Exhaust Tape

Scott

If the tape wrapping is any good it will be made from ceramic or aluminium
oxide fibre with a foil on the outer surface to reduce erosion of the fibre
in service. The fibres are usually held together with a binder, so that you
can work with it without the stuff falling apart. After some service, the
binder either burns away or sets in the shape it is in, meaning that you
would normally irreparably damage the wrap by removing it after service.
How well it insulates depends on the thickness and the diameter, as well as
the so called "shot content" with ceramic fibre. Anything over 5 micron
diameter causes skin irritations (like everyone knows from fiberglass).
Under 5 microns this is reduced, but the risk of inhaling the stuff
increases.

An exhaust system can be perfectly reliable with insulation, provided it is
made from a high grade steel and has been designed with either slip joints
or bellows to compensate for the thermal expansion. I think that slip
joints are more common in aircraft designs, since the system does not have
to be absolutely airtight.

In most cases, working with a known cracked exhaust system can be a waste of
time, unless you are willing to do dye penetrant tests to locate all the
other cracks that there are bound to be, but are too small to see with the
naked eye. Ceramics do not melt at the temperatures that cause steel to
flow, hence weld contamination is a major problem.

Regards
Keith
"Scott" schrieb im Newsbeitrag
...
Thanks everybody for the replies. .

It sounds like the wrap does work but would require extra attention for
inspection of cracks. Does it stick to the pipes? Can I remove it
every annual or every other annual to inspect the exhaust pipes?

I have heard about ceramic coating the pipes. Can this be done after
they have been used for a few hundred hours? Also once they are coated,
does the ceramic interfere when repairing them, ie..welding a crack?

thanks,

Scott

"RobertR237" wrote in message Can the DIY
be applied to the inside of the pipes as well as the outside?


Bob Reed

Yes
--
Jim in NC

Don't see why it wouldn't work inside as well.
Would certainly reduce internal rust.

The pipes need to be blasted before treatment.
Any (and ALL) imperfections will show up.

Then an acetone wipe to remove finger prints, etc.

Spray on a thin layer of the ceramic "paint"
and bake at 500 degrees for an hour.

I did it in the kitchen oven - no noticible odor
other than the smell of a very hot oven!

Lastly, when cooled, burnish with fine steel wool to
clean off the outer residue, and produce a beautiful
luster. Not quite chromed looking.

There is also a black version that is a little different.
Clean and spray, then start the engine and bring the pipes
up to temp to bake it on.

Check the description in AS&S catalog.

Richard

RobertR237 wrote:

In article , Richard Lamb
writes:


I would agree that the upfront cost of the ceramic coatings are more but
would
question the long term cost differences. I believe the long term benefits
of
the ceramic coating will totally offset the costs.


Probably true if you farm it out, but the DIY bottle cost $19.95
in AS&S catalog...



Two questions on the DIY application. How does it compare to the professional
application which is bead blasted before application and baked on? Can the DIY
be applied to the inside of the pipes as well as the outside?

Bob Reed
www.kisbuild.r-a-reed-assoc.com (KIS Builders Site)
KIS Cruiser in progress...Slow but steady progress....

"Ladies and Gentlemen, take my advice,
pull down your pants and Slide on the Ice!"
(M.A.S.H. Sidney Freedman)

If I fabricate with stainless I'll probably wrap with the ceramic tape.
If I build from mild steel I will probably go with the coating.

Bruce A. Frank

RobertR237 wrote:
In article , "Bruce A. Frank"
writes:


The wrap works to reduce heat in the engine compartment but tends to
accelerate the deterioration of exhaust systems because the heat is held
in the pipes. Also the ceramic cloth holds moisture when the engine
isn't running and collects all oil spills to smoke like crazy when the
engine is running. The wrap is available less expensively from outlets
such as J.C. Whittney. Bob's suggestion of ceramic coating is a good.
The coating is usually both internal and external, protects the steel of
the exhaust system and smoothes the flow of exhaust gasses. It also
reduces under cowl temps but I do not know how it compares to the wrap.
The draw back is that the ceramic coating costs a good bit more than the
wrap.




I would agree that the upfront cost of the ceramic coatings are more but would
question the long term cost differences. I believe the long term benefits of
the ceramic coating will totally offset the costs.

Bob Reed
www.kisbuild.r-a-reed-assoc.com (KIS Builders Site)
KIS Cruiser in progress...Slow but steady progress....

"Ladies and Gentlemen, take my advice,
pull down your pants and Slide on the Ice!"
(M.A.S.H. Sidney Freedman)

If I might throw $0.02 in on this. In researching heat protection I ran
across this article which describes why you do not want to use wraps vs.
ceramic coatings.
http://www.centuryperformance.com/heatwraps.asp
Cheers,
Hal Davey

What the sceptic doesn't tell you (or know ??) is that in Europe many of the
high quality cars have air gap insulated fabricated (tubular) manifolds (not
the cast iron stuff like the US manufacturers use). It is possible to make
the components durable by good design and using good quality materials. But
you can't take junk (mild steel) and a crap design that cannot deal with
uneven thermal expansion and then wave some magic wand to make it super
durable.

Considering how expensive aircraft equipment generally is, there is no
reason why the best materials shouldn't be used with a fair number of
bellows couplings at about $15 a throw to produce a system that it totally
insensitive to thermal expansion and oxidation effects. Then wrap the whole
caboodle in an insulating wrap to protect all the other heat sensitive stuff
in the engine compartment and forget about it.

Keith


"Hal Davey" schrieb im Newsbeitrag
t...
If I might throw $0.02 in on this. In researching heat protection I ran
across this article which describes why you do not want to use wraps vs.
ceramic coatings.
http://www.centuryperformance.com/heatwraps.asp
Cheers,
Hal Davey

Uh, Keith, did you actually read the stuff at the site that
Hal pointed out?

They are not talking about cast iron junk.



Keith Olivier wrote:

What the sceptic doesn't tell you (or know ??) is that in Europe many of the
high quality cars have air gap insulated fabricated (tubular) manifolds (not
the cast iron stuff like the US manufacturers use). It is possible to make
the components durable by good design and using good quality materials. But
you can't take junk (mild steel) and a crap design that cannot deal with
uneven thermal expansion and then wave some magic wand to make it super
durable.

Considering how expensive aircraft equipment generally is, there is no
reason why the best materials shouldn't be used with a fair number of
bellows couplings at about $15 a throw to produce a system that it totally
insensitive to thermal expansion and oxidation effects. Then wrap the whole
caboodle in an insulating wrap to protect all the other heat sensitive stuff
in the engine compartment and forget about it.

Keith

"Hal Davey" schrieb im Newsbeitrag
t...
If I might throw $0.02 in on this. In researching heat protection I ran
across this article which describes why you do not want to use wraps vs.
ceramic coatings.
http://www.centuryperformance.com/heatwraps.asp
Cheers,
Hal Davey

On Wed, 09 Jul 2003 16:30:47 GMT, "Hal Davey"
wrote:

If I might throw $0.02 in on this. In researching heat protection I ran
across this article which describes why you do not want to use wraps vs.
ceramic coatings.
http://www.centuryperformance.com/heatwraps.asp


I agree with part of what he says, but there is no such thing as the
temperature amplification he talks about.

That the temperatures may be higher than the measured EGT is quite
possible, but the actual temp can not exceed the input temperature,
which could conceivably be too high for the header material.

Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)



Cheers,
Hal Davey

Roger

Frequently we would like to make the tubes thin, but one has the problem
that the material thinning on the outer radii is too high. To get a robust
design, one wants the tubes to be as flexible as possible, but the minimum
wall thickness is dictated by what we can bend successfully. The stiffer
the tubes are, the higher are the loads that are created by thermal
expansion. The thicker the wall, the bigger the temperature gradient in the
steel itself and the higher the thermal inertia (resulting in uneven
heating and cooling).

I can assure you that the only reason why the manifolds in the EU are
fabricated is for weight reduction and survival at gas temperatures over 950
degrees C. In racing circles, the highest cost is for labor and generally
the highest quality materials are used (Inconel) and they frequently can be
very durable indeed. The cost calculation is very different when losing a
race could result in losses of 100 000's of Dollars. The turnaround time
for replacements is also a pretty big issue since the components are
generally hand made.

If you want to see an example of a air gap insulated manifold, you should
take a look under the hood of a current E class Benz.

Keith
"Roger Halstead" schrieb im Newsbeitrag
news
There are a lot of , for lack of a better term, "old wives tales" that
develop in these trades.

They are talking headers. All performance headers I've see on race
cars were developed for high performance and made as light as
possible. Not a combination that would indicate a long life product.

Show cars OTOH may have massive, chrome, or ceramic coated headers.
Sure they are tuned for performance, or most are, but they weren't
built with weight savings in mind.

Back when I was playing around with street rods...a very long time
ago... we paid a lot of money for the big name headers which lasted
about as long as the packing in a steel pack muffler which was a
fraction of a glass pack.

When I got to that temperature amplification part the site lost a lot
of credibility.

As to the wrap, or dual tube air gap insulated I would think a
manifold and exhaust ceramic coated within an air gap insulated tube,
or the ceramic coated tube *inside* the wrap would be the way to go.

I can see where a dual tube, air gap insulated exhaust could scavenge
the air through the gap cooling the tube (much like an augmenter) and
pretty much keeping the engine compartment cool...or as cool as you
can expect with an air cooled engine.

3 questions,

Is "DIY" a chemical cleaner and what does it stand for?

How does the bead blasting work inside the header pipe? I would think the
inner corners would not be properly prepared for the ceramic coating, or is
the media inserted then vibrated? I would think the coating process would be
more of a need of a chemical clean and etch (pickling process) than a
mechanical one.

why not just buy a new tuned coated or exotic metal header for the engine,
pretty cheap compared to the money invested into the motor, imho.

Pat Thronson