Replacing the exhaust heatshield with Nimbus

Exhaust Heatshield on the Elise S1 looks like cardboard with a silver toplayer.

This material degrades over time and on a lot of cars, it got damaged by replacing exhausts etc. When the aluminium top-layer damages, the lower layer seems to pulverise which completely discards the function of the material. Besides, when upgrading to another (higher power) engine, a lot more heat is generated in the exhaust bay, but also in the area between the engine and the exhaust bay.

A good way of getting rid of this (potential) problem is to replace the OE heatshield with a mixture of Nimbus GII and Cirrus GIIIx heatshield material.

To understand why to use both, you'd have to understand the characteristics of the material:

Nimbus Gll Material Properties

<tbody>

   I've removed the old heatshield from my car (the cardboard stuff with silver lining) and replaced that with Nimbus. The real hot area's (which are manifold and cat) have been protected with Cirrus.

   Nimbus and Cirrus are different.

   Nimbus is a two layer heatshield which is perfect for general use. It's good to shield an exhaust or -as I did- as a replacement of the old cardboard heatshield.

   Cirrus has an extra layer which makes it ideally suited for the really hot area's.
   This material has been tested with a 'radiation plate' 1 square meter which radiated 800 degrees C. They placed the 'receptable plate' (another 1m2 plate) at 2.5 cm and placed a sheet of Cirrus in the middle. After one hour, the receptable was warmed up to 80 degrees. (no airflow)

   What I've done is simply replace all cardboard stuff with Nimbus and extended that into the engine bay to cover the area's which were not covered by the old heatshield. After that, I placed a second layer (and formed that) around the manifold and the cat.

   In the past years, I found that not only trackdays by mainly long motorway stretches were really heating up the rear end. Wires were melted, the cable loom of my satnav which I dropped in the boot, was melted aswell. I've done Abbeville recently which means a 3,5 hr stretch of 100mph on the motorway.. temperature went down from well over 100 degrees in the boot to around 29 degrees in the hottest area
   (boot was completely packed up which stopped any airflow) 

   Quote:Originally posted by YvoTuk
   I've used one sheet of Nimbus and one sheet of Cirrus. (there were leftovers, but I've already helped someone out with that, so it was worth it )

   Nimbus is 85 Euro + VAT and Cirrus is 90 Euro + VAT

   Mind you, one sheet of Cirrus is half the size of a sheet of Nimbus, so it's effectively twice the price!

   We've got one sheet of Nimbus left and have placed a new order at the factory, but I *think* it's going to take another 8 weeks before we'll have a new supply of Nimbus. Plenty of sheets of Cirrus left 

   Quote:Originally posted by YvoTuk

       Quote:Originally posted by Black_potato
       Yvo, do you have any pictures of the heat shields in situ, it would be interesting to see how you have done it. 

   I'll try to dig out some pics.

   What I've done is very simple:

   - remove all exhaust components

   - remove the old heatshield (in one piece!!)

   - take the old heatshield and 'crush it' on the plate of Nimbus and draw a cutting line around the original cardboard. (take at least 2cm around the old stuff as you have to fold Nimbus round to stop it from falling apart ) Don't cut it at the point where the manifold goes into the engine bay, you can simply fold that around the subframe and shield the area which isn't shielded at this moment.

   Do not cut the holes for the exhaust mounts! (I did that, but it's useless and would only introduce new 'leaks', so I covered it again)

   - form the Nimbus so it'll fit in the car. Don't forget to shape some extra's (a cross or so) to prevent it from rattling)

   - use long and wide pop rivets. Drill hole, stick pop rivet in from above and push a large od washer over the other side of the pop rivet to spread the load. Prefferably use more pop rivets then original to get the whole thing stable.

   - Create a tunnel made from Cirrcus which fits over the manifold and cat. I've bend the side approx. 5cm down to catch the heat. (also, you will have to fold the sides, so you need to cut a bigget sheet then the actual size needed!). Exactly same story here with the pop rivets.

   I had a bit of a problem as the pop rivets initially were not long enough. This can simply be solved by tapping the area around the pop rivet (diameter of the washer)

   For the manifold end on the engine, I formed a sheet around the manifold and attached that to the boot bulkhead with square pipes of ali

Physical
Construction:	Double aluminium sheet, double formed
Materials:	0.3 & 0.125mm 1050A '0' grade aluminium
Material Thickness:	0.43 mm
Product Thickness:	5.25 mm
Area Density:	1.69 kg/m2
Thermal
Thermal Conductivity @ 150 ºC (1)	0.27 W/mK
Hot Plate Temperature Drop @ 150 ºC: (2)	72.3 ºC
Internal Exhaust Test (3); Horizontal flat sample
No shield:	Source: 300 ºC	Receiver: 144 ºC
	Source: 500 ºC	Receiver: 274 ºC
Nimbus Gll (new):	Source: 328 ºC	Receiver: 50 ºC
	Source: 565 ºC	Receiver: 85ºC
Nimbus Gll (Dirt impinged): (5)	Source: 286 ºC	Receiver: 63 ºC
	Source: 493 ºC	Receiver: 109 ºC
Surface Emissivity @ 150 ºC	New:	0.28
	Heat Aged (@ 300 ºC):	0.2
	Accelerated Salt Spray: (4)	0.34