Re: Header experience

["David R Johnson" <johnsnd@domain.elided>]

On Jul 21,  8:29pm, Scott Fisher wrote:

> A friend of mine swears by the Jet Hot coatings and has them on several
> of his cars.  Their theory is that by retaining heat inside the exhaust
> system, the system flows better.  Hot gases do flow better than cold,
> but I have no access to before-and-after testing that shows an
> anticipated power benefit.  The other key benefit is that Jet Hot
> coatings (if you get them done inside and out) pretty well eliminate
> rusting through.  And of course they look way cool -- was it this list
> where someone referred to the BHP factor for "bystander horse power"?
>
> Fiberglass tape, now, I have direct experience with; we wrapped the
> header tubes on my EP MGB race car with the stuff.  The primary
> advantage to fiberglass tape is that if you're wrenching on something
> down near the header and your hand brushes against it, you think "hmmm,
> that's a little warm" instead of shrieking and leaving part of your skin
> sizzling against the header tube.

I have used Jet-Hot coating on one of my cars, and it seems to work very well.
 I can't vouch for the performance because that would require a back-to-back
dyno session with coated and uncoated headers.  As for the insulation
properties, the headers still get very hot (don't touch!), but the plug wires
run very close to the headers on that car and I have had none of the problems
with burned wires experienced by many with headers on the same vehicle.  The
coating is still intact and there is no rust after a year of use (including
lots of winter road salt).  I think Jet-Hot even guarantees the finish, and
will recoat for free if it fails (but check with Jet-Hot to confirm this as
fact).

As for the tape, I have not used it but a friend did.  This was on a car with
very little clearance between the plugs and headers, and he found the extra
thickness of the tape a problem.  I have also heard reports that if the tape
gets soaked in oil or similar fluids (what, an oil leak on an Alfa ;-), then
the heat from the header can cause it to ignite in a rather spectacular way,
causing a serious or terminal engine fire.  One person experimented with some
tape soaked in oil wrapped around a pipe heated with a propane torch, and found
that it was possible to ignite it without a direct flame.  The oil apparently
becomes very flammable when distributed over the cloth surface of the tape
(like flour explosions in bakeries, I presume).  Admittedly this was not a very
scientific experiment, but it would scare me away from the tape.

Be careful out there!

Dave J.
1982 GTV-6

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