mufflers, either). The ceramic coatings--e.g. Jet-Hot--supposedly handle this problem by coating inside and out. 

I can't vouch for the ceramic coating as I haven't used it (yet), but others probably will. If you do wrap your manifold you should wrap your downpipe as well, as the gas passing from a hot to a cooler, denser region will encounter increased back pressure (or so it was explained to me by a Jet-Hot rep). 


Bob 





What is the efficacy of using exhaust manifold tape to decrease 
heat under the hood of an AH BN1? Is there a particular kind of tape 
better than others? 
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