[Healeys] [Healeys) 100-4 Heat Shield with Headers

[Bob Spidell]

Yeah, I've heard that too (usually from the 'hot rod guys'). I wrapped 
my BJ8's downpipes about 8yrs/40K or so miles ago, and when I rebuilt 
the engine 3 years ago I checked them; no evidence of any degradation.

My thinking: Rust is, of course, oxidation. Water does not rust metal, 
it facilitates oxidation by providing a medium for electron transfer 
between the oxygen in the air and the iron in steel. Manifolds, 
downpipes and headers get hot enough that the water in the exhaust 
gasses stays vaporized (until shutdown). It cools and pools in the pipes 
and mufflers, which rust from the inside out. What's unclear to me is 
how wrap, or ceramic coating, which should theoretically keep more heat 
in the system affects the steel. I would expect some embrittlement from 
the heat cycling, but haven't seen it (yet).

FWIW, I had my exhaust manifold ceramic coated (Jet Hot) and downpipes 
wrapped, and didn't notice much, if any cooler running (I was 
disappointed). The side vents seem like they would help but, curiously, 
my BJ8 and BN2/100M behave exactly the same WRT engine temps. I expected 
the louvered bonnet to help prevent overheating, esp. at idle but ... nope.

Bob


On 9/14/2020 7:56 AM, Michael Oritt wrote:
> Common wisdom isthatexhaust wrapped to rusting out.  it took 15 years 
> to happen on my car and I am not convinced even now that the wrap 
> promoted or hastened the process.
>
> Best--Michael Oritt
>
> On Mon, Sep 14, 2020, 10:16 AM Charles Schott via Healeys 
> <healeys at autox.team.net <mailto:healeys at autox.team.net>> wrote:
>
>     Bob,
>
>     I did wrap the headers but I'm a belt and suspenders type of guy.
>     Never intended it to be that much work, but once I started, I
>     wasn't going to quit on it. I'm also going to install the
>     triangular vents into the front wings which should help expel the
>     heat. And I built a false floor on the driver's side to provide an
>     air space that will act as an insulator. It gets hot in Florida.
>
>     Regards,
>
>     Charlie
>
>     ------------------------------------------------------------------------
>     *From: *"Bob Spidell via Healeys" <healeys at autox.team.net
>     <mailto:healeys at autox.team.net>>
>     *To: *healeys at autox.team.net <mailto:healeys at autox.team.net>
>     *Sent: *Sunday, September 13, 2020 11:31:10 PM
>     *Subject: *Re: [Healeys] [Healeys) 100-4 Heat Shield with Headers
>
>     Well done, but I gotta ask, why not just wrap the headers?
>
>
>     On 9/13/2020 8:42 PM, Ray Juncal via Healeys wrote:
>
>         Wow, you had fun making that. Nice work.
>
>         On Sunday, September 13, 2020, 3:38:08 PM PDT, Charles Schott
>         via Healeys <healeys at autox.team.net>
>         <mailto:healeys at autox.team.net> wrote:
>
>
>         After one more modification, the fifth one, to eliminate
>         interference with the vacuum hose fitting, I can continue with
>         mounting the carbs. Some, including me, might say it's been
>         over engineered.
>
>         Regards,
>
>         Charlie
>

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