Well I have heard many things about wrapping headers, some pro and con but could never get a real difinitave answer or pics of headers damaged. Well here is an example of the material breaking down under the wrap. It does not look like rust but the mild steel just flakes off like bad rust. I had an exhaust leak developing over the last month and finally got the header unwrapped to take a look...






The wrap had become very brittle and sensative. Easy to damage.


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At this point I will be rebuilding the complete exhaust before the turbo. Similar to the way MIDTRBO is set up.

http://myfiero.com/uploads/20207_.jpg

This will be more compact and simpler and should be stronger.

I will be ordering parts soon and I had some questions.

First stainless or mild steel that is ceramic coated?

If stainless do I have to have stainless flanges made or can I use the steel flanges off my current headers? I do want to save money where I can.

Will ceramic coating hold up?

I want to install provision for external wastage for the future, what wastage flange is the most universal? I will cap it for now but want to bolt up an external wastage when the time is right.

Any reason not to go with the thickest walled tubing that is reasonable? I want this done right and strong, not looking to save weight here.

Where is a good place to get mandrel bends for reasonable cost, where do you guys shop?

Any reason not to use V-Bands at the end of the headers into the crossover? They will be easier to remove and install than flanges.

I think thats all, thanks for the advice. I hope to order stuff tonight or tomorrow and maybe have a marathon fabbing party next weekend so I can have the car back on the road ASAP. I have a very experienced welder I am working with.

How many years were these headers on the car and wrapped?

Do you think the constant rain in Washington could have been a factor?

[This message has been edited by MountainHiBlue87GT (edited 04-28-2011).]

It doesn't look like they were made of the same kind of steel as stock Fiero manifolds.

I wrapped the headers less than a year ago, about 10 months ago. At the time I had them sandblasted and I coated them with lots of spray on ceramic coated, cured properly of course. They were sound with very little external corrosion. I just was having a hell of a time keeping under hood temps under control.

I do not think rain is a factor as the car is covered most of the time and not driven a huge amount in the wet weather. I think it was just heat that accelerated the break down process.

These headers are just mild steel and with the turbo being operated MUCH hotter than they are designed for. Stock headers are some form of stainless steel and do not get nearly as hott as these do.

My new headers will be T304 Stainless with heat shields, no wrap. Also simple log type, no long tubes and much simpler.

edit: did not see car was covered.
well i guess there is the reason not to wrap headers
the heat shielding should work much better

[This message has been edited by BlackGT Codde (edited 04-28-2011).]

Depends on the headers. If they are mild steel then no its probably not a good idea to wrap them. You could paint them with high temp paint but I don't trust the spray paint to hold up. If you ceramic coat them then wrap them you would be fine.

Now if the headers are stainless steel then there isn't a problem with wrapping them. I don't understand why some people think header wrap with destroy stainless steel.

Generally header wrap will break down over time. Better quality header wrap will last longer. Its also a good idea to "seal" the header wrap. If you read the instructions with the wrap they usually suggest you to spray the header wrap with the high temp ceramic spray paint. The paint holds up better in my experience when sprayed onto the wrap. Painting the wrap helps the wrap to not absorb water, dirt and grim as easily.

Header wrap can ruin even ceramic coatings if it gets wet often enough or is allowed to suck moisture from the air. I had a leaky rain tray on my 87GT decklid and the forward header lost most of its ceramic coating. If you're going to race the car and keep in a garage most of the time, wrap them. You can also add one or two underhood fans to help displace the heat. We do not recommend heat wraping our headers.

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trueleo.com
RSpiderII@aol.com

Well Im ordering parts!

2x 2" stainless (304) Vband kits... ebay $60
1x T3 Stainless (304) turbo flange... ebay $8.99
1x 38mm stainless (304) wastegate flange... ebay $10.99

Tomorrow I will order 450 dollars worth of T321 Tubing/bends 16 gage from Burns Stainless.

I will order a flex section as well but I need to find one that is all stainless with no braid inside. I need the ends to be stainless as well.

What size tubing should weld up to the wastegate flange? I am having a hard time finding specs but I only need a little bit.
Is there anything wrong with cutting off and using the mild steel exhaust flanges off the exhisting headers? They look great and will save me some money.

Let the parts roll in, and the fabricating begin!

Oh wow. I wrapped by headers from Francis T, and i didn't notice that much deterioration at all. I think Header wrap is good for normal applications, NOT boosted applications. Turbo's create way too much heat for the wrap to handle.

My dad is getting into ceramics (buying a coating busness) I will ask him when he gets up. From what I understand you do not need to wrap coated headers. On a normal 4 cylinder, he was able to tuch the manifold once it was warmed up. It was hot, but did not burn him. But you have a turbo, so normal cermics may not be strong enough. Check out 'jethot' coatings, there stuff should be able to take the heat. I'll check with dad when he is up.
Matt

Embrittlement causes the destruction of headers that are only coated outside and not inside, or are wrapped. Stainless is still subject to heat related embrittlement from being wrapped.

I had a Hooker Tri-Y header on my 2.5L. I wrapped it and for about 6 years or so was great than it rusted through right at the point the tri part came together. It seems that this is were moisture/water collected when it rained and the deck lid was opened. The wrap got wet and rusted the pipe.

So I talked to dad. He say jethot is not what you need. The inside of the pipe need a heat barrier/reflecter and the outside needs hest dispersent. He said some shopd dont do the inside of the pipe, only the outside (just to have it look good). If its done right, you will not need to wrap it.
Matt

Water itself isn't corrosive but the fact it carries oxygen very well makes it a bad idea to do something that keeps it in contact with other materials that can corrode. Header wrap does exactly that, and since all chemical reactions (which is what rust is, O2+Fe = FeOx, iron oxide, rust) are sped up by heat, having heat wrap on a hot exhaust makes it that much worse.

Those look just like the headers that I used to have on my car. I wrapped them and in less than a year they were junk as well.

quote Originally posted by JazzMan: Water itself isn't corrosive but the fact it carries oxygen very well

Thats not why water leads to rust. Oxygen is carried well-er by the atmosphere than by water (higher energy) (main reason we can't breath underwater)

Water increases the rate of the rxn because it provides an ionic solution (water plus carbonic acid plus salt (Na+ Cl-) plus other trace salts) allowing flow of electrons from iron to oxygen (its an electrolyte).

Our rule of thumb is to never wrap mild steel and wrap stainless steel. Jet Hot looks great, but does not reduce underhood temps (I have the burns to prove it). Wrapping allows you to grab the exhaust pipe after a hard drive.
When you make your headers, make sure you are welding with stainless wire or the welds will rust out.
Dave

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www.hausofguru.com

Well I just ordered $424 dollars worth of 16 gage T321 stainless tubing. Everything will be 321 except for the vbands and flex joint and flanges. I can only get those in 304. Should hold up very well.