Header coatings

[chevynut]

When I was at SEMA in early November I talked to a rep from Jet Hot about coating my headers. I spent quite a while with him trying to understand the different coatings, colors, and limitations. Honestly, I was not impressed with what he had to say. I was wanting a shiny silver coating but when I told him I had a 502 he said it wouldn't work and would fail and burn off. He said if I wanted silver I would have to go with their 2-step coating which was rough and not shiny. Apparently their shiny coatings are only good for something around 1300F. The 2-step coating puts some other layer under the final coat, and that other layer goes on rough. He didn't give me a warm fuzzy feeling about their coating working well in my application but he said they'd re-coat them once for free. I don't want something I'll have to re-do

So I'm looking at alternatives. Also at SEMA I came across the Cerakote booth and talked to them about their clear-coat as well as their header coatings. I had heard about them in reference to coatings for guns, but never for clear-coating or high temp applications. I just ordered their MC-160 clear-coat for my suspension parts after considering all the other options I could find.

http://www.cerakotehightemp.com/

The nice thing about Cerakote is they have both air-cure and oven-cure coatings. You can actually buy the air-cure material and apply it yourself. It's supposed to be really tough, but again it's only good for 1300F. It looks like you have to put down an insulating layer under the color coat to get a higher temperature rating, but their website is a little confusing. Here's a link to their oven-cure coatings that says they're good for 1800F, but the Glacier Chrome link says it's good for 1300F.

The good thing is I found out there's an applicator in Denver. It looks like Pinkees Rod Shop has used them.

Anyone have any experience with Cerakote or Jet Hot to share? Any other recommendations?

[Rick_L]

Your 502 is not going to have EGTs of 1300 degrees F. unless you screw up the tune badly. In which case it won't run well and you'll possibly be seeing internal engine damage too.

That said, if Jet Hot downplays their stuff, why mess with them?

I've seen a lot of posts on various sites complaining about Jet Hot ever since they merged with HPC.

I'm going with a local company (Polydyn) just because they are local (shipping headers and pipes adds a lot to the expense). They've been in the business a long time. I can't say they are any better or worse than anyone else. I think header coating quality is like a paint job, it's whether the prep is done right or not. Anyone can do that right - or wrong.

[Bitchin'57]

That guy was a moron. The size of the engine means nothing. I had built a 528" blown Hemi, and I got the headers coated in bright silver by a local powder coating shop. Street drove it for 5 years and it never burned off or discolored.

[chevynut]

Yeah, I didn't understand why the engine size mattered either, and I challenged him on that. But he didn't seem to back down. I don't know if he was just trying to get me to go with the more expensive coating or what.

I think I'm going to seriously consider the Cerakote since they have an applicator that's kinda local to me. At least if there's a problem I wouldn't have to ship my headers back and forth multiple times.

[JT56]

CN, been down this road...let me recap...bought a new set of Stainless Works and had them sent to Jet Hot for the Polished Silver coating. I was running a 450hp motor. They seemed to be ok, but were fading some by the exhaust. When I changed the heads I sent them back in for warranty. Came back nice and shiny but again didn't last long. I sent them in again when I changed the motor. Now this motor was dyno'd at 598 hp and shipped to me. So this wasn't a new motor that didn't have a tune in it. In a short time this coating again failed. Remind you the plugs are fat! No lean condition and timing is around 36 degrees! Car never ran hot either. When I called they told me they couldn't keep doing this same coating under warranty that I would need to upgrade. I did and really like the Platinum color. Well they fade at the same place again. I tried one more time after the ProCharger and they still do the same thing! My AFR is my car from idle to WOT with Boost is 10 WOT and 14.2 idle...They are really nice people but I just dont understand why it doesn't stay on? I have ask if the stainless material has something to do with it???

[Rick_L]

Why would you want to coat stainless headers? Seems redundant.

Retarded timing and rich mixtures are what increases EGTs. The excess fuel burns in the pipes because being retarded the burn isn't done yet.

[chevynut]

Header coatings are also used to keep the heat in the pipes and reduce under-hood temperatures, not just for cosmetic reasons. I don't know if it's worth coating the inside of the headers or not. Jet Hot used to use that as a selling point, but the guy at SEMA really played it down and said it would go away anyhow. He's not a very good salesman. ;)

Cerakote offers an "insulator" coating for the inside of headers and exhaust pipes. I don't know how well it works but it might keep stainless or chromed headers from turning blue.

[Rick_L]

Header coatings are also used to keep the heat in the pipes and reduce under-hood temperatures, not just for cosmetic reasons. I don't know if it's worth coating the inside of the headers or not.

And the beat goes on about coatings, mostly bad but they are obviously still on the market and people buy them. Coatings are still better than paint.

The trend to stainless headers is spurred from a performance standpoint because the inside of the header tubes don't rust. Coatings don't generally do that. Tell me how you can get a coating applied fully and evenly in the middle length of a 25-30" tube. Every set of race car headers I've ever had rusted on the inside, right away. A ritual was to tap the header collector on the shop floor before reinstalling if they had set over a few days - a bunch of particles would drop out. It had to affect performance. I guess the only real deal there was that the inside was rusted and had a rougher finish right after the first use. Probably before you figured out what the engine liked for fuel and timing.

The stainless stuff I see on race cars is not coated or polished, and there is some discoloration but it never changes. Not quite the same as chrome. One difference is the chrome will be polished. Chrome headers are a PITA, and I've never considered them since my one experience 35 years ago. I had 2nd degree burns on my arms constantly just from doing routine engine maintenance like checking lash and valve springs. This did not happen with plain steel headers that were painted.

[chevynut]

http://www.hotrod.com/how-to/engine/high-tech-ceramic-coatings/

"Jet-Hot points out that realizing the full anti-corrosion benefits of header coatings requires coating the headers on their inside as well as outside surfaces. Not all competitors coat the inside surfaces, which isn’t good because exhaust gases themselves contain corrosive compounds. If the inside isn’t coated, the header eventually rusts through from the inside out. Coating only the outside can also cause another problem: Mild steel tubing fatigues when it gets too hot. An outer-only thermal barrier blocks the heat from radiating through the exterior metal surface, while the lack of an inner barrier exposes the metal to added “trapped” heat. In a scenario reminiscent of that caused by the dreaded “curse of the mummified headers” (outer cloth wraps used by some racers), the result can be literal disintegration of the mild-steel tubing."

"Header surface temperatures were a whole ’nother story, however. We checked header-tube surface temperatures both at idle and—in an attempt to simulate part-throttle, sustained cruise conditions—at 3,200 rpm with a light, 60 lb-ft load applied to the dyno’s water-brake. In both cases, the coated headers cut the painted set’s surface temperatures by over 50 percent. In a real car, this would significantly reduce both coolant and underhood temperatures. In the dyno-cell, we could actually touch the coated headers with our bare hands within 5-7 minutes after engine shut-down!"

[Rick_L]

exhaust gases themselves contain corrosive compounds

Known to most as water.

I always figured that the higher temps allowed more water vapor after shutdown. That and the higher temperature of the tubing allowed it to rust faster.

[JT56]

Why would you want to coat stainless headers? Seems redundant.

Retarded timing and rich mixtures are what increases EGTs. The excess fuel burns in the pipes because being retarded the burn isn't done yet.

Stainless Headers were not polished and looked pretty ugly.http://www.trifivechevys.com/attachment.php?attachmentid=5385&stc=1http://www.trifivechevys.com/attachment.php?attachmentid=5384&stc=1

I agree excess fuel can burn in the exhaust, but a lean condition can make headers glow!

[Danny57]

DIY Ceramic Coating my way.

I recently upgraded my headers to Long Tube Dougs, because the existing Flowtechs hung down about 4 1/2 inches too low & dragged often w/stock spindles on my 57 150 2dr w/378 sbc. I contacted a few of the commercial ceramic coaters including Jet Hot. They said they only spray what they could reach from the ends for the inside & I thought the price (380) was quite high plus shipping both ways.

With a short internet search, I found Cerakote & watched their YouTube application video. I was concerned about thoroughly coating the inside. I called cerakote technical & was told how to "flow coat" the inside. That consisted of taping up one end of the headers & pouring cerakote in then taping the other end & tilting/turning the headers back & forth coating the insides. According to their estimates 4 oz. should be enough. I bought a pint (16oz) to be safe, I didn't want shiny so I chose titanium finish cost was $70 plus shipping. Shiny takes a machine like a big "vibratory tumbler."

Of course, they say to blast with aluminum oxide or similar (not glass beads) to get a good "tooth" prior to coating. Inside the tubes presented a challenge to blast, but I made an 12" extension for my gun with a thin steel tube (bendable) for my blast cabinet. I felt like I made a pretty good effort & washed in & out with acetone.

As described before, I "flow coated" the inside & saved the excess poured off from the inside in a separate container. For the outside, they recommend a HVLP with .8 tip, I only had a 1.0 for my Devilbiss touch-up gun so that is what I used. Harbor Freight has a touch-up gun with a .8 tip for $35.99 (SKU 46719). It is easy to spray, I had a few runs & let it dry 24 hr. to sand & touch up. I then allowed 5 days for air cure. By the way, their tech told me the heat & air coat formulas are the same.

I've only run the engine about 4 hours since finished, temp between 160 & 190 & they still look great. Of course long term use is the real test.

I'm pretty stubborn about DIY & so far, I'm satisfied with my effort & plan to coat the old headers outside only with the left over coating then offer them for sale at Pate Swap meet in April.
That's my 2 cents
Danny

[chevynut]

Thanks Danny. What you did is what I concluded after reading the Cerakote information and visiting Applied Plastics in Denver to discuss their coatings. I just finished trying the Cerakote Clear on my polished suspension parts and it wasn't too bad to apply. Since there's no heating required on the header coatings, I concluded that you can do it yourself too. Applied Plastics told me this stuff can be put on anything you want, even plastic parts. To me it looks like a urethane basecoat without clear over it....a flat finish but it's supposed to be very tough, hard, and heat resistant to 2000F once it cures.

I have kinda put this on the back burner for now since I have so much going on. Since all my exhaust is polished stainless, I'm still leaning toward their polished silver which I can't do myself. It's $290 to have them do it. The downside is the shiny coating is only good for 1300-1500F....which may not even be a problem. They can put an "insulating" layer under it that adds cost but supposedly raises the temp rating 200F or so.

In talking to them I found out they also apply the Cerakote Clear and he estimated $500 to do all my suspension parts. I had already spent almost $150 on materials and $30 on a 0.8mm spraygun I probably didn't need so I decided to do it myself. So far so good.

Thanks for the feedback.

[55mike]

I'm another guy who has not been very happy with coatings on headers. Like Rick said, coating is better than paint.. but.. for me, the shiny goes away to a dull grey from the heads down about 2'. I have Hooker SuperComp 2112's with Jet Hot right now. Years ago, I ran Patriot's with their coating and the finish was also crappy within a few months. I keep my engine very clean, and the tune is OK.