Thread: Thermal Wrapping/Thermal Shielding of Exhaust

Originally Posted by travelrover

Hi Jon

Just read your earlier thread. Sounds like a great plan. Do you recall the dimensions of the magma wrap? Was it 2" wide? And what length? Would 5 meters be more than enough for 110?

Cheers - Simon

It's been a while since I did it so I can't remember for certain. I think one roll of the 2" was enough. The trick is to not overlap it too much.

Also when applying this stuff underneath a vehicle you really need to wear gloves, a mask and eye protection. The small glass fibres get everywhere and can do nasty things to your lungs - and you'll be lying underneath it.

Cheers,
Jon

Originally Posted by 123rover50

I was in town yesterday getting some 8mm studs for my new turbo manifold and asked the exhaust guy about this. he did not recommend it as it traps moisture and promotes rust. I said I had stainless and he said thats worse as the heat buildup makes the stainless prone to cracking.
So maybe I will make a heat shield and more underfloor insulation.

Your exhaust guy is half right.

A wrap can trap moisture if left sitting for a while. However any run that gets the exhaust warm will evaporate the moisture pretty quickly. Also, being stainless steel its pretty much irrelevant.

Heat cracking can be an issue in stainless steel. The crystal structure of any steel changes depending on temperature. Time spent at an elevated temperature as well as the rate of heating and cooling affects this structure. Different structures have different properties - this is how heat treatment works.

If you look at a TTT (time, temperature, transformation) curve for stainless you'll see that pretty much nothing happens below about 500 degrees C. Cracking can be an issue in high temperature applications, such as when welding and also in the headers in a turbocharged engine. However, the temperatures your exhaust sees after the turbo and cat should be well below that.

Cheers,
Jon

Originally Posted by 4xsama

Re: Trapping moisture its a good point but would this be more relevant if the vehicle was only doing shorter trips and the exhaust didn't have time to heat up adequately?

the trapping moisture thing gets floated just about every time this conversation is had.

never had the issue on any of my vehicles and i had one sit for 4 or 5 years while i worked on it so i personally think it's a furphy based on my experience and i live 3 streets from salt water...

as for stainless steel, you never wrap stainless as it will crack due to vibration and the constant annealing.

i always do a 50% lap so it ends up double the thickness of the wrap itself.

Can I ask how the wrap is actually attached - does it just stick on?

Originally Posted by DiscoMick

Can I ask how the wrap is actually attached - does it just stick on?

The start of the wrap is held tight by the overlapping section at first, before stainless steel zip ties are used to hold it in place.

Other end is also zip ties.

It's important to completely soak the wrap before applying and really stretch it out while you are wrapping to make sure it doesn't come loose when it gets wet later.

Originally Posted by JoeFriend

The start of the wrap is held tight by the overlapping section at first, before stainless steel zip ties are used to hold it in place.

Other end is also zip ties.

It's important to completely soak the wrap before applying and really stretch it out while you are wrapping to make sure it doesn't come loose when it gets wet later.

Am assuming soaking in water JoeFriend?

Originally Posted by JoeFriend

It's important to completely soak the wrap before applying and really stretch it out while you are wrapping to make sure it doesn't come loose when it gets wet later.

i've never used water and have never had an issue with it unbinding....

Yes, just soak in water. It helps to you to stretch the wrap when you apply it.

Clearly Inc has a stronger grip and more muscle than me!