Kart roadracers know that after 30-45 minutes, your engine is right hot. For years, racers have been using anything they could find (usually a thin plastic number panel) to keep high engine heat from burning their suit, or their arm. Using Teflon plastic sheet (above, left) as a heat shield virtually eliminates heat transfer through the material, keeping the heat off you for a more comfortable race.
This stuff will withstand up to 450º. It bends easily and cuts with a common tin snip. Wrap around your seat to the rear (above, right) , protecting you from exhaust heat. The first time you use this stuff, it will take a "set" around the heat source, and that's it. Comes in white only. Available in various thicknesses; while it bends quite easily, thin (3/32") is better in applications like the back of your seat, so that it can conform to the shape of the seat. I used aluminum angle to mount the Teflon to the seat; I used
buttonhead screws, washers and nylon-insert nuts to fasten. I find that rivets tend to pull right through the teflon sheet. I found my Teflon samples at U.S. Plastics.com