There is always a price to be paid when a change from the engineered
design is made.And trying to deal with heat is a biggie! For exhaust
systems in cars I'm not sure there is a good alternative to letting it
all hang out in the breeze to utilize the moving air to carry away the
heat.It's a bit like the problem that NASA had when trying to solve the
re-entry problem of over heating the skin of the early space vehicles
and the space shuttle. In the case they solved it by applying an
ablative material on the nose and leading edges of things to dissipate
the heat. Ablative materials are sacrificial materials that burn away
and are not retained.They absorb heat, gasify then carry the heat with
them as the gas dissipates.

With header pipes, collectors, and exhaust pipes they get really hot - I
have seen them red hot at night on a hard run - and anything that keeps
the heat in is going to help destroy them - shortens the life
considerable. And any moisture that wicks it's way in - that just speeds
the destruction.

John Rodgers
88 GL Driver

Chris S wrote:
> Well, I bought some exhaust wrap, but not to wrap my exhaust, mind you.  I
> needed to shield some not-so-hot parts from the hotter-than-H parts.  I've
> read reports of exhaust headers rusting very quickly after application of
> fiberglass exhaust wrap.  Why?  The stuff soaks up water like a sponge and
> holds it.  Yes, I just tested it.  So you can imagine what happens over
> night when the dew point drops, no?  Yes.  The doom of all bare steel,
> moisture, gets sucked up against the headers.
>
> It seems that sealing it against moisture would be the correct way to apply
> the stuff, which can be done by applying the appropriate and expensive
> sealant.
>
> No problem for stainless steel headers, right?  Maybe not so, since the wrap
> causes the temperature of the headers go up, which may be too much of heat
> stress for the metal to handle.  And that might be another DEEP, DARK secret
> in itself.
>
> Chris S.
>
>
>