What about wrapping over POR20? That would resist whatever moisture there was, right?

 

be cool to have a 100% ceramic header

 

Most of the coatings are pretty thin. They need to be applied thick to be an effective insulator. Heat wrap will trump those 'pretty visual' coatings that many header companies are using.

Flaking, as already noted, is caused by not using the correct coating for the temperature range. And, prep is also very important. You should question whoever does your coating to see how they prep the component prior to coating.

If you want to coat, get the header/pipes/whatever coated inside and out if possible. The inside coating will prevent the header materials and welds from overheating, and will provide that 2nd level of insulation if you want to reduce underhood heat.

Ask your coating company on the difference between cosmetic coatings(the most popular) and functional coatings(which will actually insulate). And, compare that info to the dozen or so other coating companies.

 

Wow, this got dug up?
Anyway, I guess por-20 coating would work. I have no experience with it though. As for a solid ceramic header, I'm not sure if ceramic is sturdy enough to handle the constant vibrations of the engine. I'm not basing this off any hard facts, I would just think that it would end up cracking over time.

 

Awww yeah, seeing that nice, flat orange terra cotta right there on the side of your engine like that! You could even make an extra one and plant petunias in it.

I tried to make a 100% ceramic header one time, but the damn pottery wheel was going WAAAAAY too fast!

 

I don't know if the way I did mine was correct or not, but I first sprayed my DP and MP with DEI HT Silicone Coating ,wrapped the pipes and then sprayed over top of the wrap, like a sandwich

 

the coat of spray underneath isn't necessary but it's not going to hurt anything

 

one thing that seems to be missing (unless i missed reading it), is that the coatings are inside and outside on the piping. header wrap is just on the outside. so essentially you've wrapped the tubing into it's own oven. this is one of the reasons a set of wrapped headers will fail faster. you've elevated the overall temp the headers are retaining and the higher temp now creates a greater delta in the cyclical heating and cooling of the metal.

 

True, but with a high flow exhaust system and normal to spirited street driving, I don't know how much difference it would make. Plus, if ceramic coatings keep heat in better, then the temperatures the header metal is subject to should be higher?

 

you aren't reading my post. the coatings are applied to BOTH sides of the tubing. so less heat is making it into the metal (if the coating is doing it's job). also in response to "I don't know how much difference it would make", if it didn't make a difference then why bother doing it? plus holding more heat is holding more heat. you might not be obtaining the temp levels of road racing, but you are still going to have elevated the temp of the header considerably (once again if the wrap is doing it's job).

 

I got a set of road race headers ceramic coated (outside) by a local shop. They said it's good for about 2000F and the guy guarantees it.
Anyone know what the underhood temp difference was after installing their setup? I haven't installed my headers yet, but IIRC the stock manifold gets to about 350F sitting at idle.. Measured around the o2 sensor bung.
Anyone know for sure?

 

I read your post, but use some common sense. If the ceramic stopped the heat from getting into the metal, then why coat the outside at all? Now let's say that you DO coat the inside and the outside. Now what heat manages to make it to the metal isn't going to come out the other side, so it would reflect back and forth. It would probably heat up slower because of the internal coating, but hold heat longer because of the external one.

When I say it's not going to make much difference on a road car, what I'm trying to say is that for these Formula cars and Nascars are experiencing header failure, that's something of an extreme condition. Your choice is your choice. I wouldn't put a $6,000 sequential six-speed in my street car either, but people do it. Does it work any better for highway driving than a totally rebuilt factory five speed? Probably a little. That's what I'm trying to say.

What I'm interested in is the price. I personally believe dual coating of headers is probably more effective than header wrap. How much does it cost to have your headers coated? If it's 4, 5, 6 times the cost of header tape, I think tape is probably fine. If my header only lasts 6 years because of that? Buy another used one for $30.

Now, if it's only like, twice or one and a half times the cost of header wrap, then that's something to think about. Those who've had it done, how much did it cost?

 

Heat OBVIOUSLY makes it into the metal, but when its coated on the inside less heat gets in.

Read above post. Less heat gets in. Although its harder to leave because of the coating, there is less heat to begin with. The argument here is moot.


To each his own. Every little bit counts. And if anything - on a rotary this is going to be more of an issue (heat from exhaust) then on ANY other car. Street or not.

Beats me, Im a header wrap guy - I stick with my original point of header wrap netting pussssay.

No. Its only an option - that you pay for - but you can do outside only, inside only or both.

 

I used header wrap on my 3" downpipe and now i have holes in it because it rusted so bad.

At the very least, get some high temp. paint and spray the pipe to prevent rust.

 

maybe the heat bouncing back and forward between the 2 coatings causing the medal to cool slower would be an advantage? i mean maybe these headers fail because they cool down and heat up TOO fast, too much expanding and shrinking in not enough time.. coating inside and out would slow down both processes

 

I am doing a PolyDyne coating for my internals, manifold and DP.

some light reading on it...

http://turblown.net/

 

See again, their stuff looks pretty sweet, but you can buy two engines cheaper than you can buy one and have them coat it. Just like ceramic coating of headers, it's all about how much it's worth to you. If it's cheap to have them coated, I'll be next in line. A friend of mine just bought headers for his '68 Camaro that came coated and looked like chrome. The set of TWO cost him less than $180, that's new headers AND coated.

I just have this horrible feeling it would cost $180 to have my 20 year old crusty stock manifold coated, and then they'd probably charge me extra to bead blast it or whatever, and then I'd end up having to buy a new one because they "let the spirit out of it" or some other balderdash.

 

I have to agree on the slower heating and cooling being a benefit. What people seem to be missing here is that HEAT = ENERGY The more heat you keep inside the header the more heat spins the turbo. So if your header fails a little early so what. I think a nice stainless piece with proper bracing, tig welded, ceramic coated in and out, will last a LONG time.

 

They say keeping the heat on the inside using header tape or ceramic coating helps to spin the turbo faster. Unfortunately, I'm just a cheapskate with an N/A and 4 other other children to feed. :P (Cars, not real children)

 

I have a 89 vert and I put a RB header on it in 1997. I painted it with high temp silver paint. I then wrapped it and let it dry in a kiln. I then painted the wrap with the same high temp paint. I sold the car to a friend in 99 and he drove it maybe once a month. I just bought it back from him and the header is still in great shape. It still keeps most of the heat out of the engine bay and no rust or degradation noted.

David

 

Heat wrap insulates better. Ceramic coating withstands higher temps (probably doesn't matter?) and coats better, so nothing can get in. Both never corrode or degrade, though ceramic can crack. I have no experience with this, I just know about the two materials from my engineering education. I'd do both. I don't see how trapped moisture could cause damage if there's a ceramic coating underneath.

 

ceramic frequently will flake/peel off..

my friend has a megan racing tube header on his DSM and has had it recoated twice, it just keeps coming of.

My turbocharger is ceramic coated and is starting to rust underneath the coating, forcing the ceramic off.

Both of these are probably from less than ideal surface prep or something - but that's my experience with it.

my header and downpipe are both wrapped in heatwrap - I can touch the downpipe with my fingers if the turbocharger is glowing RED hot.

 

Something I've ran across posted but I haven't seen mentioned is the coating will flake if the hot coated manifold gets hit with water repeatedly.I assume like driving in the rain and water splashing as an example.Now I don't know if that is related to bad prep techniques at the coating places or what .But have seen it posted a couple of times.

 

I had to pull the old wrap off my downpipe after about 15k miles because it was just falling apart. But here is what my RB DP looks like on the inside after those miles.

 

My old thread got dug up!
Anyway, thanks for the pics. It appears to be just basic surface rust, right? I've actually seen worse on an RB downpipe (NA, though) that was just open to the elements. I suspect it had a lot more than 15k miles on it, and possible northern salt exposure. Still, not that bad. Not great, but hardly anything more than cosmetic.
That is, unless I just totally misread the pics. So is there anything more than surface rust?