Even with the new Aluminum cover I still need to protect the back of it to reduce the heat transfer to the engine. I purchased some high-tech heat reflection foil that is supposed to reflect 96% of the radiant heat:
But given the fact that the last protective material I put on the cover vaporized in a matter of minutes, I decided to first do a semi-quasi-scientific study on heat transfer to the cover with and without protection.
For reference, the melting on the cover from the Turbo looks like this:
To recreate the indirect heat of the turbo, I set up a propane torch approximately 1.5" from the cover. I placed a sheet of thin steel between them to convert the direct flame into a radiant source:
I used an IR temp sensor capable of measuring up to 1400F to measure various points. With a moderate flame I was able to produce a radiant spot about the size of a quarter.
This in turn heated the cover to about 300F at the closest point. At this temperature the cover began to melt in about 1 Minute & produced a melting pattern very similar to the one caused by the Turbo:
I then tried re-running the test with a cover I had painted with a high-temp ceramic-embedded paint. This did seem to improve the behavior somewhat; it now took two minutes to get to the same level of melting:
Next I tried a section covered with the Foil:
I ran the torch for over three minutes this time and it showed absolutely no signs of melting. Furthermore, I tried to measure the inside temperature (a bit tricky) & I believe it stayed around 100F. Finally, in true Mythbusters fashion I decided to "crank things up a bit". I moved the torch a bit closer together & increased the flame on the torch:
With this setup the cover temperature reached 500F and the metal sheet got to 800F. I let it sit like this for over a minute. I only stopped it because it looked like the torch was about to burn through the metal sheet.
The end result looks like this:
i.e.....nothing. No bubbling, distortions, discolorations or anything else. Color me impressed. It's definitely going on the car!!