learn me: header life expectancy decrease with wrap

the main drawback i hear regarding header wrap is that it holds moisture as the header cools, which eventually causes the headers to rust through.

question: has anyone quantified the decrease in header life as a result?  i mean, does it cause perforation in 1 year vs 5 years, etc?  i'm sure it is dependent on the number of heat/cool cycles, ambient humidity, etc.

Thanks!

Depends on if it's its SS or mild as well, mild it looks bad after just a season of drag racing and you get holes in a few. SS we usually are changing the setup and selling off before any damage. Road racing and sustained temps may be different.

I wonder how much ceramic coating might enhance longevity?

I'd go with a coating instead if you need to do anything at all. Why do you want to wrap it? 

Most of my experience is on dirtbikes which makes the moisture issue much more dramatic (every dual sport guy seems to want to wrap their exhaust...), but the one car I had with a wrapped header cracked it in one track day. Repaired the cracks, removed the wrap, and it survived the rest of my ownership and thousands of miles of track use until I took the header off to replace with a turbo manifold. 

good feedback so far, thanks.

mild steel, home-built from used junk. challenge car, so not a lot of budget to work with.  wrap is cheap relative to Jet Hot, although JH is significantly less $ than i expected.  I think they quoted $450 shipped for inside and out.

step 1 is to extend and insulate my heat shields.

step 2 is to add a couple small centrifugal fans to force air through the shields and out the back of the car.

step 3 (if necessary) would be header wrap.

Keeping in ind I live in the desert:

I wrapped the headers on my Datsun 20 years ago; about a 4 years ago I had reason to redo the wrap..............the headers were fine. 

Haven't had any problems clearly caused by the wrap on my 4AGE 20v headers on the AE92 so far. Had to re-wrap it once when a crack formed after the first year or so, didn't look worse for wear underneath.

I wrapped the headers I made from used header parts for my 2018 challenge Miata. The car sees Street use and track use, but not driven in the rain or inclement weather. It is stored outside. Under a carport and car cover. The headers were painted with poor 15 exhaust manifold paint prior to being wrapped with eBay header wrap. So far the headers seem to be solid and have not noticeably had their life shortened. The header wrap that I used is however failing. It also didn't seem to do much for reducing the interior heat of the car or the underhood Heat.

Our last header on our champcar was wrapped. It lasted a couple seasons before a huge junk exited stage left at Lemons Sebring in 2021. No more wrap for us. 

Mild steel headers, 35K miles of street and "spirited" driving, 8 years so far......no issues. When I removed the engine last time I looked under the wrap along the edges and saw no damage or rust pits. Looked pretty much the same as when I put it on

Link

Design Engineering Inc. has a silicone based spray coating to spray on top of wrap to help seal out dirt and moisture from the wrap. Maybe it also adds to trapping moisture in as well? I used it on my downpipe off my turbo, but I painted it with VHT exhaust paint first, let that cure a couple days, then wrapped it, THEN a couple coats of the spray sealing with a couple days of cure time prior to installation. 

At a listed price of $19.79 it's priced challenge friendly to maybe assist?

I've had DEI Titanium on the stainless steel header in the One Lap CRX for over a decade with no issues.  I've had to rewrap it a couple of times, as the stuff does eventually burn off.

That car has seen plenty of rain use, but not nearly as much as a typical street car.  And it is garage kept.

We get about 1 year out of our exhausts on the champcr when we wrap the headers.  

Mild steel.

In reply to AngryCorvair (Forum Supporter) :

So during your presentation, mention that you were inspired by the Aston Martin v12 Vanquish.  That, too, had a lot of special cooling things for the exhaust.