I will be removing the asbestos heat shield from the firewall and gearbox tunnel soon and am toying with the idea of replacing. A chunk of it has broken off at the bottom right side and there is an intact one available currently, I need to remove it to paint behind it thanks to brake fluid spillage by previous owners.

Replace like for like ? - or I've been looking at some of the other stuff available such as this - I'm interested in exploring modern materials that weren't available when the XJS was created - prevent starter, sterering rack and anything close being cooked by exhaust.

I'm not interested in soundproofing claiming to be heat shield - most of that is open cell foam based (water trap) and the best I've found can only stand 190°C - perhaps a closed cell type covered in DEI ?

 

Ben
The heat shield is compressed woodchip stuff, I believe, certainly that is what it looks like.
With heat shielding, air gaps between it and the body being protected are crucial. The OEM shielding has these, and if you can find a modern material that is rigid and can be similarly mounted, then it might be better.
If not the OEM shield does a very good job indeed, and anything stuck to the body would be unlikely to be as effective.
Any soundproofing is far better on the inside, but not until you have painted the inside of the floorpan with POR15 or rust bullet. The floor pans rot from the inside outwards at least as fast as from the outside inwards, as 2 inches of carpet and factory sound felt retain enough moisture from damp or wet feet to do the damage over time that is often never seen.

Grant swears by removing the OEM foam from the gearbox top, as this allows far better airflow out of the engie bay. I followed his advice and it works! This is where I did use some modern stuff, stuck to the tunnel and the gearbox

 

I've not noticed anything on top of the box is that the lower picture that is stuff to the top of the tunnel - perhaps will become aparrent - looks like you dropped your box as a separate task too and yet I saw images of you pulling them out together ?? - I also thought I saw some work you did in a similar area to mine - right hand side but couldn't find it, appreciate the pics.

I'll chase down the replacement OEM item because what you say makes sense and is what I was thinking, I did wonder thought whether the new materials would eliminate the need for the air gap. I do intend to ceramic coat the manifolds, I'll be putting an extractor exhaust from A6 engineering in now - I've come this far - but I'm not sure how to stop that radiating heat - it's kinda pretty - I'll be putting a thermal blanket on the starter.

The interior is so far off (probably this time next year) with all this other stuff but I'll take your comments on board.

 

Yes, I lucked into a new box and fitted it separately. Not as hard as I feared.
If you want to be super-cool, then some gold stuff stuck to the OEM shield would be even better!
The OEM heat shielding fitted above the exhaust pipe run each side of the gearbox will be fine with the TT exhaust.
The key, however, to a cool engine bay and adequate airflow through it, (and this is controversial to some) is to remove the foam pads round the radiator, move the horns out of the airflow, keep the top of the gearbox area clear of foam padding, and remove the seal along the vertical edge of the radiator top closing panel. Also if you go to electric fans, ditch the shroud and ensure the fans are well mounted 1/2 an inch from the rad.
In my own case I proved that the cooling problems are airflow problems, and I made an extra slot in the bumper. This made the coolant temp after a hot stop in traffic, for example, drop precipitately on getting moving again. Now I understand not everyone wants to do this, but if you do not believe me, unbolt the front bumper and go for a spin on a hot day. This means the engine bay gets far better airflow too.
Pics of the engine bay work a requested, plus the slot!

 

I think that they knew there were airflow issues, that's why there are warnings about running without the chin spoiler, it's very clear now I have all the radiators out that unless you're moving the sides of the engine get nothing especially the right hand side where the starter lives. If I can get my hands on another bumper I may try that mod.

I was wondering what to do about all that spongy rust generating nonsense because the books say to be sure to replace it - based on how readily it soaks up water I'd rather not put it back I've already binned the stuff I removed.

I'll probably be poking thermocouples here and there and running trends on them just for curiosities sake - program up an Arduino Mega or similar.

I've already obtained a different oil cooler that seems on the face of things to present less air resistance from a place in Northampton - they do three different kinds - Standard, High Efficiency and Race. Supposedly even standard is 30% more efficient but like so many things the numbers are never posted to justify the claim.

 

This is what I have used on a couple of MGB projects and I have noticed a big difference on the amount of heat that gets in the cockpit on both a GT and a roadster. It's not cheap but it's not expensive either and seems to work very well.

 

The good stuff never is .... DEI is about £24 for a similar size, it is much thinner but not able to tolerate the high face temperatures that is - I may get some of each and experiment - things that are stick on make me nervous (water wicking) but I may be able to use this on the existing heat shield.

 

I removed the engine and the large tunnel section of heat shield is fine, the side pieces are not servicable though fortunately new ones are available at the moment.

There's no corrosion at all hiding in their, it is all surface rust and 100% down to carelessness with brake fluid - you can see the damage is where it has run, the main damage is where the fluid has soaked into the heat shielding /. sound proofing below the servo and stripped all paint under it - I'll take some pics when I start attacking it.

Also popped the expansion valve out - I'll be replacing all the A/C system - got a friendly AC man that's going to come and flush the evaporator prior to re-assembly. So much easier with no engine in the way.