Heat & Sound Mat Installation

[jengum]

I'm planning to start installing some of the DS & PS foot box panels.

Is there any advantage to using the aluminum panels as templates for the heat and sound mat cutout's prior to attaching them to the frame?

I read that some builders use the carpet pieces as templates for the heat and sound mat cutoff's. Does one method yield better results than the other?

Also does the bottom lip of the front DS foot box panel rest above or below the foot box floor panel? I missed this area in photo's before removing the panels. Thanks in advance.

[cv2065]

I placed the insulation on the footbox panels before I installed them. Just remember to leave a little edge so that you can rivet metal to metal. I use the panel itself as the template. It's kind of a pain trying to bend and twist to get in there if you do it after riveting on to the car. I think that tab on the footbox panel is on top of the floor panel. I tried to go seamless on the outside of the car, so all of the connecting folds on the panels are inside not out.

[dbo_texas]

I just used large rolls of craft paper to make templates of each panel (after riveted together)...then trace onto heat+sound mat and cut. A little trimming here and there but it works and its easy.

[gbranham]

I used strips of discarded cardboard boxes to create templates. Super quick and easy. Just lay each strip in one at a time around the perimeter of each panel, taping together as you go. Worked great. No measuring required.

Greg

211154211155 211158211156211157

[egchewy79]

I took the time to create cardboard templates of all the footbox pieces before I installed them. Those cardboard pieces sat in the corner of my garage for about 18mo before I ended up using them. A lot more convenient than crawling in and out of the footboxes getting measurements. Just make sure you transfer the shape to the correct side of your sound insulation. I had mult mirror images of what I needed when tracing them out.

[gbranham]

I took the time to create cardboard templates of all the footbox pieces before I installed them. Those cardboard pieces sat in the corner of my garage for about 18mo before I ended up using them. A lot more convenient than crawling in and out of the footboxes getting measurements. Just make sure you transfer the shape to the correct side of your sound insulation. I had mult mirror images of what I needed when tracing them out.

Same on the mirror images, but I didn't realize it until after I cut it. That's frustrating, because this stuff ain't cheap at $80 a roll, and I needed 6 rolls.

[i.e.427]

I just saw a video about this the other day. Here's the link:
https://www.youtube.com/watch?v=5yNnv86kg98

And for a typical Mk4 including the trunk, you need 75 sq. ft. of material. About $150 directly from Fatmat for their 50 mil. product. It works great. Link to Fatmat: https://www.fatmat.com/product-page/fatmat-50-mil-no-logo

[jengum]

Thank you all for your insights...I really appreciate it.

Frank...you're starring in your own video that you just watched! Your YT channel has been a wealth of information for me along with this forum.

[PMD24]

Offering my very long two cents for your consideration. Hopefully this won't create a ruckus since it runs against what most everyone does.

These mats aren't used in everyday cars and trucks because they don't make sense technically. Lift your carpets and you'll find some thick sound deadening mats against the metal and some high density insulation with actual R-value (albeit small).

Heat transfer takes place by convection, conduction, and radiation.

In this case transfer by convection is through the air between the hot engine and headers to the outer surface of the footbox. Convection is extremely inefficient as air is a poor conductor. The RELATIVE impact of this is negligible.

Transfer by conduction is from the outer surface of the aluminum panel to the inner surface of the carpet. Consider this like a wall in your house. The primary way you reduce conductive heat transfer is with more insulation (R-value). These mats have essentially no R-value. A few manufacturers publish the thermal conductivity number, which is easily converted to a (very low) R-value, but for most it's challenging to find this detail. Look at it this way. The footbox is the inside of your house and you want it to stay below, say, 75 degrees. Outside, let's say it's 150 (surface of aluminum). Would you use one of these products to insulate your wall? While it's not practical to add a useful amount of R-value to the footboxes, you can concentrate on the other sources of heat, which are a far more significant factor. Note that these products do provide what's called a thermal break at the highly conductive aluminum material, but since conduction isn't the primary heat transfer here, the relative value of the thermal break is small.

Transfer by radiation is the potential biggy here. If the outside of your footboxes are painted a dark color or have a non-reflective surface they will absorb significant radiant heat. This transfer is through electromagnetic waves between the hot surfaces (engine and headers) and line-of-sight surfaces (primarily footbox front and inside panels). If you've left your aluminum panels unfinished or polished them, you already have an excellent radiant barrier. Shiny aluminum will reject 97% of radiant heat transfer.

The final element here is leakage. In building sciences this is called fenestration, and it is absolutely the number one construction element to be addressed properly. A leaky building is an uncomfortable building. These footboxes have lots of leak points and good sealing is the single most important thing to address from the technical perspective. A small hole between the engine bay and the inside of the footbox can move a ton of heat. When the car is moving the relative pressure difference from the engine bay to inside the footbox is significant and air will follow that differential. So, seal all the gaps and holes.

Final point... having the reflective side of the "insulation" material facing inside the car is creating a radiant surface that will reflect cockpit heat back at the passengers. This has been pointed out numerous times on this forum and is technical fact.

If your footbox panels are non-reflective on the outside having your headers ceramic coated can reduce radiant transfer. Cost for this is relatively small. Gas-N is doing mine for $75. I'm also leaving the panels reflective.

On the inside I'll be focusing on air sealing and sound deadening. If I use a mat material, I'll look for something that doesn't have a reflective foil on the inside. I also won't focus heavily on matching the mats to the size and shape of the panels. My focus will be on overlapping the sheets for added air sealing. My ideal choice is Lizard Skin. Lots of info on that here in the forum. Great sound deadening, great air sealing, thermal break, and no interior reflective surface. I'm also going to look into using duct sealing compound (not tape). These materials have been around forever, are mandated by the building code because they are so effective, work well in application where vibration is always present, and tolerate continual temperature fluctuations. BTW, Lizard Skin is a lot like duct sealing compound.

Again, these are just my personal thoughts on this. As always folks should do whatever they want for their own cars. This is one of the things that makes these projects so much fun, and this forum so useful.

Pat

[gbranham]

Offering my very long two cents for your consideration. Hopefully this won't create a ruckus since it runs against what most everyone does.

These mats aren't used in everyday cars and trucks because they don't make sense technically. Lift your carpets and you'll find some thick sound deadening mats against the metal and some high density insulation with actual R-value (albeit small).

Heat transfer takes place by convection, conduction, and radiation.

In this case transfer by convection is through the air between the hot engine and headers to the outer surface of the footbox. Convection is extremely inefficient as air is a poor conductor. The RELATIVE impact of this is negligible.

Transfer by conduction is from the outer surface of the aluminum panel to the inner surface of the carpet. Consider this like a wall in your house. The primary way you reduce conductive heat transfer is with more insulation (R-value). These mats have essentially no R-value. A few manufacturers publish the thermal conductivity number, which is easily converted to a (very low) R-value, but for most it's challenging to find this detail. Look at it this way. The footbox is the inside of your house and you want it to stay below, say, 75 degrees. Outside, let's say it's 150 (surface of aluminum). Would you use one of these products to insulate your wall? While it's not practical to add a useful amount of R-value to the footboxes, you can concentrate on the other sources of heat, which are a far more significant factor. Note that these products do provide what's called a thermal break at the highly conductive aluminum material, but since conduction isn't the primary heat transfer here, the relative value of the thermal break is small.

Transfer by radiation is the potential biggy here. If the outside of your footboxes are painted a dark color or have a non-reflective surface they will absorb significant radiant heat. This transfer is through electromagnetic waves between the hot surfaces (engine and headers) and line-of-sight surfaces (primarily footbox front and inside panels). If you've left your aluminum panels unfinished or polished them, you already have an excellent radiant barrier. Shiny aluminum will reject 97% of radiant heat transfer.

The final element here is leakage. In building sciences this is called fenestration, and it is absolutely the number one construction element to be addressed properly. A leaky building is an uncomfortable building. These footboxes have lots of leak points and good sealing is the single most important thing to address from the technical perspective. A small hole between the engine bay and the inside of the footbox can move a ton of heat. When the car is moving the relative pressure difference from the engine bay to inside the footbox is significant and air will follow that differential. So, seal all the gaps and holes.

Final point... having the reflective side of the "insulation" material facing inside the car is creating a radiant surface that will reflect cockpit heat back at the passengers. This has been pointed out numerous times on this forum and is technical fact.

If your footbox panels are non-reflective on the outside having your headers ceramic coated can reduce radiant transfer. Cost for this is relatively small. Gas-N is doing mine for $75. I'm also leaving the panels reflective.

On the inside I'll be focusing on air sealing and sound deadening. If I use a mat material, I'll look for something that doesn't have a reflective foil on the inside. I also won't focus heavily on matching the mats to the size and shape of the panels. My focus will be on overlapping the sheets for added air sealing. My ideal choice is Lizard Skin. Lots of info on that here in the forum. Great sound deadening, great air sealing, thermal break, and no interior reflective surface. I'm also going to look into using duct sealing compound (not tape). These materials have been around forever, are mandated by the building code because they are so effective, work well in application where vibration is always present, and tolerate continual temperature fluctuations. BTW, Lizard Skin is a lot like duct sealing compound.

Again, these are just my personal thoughts on this. As always folks should do whatever they want for their own cars. This is one of the things that makes these projects so much fun, and this forum so useful.

Pat

I know what the textbooks say, but in real life this stuff works. There was a world of difference in my first build from driving around with a naked cockpit vs installing Cool-It Thermotec, or any of the other similar products. The sound deadening benefit of this foil/butyl stuff is pretty awesome, too. Makes a world of difference.

Greg

[PMD24]

Agree 100% on sound deadening.

[CW_MI]

Has anyone tried this ? I know it's expensive, but if heat mitigation is important , it's probably worth it.
https://headershield.com/

I also remember seeing in the coupe build sub forum a member used a product similar to this, with spacers, so it had an air gap, and held on with button head screws on his firewall, and footboxes. Seems like this would work well.
https://www.designengineering.com/heat-control/reflective-heat-barriers-shields/form-a-barrier/

[PMD24]

JohnK's build thread has an interesting product to apply to the outside of the footboxes. Post 147

https://thefactoryfiveforum.com/showthread.php?31167-Greek-Guys-Garage-Roadster-Build-9509-(Nice-shoutout-on-Insta-about-my-build)/page4



Pat

[65 Cobra Dude]

Take a look at Second Skin Audio Damplifier Pro. Easy to install and works great. Can be applied after aluminum is riveted in so no extra steps. I’ve used it on many, many builds.

Henry

[Mike.Bray]

I was really concerned about heat in the footboxes as my wife is usually in shorts and flip flops in hot weather. I did footbox cooling fans as detailed in my build thread.

On the inside I installed Thermo Tec under the carpet with the seems sealed with tape. Turned off the lights in the garage and with a flashlight looked for holes and openings to seal up.

On the outside of the footboxes I installed reflective foil heat barrier https://www.summitracing.com/parts/dei-010393

And the headers are ceramic coated.

My wife and I have been out a few times in Texas heat and honestly we've not felt any discomfort at all in the footboxes, even in her flip flops. Other than for testing we've never used the fans.

I'd like to say this was a well thought out plan but it wasn't, it just seemed to work. Sometimes better to be lucky than good lol

[cv2065]

I did regular Cool Mat on my last build in the footboxes and never had any heat issues, even in bare feet. Heat will however come up from under the door where the pipes are if you don't properly insulate it. I placed some heat barrier there this time around in hopes that it will help.

[jengum]

I was really concerned about heat in the footboxes as my wife is usually in shorts and flip flops in hot weather. I did footbox cooling fans as detailed in my build thread.

On the inside I installed Thermo Tec under the carpet with the seems sealed with tape. Turned off the lights in the garage and with a flashlight looked for holes and openings to seal up.

On the outside of the footboxes I installed reflective foil heat barrier https://www.summitracing.com/parts/dei-010393

And the headers are ceramic coated.

My wife and I have been out a few times in Texas heat and honestly we've not felt any discomfort at all in the footboxes, even in her flip flops. Other than for testing we've never used the fans.

I'd like to say this was a well thought out plan but it wasn't, it just seemed to work. Sometimes better to be lucky than good lol

Did you install the heat barrier on the outside inner faces of the footboxes? I looked at your build photos and saw you did the outside front faces.

[Mike.Bray]

Did you install the heat barrier on the outside inner faces of the footboxes? I looked at your build photos and saw you did the outside front faces.

It's on the engine side of the footbox panels to radiate heat away.

https://www.imagecoast.com/images/MichaelBray1/20241115171323.jpg

[KayzDad]

I was really concerned about heat in the footboxes as my wife is usually in shorts and flip flops in hot weather. I did footbox cooling fans as detailed in my build thread.

On the inside I installed Thermo Tec under the carpet with the seems sealed with tape. Turned off the lights in the garage and with a flashlight looked for holes and openings to seal up.

On the outside of the footboxes I installed reflective foil heat barrier https://www.summitracing.com/parts/dei-010393

And the headers are ceramic coated.

My wife and I have been out a few times in Texas heat and honestly we've not felt any discomfort at all in the footboxes, even in her flip flops. Other than for testing we've never used the fans.

I'd like to say this was a well thought out plan but it wasn't, it just seemed to work. Sometimes better to be lucky than good lol

I'm thinking of doing something similar, so I'm glad to hear it's worked for you. I was watching an episode of Engine Masters last week where they were testing heat barriers, and Sticky Shield performed the best of the products they tested. https://www.heatshieldproducts.com/hp-sticky-shield. I'm leaning towards giving it a try.

Stay cool,

Geoff

[Mike.Bray]

I'm thinking of doing something similar, so I'm glad to hear it's worked for you. I was watching an episode of Engine Masters last week where they were testing heat barriers, and Sticky Shield performed the best of the products they tested. https://www.heatshieldproducts.com/hp-sticky-shield. I'm leaning towards giving it a try.

Stay cool,

Geoff

The reflective heat shield I used wasn't a well thought out plan with hours of research behind it. I was at Summit one day and they had a display of it that I was looking at. A guy came up and started telling me he used it on his race car and it worked well. So I bought some to try.

I think anything on the engine side of the footboxes that reflects heat will be a good help.