J'ai entendue dire que le wrap peut causer quelques problèmes de EGT.
A part garder le uppipe plus chaud pour un meilleur spooling de ton turbo, il y avait trop de désavantage tant qu'au reste.
Voici quelques exemples:
nhluhr a écrit :the problem with wrap is it retains the heat in the metal - which bakes the headers mercilessly. Many header manufacturers void your warranty if they have been wrapped. Sounds serious.
Coating, on the other hand, is applied to the INSIDE of the pipe (as well as the outside) and thus prevents the majority of the heat from ever even reaching the metal.
You also have the issue of flammability (oil-soaked header wrap has been blamed for more than a couple fires), corrosion (wrap retains moisture), thermal expansion (wrap makes the headers grow more since the metal gets hotter), durability (wrap deteriorates over time, getting brittle and eventually flaking off), and fitment (wrap is nearly impossible to apply to some headers and makes tight clearances impossibly tight).....
http://forums.nasioc.com/forums/showthr ... t=wrap+bad
SilverSurfer04STi a écrit :I think the fire story is from Clark at Kingpin. He knows a guy that this happened to IIRC. Burnt up his whole car and it was totalled. As bad as that sounds, I remember a part of the story which is often forgotten. The car in question had just had an engine swap or turbo swap (I don't recall which, but I thought it was engine) and while doing the swap quite a bit of flammable engine fluid got onto the header and soaked into the wrap. Somehow this caught fire during some heavy usage and the car was wrecked. Remember, if you wrap your headers or other exhaust components, just be careful not to get any flammable liquids on the wrap. I think this situation is easy to avoid if you are careful. After all, how many times have you heard of this happening and how many people use wrap???
I think a more realistic thing to be afraid of is the wrap causing the welds and steel to corrode more quickly. While I think this does happen, if you have 304 or better SS I don't think it should be much of an issue for several years (if at all), even if you live in an area with alot of winter salt (like Illinois). After wrapping, make sure you use the after wrap treatment spray which makes the wrap hard and liquid absorbant resistant. This should prevent corrosion alot more than just using wrap. Yes, welds crack on some wrapped headers, but welds crack on unwrapped headers too...
I've been running wrapped and sprayed GTSpecII headers for a year with no problems.
http://forums.nasioc.com/forums/showthr ... t=wrap+bad
What about ceramic or other heat wrap coating?
Pros:
Increased heat retention, which is beneficial for exhaust flow.
Reduces underhood temps, which decreases IC heatsoak.
Cons:
Additional expense.
Additional lead time, in the case of coatings.
Increased heat retention, which accelerates metal fatigue, especially at weld joints.
No proven HP increase.
If you plan on using a coating, ensure you are aware of what impact this will have on your uppipe warranty if applicable. Coating or wrapping your uppipe can void exhaust component warranties. If using a ceramic-type coating, ensure it's working heat range is above the known uppipe EGT. EGTs can be as high as 1400-1600 degrees in the extremes. Some normal coatings are not rated to this temperature level.
http://forums.nasioc.com/forums/showthr ... t=wrap+bad
mick_the_ginge a écrit :I wrapped my HKS exhaust headers before I installed them onto the car, including giving them a good coating of exhaust wrap spray. They were installed on the car for about 1 1/2 years which included about 20+ track sessions at PIR.
Recently while upgrading my block I decided to change from wrap to a ceramic heat coat.
The exhaust wrap was in a bad way, it was just falling apart on touch
As you can see the exhaust wrap not only degraded but you can see that it kind of eats into the metal itself. I knew it would do this, but it's amazing to see it up close.
With all the wrap off I also spotted a crack in the welding
Not too much of an issue I had this repaired
I used a local company in Portland Oregon to apply a "high temp" ceramic coating to the headers. I must admit they turned out great
They are coated inside and out. The ceramic coating is very thin but supposed to reduce under hood temps significatly.
Here you can see them installed in the car
What I did not expect was what happened next. First track session and I noticed a smell of burning plastic....... Bugger, the bottom of my radiator fans melted!
As you can see from the above pictures the headers do not touch the radiator, but it is pretty close. 20+ track session with exhaust wrap no issues, one track session with ceramic coating and melted radiator fan.
I am sure for street use the ceramic heat coating is fine, but for the track I am about to re-wrap my headers....
http://forums.nasioc.com/forums/showthr ... t=wrap+bad
Comme vous pouvez voir, il y a des pro Wrap, et des contres.
À vous de décider.
The Possession of anything begins in the mind. - Bruce Lee.
et au idle il me donne 900 ou 1000degré . Lorsque j'arrete le moteur l'aiguille du cadrans reste jammé sur le 800 ou 600 degré elle ne descent plus a 0 comme avant 
vendu 
