Insulation questions

[RcT]

I recently puchased three rolls of heat and noise insulation for the firewall, doors, kick panels and floors of my coupe. This is a self-adhesive, 3/16" foil-backed product. I have a couple of questions:

If I install this on the passenger side of the firewall, the foil will be visible and I wondered if the foil can be painted without compromising the insulation. If so, what type of paint?

I had this idea about the floors; what if I stick the insulation to the bottom of the rubber floor mat, rather than the floorboards? It will make life a lot easier for access to the battery, etc,, but the foil side will be in contact with the floorboards, rather than the insulation. Does this make any difference? Any thoughts on this?

Lastly is a physics question. What, exctly, does the foil do? Does it actually reflect heat back to the source? Just a side note here; a couple of years ago I had my house re-roofed. The roofer replaced the space sheathing with solid plywood, foil side on the interior and I got a rebate from our utility service for this product. The heat goes through the roof and the plywood before it hits the foil. This will be the same with the car firewall, as the heat will go through the firewall and insulation before hitting the foil. What does the foil do? Reflect the heat back toward the source?

I like to know how and why things work. I know there are much smarter people here than I am and someone can answer my questions. BTW, it was all the past, positive posts on insulation that got me going on this latest effort.

Thank you in advance, Richard.

 

[Phil Wilson]

It seems obvious you don't want to see the shiny foil on the engine side of the firewall, so it goes on the inside wall. Tuck it up behind the gas tank as far as possible and fit it between the side cowl panels. It can come down as far as the top edge of the "foot board". This will keep/ reflect some of the engine heat/ noise from the interior. I don't know of any paint that will adhere to the foil long enough before it'll flake off due to hits, kicks and vibration. The foil actually supports and keeps the insulation together and in one piece. It's like wall insulation batting with a paper side on one side and open on the other, it "holds" the fuzzy insulation, OK? If you want to keep the mufflers heat from roasting your passengers feet, install a muffler heat shield and/ or put that foil insulation under the floor boards, from the fire wall back to the area under the back seat. Then the foil will reflect some of that heat away from the bottom of the floor boards. I suppose there's more ideas, that will come to, you from other readers. Good Luck!

 

[john in illinois]

RCT,,I used a molded black firewall insulator from Snyder's. This is a copy of the 32 insulator and looks like part of the firewall.

I used foil backed insulation on the floorboards under the floor mat. This helps with heat and noise. also used a muffler shield.

 

[Tom Wesenberg]

When I bought foil faced firerglass insulation for my house the instructions said the foil reflects the heat back into the room and must face in, but for it to work correctly I need to leave an air space of about 1/2" between the foil and the drywall.