Foot Box Insulation... Again

[kirby]

I am thoroughly confused on the footbox insulation suggestions here and would like to look at it from a product standpoint. I see the following being used.

1. Thermo-tec cool it. This is basically a butyl layer with foil.

2. Breeze Pre cut - This does not appear to have a foil layer but i would guess is using a closed cell foam layer. Can someone confirm?

3. Reflective Foam Insulation - This appears to be foil faced closed cell foam.

The options above all vary in approach.
Do we need the foil facing?
I would assume closed cell foam is much better than butyl for insulation.

Is there a peel and stick product that has both foam and foil? I can find a foam and butyl combined type but not foil.

[Lidodrip]

I sprayed Lizard Skin and have been very happy with the result. While a thermal barrier is important, preventing any air infiltration is equally important and I think a spray product works well at meeting both of these requirements. I would use Lizard Skin again without hesitation.

James

[kirby]

I sprayed Lizard Skin and have been very happy with the result. While a thermal barrier is important, preventing any air infiltration is equally important and I think a spray product works well at meeting both of these requirements. I would use Lizard Skin again without hesitation.

James

Thanks for the reply. I should have mentioned that spraying is not in my wheel house and not something I want to attempt. I have heard great things about lizard skin and if I had thought further ahead may have used it myself.

[egchewy79]

I used kilmat. relatively cheap. peel and stick. foil on one side and butyl adhesive on the other. if you haven't gotten too far yet, making cardboard templates of the panels before you install them makes it easier to cut your sound dampener to size before you install it. I just used the cardboard from all the boxes that the parts came in.

2 boxes will cover the cockpit and trunk

[JJK]

I spent some time researching this we well for my build. Here is a quick summary. Various materials can be used for insulation, for both thermal and acoustic. Closed cell foam and butyl rubber each insulate both, and thicker variants insulate more. For acoustics, closed cell is better at sound blocking while butyl is better at sound deadening (removes hollow sound from panels). For thermal insulation, closed cell is better but butyl still has thermal insulating properties. Butyl takes the edge in filling in small gaps in panels that could let heat pass through. The foil layer is predominantly there for radiant heat transfer, but you lose all those benefits once you put carpet on top. Those benefits only apply if the shiny surface faces the environment. The foil also helps with vibration damping on the acoustic insulation though, so it is not totally useless under carpet.
Like egchewy noted, I also used a butyl rubber foil faced mat for my build. I used a thicker mat for the footboxes and transmission tunnel, and a thinner mat everywhere else to remove the hollowness and make the overall car feel more solid.

[Namrups]

On the inside of my coupe footbox I used a layer of Dynamat, which is a peel and stick aluminum backed noise reducing butyl, covered by a layer of Dynaliner, which is a peel and stick heat reducing synthetic foam. The floor and the rest of the interior aluminum will be Lizard Skin.

[Papa]

I spent some time researching this we well for my build. Here is a quick summary. Various materials can be used for insulation, for both thermal and acoustic. Closed cell foam and butyl rubber each insulate both, and thicker variants insulate more. For acoustics, closed cell is better at sound blocking while butyl is better at sound deadening (removes hollow sound from panels). For thermal insulation, closed cell is better but butyl still has thermal insulating properties. Butyl takes the edge in filling in small gaps in panels that could let heat pass through. The foil layer is predominantly there for radiant heat transfer, but you lose all those benefits once you put carpet on top. Those benefits only apply if the shiny surface faces the environment. The foil also helps with vibration damping on the acoustic insulation though, so it is not totally useless under carpet.
Like egchewy noted, I also used a butyl rubber foil faced mat for my build. I used a thicker mat for the footboxes and transmission tunnel, and a thinner mat everywhere else to remove the hollowness and make the overall car feel more solid.

This is exactly right! In my experience, the issue with heat in the footbox comes more from gaps in the panels and where the panels contact the body more than from radiant heat. The best advice I can offer is to eliminate any source of air flow from the engine bay into the passenger areas of the car and you'll be good to go.

[John Ibele]

I spent some time researching this we well for my build. Here is a quick summary. Various materials can be used for insulation, for both thermal and acoustic. Closed cell foam and butyl rubber each insulate both, and thicker variants insulate more. For acoustics, closed cell is better at sound blocking while butyl is better at sound deadening (removes hollow sound from panels). For thermal insulation, closed cell is better but butyl still has thermal insulating properties. Butyl takes the edge in filling in small gaps in panels that could let heat pass through. The foil layer is predominantly there for radiant heat transfer, but you lose all those benefits once you put carpet on top. Those benefits only apply if the shiny surface faces the environment. The foil also helps with vibration damping on the acoustic insulation though, so it is not totally useless under carpet.
Like egchewy noted, I also used a butyl rubber foil faced mat for my build. I used a thicker mat for the footboxes and transmission tunnel, and a thinner mat everywhere else to remove the hollowness and make the overall car feel more solid.

Good summary. Although I would modify the explanation related to foil ... it makes no difference whether there is carpet covering it or not: If you install it inside the footbox, the foil's on the wrong side of the panels to reflect radiant heat coming from the headers and engine bay in general. (I'm not suggesting it should be placed on the outside though.)

I used Thermo-tec product. I'm satisfied with it, and since I'll never have a comparison with alternative products on my car, I'm sure I'll stay that way. All I can say is that the before / after sound reduction was significant.

[BEAR-AvHistory]

With side pipes paid no real attention to sound reduction, went all in on thermal protection. Its hot enough in NC during the summer.

https://thefactoryfiveforum.com/attachment.php?attachmentid=172565&d=1663357269
Thermo Tec heat barrier on all surfaces that face heat like outside of footboxes, firewall etc, including inside of transmission tunnel & side pipe heat shields.

https://thefactoryfiveforum.com/attachment.php?attachmentid=155089&d=1635708178
ReflectX attic alloy sandwich insulation on all interior cockpit surfaces under the carpet.

Last filled cavities & openings that passed heat from engine compartment to interior with expanding foam insulation.

[kirby]

So it sounds like just about any well installed liner will work as long as you stop air flow from the engine bay.

Anybody ever use something like this?

https://www.amazon.com/Siless-LinerPRO-Deadening-Insulation-Closed/dp/B09LQQ4KSW/ref=mp_s_a_1_3?crid=1O60N0FTF4CFR&dib=eyJ2IjoiMSJ9.VjL2Eo_OFz9EbB-JkMH-JSjcTvfwK0x40ZgSpbUuBTM90CHul8NcjJur7UMcuY6LgblXD9 gSv5DIVq4FiJZvX_fEy249e1LzwavDebpy0FZebbkMOW8kFfOQ TaxY2bk6j8WRDEJvLcaLvvcDgrj0NA.ERELtMba8O2WWF9nz0v Tl5Nvyq6n2PkBXgdAVqKhOvE&dib_tag=se&keywords=siless+pro&qid=1709864579&sprefix=siless+pro%2Caps%2C179&sr=8-3

[OSU Cowboy]

I used two products from the same company - Second Skin Audio.

First - I applied Damplifier Pro which is sticky tar / butyl backed with heavy aluminum ... dampens the sound. Certainly provides some thermal protection as well. I did not want my car to sound like a bucket of bolts from general vibes or rocks / debris coming up from the pavement hitting the panels on the bottom side.

Second - I applied Luxury Liner Pro for heat insulation. Focus with both was foot boxes, firewall, trans tunnel, cockpit floor. Had enough to cover the large rear panel. Also did the entire trunk with the Damplifier. I even put the stuff on the back sides of the elephant ears to dampen the rock/debris hits there, along with the underneath side of the wheel wells.

Excellent products on their own, work great in combination.

They also had the Lizard Skin product ... but I'm not a sprayer either ... so went with these other materials.

[egchewy79]

IMO most heat comes from poorly sealed space between the body and footbox. The adhesive films are more for the reduction of sound from the aluminum panels and rocks hitting the panels.
If your headers are really close to the front of the footbox, I've seen some put reflective material or even a heat shield on the forward wall of the footbox on the engine side.
Most of my cockpit heat issues were gone when I got it back from the painter, who installed the final foam insulation around the outside of the footbox.

[GoDadGo]

Here is a great source of goodies from the folks over at D.E.I.

https://www.designengineering.com/products/heat-control/

Good Luck!

[Tom Welch]

I installed the generic version of the foil and butyl from Summit Racing and am very happy with it. Its easy to work with and when its all said and done its covered by carpet and you'll never see it again. I taped over the seams to cover any gaps with aluminum tape, the kind HVAC workers use, making the boxes almost airtight.

I also DIY'd some exterior heat shields between the headers and the footboxes since they are so close to the footbox walls.
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[gbranham]

Don:

Feel free to come check out the Thermo-Tec I installed. They make two options: One for acoustic damping, and one that does both acoustic damping and heat reduction. I used the latter.

[cc2Arider]

Hi Tom,

I saw this done by a local builder (added extra panels as heat shields) and I plan to do the same ... in addition to the sticky mats and properly addressing the gap between the body and frame sides :)

Craig C

[Tom Welch]

Hi Tom,

I saw this done by a local builder (added extra panels as heat shields) and I plan to do the same ... in addition to the sticky mats and properly addressing the gap between the body and frame sides :)

Craig C

It's worked very well for me. Even in 90+ degree weather days, my feet are just fine. pretty easy to do as well.