Guys,
ha sanyone had any experience with exhaust wrap?
I have just been surfing the net and are left totally confused. Some slag it and point to premature exhaust manifold failure and increased internal engine temperatures which can lead to terminal failure ( Guy Croft in particular ) yet others sing its praises and point out that as long as the overlap is keep to 1/4" and the wrap is not used excessively then it is a good thing...
This application will be for a race car in an attempt to reduce underbonnet temperatures especially with the carbs sitting just above the exhaust.
Any thoughts/comments/personal experiences?
Cheers
dave

That's all correct.

* Reduces underbonnet temps
* Also leads to metal fatigue over the long term

Does not generally lead to engine failure as long as you have a good exhaust system.

i have had it on my l20b for 4 years with no problem. you need to paint your extractors, wrap them and paint the wrap

You could always ceramic coat the extractors and run a heat shield plate between them and the carbs

Thats what I did on my racecar

Extractors? He was asking about "exhaust manifold failure". Yes, cast iron exhaust manifolds often crack some time after being wrapped.

I recently bought some exhaust wrap with the intention of using it with my turbo upgrade on my Patrol. The instructions on the package clearly state that you must not use it with cast iron manifolds as they can heat up and crack quite quickly.

My exhaust dude even poo-pooed it with my new exhaust for the Patrol. In his opinion if you want to reduce under bonnet temps, ceramic coating is the only way to go. In his opinion, all the wrap does is cause the pipes to fail earlier. Aparently, since the wrap keeps the heat in the pipe, it causes the metal to "fatigue" faster than normal.

So if you are trying to reduce under bonnet temps, go cermaic coating.

ceramic coat cheap or big dollars??, hoo and where (nsw)

I have used these guys before, Not bad pricing. I had my A-series GX exhaust manifold coated there...

Ceramic coating

cheers

Sorry Guys, I should have been clearer- its for exhaust extractors, not cast iron manifolds.
I have considered the ceramic coatings but to be honest my headers are just off the shelf items and I'm not sure that the cost of coating can be justified on them hence the wrap but the more that I get into it the more nervous I am getting about using it.
Dave

there is so much crap around about wrapping an exhaust, and 99% of it just isnt true.

First up - why wrap?
Mostly it is done to reduce underbonnet temps, and particularly for non-crossflow head designs such as the datsun (where the carby is on the same side as the exhaust) Now, while this is definately the case, similar results could be obtained using a simple heat sheild, and getting one of a late model car and adapting it to fit would probably work even better. My pick would be a heat sheild off any car with lots of plastic under the bonnet, such as a commodore.

HOWEVER!
There is also a fairly massive advantage to be gained that is quite often overlooked, and that is the one of keeping the exhaust hotter. This is because, as those of you that still remember basic high school physics will atest, a hotter gas has a much lower density, and ergo, can be kept at a higher speed a lot easier. Not only does this make for a free flowing system, but it can actually increase the pulse scavenging effects of a well designed set of extractors, which, in turn, can assist with port air speed and cylinder filling throughout the rev range.

As far as the argument about making pipes fail faster - its a crock IMO, if the wrap is applied correctly.
Exhaust systems rust. Deal with it. This happens because when an exhaust system cools down, it condenses moisture from the atmosphere, and this moisture can actually penetrate all the way through the (relatively thin) wall of an exhaust pipe. Obviously fibreglass wrapping will help to trap this moisture against the pipes and accelerate this process, BUT ONLY IF YOU DONT SEAL IT PROPERLY!!!!

and herein lies the problem - the amnount of people who buy and apply the wrap, then stand back and congratulate themselves for a job well done amazes me. For the sake of a couple of coats of exhaust paint, you could extyend the life of your system indefinately.

I wrapped a brand new set of extractors for an XD falcon I did up over a decade ago, and that exhaust system, in its entirety, is currently serving time on its 4th succesive car (the first 3 are now pushbike frames in south korea, I suspect) and the extracors are still sealed tight, and still in their original wrapping.