I know for a fact my OEM starter solenoid failed due to heat. The plastic was hard and brittle and the contact point of the stud was arcing as a result.

If you haven't had a problem that's awesome! I hope you never do. But on my kooks setup I felt it was necessary to wrap the header to keep the heat away from vital components (much the same way the OEM header is heat shielded..)

 

It's not a bad idea, maybe I should wrap mine there. That's a tight area, I had to bend my floorboard pinch weld out of the way of the headers, Nick told me that some cars are like mine but most aren't.

 

Of course not. You don't develop anywhere near the kind of heat on the street/drag strip that you do on a road course. If you aren't tracking your car then I don't think it should be a concern. I'd only coat them to help fight off actual heat issues....and those issues aren't popping up on the street.

The only reason to coat would be for cosmetic apperances, but personally I like the way stainless looks after they've been run.

 

Coated my Kooks headers when they are brand new. Sold them 3 years later and still looked great! lower underhood temps to boot!

-Carl

 

Here's a way to keep the heat in and retain that stainless look, without making them brittle: have them coated on the inside.

Is the word you're looking for "emit"? The word used for comparing the thermal radiating characteristics of different surfaces/materials is "emissivity".

I think you may have it backward...coated headers (no matter what the material) will retain more of the heat in the exhaust gasses. Hotter gasses have more energy and will move faster, improving scavenging performance. An added bonus: if you're still running cats, they'll operate more efficiently, too.

 

Nick at ARH told me face-to-face that it was unnecessary to coat their headers when I was down at their facility.

It may look nicer and also may lower under hood temps but that has not been an issue for me. As far as looks, with the E-Force FRC's, you can't even see or tell I have headers installed.

 

I'm on my 4th C6 Corvette. Had Kooks headers with no coating on three. I've not had a problem thus far. The last one was supercharged and over 950 rwhp so I had the headers coated on that one.

 

Did some research on this subject as part of my build. In the end, the experts said a high quality material header does not need coating.

I purchased ARH's and love em'.

 

Yes, but what does "does not need" mean, exactly?. If they're saying that a good set of stainless headers doesn't "need" coating to last a long time, well sure, they're right. But what if your goal is to keep more of the exhaust heat inside the exhaust instead of spewing it all over the engine compartment? Any kind of single-wall bare metal is going to emit a fair amount of heat, period. If you can mitigate some of that effect, and you don't mind the extra expense, then why not have the headers coated? Your under-hood components will be happier and your interior will be cooler. It's a win/win. And anyone who tells you that coating headers will lose you power is just filled with poo...

 

Stainless Steel headers hold about 200% more heat than mild steel. That's why we all want them.
ARH does not suggest you coat your headers except in extreme situations where you might live in the Middle East where temps can get to 120deg in the shade. Or you have a very high hp car that's supercharged and heat is a big issue.
We supply some car manufacturers with headers for the cars they race. They race them in Utah, Arizona and elsewhere. Cars making over 600hp and spending 1+ hours at a time on the race track. We don't coat their headers.
So, you need to decide what best works for your particular application.
If the goal is appearance then sure, coat them.
Someone emailed me about wrapping SS headers. We do not suggest you do that.

On a personal note, I've had a 2006 Z06 and a 2008 Z06 with SS AHR on both vehicles. They both made around 650 FWHP and never a heat issue.

Hope this helps.

Bobb

 

Well, I just googled "thermal emissivity of metals"...and he's right, but he may have understated the advantage that stainless holds over mild steel in this regard. If I'm reading (and understanding) the tables correctly, the difference appears to be more like several hundred percent. Here's the link:

http://www.ib.cnea.gov.ar/~experim2/.../emisivity.htm

They do state that specific temperature and surface finish can vary the actual values quite a bit. In general though, it appears that polishing a surface (which reduces its surface area, and so its emissivity) is roughly comparable to coating it...for those who still want to further improve the heat retention of your stainless headers. And by the way, if there was a way to accomplish it, coating or polishing the inside of your headers would be at least as beneficial as doing the outside. I wonder how much effect Extrude-Honing(TM) would have on stainless tubing...

 

And that's really all anyone needs to know

Coating headers = waste of money (unless you want the look)

 

Glad to see ARH commented, as I thought I remembered reading this back when I was doing my research on headers. I do remember making a decisive decision not to coat after reading whatever I read, so it had to of come from ARH themselves. I do believe the "brittle" comment was when someone asked about wrapping those headers made from 304 SS.

 

Thanks Bobb.

 

All last year my underhood temps reached a point (coolant @217-220deg) where the A/C would turn off while giving me a message on the DIC. Not fun in 100deg Atlanta weather. Oh, and this was with a non-stock hood. I've had two vented hoods on the car and the Hi-tech version did the best job but I wasn't in love with the looks so I got rid of it for a simpler Carravaggio vented hood.

I recently just had my headers coated in hopes of not having this issue again this year. So far so good but we havent had the blistering heat yet so only time will tell. I have Stainless Works headers by the way.

If it happens again this July/August then I'll know for certain it was a waste but if it doesn't then it was $200 well spent.

 

Header Coating Test conducted by HotRod Magazine

All the preceding tests were with uncoated, stainless Kooks headers. After completing the internal-coatings evaluation, the headers were sent out to Xtreme Coatings to receive inside and outside thermal-barrier protection. The headers were evaluated in this standalone fashion because this popular coating is widely available directly from header manufacturers, and it is also one process the average enthusiast can get done quickly without hassle.

Testing coated versus uncoated headers on an otherwise internally uncoated engine showed no statistically significant changes in overall torque and power output, although the engine was up a couple of numbers in the midrange. It could be that stainless steel headers are just less sensitive to thermal-barrier coatings than typical mild-steel headers. In any event, ambient temperatures with a heat gun in the vicinity of the headers did show a 200-degree-F temperature drop near the pipes at the pipe surface. Although the dyno numbers don't reflect this drop, in a tight engine compartment not using cold-air induction but rather ingesting inlet air from inside a hot engine compartment, a reduction in exhaust-radiated heat could translate into a big power gain: On a normally aspirated engine, every 10-degree-F inlet air temperature decrease increases engine power by about 1 percent. Even if the air were only 50 degrees cooler by the time it got into the inlet tract, that's a 5 percent improvement.

 

I think it all depends on your situation. I just bought some ARH and had them Jet-Hot coated for my Camaro. I wanted the chrome look and I didn't want them turning blue after a while. An uncoated header and a coated header look totally different after a year.

I am also supercharged and cammed at over 700HP, so I thought it was necessary. I intend to take my car to shows and all and I'm spending a ton of money in the engine compartment so I wanted to make sure they looked good. And I figured it couldn't hurt with it being supercharged and cammed.

 

Ditto, stainless steel does not need coating but if a cooler engine compartment which may mean cooler intake air and keeping a boat load more of the exhaust heat contained to the inside of the header tubes which keeps the exhaust flow speed up that is conducive to making more HP and the extra cost is OK then go for it!


Other than cost there is no down side and if your doing headers you are looking for all the performance you can get, right?

In full discloser my Mirage headers are not coated but that is because I did not want to sent them out to be coated because I am cheap! but I have used coated headers in the past when I was not so cheap.

 

I have read that part of the reason the CEL will go on with LT even running cats is that they do not warm up fast enough (or something to that effect). Will coating headers (SS or Steel) aid with this code not being triggered? Just wondering that if headers with a coating on them keeps the heat in - will that warm up the cats quicker and not as easily throw the CEL code?

 

Yes...though the degree (sorry, couldn't help it) to which it will help is unclear. Cats dig heat, so how could more heat to the now-remote cats hurt their heat-starved performance?