Can anyone tell me what thin walled headers are, and why they are advantageous to the EVO?

I was going to get the header ceramic coated to increase exhaust gas flow, but I'm thinking if there's a good reason why the header walls are kept thin, then ceramic coating would defeat that advantage.

 

Advantage? None. Cheaper to manufacture and a lighter component on the car? Yes.

Ceramic coating won't make the exhaust flow increase. It will just make the exhaust retain more heat.

 

True.. Thin walled headers have a few advantages, and a few other disadvantages.. First, thin walled headers usually flow better than stock, and may have smoother curves and radiuses in its tubes than a cast manifold. Thin walled headers don't retain as much heat as cast, however as mentioned, ceramic coating will keep the heat in.. Depending on your school of thought, this may be desirable or undesirable.. From my background, I'd consider it desirable.

The bad things about headers, especially steel tube (NOT STAINLESS or TITANIUM) is it corrodes and will eventually rot.. Installation, and servicability to other components may also be impeded.

My experience with headers is its ALWAYS at least a slight improvement over a stock manifold. On a Turbo car, it definitely can be put up for debate because your biggest restriction at that point would be the turbo anyway.

a header is expensive, and unless you plan on having other supporting mods, it may be cost prohibitive and not worth doing initially. Also, since thin-walled headers (Not coated) will shed alot of heat, you have to take into account the amount of additional heat that you will generate under the hood.. and the risks involved with it.

and there have been some tests with and without ceramic coating.. "Supposedly" the extremely smooth surface of the coating can improve exhaust flow slightly.. Let me point out that the improvements in flow are marginal when the header is **NEW** However after a few weeks when the steel begins to corrode and pit, and flake.. That is where the ceramic coating has its advantage, since it will not allow the steel to do that until the coating fatigues with age, which is usually several years (make sure the header is coated on the inside, otherwise it looks pretty, but is essentially a waste of money!! Buyer beware and ask the right questions)


Its main claim to fame is retaining heat until it gets into exhaust system.

 

I was assuming he was talking about the factory cast manifold, which people usually call a "header". I wouldn't coat the inside of the manifold or header with ceramic coating. The coating flakes off relatively easily under direct exposure to exaust flow, and will go through the turbine and can ruin the blades.

 

Evostang/MalibuJack,

Thanks for the replies. Yes I did mean the stock turbo manifold.

I'm not thining of replacing the stock manifold, but lists one of the features of the Evolution, as having thin walled manifolds. From what I am seeming to get, "thin walled headers" use welded pipe, as opposed to a cast manifold. would that be right?

I think I will coat the outside with ceramic. From what I've heard, it keeps under bonnet temps cooler, it keeps the exhaust gas hotter, and therefore more fluid and greater momentum.

 

you can get heat absorbing jackets or wrap for your manifold cheaper prolly. They aren't pretty, but they get the job done. Try www.optauto.com
I have ordered from them before, good shop, cheap prices.

 

Strangely enough, it's cheaper for me to get it ceramic coated...

Header wrap is $105 for 20m (Australian dollars)

I got quoted $80 to do the S2000 header (does not include removal or refitting.

I've also been told header wrap increases rate of metal break down, where as the ceramic protects it. No I didn't hear it from the guy selling me the ceramic coating. I heard it from a mechanic who had no stake in either method whatsoever.

 

I think if there is a way to prevent the coating from flaking off, extrudehoning, and then cermic coating a stock manifold does really well.. But as another writer said, it does eventually flake off unless the surface is prepped REALLY well.. But like I mentioned earlier, as a stock steel manifold (or header tube) oxidizes, the surface becomes pitted and no longer smooth.. I also forgot to mention that stainless headers (I haven't seen this with titanium, but its possible) when their hot, if they come into contact with alot of water that causes it to quench the heat quickly, could cause them to crack, at least at the welds..

Coating the outside will help retain heat, and it does wonders for appearance.. its a good compromise..