Header Rust

[Jeffrey Walker]

Pete,

Exhaust header coatings have been done for performance engines for a LONG
time.  The cheaper solution used to be to wrap them.  The theory is that the
more heat you retain in the header, the greater the exhaust will expand, the
greater the velocity of the gas out the pipe, the more scavenging there will
be in the system and therefore a slight performance boost, and incidentally
will pull the hot exhaust gases away from the exhaust valves and seats
faster.  With a tuned header, it is actually a sound theory.

I don't know how brittle it is, that is a very good question.  I believe
that they offer a warrantee on the work, so the differential expansion rates
probably add fatigue to the bond between the metal and coating, but last
long enough to outlive the warrantee.  In fact the ceramic coating is a
metallic compound, so I don't expect the expansion rates to be all that
different.

Another thing that I may look at instead of a ceramic coat is to aluminize
the header.  Aluminized headers last a long time.  My Mercedes has this.
Aluminum oxide is VERY hard and corrosion resistant once the surface is
nicely passivated.

Anyway, I'm just contemplating this and thinking aloud. I really didn't want
to go the barbeque black paint route yet if I can help it.  And I don't
think it is the down tubes coming off the head that are rusting, but the
lower section where the collector is and it goes 4 into 2 into 1 into 2. In
fact I think that the down tubes are already coated with something, perhaps
a aluminum powder coating?

Thanks,
Jeff


Date: Fri, 3 Oct 2008 10:11:57 -0400
From: "schnowz" <schnowz at localnet.com>
Subject: Re: Header Rust
To: <gpzlist at micapeak.com>
Message-ID: <000701c92561$ffcf9760$9c0e9942 at xxx>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
	reply-type=original

I have the same problem..- you can't ride in a New England winter without 
having this problem.
Questions I have for the ceramic coating is
1. How brittle is it if you want to put a jack under the header - will it 
chip?
2. The fact that it acts a insulator is not necessarily a good thing for the

exhaust valve seats??
3. The rate of expansion for cerramic and steel is different, so the longer 
the part the more of a problem this may be.

If you do it let us know how it works out..

  Pete S


> From: "Jeffrey Walker" <walkerjl at charter.net>
> Subject: Header Rust
> To: <gpzlist at micapeak.com>
> Message-ID: <00ca01c9240d$ca5c6f40$5f154dc0$@net>
> Content-Type: text/plain; charset="us-ascii"
>
> Well, here's a problem I didn't have before:  My headers are starting to 
> get
> rusty.  Not the headers coming off the cylinder head, but down below where
> they collect, and where they are exposed and get spray off the road. This 
> is
> most annoying.  I noticed it when I put a jack under there to raise the
> front wheel off the ground to get my new front tire mounted.  In the 
> desert
> where I lived before I certainly didn't notice any rust.  Now that I live 
> in
> the salty sea air (and fog) at Pismo Beach... and I'm getting rust.
>
> I'm a bit concerned about this as I really love the stock GPz exhaust.  I
> have no desire to ever go with an aftermarket pipe.
>
> So I'm contemplating having to remove the header at some point and getting
> it blasted and re-coated.  I'm thinking of aluminizing it or having it
> ceramic coated.  But unfortunately I won't have a 'winter storage season' 
> in
> which to do projects like this.  I'm riding my bike everywhere, every day
> and there is no winter down here of note.  (In eastern WA I would usually
> lay the bike up just before Thanksgiving and bring it back out sometime in
> late February, with my electric vest.)
>
> So anyway, if I do this project, I'll want to do it before the rust gets 
> any
> worse and corrodes any more metal off, and will want the bike to be out of
> commission for as little time as possible.  I have no idea what the
> turnaround time is for this kind of work.  I'm guessing a Saturday's worth
> of lazy wrench time to remove and replace the header, but I wonder how 
> fast
> the shop could get it done.
>
> What I'm contemplating is a coating like what Performance Coatings in 
> Auburn
> WA does: http://www.performancecoatings.com/index2.html  in Satin Black.
>
> Jeff