how well do header coatings work ?

Well, they keep them from rusting and they look a lot better.

I think they keep things cooler, as things that used to show signs of heat stress (spark plug wires), no longer do, even after several back to back chassis dyno runs on a motor putting out over 500 flywheel HP at 5300 RPM.

I used Jet Hot mostly becuase they are down the street from me a few miles.

Doug

 

I was thinking on removing my heat shields and jet coating my headers.My local Ferrari dealer recommended not doing it. They told my they have seen heat related issues with heat shields remove and coated headers on some 308's

 

JetHot caused about a 10C temp reduction for track use 308 (personal data/experience). Besides looking better, obviously the coating makes for a smoother surface for the exhaust gasses to flow through.

 

Does anyone know or has anyone seen any data that favors any particular color of header coatings for temp reduction? I've seen lots of Silver and lots of black ceramic coated headers. Does color make a difference or is it a wash?
Rick

 

The data you are looking at is most likely for mild steel, the effect would be about ½ as pronounce for SS due to the much lower thermal conduction rate.

Beyond that, think of the temp reduction as a free bonus. The main point is generally cosmetic followed be corrosion control. If you already have SS header and want additional heat control header wraps are MUCH more effective than coatings. On my 308 with the headers double wrapped I could lay my hand on them without fear after a hard drive…..don’t try that with coated headers.

 

What a good question.....no idea. Normally silver is the best insulator and black the worst, but I've never seem any data on headers.

 

Mr. P.E. Irving in his book "Motorcycle Engineering" says " A polished surface emits less heat by radiation than a black one. The rate of heat emission from a polished surface is approximately one-tenth that from the same surface covered with a thin film of black"

ALCOA's Engineering Handbook compares an as-cast surface with one that has been black anodized to a depth of 0.0017 inches. The black surface is more than ten times better in heat-radiating ability than a plain as-cast surface.

Steve

 

Jet Hot on the exposed headers brought down the ambient temp in the engine bay of a mid-engine exotic I drive sometimes - by about 25 degrees, and reduced the operating temp of the engine (no thermostat) by about 5-10 degrees. So, it does make a difference. My $50 IR heat scope indicated that the surface temp on the headers came down about 20% overall - a little more than 20% right up by the heads, and more like 10% farther downstream. So, the 60% claim seems a bit out there.

The place that did my headers was quite clear about the fact that their process was a surface spray application, not a dip process. In other words, it isn't going on the inside of the header, so, don't expect the interior surface to have any increased corrosion resistence or change in surface properties. Perhaps other places somehow get the coating on the inside of the headers through a dip process, I don't know.

So, net, it's not a complete waste of money from a performance standpoint. But like another poster said, don't go touching those headers with your bare hands after a "spirited" drive....or if you have an ignition problem on one bank!

 

HPC Coatings does do the inside of the pipes as well. When I asked them how they do it, I got a long smile and no words -Steve

 

Mark,
I just spoke to Gus at Jet Hot and got quotes for their Extreme Sterling which they rate at 30-40% temp reduction. The (satin) black does cost more than the (shiny) silver, but performance is the same. The product is rated at 1700 degrees and color does not matter. The regular Sterling product reduces tube skin temps about 300 degrees, the Extreme Sterling reduces tube skin temps about 400 degrees.

Rick

 

I have and it hurts! dont recommend it. Unintenional of course! I coated them for cosmetic and corrosion control. I dont know have any reliable data about being cooler or not? 7 years and holding up fine!

cheers

 

I that on SS or mild steel? I'm guessing mild steel.

I'm very surprised about the answer on color, but every material is different and if that's hat the data says......

 

Mind sharing what is quote is?

Ace

 

Not at all... $310 for Extreme Sterling Silver, $375 for Extreme Sterling Black. $34 shipping back to Northern California.

Rick

 

I coated them for cosmetic and corrosion control.



I have not had good luck with longevity of the cosmetic/corrosion with My Jet hot coated headers in the Muscle car. Jet Hot did redo them once for free but they are peeling and crusting at the collectors after 2 years.

 

bummer! Mine have only faded slightly. no peeling or cracking so far, knock on wood.

 

That might be SS vs mild steel. The stock ferrari headers appear to be 400 series SS so they really don't corrode much anyway vs mild steel headers rust like a mother.......I remember 2-3 year to rust though on my steet car with mild steel headers.

 

Sounds reasonable to me. I have another set of stock 308 headers and they have some rusting in the inside. They are NOS and still have some of the Ferrari tag on them. I should treat them I suppose to stop them from rusting from the inside out. Does anyone know if jet coating process kills the rust or just seals it in so it can eat it ways out like a cancer? Most of the chassis paint neutralizes the rust and converts it, I wonder if the jet coatings do this as well?

Cheers

 

Good test here: http://www.carcraft.com/techarticles/high_tech_ceramic_coatings/index.html

 

The print version of an infomercial.

The test data given is for very specific conditions where the product is known to perform well......mild steel and modest load and I'm guessing they also had the fans turned off or turned away when they took the temps. It's basically a rigged test. They ran the engine at full power but notice the temp data is not reported. Also notice they don't compare the stuff to wrapped headers, becasue it doesn't even come close to matching the results in temp reduction of wrapping.

It makes headers look good and makes mild steel header last quite a bit longer....but I suspect they realize they can sell a whole lot more if they imply it actually solves a common problem, overheating, without actually producing any data meaningful data to prove what they are implying.

 

Well I partially agree with you but the test presents factual data - They note the change in temp and dyno results. They "overstate" the value at the end, especially since the dyno shows no change at all (contrary to JetHot claims) but one thing that is sadly true is that magazines have to tread a line between being totally objective and not upsetting their advertisers.

You have to read between the lines on virtually any test of a product for that reason. The nice writeup at the end gives an "endorsement" of the product, emphasizing the reduced temp, but with no mention of the Dyno results.

I agree that if I had done this test personally and did NOT work for the magazine I would have said, "save your money." But OTOH, having been involved in tests like that for car mags in the past, I realize that most of the time you can't say that sort of thing at the risk of losing advertising. Often you really do have to read and sometimes re-read an article to dig out what the testers mean because what they are trying to tell you may not be exactly what they are saying...

 

I've done my fair share of header wrapping over the years and in trying to make sound at the track with the GT1 car, wrapped the whole exhaust. (didn't really help...) My personal experience and that of motor builders we deal with is keeping the heat in with wrap works well but accelerates the ablation of the headers from the inside out. Obviously cheap mild steel off the shelf fares worse than high quality hand made stainless units.

Good to high quality headers Jet Hot coated don't see the temp drops you get with wrapping but I've had some phenomenal results with longevity with Jet Hot or HPC coatings.

So, to finally get to my point. Anyone now of any issues with wrapping coated headers? I suppose getting the wrap to stay in place is a pain, but once on do you get the best of both worlds??

Rick

 

It seems like it should work but I've never tried it. I've also never had any hint of a problem with wrap on SS headers on a street car either, but as you say hotter metal has to mean faster corrosion rates, i guess I've just never run anything enough to get to a problem.

To keep the wrap in place I safety wire tie it every 3-4 inches then absolutely hose it down with high temp paint which makes the stuff look a whole lot better, helps glue it in place and sort of helps keep it from soaking up...a little any way.