Ceramic Coating on Heat Sheild?

[Daryl Smith]

Has anyone tried a ceramic coating on the heat shield?

A comment on the 'new header' thread got me thinking...the proximity of the heat sheild to the header, coated or not, will have it heating up and radiating heat, less so than the exhaust, but still radiating. If coated, it should not absorb/radiate as much heat, keeping the carbs/gas cooler....

For that matter, it might be worthwhile coating the intake manifold as well...on crossflow heads it is much less a problem, but with the R/G/U engines that have the exhaust and intake side by side, that heat is significant to intake temps...

Thoughts? Anyone try it yet?

Something I may try with the stroker engine.

[greydog]

Just thinking (or wondering) out loud here Daryl.
Aluminum conducts heat well so an aluminum fry pan heats quickly but cools quickly also.
A ceramic pan heats slowly but retains the heat much longer.
It may take longer but wont a jet hot coated heat shield eventually reach the same temp as a bare or plated shield? If so, it'll stay hot longer which may cause restart issues.
I had an '81 280ZX Turbo for a while. It had all sort of heat shields under the manifold, in front of the master cylinder and brake lines, etc. It had a funky sort of fan that blew air down over the center runners of the manifold and turbo that was supposed to come on at a temp or when the engine was turned off. The idea was to move air down and out the bottom rather than allowing it to rise and heat the manifold.
Point is, I don't know that a coating actually prevents heat from conducting....it may slow it and reflect some but won't it still eventually reach the same temp?
Would be interesting to do some scientific study with a thermocouple on a dyno so conditions could be controlled but, in the end, I doubt the gain would be worth the cost.
Look nice tho......
Dan

[Daryl Smith]

Dan,
Thanks for the response.
Sounds like you're talking about heat soak there. If that were the case then ceramic coated headers wouldn't work either, but they do. Ceramic coating on turbos seems to be a popular upgrade these days. Keeps heat where it should be, and away from where it shouldn't.

An insulating coating on the header side of the heat sheild, 'seems' to make sense in keeping heat away from the carbs...

I realise it may not be a 'problem' in most cases, so the 'worth it' question is mute, tho I don't see ceramic coating a heat sheild as very costly...
I thought perhaps some of the racecars may have tried it, as every little bit can help...there are likely other ways.

Just looking at ways to improve the engine with current technology.
And asking questions....

[greydog]

Yes, couldn't think of the right term.
I always wondered if the coating was used more for esthetic reasons and longevity.
It would be interesting to see.
What about 2 shields withan air gap?
Dan
..

[CSP311]

What about 2 shields withan air gap?

Just an thought from this, the stock 260z (on the European models anyway) had a heat shield over the ex manifold, but also had small heat shields that bolted to the underside of the carb (as on the carb design, the fuel bowl is an intregal part of the carb body). (not saying this woould work, just thinking...)

What about a heat reflective blanket stuck on the underside of the stock heat shield?

[notoptoy]

What about that perforated aluminum “sandwich” type of material that is used on modern cars on the exhaust and firewalls of many cars. often it’s placed between the muffler and the passenger compartment. Seems like a shield fabricated from that material would be perfect for what you’re looking for?

[JT68]

The highly reflective gold tape is pretty useful on the back side of the heat shield and can’t be seen. (looks like the stuff on spacecraft) The low cost heat shields I make are stainless and compared to plain steel or AL, SS is a terrible heat conductor. When combined with the reflective gold surface it works well. If you also added an insulation layer(like Mr. gasket 1/16" exhaust gasket material) and then another SS layer. (Rivet the three layers together) that would be extremely effective. gold reflector-SS-insulator-SS j

[Vinnyz]

The highly reflective gold tape is pretty useful on the back side of the heat shield and can’t be seen. (looks like the stuff on spacecraft) The low cost heat shields I make are stainless and compared to plain steel or AL, SS is a terrible heat conductor. When combined with the reflective gold surface it works well. If you also added an insulation layer(like Mr. gasket 1/16" exhaust gasket material) and then another SS layer. (Rivet the three layers together) that would be extremely effective. gold reflector-SS-insulator-SS j

JT's plan is golden (see what I did there? ) Super good and as thin a solution as one is going to get I feel.

[JT68]

Yep a golden idea hah! back to Daryl's original proposal, if you had a SS shield, ceramic coated it, and covered the (back side) ceramic with foil, that would probably be very effective too--foil is reflecting the heat from the header, ceramic insulates the SS, the SS fails to conduct what makes it through. Would be easier to make than the 3 layer laminate and very thin.

[GeoffM]

Knowing Daryl, he'll come up with an aerogel heatshield somehow.....