Author Topic: Next question, heat shield  (Read 740 times)

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Offline rjbaren

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Next question, heat shield
« on: Thursday,November 07, 2019, 03:52:23 AM »
I have repaired the fiberglass luggage box and figured out there is a heat shield that should be attached to the bottom.   The parts book shows asbestos too.  There were rivets in the luggage box floor which I drilled out with nuts on the outside.  I found and cleaned up the metal heat shield.
Do I just nut and bolt the plate back on?  What have you guys done when putting this back together?  Is the asbestos necessary?  Can exhaust wrap be used?

Offline EuropaTC

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Re: Next question, heat shield
« Reply #1 on: Thursday,November 07, 2019, 04:46:25 AM »
On my TC I used a thin sheet of stainless bolted the floor of the luggage box and with approx 1/2"  spacers to leave an air gap between the box & steel.  For my purposes that's enough but I suppose if you spent a lot of time sitting in traffic then you could add a layer of insulation between them.  On the Elise I used modern stick-on fibre insulation with a reflective foil covering, but that's a lot more compact & hotter space than on the Europa. This sort of stuff....

https://www.ebay.co.uk/itm/6-Sheet-Car-Turbo-Exhaust-Muffler-Insulation-for-hood-Fiberglass-Cotton-5mm/362805198865?epid=1088392217&hash=item5478e00011:g:59sAAOSwARZXmtfh

Thinking about it, that would probably be good enough on it's own ?

Brian

Offline jbcollier

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Re: Next question, heat shield
« Reply #2 on: Thursday,November 07, 2019, 07:22:19 AM »
Don't use asbestos.

There are a wide variety of safer heat shield products out there.

Truth be told, nothing really works as the problem is a lack of air flow, and too much recirculation of that air flow.  Cool air flows in the rear wheel wells, up through the engine compartment and then is drawn out the engine compartment vents.  It then flows rearward and a significant portion flows back in at the rear, especially on S1/2 Europas with their open rear panel.  TC/S Europas are little better.  As shown in other posts, this leads to engine compartment temps much, much higher than the ambient temperature.

The solution?

Good question.  Lots of mid-engined cars have this problem.  That's why they tend to be festooned with air-flow disrupting scoops.  NACA ducts don't flow much.  They help but don't even supply enough air for the engine intake.

Honestly, there isn't a good solution.  Certainly follow other posts and duct cold air to the engine intake.  Never put an oil cooler in the rear area.  Don't put temperature sensitive items in the rear luggage area.

Offline surfguitar58

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Re: Next question, heat shield
« Reply #3 on: Thursday,November 07, 2019, 09:05:54 AM »
I just used a sheet of aluminum separated from the box with 3/4 inch stand-offs. Th aluminum is less than 1 inch from the muffler, and I am amazed how little heat gets through the air space. I wouldn’t recommend driving long distances with a box of chocolate in the boot, but it’s cool enough for most things.

t
"A designer knows he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away."
Antoine de Saint-Exupery

Offline 4129R

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Re: Next question, heat shield
« Reply #4 on: Thursday,November 07, 2019, 09:47:01 AM »
Thin aluminium sheet and 1/2" plywood would be a heat shield to stop your luggage melting.

Shiny aluminium would reflect the heat, and plywood should stop heat conduction onto the fibreglass tray.