Has anyone used header wrap on their 8? I was wondering if this would help with controlling under hood temps and raising intake temps. Also a side benefit would be the increase in exhaust flow.

 

Have you tried a google search to see the pros and cons of header wraps? I've seen some negative stuff regarding rust and internal deterioration.
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Ship Sale

 

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.

Also, Exhaust components are not a problem due to the added flow of the exhaust. Increasing flow also increases the amount of heat extracted from the engine and manifold.

Using only 1/4 inch overlap draws the heat from the motor but still allows the heat to evenly dissipate through out the system. If you use more than 1/4 inch overlap you may cause fatiguing due to hot spots in the tubes.

It just needs to be done properly. I have heard of the horror stories too. I have to imagine though, due to the extreme heat from rotary engines that our headers would be able to hold up.

 

1. Header wrap traps water which accelerates rust from the outside.
2. Header wrap does nothing to protect the inside which can be "eaten" away by the hotter exhausts.

Which horror stories have you heard and why do you consider them unimportant?
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Mazda Mazdago

 

I have seen people not properly wrap them to seal out the water and moisture. They wrap them with too much material. Thinking the more the better. You should only use 1 layer of the wrap. Which I think would allow the moisture if there would be any to evaporate.

 

1st- Several guys on the Miata list had their headers prematurely deteriorate from wrapping them... that was enough for me to be wary of them.

2nd- if you look at the location of our headers, I don't think they contribute much to underhood heat due to the design of the rotary- they're way down low by the bottom of the motor, unlike just about every piston car... so I don't think it's a concern.

 

Another thought: if the header wrap is letting less heat escape through the headers, the heat has to go somewhere--> down the exhaust pipe into the cat. So the cat is going to run hotter, which--according to Mazda and their infamous (ahem) Cat Friendly "J" PCU flashes--is bad.

Last year my mechanic showed me a Big @$$ motor home with a 440 in it. The owner had wrapped the headers to keep the heat down in the engine compartment. This resulted in the downstream exhaust pipe being so hot that it melted and deformed the fresh water storage tank (empty) that was near it.

 

I don't see any scientific proof that a wrapped header will force more heat to esacpe doen the exhaust pipe.

If that's your theory, why don't you just wrap the whole mid pipe?

 

Here's a simple thought experiment that might suffice:
1. Header heats up from exhaust gases.
2. Header normally radiates some of that heat.
3. Wrapping or coating the header reduces the amount of radiant heat lost.
4. That retained heat has to go somewhere. Further down the exhaust is the mostly likely direction.
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Lovely Wendie99

 

Why isn't it wrapped from the factory ????

 

Exactly.

And that is one gorgeous 240Z ^^^^^^^ Damn!

 

wow nice Z :D i likes ...i likes it a lot.

so dont' wrap the header...can' tyou just coat it...not rust problems there, granted i here coating it (ceramic?) isn't as effective as the wrap...but then it may not have all the problems...just a thought :D

 

I don't think the heat would be a problem as the hotter air will be expelled much easier due to the properties of hot air (thinner). There is different types of header wrap out there, ones that totally trap heat, ones that allow some heat to escape. As far as our cat's are concerned, the reason why our cars run so rich are because the cat's can't take the extra heat for the warranty length. That heat is going somewhere.

 

^was't aware there were different types of herder wrap out there (i new different companies but wsnt' aware of different types). guess you elarn something new every day :D

 

Why should it be? I'm sure factory engineers took into account stock exhaust manifold temps (along with everything else) in their design. It's then you add a turbo and its increased heat that thermal barriers become worthwhile.
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AVANDIA CLASS ACTION

 

Different companies use different wrap materials. Mostly just for the amount of heat that is trapped or released. There is Ceramics Coating, Woven Ceramic Yarn, and Silica based fabric. The Silica based wrap conducts heat across hot surfaces instead of through itself. Has the lowest surface temperture of the three. The Woven Ceramic Yarn acts like a heat shield and conducts heat through itself, resulting in higher surface tempertures. The coating only acts as heat shield, it doesn't do anything with the heat. One other side benefit to the Silica wrap is that it does collect moisture. Also, there are alot of cars that have some kind of a heat shield to reflect that heat down toward the road.

 

I consider a heat shield and heat wrap two different things.

I'll go along with the idea of a heat shield to deflect the heat in the down ward direction.

I don't believe in the heat wrap.

 

Header wrap has it's advantages and disadvantages. first off I have no idea how you are going to wrap a stock RX-8 exhaust manifold with it. The shape is too weird. With a set of aftermarket headers you could do it though.

Before stainless steel and ceramic coatings became popular, header wrap was widely used by race teams. Header wrap does keep more heat in the exhaust pipe. More heat in the system is more energy that stays in the system which in turn translates into more gas velocity down the exhaust pipe. This aided in the scavenging effect of a good header system. Using header wrap after the header downstream of the it didn't need to be done because almost all of the tuning and scavenging of the exhaust was within the header. The key was to optimize it. Header wrap was relatively cheap especially compared to more exotic materials such as ceramics and stainless steels.

The downsides to header wrap are that it does trap moisture against the pipe. For mild or carbon steels this means that corrosion will set in faster. The pipes have also been known to deteriorate faster on the inside. This is due to the added heat within the system. these types of steels aren't as tolerant of the high temperatures and will break down faster. Since this was primarily used on race engines (and made it's way to the street) longevity didn't really matter. Make it through the race or the season and you were fine.

Along came the more expensive and more tolerant stainless steels. Stainless does a better job at holding more heat within the system than carbon or mild steel tubing. It is also much stronger and resilient to corrosion. Stainless does many of the things that header wrap was intended to do.

Ceramic coatings also do the same thing that header wrap is supposed to do. It insulates and protects the metal from the higher heat. The good thing about ceramic coating is that it can be done to the inside and outside of a pipe. It can also be used on any type of metal but is most preferred on mild steel, carbon steel, cast iron, and aluminum.

Header wrap and ceramic coating are not recommended on stainless steel. This has to do with the thermal expansion properties of stainless. Stainless expands more than many other metals when superheated. Many people use mild steel exhaust flanges with stainless steel exhaust tubing and report that the weld joints crack easily. This is because the stainless wants to expand much more than the weld joint or the flange does. Something has to give. Special care needs to be taken when welding stainless to stainless. The weld joints need to be back purged with argon gas to make sure the weld is strong. An improper weld joint here may crack easily also. Header wrap and ceramic coatings on stainless steel aggrivate this by holding more heat into the pipe whihc causes it to expand even more. This is alot more stress on the weld joints and even a good one may break under these circumstances. For this reason you should not use wrap or ceramics with stainless. Some people still think more insulation must be better. Stainless pipes that have been ceramic coated and header wrapped may sound like a great way to go but will fall apart very quickly.

Header wrap does have it's uses but it is really more of a low tech solution from the past in a high tech world. You just need to know the consequences of using it.

 

RG,

So then from your post. You would say that jethot coating a set of stainless steel headers would not be in your best interest? Aka it would be better to just leave the headers alone, and let the properties of the SS do its job.

I ask because a set of beautiful SS headers/ypipe just came out for the 6. We were thinking that it would be in our best interest to jethot coat the headers, to help with the insane amount of underhood temps. Additionally, because of the proximity of the Y pipe to the alumnium oil pan, we were thinking it might be helpful to wrap the area which extends around the pan itself to try and keep the heat from radiating over and effecting oil temps.

 

Alot of people still do it but I personally don't recommend it. Typically when you see companies offering different header types (any vehicle), the cheap ones will be mild steel possibly with a ceramic coating option and the upper end ones will be uncoated stainless. It would be best if you could fabricate some heat shields up to insulate the problem areas. If you do decide to use any wrap or ceramic coatings, just understand that there may be consequences later on down the road someday. You might get lucky and nothing would happen. Like I said, many people ceramic coat stainless parts and swear by it. I'm just not a fan of it.

 

I'm a noobi at this stuff but to me it seems that using both would b all pros and no cons ?? .... The ceramics coating would prevent water from rusting and degradeing the pipes and the wraps r more effective at sealing in the heat keeping our engine bay cooler and giveing us better exhaust flow !!?!?!?! ... ??? Is there an unspoken rule or reason y useing both isn't a possibility??? I can't imagine I'm the first 2 think of this ??!?

 

the pros & cons were discussed in this very thread when it was fresh meat 9 years ago

 

Apparently the FNG failed to read this post.

 

;/ ACTUALLY ...the ******* New Guy did read that that post ya peckerhead ;/ ... I'm asking y not use BOTH on the same exhaust ... The wrap works better for heat containment but the ceramics keep out rust right ... So y not ?? Sure it's a little exspensive but I mean it's a better/more dependable set up that way right ??? Is there any reason u couldn't use them both on the same exhaust ??

 

Kallen i literally just read the post right above yours and i know the answer to your question. So how are u still not clear? You can use both if you so choose to. It WILL break down still because of the high heat. So in all reality your just wasting money.