Dr_KarlB

So then the external coating is just a poor wrap ? It allows the exhaust gases to stay hot, but not so hot that the headers reach super high temperatures and disintegrate ?
Surely by this, coating the inside would be the best wouldnt it ? Stop the hot exhaust from transfering energy to the header materials by using a thermal insulating barrier inside ?

tkerrmd

so what is coated inside or out?? If inside how do you know no turbo damage?

markski

dont coat the inside casue it will damage ur turbo and even get into ur engine... actually check when u get them back caause mine were not supposed to be and the company did.... I ad to wait 4 more weeks.... MAKE IT VERY CLEAR to the company... they r not used to not doing the insides.....
Kevin does a great port and coat job....

Kevin

Folks, I can give you a list of known people who have had there headers coated and when they receive them the outside and inside are coated... They have to have them redone.. So whoever does your coating... Put it in writing not to coat the inside... The ceramic does not get enough adhesion to the stainless because there is no physical way to burnish the metal.. When heated and cooled, the ceramic WILL flake, chip, dislodge and destroy your turbine wheels.. Not good in terms of perfromance, and the wallet..

gunther1

I had Jet-Hot do mine and wrote a formal note in my quote request and when I shipped them I also attached a card to each header to make sure there was no misuderstanding. Also whoever you have do the job make sure you clean the inside of the header prior to installation. This is to make sure that none of the abrasive used to prep the header for the coating is left insde the header tube. I used compressed air to start and hot soapy water and bottle brush to really go at it. I then dried the inside out with rags and compressed air. Just my 2 cents.

sharkster

Seriously don't coat on the inside. It's just not worth the "risk". If you love your turbos (Kevin is biased since he makes them all day long lol) then why bother? I've got three sets of used headers with coatings that have peeled on the outside. Jet Hot and other places. Now imagine that stuff was on the inside and then it goes through your turbos... Not good.

Gary (Fl)

Okay, now I'm confused based on everybody saying NOT to coat the inside of the headers....

If the heat is radiated through the headers inside to out, then just coating the outside is no different than wrapping the outside. It just provides a way to keep heat in that has already been absorbed by the uncoated metal inside the header... How is coating just the outside any different than wrapping?

I can see why you don't want to coat the inside based on Kevin's and Alex's comments.. But if the heat is generated inside out, the only way that Bob's explanation works above is to coat the inside so that the metal does not absorb all the heat in the first place. Am I missing something?

ebaker

The coating on the outside reduces heat radiation by the headers. Wrap probably does a better job but the wrap leads to hot spots that promote cracking. The wrap also may hold water if you drive in the rain. Both will help keep the heat from cooking all the underhood rubber and plastic parts.

Garey Cooper

I have the stock ported headers with the Jet-Hot external only coating. After the porting I had the headers extrude honed and they came out very nicely. I did order the high-temperature coating in black and didn't go with any fancy colors or bother with the lower temperature rated coating as these are 'Turbo cars that generate very high temperatures at the exhaust. In addition I have Kevin's Stage 1 hybrid turbo's with the coated hot side.

Don't coat the interior for the reasons stated above, it probably will flake and float some kind of detritus through your turbo's and motor. And, this is not a good thing......

http://www.jet-hot.com/Pages/coatings.html

Craig.

My headers have Tech Line Turbo X ceramic coating on the OUTSIDE only. Xtreme Performance Heat Coatings in Camarillo, CA did the work: http://www.xtremeperformanceheatcoatings.com/ .

Craig

Porscha

Flaking coating of the headers internally will only affect the turbo. It will not get in the engine as suggested. Even so, still not a good thing for the turbos, CAT's etc. Just my $.02.

Alan C.

I read the link and there aer some errors. If anyone thinks the header tubes will approach the melting point of 304 then you are sadly mistaken. That temperature would be in the realm of 2900F, white hot. The note on 410, that alloy isn't used in any auto header allpication I know of.

Someone got it right when they mentioned water retention. If the water has any salts in it then they will attack the header material.

Oxidation is a fact. As noted carbon steel is poor in this respect. However, on a 304/321 type grade the oxide formed is very stable. After numerous cycles the material will suffer weight loss but in the real world the system won't fail do to this item.

Failures in the weld areas are due to IG corrosion. Contrary to what some manufacturers will tell you the thickness of their product will not solve the IGA problem. You need a product such as 321, Ti stabilized, to solve that problem. If the vendor isn't using 321 ask him why not.