Heat Wrapping Headers
 

Can somebody give me advice please. MY95 WRX JDM wagon.

I am fitting a set of standard exhaust headers which have been ported and am heat wrapping them.

This might be a stupid question but should I leave the heat shield on to protect the flexible section? If so, should I heat wrap the pipe first or wrap over the heat shield?
:wonder:

Many thanks.

Anyone please?

If you want expert advice PM Harvey that's what he does Heat wrapping and porting, he is a member on here and very helpful. If you want my advice I would take off all the heat shield and wrap and wrap the flex making sure its still got a little play for movement. Make sure you use the good quality wrap and use plenty of ties. When applying the wrap it needs to be damp but not wet and keep it tight as possible when doing it.
Hope this helps :thumb:

Thanks for that I knew about using wrapping damp but wasn't sure about the heat shield.
Is it best to use wire with the special pliers or the SS ties?
Thanks for the suggestion to PM Harvey. I thought he might have picked up the thread.

It's perfectly fine to wrap over a slip joint or flexi joint.

You can leave the standard heatshields off, once the manifold and uppipe are wrapped - The wrap will keep more heat contained than the standard shields.

I always secure the wrap with stainless lockwire, using a minimum of 0.8mm thick wire, curling the finished wire twists over, to aviod stabbing your hands when fitting the manifold :)

I think the stainless steel ties are better, the only down side they are a little more expensive than using wire, Look on eBay they do loads on there and if you message them they should do you a deal if your purchasing a few.

Either one or the other but not shields and wrap. To wrap properly the lugs or posts that mount the heat shields are best removed. Properly wrapped will be far more effective than refitting heat shields.

Here are the instructions based on my practical experience:

Heat wrapping is not difficult if you follow these instructions but you cannot expect to achieve a professional standard on your first heat wrap operation unless you follow these instructions exactly.
Because of the cost of heat wrap ties I only use stainless steel tie wire and generally the more ties the better the job.
To use tie wire it is best to have a set of tie wire pliers/ lock wire pliers which makes twisting the tie wire that much easier.

The DEI heat wrap has a stitching down each side to show the amount of overlap required and you should follow the overlap guide stitching where possible. This is not possible on the inside of tight bends.
The wrap should be applied damp but not wet. There are chemicals in the wrap to help it bind and these should not be diluted out. You can use a house plant leaf sprayer or any other water aerosol/spray to dampen the wrap or set the tap to a very fine trickle and run the wrap through the trickle quite quickly. In a few minutes the water will have spread evenly throughout the fabric to dampen it. Do not let the impregnated chemicals run out.
Wrap from the bottom to the top with the appropriate overlay.
Keep the wrap as tight as possible.
Remember that the wrap on the outside of a bend requires more material and therefore the corresponding inside of the bend will have big overlaps and on a tight bend this can be almost 100%.
Do not cut the wrap in to short lengths but try to apply in continuous lengths and certainly 15 feet at a time.
The rolls come in 50 foot by 2" .
A 3" open neck downpipe wll generally take three quarters of a roll of wrap done properly.
Remember. Keep it tight.
Tie at the end and then every 3 or 4 inches but on curves or corners you can increase the number of ties.
The tie must be applied while the wrap is still damp.
Cut off any strands and loose ends.
When put on the car first there will be a lot of moisture released from the wrap. Do not be alarmed.
On damp and humid days the wrap will absorb moisture so again there will be a lot of steam.
It is quite normal for the wrap to smell for three weeks after applying as it dries through thoroughly.
Happy wrapping.
If you need further assistance please do not hesitate to contact me.
Regards,
Harvey Smith.

We have just removed a set of headers and uppipe from a car that we wrapped over three years ago. The wrap is in very good condition. Two small areas need touched up where there has been some physical damage from road debris, a lump of wood or a bolder perhaps. So wrapped properly it can last for years.
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Thanks for that Harvey. Great guide.

no point leaving the heat sheild lug's on as harvey says as you just end up with screaming hot lugs poking through the wrap and the whole point is to keep the heat in.i got some spray on silicone based waterproofer from demon tweeks for mine, they don't soak up water like just plain heatwrap does,works a treat.i also put the front heat sheild back on after wrapping the flexi pipe just to make sure it didn't melt the loom that runs along the front.defo use the wire like harvey said as those steel tie wraps work loose over time.

Am i correct in thinking the best way to dampen the wrap is when it's still rolled up and let it absorb the moisture? Would be a nightmare with 50M of wrap unrolled in the sink!:D

As regards dampening the wrap, it is in the guide above.
I would not run with the heat shields back on :
1) The wrap is there to keep heat in and the external temp. of wrapped headers will be less than that of those with heat shields.
2) You don't want too much temperature which I guess is unlikely to happen in that section but DEI are very clear that you are not to double wrap manifolds. I think there is a limit to the heat the wrap can take and in my experience when I double wrapped some stainless headers just to use wrap up over a third of the headers in the early days it was the double wrapped section that eventually failed.

I used to use the Thermal Paint Spray but stopped using it when I realised it caused the wrap to go brittle and in time it flaked off. If anyone wants some of these aerosols some used, some unused, I am happy to get rid of what is here. There are about half a dozen, £10 plus £8.50 postage overnight.