Ceramic Thermal Coating on Flanges of ACE Header?
 

I just ordered an ACE Type-A 4-2-1 350 header from CounterSpace Garage and I'm going to have them ceramic thermal coat it before they send it out to me. I've seen several examples on the forum of headers that have been coated and some people have masked off the flanges, while others have coated them - is it just a matter of personal preference, or is there a benefit to doing it one way or the other? To me it seemed like the former, but I did wonder if leaving them uncoated (my preference) could create a hotspot? At the same time I could see how it could provide better sealing for the gasket, so I thought I would ask for people's opinions here on the forum. Well, what does everyone think?

On a sidenote, I want to give a shout out to the people at CounterSpace Garage - these guys couldn't have been more patient or professional with me, and they really know their stuff when it comes to our cars. Highly recommended!

You're kidding me, right?

OP, I don't think it would make a huge difference, but to me, id rather them be not coated, just for peace of mind in avoiding any possible fitment/leak issues.

The coating is fractions of a mm thick. You can coat the whole lot including inside and the o2 threads. It makes no difference to fitment.

You'll become a believer the first time you touch a ceramic coated exhaust pipe immediately after the car is parked.

Then ceramic coating is probably not for you, but there is a very tangible purpose and function to the coating.

Why both sides? Inside makes perfect sense but doesn't the outside just trap heat in the header itself?

Same reason you do double/triple pane windows. More layers = more insulation.

The goal is to keep the heat in as much as possible, so having two layers of ceramic with a hot header in between keeps MORE heat (energy) in the exhaust gas.

Right, I get that but we don't like header wrap because of embrittlement, and we are essentially doing the same thing to the header with that outer layer.

You mean the wrap becoming brittle or the header itself?

The header itself will become brittle over time. Wrapping a header shortens it's lifespan, I'm not sure by how much, but do know that if your doing any racing with it it will be significant because of the heat the header will be exposed to. If I understand my research correctly, this is mainly due to the higher heat and cycling it is exposed to vs designed to hold, and I've seen some things about condensation playing a roll too.

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The header itself. Or is that header wrap thing just a myth?

I have never seen a discussion about that with stainless steel headers before.

Ceramic coating is almost always reccomended.

I've not seen that become an issue with stainless steel headers... but my experience is fairly limited.

Yes, but I wonder if there isn't an advantage to only coating the inside of the header. I have zero personal experience but, based solely on my understanding of heat transfer and assuming there is something to this embrittlement rumor, there might be something there.