Thread: C5 gto
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Old 01-08-2011, 12:45 PM
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heinke heinke is offline
MetalShaper of the Month Jan 2018
 
Join Date: Nov 2009
Location: Prescott, AZ
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Default Interior insulation

I’d like to take you inside the C5 GTO for interior construction. The original GTO’s had aluminum sheet interior with almost no insulation and were usually painted with grayish hammer tone paint. That’s a fine choice for what was essentially a race car. Here’s a picture of an original GTOs interior minus the transmission tunnel.





The main criticisms from a driver comfort perspective were that GTOs were loud and hot. In other words, the V12 whine and road noise were clearly audible when driving and the exterior “fresh” air venting was mandatory. I on the other hand am looking for greater driver/passenger comfort without necessarily sacrificing the high performance nature of the car. I also want more styling in the interior than plain sheet but want to retain a “metallic” look.


The design choice I ended up with is double sheeted aluminum sandwiching insulation in between. The largest chassis tubes are 1.5 inches diameter so this gives me 1.5 inches of space for insulation. I anticipate the two hottest areas will be the firewall that’s exposed to engine headers and transmission tunnel where exhaust is routed and mufflers are located. My first line of heat protection is an all stainless steel exhaust system.
Earlier in this post are pictures of the belly pan. This forms the outer skin for the floor boards. Here’s a top view with some insulation in place.








I decided to use rigid urethane foam sheet for the insulation. It’s easy to get (bought mine at Home Depot), comes in various thicknesses, is relatively inexpensive, easy to cut and install. My first concern was if high heat would somehow adversely affect this material. To test, I held an industrial heat gun at about 1 inch from the bare foam (not the foil covered) turned on high for over 10 minutes and there was no appreciable damage apparent. There was a little bit of melting but not much. My main concern was whether it would catch fire and it didn’t so I figured it was safe for this application.





Here’s one of the high heat areas. Given the engine location, there’s only about 3 inches clearance between engine headers and this panel. The gas pedal and thus driver’s right foot will be on the opposite side of this panel. I’m hoping 1.5 inches of insulation will suffice to keep the heat at bay and my foot from cooking.


If anyone knows from experience that using this type insulation has any issues, please speak up. While it sounds good to me in theory, I’ve never actually seen it used in automobiles before.
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