I saw this interesting article about why you shouldn't wrap headers a few days ago. HRP http://www.centuryperformance.com/exhaust-header-heat-wraps-do-not-use.html
Header wrap was/is popular with the turbo boys; they want to retain the heat as that makes more power. For everybody else, a bad idea.....
Header wrap DOES work well for under floorboards area of exhaust pipe where heat is an issue, such as near master cyl or fuel/brake lines.
Excellent read, however, I wrapped the headers and pipes to behind the transmission in my 36 sixteen years ago, back when I didn't know better. 327, shorty headers, turbo 350 trans, I did it to keep out any residual heat from the engine bay, still intact, still wrapped, never been apart. And, it does keep the heat down, I suspect that I don't push the old girl hard enough to eat the pipes, but it has worked for me.
Of course he would say that he is trying to sell his coating LOL. Every car I have had since 1971 has had header wrap like from these guys and drag raced them all. http://www.thermotec.com/products/products.html Disclaimer I have no connection with these guys what so ever just like their product. If you read their Faq section you can learn why sometimes there are problems BUT they are INSTALLER CAUSED by not following instructions. My latest OT car has had this brand wrap on for 8 years with no rust, no replacement, no problems at all. And no problems with the rest of them either.
Except for one little flaw in your first statement ~ Century Performance does NOT "sell his coating" , they don't do coating at all. They are a Speed Shop, not a coating company. You say "Every car I have had since 1971 has had header wrap like from these guys and drag raced them all" ~ Hmm, Thermotec has only been in business since 1987 and DEi, the other large supplier of header wrap started in 1995. Maybe there were other's before them, not sure who they would be. Also you say you "Drag Raced" them. A drag car is a different scenario than a street car as it is subjected to very little heat time and not the environmental issues of a street car with wrap. I have been in the exhaust header business a long time and I can tell you that not only is the science of what happens, as described in that Century article correct, I can tell you for a fact that during my time with Hooker Headers we received many headers back that were destroyed by wrap having eating the metal away completely. I still see it today occasionally on some of our Doug's Headers, but it appears more folks have gotten the message. As always there are exceptions to every rule, and it's great that you have gotten away with it, but that does not mean that everyone else will be so lucky. That is good information for people to read and then make their own decision. I can also tell you that just about every header manufacturer on earth says header wrap will void the warranty ~ and for Good Reason!
I first saw the asbestos wrap used on airplanes, but I think the first time I saw it on a race car was in the late `60's. hope that helps.
OK, I looked at the FAQ from your link - Here is what is there; FAQ's Increase horsepower - Wrapping your headers with Thermo-Tec Exhaust Insulating Wrap can increase horsepower Wrapping the headers maintains exhaust gas heat within the header. This translates into more exhaust flow due to maintaining exhaust temperatures as it flows out of the engine. By improving the scavenging of spent gases, the engine breathes more efficiently. This reduces contamination of gases, thus allowing the engine to develop more power. Wrap required for headers - How much wrap is required to do a set of headers How much wrap is required to do a set of headers? Guidelines recommend: (1) 2 inch x 50 ft.roll for a 4 cyl., (2) 2 inch x 50 ft. rolls for a V6 or V8, and (3) 2 inch x 50 ft. rolls for a big block or 180 degree set of headers. Nowhere does that address anything about the damage wrap Can cause to headers I was not dismissing the potential power benefits, only that it is hard on the life of the header.
Would header wrap also be a bad idea for exhaust pipe; as I have a section that comes very close to master cylinder under the floor and thought I would wrap it? Whoops, I now see Gearheadbill already answered my question.
When got my Lake headers, I played with the thought of wrapping them. My grade school science lessons kicked in and it didn't seem to be a good thing to do. Exhaust heat makes the pipes hot. When the pipes cool, they'll probably cool quicker than the wrap. That difference in cooling creates condensation. My thinking would be the condensation would be trapped or absorbed in the wrap. Condensation is moisture. Moisture on metal creates rust. Rust is bad. My theory may not be 100% correct, but it seems like a likely occurrence.
Some guys on a motorcycle forum I frequent tried wrap to cover up the rust on their OEM pipes. The wrap accelerated the rusting and the pipes rotted right in two. Bit of a bummer as these bikes are 'vintage' and replacements are no longer available.... Plus the added bonus of it smelling like a stinky dog when it gets wet....
I just read most of HRP's link. I was aware of the obvious rust that can be caused by the wrap. I had no idea it held in so much heat that it would destroy the integrity of the tubing....even S.S. I think I'll stay away from this stuff. I've got a lot of time in my stainless headers. I don't want to do it again. I was thinking of using it on my current project just to keep kids from being burned, but I think I'll just stand guard for 10 minutes or so after parking if there is a good chance of little ones wanting to have a look.
Short sections are not usually a problem, although that section still will deteriorate faster than the rest. I just replaced a section of custom mandrel bent exhaust on a 40 Ford I built for a customer that was ceramic coated and wrapped because it had rotted out from the inside after 7 years - the rest of the exhaust was fine.
Adults too. I had a guy GRAB my headers and look surprised that a hot exhaust would burn his hand. He said I should have warned him and I asked if he would have grabbed a motorcycle exhaust. Again with the stupid look, as he walked off.
Wow...no common sense. Maybe that'll teach him not to put his hands on other peoples property. No, it probably won't.
Don, I swear I have no idea. I had just pulled up. I hopped out, he said my car was cool and grabbed the header. By the time I said, no, he was pulling his hand back looking stupid. I laughed about it later. Thought about the first man to discover fire.
I was gonna wrap mine, but my freind talked me out of it. His headers got brittle & cracked over time. They got so hot they would actually relight any raw fuel in the headers
Wow, this thread got steered in a different direction. I did my own research and found the heat wrap materials date back to the 1800s in industrial use, still not sure when they were used widely on cars but have found packards and such in the 30s with wrapping.
OK my bad for not reading it yesterday. BUT it used to have the info you were looking for it looks like they are in the process of re-building their site.
Haha, well it's a good thing you answered your own question. We have a tendency to go off track here It's HRP's fault this time.
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