Header wrap

carl

carl

True Classic
An interesting episode of Engine Masters on Motortrend TV last night. They compared power improvement of three headers. One painted, one ceramic coated and one with header wrap. The hp was identical on all three. The ceramic coated headers lowered external surface temps a little bit. The wrapped headers reduced external surface temps about 20 degrees. My take was, why bother. They did say wrapping will destroy headers with rust since the wrap retains moisture.

One of the MCs did relate that wrapping made a vast improvement on cabin temp reduction. I don't see this as much use in an X but could see wrapping the downpipe and front exhaust pipe on a spider might help reduce the heat coming through the trans tunnel.
 
Having had an $$$$ header on my old Volvo T5 setup rust out due to wrap, I'd never ever use it on anything that can be exposed to moisture. Anyone want to buy a new (old stock) roll of treated DEI header wrap? 🤪
 
My brother has header wrap on his headers on the Celica Alltrac. . . . Can't tell you how many times I've helped reach into the engine bay or rested my hand on them while working on something and getting an arm/hand full of fiberglass. Enough for me to not install on my X tbh. Especially with how tight our bays are.
 
I had header wrap on SS headers on my daily driver for a dozen years, had no issues. I have had it now for 7 years on my mild steel headers on my track car, so far so good. But it doesn't get wet very often, and gets pretty hot when in use. My theory is it will keep the carbies a bit cooler and therefore give a tiny bit more hp. (Edit, not long after this I had to take the headers off and found a pipe with 2 cracks in it).
 
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This was another one of those "tests" recently aired on the TV program about engine dyno results. They were primarily interested in testing the claims that insulating the exhaust will increase power. But they also recorded the internal and external temps during the dyno runs. The tests compared a plain steel (not insulated) header, the same header with ceramic coating, and the same header with a wrap product on it. The results found no change in power from any of them (see the note below*). But of more interest to me was the heat insulating properties; ceramic offered a rather small decrease in external temp (and therefore small increase in internal temp), while a wrap offered a significantly greater decrease externally (increase internally). These results suggest a wrap is much better than ceramic coating for reducing engine bay temps....which to me is the primary reason for doing it, as @GregS said. I was surprised to hear ceramic coating did not perform all that well.

*It should be noted the tests were performed on a dyno and therefore not able to measure any power improvements offered by reducing the engine bay temp (e.g. lower intake temp). In my opinion anything that will reduce the temperature surrounding the engine is worth doing, for several reasons.

Obviously these tests had nothing to do with the longevity of the headers. However I've found results similar to what Greg said. If you do NOT soak the wrap before applying it (something that was suggested for a long time to help with the installation), and the car is not driven in wet conditions, then a wrap does not seem to greatly affect rusting issues. There is also a spray-on product that is supposed to help seal the wrap material, making it more impervious to water intrusion. However wrapping over a stainless or ceramic coated exhaust would provide foolproof protection from corrosion.

Another potential issue I've heard is the creation of excessive internal heat (inside the exhaust pipes), as a result of any insulation, can cause them to crack. But considering the amount of thermal change that was measured I seriously doubt that will be the case. I'm of the belief that cracking is more a function of stress caused by vibration, tension, rapid hot/cold cycling, etc. And the tests found that insulating the pipes slowed the rate of heat increase and decrease deltas (i.e. reduced temp cycling), which should reduce the risk of cracking. One exception might be with a turbocharger, where thermal loads are through the roof and can lead to cracking even without insulation. So I'm not sure if adding insulation to a turbo or it's downpipe is a good idea or not?
 
I saw that episode of Engine Masters recently and found it quite interesting how little the ceramic coating helped. The change was just about in the noise level. Probably not a great advertisement for that industry although I had a friend who used that process on his 308 exhaust to keep it from rusting back in the 80s (no SS exhaust available then). Changing the exhaust on a 308 is not easy and this allowed him not to have to do it again.

All the wrapped headers that I have seen with any age on them looked like crap (as well as many of the unwrapped headers) but none of them were stainless. When I bought my X headers in 1980, the only options available were plain steel. It is a fair amount of work to maintain plain steel headers for over 40 years. My last attempt in 2019 was to strip them down with a wire wheel and use Rustoleum 2,000F paint on them. That was the best painting solution I have used on them. The 2,000F paint seems to take a powder coating type of approach except that there is no electric charge on the paint. Once the paint is on, you put the piece in an oven and ramp it up to 600F for a period of time (I had a spare oven and the headers fit inside with about a quarter inch to spare!). My observation was that at that temperature, the paint appears to reflow and set up. The end result looks quite a bit like powder coating. So far, it seems to be holding up and is more resistant to damage than the typical 500F stuff. Given a choice today, I'd definitely go for SS. As for SS with wrap, it would be nice to see some more examples of that working over a period of time in a daily driver environment.
 
dllubin said:
All the wrapped headers that I have seen with any age on them looked like crap (as well as many of the unwrapped headers)
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This is a good distinction to make; unwrapped mild steel headers are just as prone to corrosion as wrapped headers. And that was what I was intending to say earlier regarding my results being similar to Greg's.

Don's mention of powder coating reminded me. Apparently there is a high temperature version of powder coating that can be used on exhaust pipes. The Harley crowd uses it, mainly for esthetics (colors, etc). I've not tried it so I don't know what sort of temp it is good for. Perhaps it is only for exhaust pipes beyond a certain distance from the head, where temps are much lower? If it can endure the temps of a header then it would be a more affordable alternative to ceramic coating as far as corrosion protection goes (but no insulation properties).

Even if ceramic coating turns out to be less efficient as a thermal barrier, I agree it is great for corrosion protection. Ideally it should be performed on the inside surface as well as the outside of the pipes. Moisture from condensation will cause mild steel to rust from the inside out. Given the test results seen on that program, I'd be inclined to add a wrap over it for thermal control. However I agree, stainless is much better than ceramic coated steel. Not only due to the improved corrosion resistance, but it is more durable with less failures. The stock SS exhausts on many cars will last longer than the car. How about stainless, ceramic coated, then wrapped? :D
 
Most 'ceramic' coatings are little more than paint, even from the service places that offer the coating as a service. One of the few that is an actual, thick .015" ceramic coating is from Swain Tech.. It has a rough, sand like finish and only comes in white. It is not a Glamour coating, but a real heat reducer. You can paint it with header paint if you don't like the white.. I did my Datsun header and intake, you can put your thumb on the headers while it's running for a few seconds easily before it's too hot...
Mild steel cannot take the thermal stress from the extra heat/cool down cycles that will occur with wrapped headers, regardless of moisture or rust they will eventually crack.... Only stainless or exotic metals like titanium and inconel can take that cycling.... The only problem is if you have a beautiful set of SS or titanium headers, do you really want to hide them under header wrap?😁
EDIT: Dug up a few pics of the Swain Tech Coating, White as delivered..
DSCF4952.JPG
DSCF4954.JPG

After paint: Black Header Silver Intake...
DSCF4962.JPG
 
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I did ceramic coating on the mild steel headers I built for the GTV6. It has held up well over the ~3000 miles on the car since completion. This is what they looked like at installation. They have since mellowed to a duller aluminum look with indications of higher temps near the heads. The car regularly runs in the low 15s AFR at cruise, so they do get hot.

My goal was longevity, not looks or heat reduction.

1662657531672.png
 
OH - and the shop that did them said "never again" on the "polished" finish - too many nooks and crannies.
 
Lowtechprime said:
Most 'ceramic' coatings are little more than paint, even from the service places that offer the coating as a service. One of the few that is an actual, thick .015" ceramic coating is from Swain Tech.. It has a rough, sand like finish and only comes in white. It is not a Glamour coating, but a real heat reducer. You can paint it with header paint if you don't like the white.. I did my Datsun header and intake, you can put your thumb on the headers while it's running for a few seconds easily before it's too hot...
Mild steel cannot take the thermal stress from the extra heat/cool down cycles that will occur with wrapped headers, regardless of moisture or rust they will eventually crack.... Only stainless or exotic metals like titanium and inconel can take that cycling.... The only problem is if you have a beautiful set of SS or titanium headers, do you really want to hide them under header wrap?😁
EDIT: Dug up a few pics of the Swain Tech Coating, White as delivered..
View attachment 65768View attachment 65769
After paint: Black Header Silver Intake...
View attachment 65770
Click to expand...
I attempted to use Swain Tech once. I had a component from a rare vehicle that I wanted them to do their coating process to. The part was a original item that cannot be replaced and was in excellent condition, which made it very valuable. So I contacted them in advance to make sure everything would be good. They assured me it would and suggested I packed it really well to avoid shipping damage. I did and sent it out to them. Tracking verified it arrived there a couple days later. Several months later I had not heard anything so I called. They gave me some excuses and said it would be done in a week. A couple more months later and the same. A few more months (going on almost a year and a half now) and more excuses, so I told them to cancel the order and return my part. A couple weeks later a box arrived, looking a bit tattered. I opened it; not only was it not packed well and damaged in shipping (not insured), but I also discovered the part had been sandblasted yet never coated - allowing it to rust badly while in their possession. I called only to be told everything is at the buyers risk and they would not do anything about it, other than return my money for the cost of the coating (which was never done) but not the shipping. I'll never do business with them again, so I can't say if their coating is better than others or not.
 
Ouch! I've been lucky enough to find coaters locally (pistons and headers) so never had to risk my one-off parts to shipping.
 
Regarding ceramic coatings and header wraps, I saw a online advertisement for a ceramic coating company. They were praising the merits of a ceramic over a wrap. A couple of interesting things caught my eye.

When claiming the heat reduction properties of ceramic they showed a test result of a engine fitted with headers, one ceramic coated and one un-coated. The image was from a thermal sensing camera where color changes represent temp levels. Although they said there was a "significant" reduction of heat coming off the ceramic coated header, if you looked closely at the image and compared the colors to the legend there was less than 10 degrees difference (actually closer to 6 or 7*) over most of it. With the exception of the first few mm's off the head, where the uncoated one was noticeably hotter. They did not compare the thermal values of ceramic to a wrap.

Then when discussing the drawbacks of a wrap they said it wears out and needs to be replaced every six months. :rolleyes:

I'm not trying to make a case for or against either product. But simply pointing out how ridiculous many advertisements are.
 
The only time I have ever wrapped either a header or exhaust system is because the header tubing was so thin it was cooking something in the engine bay. I suspect any performance gain comes from reduced heat of other components in the engine bay and not actually increasing the flow of air through the header. Back when I had my X1/9 I thought about wrapping a CSC header, but ended up just making a heat shield to protect the intake manifold a bit. The Bayless header setup ran significantly cooler so I never worried about it..
 
Lowtechprime said:
Most 'ceramic' coatings are little more than paint, even from the service places that offer the coating as a service. One of the few that is an actual, thick .015" ceramic coating is from Swain Tech.. It has a rough, sand like finish and only comes in white. It is not a Glamour coating, but a real heat reducer. You can paint it with header paint if you don't like the white.. I did my Datsun header and intake, you can put your thumb on the headers while it's running for a few seconds easily before it's too hot...
Mild steel cannot take the thermal stress from the extra heat/cool down cycles that will occur with wrapped headers, regardless of moisture or rust they will eventually crack.... Only stainless or exotic metals like titanium and inconel can take that cycling.... The only problem is if you have a beautiful set of SS or titanium headers, do you really want to hide them under header wrap?😁
EDIT: Dug up a few pics of the Swain Tech Coating, White as delivered..
View attachment 65768View attachment 65769
After paint: Black Header Silver Intake...
View attachment 65770
Click to expand...
I had read an article on this, trying to find it but the summary is basically ceramic coating that are pushed by most people are not very effective at heat reduction. There are a few that like this one here are effective, the one that was most effective went on almost like blown insulation it was very think and did a very good job of shielding heat but was very brittle and would scratch off easily.
 
KBabcock said:
I had read an article on this, trying to find it but the summary is basically ceramic coating that are pushed by most people are not very effective at heat reduction. There are a few that like this one here are effective, the one that was most effective went on almost like blown insulation it was very think and did a very good job of shielding heat but was very brittle and would scratch off easily.
Click to expand...
That makes sense. I've also tried some ceramic coatings that are made as a "DIY", where it doesn't require baking in a oven. It is referred to as "air cure", meaning it cures in a couple days of just sitting. I found it to be extremely thin (like water) and not the greatest coverage or adhesion. I never tried testing the temp reduction it offered so I can't say. But I'm inclined to think it falls into the same category as what you described.

One of the most common/popular brands of ceramic coatings is "Cerakote", made by NIC Industries in the north-west. They started out making it for guns, I guess to keep the barrels from getting too hot. For that application it needs to be really thin to avoid interfering with the fitment of parts. The stuff they supply to other industries (like automotive) is the exact same product. Therefore I imagine it also might fall into your description as less effective. By the way, it was their "air cure" product that I tried.

There is another manufacturer of ceramic coatings that is a small company producing a handful of products. They started in SoCal but have since moved to an area outside of Vegas. I know the owner and he's mentioned there are differences in the formulations for various uses. However I don't know any details. To be honest I consider them to be something of a 'home-brew' product and have never tried it.
 
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