Why header wraps suck..., .. just an article I came across. Options

[KAOS]

Read the article HERE first; then post your comments below about your experience or knowledge.

I'd like to see a decent debate here; NO FLAMING!

Thanks guys.

[Tigawoods]

i couldnt read the whole thing but i might later. i have had header wrap on mine since last fall, and soo far no problem

[Fastbird]

Ok, that entire article was a huge piece of propoganda promoting ceramic coating for headers. Take what's written with a grain of salt. This I found amusing:

Under normal use, and even more with higher EGTs and header surface temperatures, headers will oxidize and material is actually removed from the headers. This means they become lighter and weaker.

Try these actual test numbers:
-- Mild Steel (1010) uncoated header exposed to 1200º F. in normal air will have a weight loss percentage of roughly 25% with only 10 hours use at this temperature.
-- Stainless Steel (410) uncoated header will have roughly 8% weight loss in the same 10 hour period.
-- A coated mild steel header will have NO weight loss at temperatures up to 1200º F. In fact it will actually gain a bit of weight! Between 1300º F and 1600º F the coating will begin to show signs of mud cracking or like the look of lacquer checking. However, limited diffusion takes place between the coating and the substrate, producing a very thin film of iron aluminide, which continues to inhibit oxidation.

They're saying that a mild steel uncoated header running for 10 hours at 1200 EGT will lose 25% of it's weight/mass. IMPOSSIBLE. Same for the stainless losing 8%. Not going to happen. If that was the case, then my stainless downpipe would have been LONG gone with all the extended high RPM road trips I've made with the car. Mild steel exhausts would be disappearing from cars in a matter of a few months to a couple of years.

Exhaust wraps have and will continue to be used by lots of people, from DIYers like myself and others here to race teams. Here's the biggest downfalls I've found with my research and knowledge of wraps:

-- Combustability. If you have an oil leak, or a fuel leak, and it gets in your exhaust wrap, this can quickly turn into a bad situation. YES, they can and will catch fire. Look up the name Tom Byrne, formerly of TByrneMotorsports. He had a KILLER supercharged 93 Z28 camaro back in the late 90's, with wrapped headers. Oil leak developed, soaked a wrap on one of the primaries, caught fire, and the car burned to the ground.

-- Water damage. This isn't so applicable to stainless as it doesn't rust, but mild or aluminized steel parts that are wrapped will be very prone to failure due to rust. This is why I do not recommend the wrap for anything but a stainless component.

I actually just over the weekend picked up a 50' roll of Thermotec wrap for the DP on our Celica with the full intention to go through with it. I'm doing this to help cut down on engine bay heat, and hopefully oil temps with the proximity the exhaust and DP are to the oil pan (I think I'm getting some thermal heating of the pan from the exhaust).

[darthripley]

i agree with fastbird.
one other thing to note with header wrapping is if you have a crack develop it's not always easily found as its hidden under the wrapping.
personally i like ceramic coating better since it is cleaner and neater in an engine bay imho, but thermo wrappings can definitely have their place on items like throttle cables that can be easily deteriorated by heat esp. in a 3sgte.

This post has been edited by darthripley: Aug 21, 2008 - 12:24 AM

[celicaGT96]

I plan on using the header wrap once I get my swap done. I started thinking maybe..wouldnt the extra heat kept inside the header (since its wrapped) maybe put more "stress" on the header itself?

what about coating then wrapping? thats what I planned on doing.

[Fastbird]

what about coating then wrapping? thats what I planned on doing.

The ultimate in cooling. That would probably work pretty well. Pricey, but well.

I'd have actually gone the coating route, but I'm not going to pull the car apart just to coat the DP as it's my daily driver right now. I am doing the wrap more as an experiment (costly one at that) to see if I'm getting heat soak in the oil pan from the down pipe passing right in front of and just underneath of the pan.

[91sofla]

I agree with Darthripley about not being able to see a crack developing. I experienced that with a wrapped turbo exhaust manifold.
I would take note of the climate you're in--I personally wouldn't use it in a high humidity climate such as where I live in South Florida.
Might also depend on how often you drive the car...just a thought, but if the car is not driven often or is stored outdoors, it would be easier for exposure to moisture from rain and snow to occur.

[darthripley]

I agree with Darthripley about not being able to see a crack developing. I experienced that with a wrapped turbo exhaust manifold.
I would take note of the climate you're in--I personally wouldn't use it in a high humidity climate such as where I live in South Florida.
Might also depend on how often you drive the car...just a thought, but if the car is not driven often or is stored outdoors, it would be easier for exposure to moisture from rain and snow to occur.

sofla is exactly right about the humidity/weather elements causing probs to develop faster than in drier climates.
when we got our 4agze motor it had a nice quality wrap on the header and the b-pipe (midpipe) and after removing it we found the welds around the flex pipe were rusted with cracks and there was a crack on one of the header primaries that we had rewelded.
we have no way of knowing how long the wrap was on but after everything was repaired we had it ceramic coated and its been fine for almost a year now.