Heat Shield polish

[talon749]

I was wondering if anyone had advice on polishing a heat shield up on the exhaust manifold, until I buy headers

 

[leet]

3M Roloc abrasive pads. You'll need an air powered die grinder of some sort, but they work superbly.

 

[arash15]

3M Roloc abrasive pads. You'll need an air powered die grinder of some sort, but they work superbly.

nice. but you could use a high speed drill too. pretty ghetto. need more elbow greese but you'll get some nice results

 

[leet]

Yeah you could use a drill, but the finish will not be as good (due to lower RPM). Typical mini die grinder spins at close to 30K RPM @ 90PSI.

 

[talon749]

3M Roloc abrasive pads. You'll need an air powered die grinder of some sort, but they work superbly.

where dose one get these 3M pads? and how much do they cost?

 

[BLockDsm]

You can look in the auto-motive section or your local hard ware store should have them in stock

 

[Defiant]

Do you realize you want to polish the underside, and paint the visible, top portion flat black? That's if you want it to shield heat instead of impress the clueless when the hood's up.

 

[talon749]

ha ha yeah, but dose anyone know if i can get a high temperature clear coat or some sort? VHT brake paint works great to paint the heat shield...just cracks a little around the bolts, but dose anyone know of a high temperature clear coat?

 

[boostedinaz]

Do you realize you want to polish the underside, and paint the visible, top portion flat black? That's if you want it to shield heat instead of impress the clueless when the hood's up.

Thats what I did with mine. I just used regualr spary paint and just hit it with maybe 10 coats and it still looks just like this even after driving it alot.

 

[Attack Eagle]

nice.

I jsut "polished" mine (more brightening than polish) with a generic scotchbrite type pad, some elbow grease, water adn some CLR kitchen cleaner.

It isn't perfect but it looks good in person.

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One thing I noticed, as long as you don't get water on it it stays pretty shiny unlike the valve cover that turned gray.

 

[12sec92Tsi]

Back when I had my 2gnt I "polished" the heat shield with a can of Mother's aluminum polish that I got at auto zone. I work great and after about 10 times of polishing it you could see yourself in it. I also use it on my shaved valve cover that came with the car when I got it to keep it shining and clean. This car didn't have a heat shield when I got it but I do plan on getting one soon and polishing the underside and painting the outside as Defiant stated. Pics of the valve cover are in my gallery, the polish worked great for me.

 

[jpape]

Flat Black Top, somewhat polished underside for me!

 

[Attack Eagle]

you guys are aware that painting the top black helps it to radiate MORE heat into the engine bay, not less right?

Afraid your fans will get cold?

 

[Defiant]

you guys are aware that painting the top black helps it to radiate MORE heat into the engine bay, not less right?

Afraid your fans will get cold?

Check your math.

 

[redfury]

I actually didn't realize it would be a better idea to polish the underside of the heat shield, I painted the inside/outside of mine.

 

[Attack Eagle]

Check your math.

Defiant you know how the blackbody effect works.

IF the temperature is greater than the surrounding area then black will radiate the most heat. I think a heat sheild would qualify as hotter than the surrounding air. If it were cooler than the surrounding air then it would absorb the most heat of any color.

IS it going to be a huge difference? I don't know and i am not going to do something wrong just so I can find out. Runnign with out one was a huge difference as compared to a nice shiney one. and i noted a little difference on the hottest days between before cleaning and after, but not a huge thing.

 

[PieEyedPiper]

My math tells me that flat black would retain/absorb heat more effectively than a polished heat shield would.

Q. Why is a black car hotter than a white car sitting side by side in the sun?
A. The white car reflects sunlight and heat energy out and off of the paint more effectively than the black car.

Q. Where would the heat and light energy go?
A. The surrounding enviroment. And in the case of a manifold heatshield - the engine bay.

 

[speedy13]

But there's no light under the hood?Does it really matter if the cover is polished or not?does anybody have any real proof or a study on this?and if they did,they got to much free time!!.suppusedly the heat shield cools down as air passes thru it right?and it dsipitates the heat from the exhaust/turbo manifold and surrounding areas to the heatshield while stopped at a light right?so what would be the difference if the piece of tin is painted or not?

I recall I checked the engine temp diffrence before and after i installed a header on my 2gnt last year and it was only like 3-5 deegrees difference.Now i am aware that their is greater heat and friction on a turbo mannifold then a NA one but i still don't think it would make a noticable difference.

 

[Attack Eagle]

My math tells me that flat black would retain/absorb heat and radiate it more effectively than a polished heat shield would.

Q. Why is a black car hotter than a white car sitting side by side in the sun?
A. wrong.

The black car radiates the heat more effectively than the white car so it feels hotter.

Q. Where would the heat and light energy go?
A. The surrounding enviroment. And in the case of a manifold heatshield - the engine bay.

The idea behinds a heat shield is to reflect heat back towards the source, not paint it black to effectively radiate the heat out and away and cool the item.

That is a heat sink or radiator's job.

 

[PieEyedPiper]

ehh..
I'm still with defiant on this one. But to each their own.

 

[shpyder]

The idea behinds a heat shield is to reflect heat back towards the source, not paint it black to effectively radiate the heat out and away and cool the item.
.

Exactly, so its meant to contain the heat and prevent it from going to the surroundings, in this case the rest of the engine bay. So, painting it black would mean that the shield just absorbs the heat better than silver, and therefore contains heat better than silver. Is my logic correct?

 

[Attack Eagle]

no b/c you are talking about taking a reflector and painting it black...

would your headlights reflect as much light from the bulb if they were painted black? Would the backside of the housing stay cooler or warm up?

they would absorb most of the light, nad would be warmer on the back side than if they were shiny...

painting a heat shield effectively transforms it from reflector to radiator. Why cool the exhaust manifold at the cost of heating the radiator and the rest of the engine bay?

Besdies you don't want to cool the manifold, it reduces thermal efficiency.


For those who don't understand that black is the best color for radiating heat,not absorbing it, think about what color is used on the bottom of the space shuttle.

 

[ISUJakey]

When you are ready for the actual polishing, I would recommend nothing other than White Diamond polish. It continues to impress me as it has taken down everything I have ever thrown at it.

 

[napkinthief]

actually, black cars heat up cuz black is the color when there is least light present, white is all light colors being reflected. I dont think heat has anything to do with colors, just light is captured by the black and turns into heat as the energy is released.

 

[Attack Eagle]

black absorbs (and radiates) all wavelengths unlike other colors that reflect at least some.
Black is the absence of radiated or direct light, but not the absence of pigment.