Exhaust Heat Shield
 

Since fitting my custom made 3” exhaust heat transfer to the cockpit has been high, especially around the hand brake. Years ago, I put some Thermotec heat barrier on the underside of the transmission tunnel from the firewall to the shift lever. I researched on this website how others handled the issue of heat mitigation from a 3” turbo downpipe. One aspect I did not consider is heat transfer to the gearbox. Armed with this information I went to DEI’s website, Heat & Sound Insulation Products | Design Engineering, Inc. .

I also asked DEIs sales guys which products they recommend for my situation. Their firs recommendation agreed with my idea of using the Floor and Tunnel Shield II. This is a self-adhesive product with a dimpled 10mil aluminum layer with 1/8” glass fiber layer to absorb sound. I lined the entire transmission tunnel from firewall to fuel tank. The adhesive in believably strong, so I have no doubt it will stay in place. The material is so stiff I was able to make a box of it to go around the hand brake lever area. One of my photos shows this, but it’s hard to see because everything is covered with shiny aluminum. By making the box, I eliminated the OEM heat shield to gain a little room. I bought the largest size they sell, 14 square feet, #050503. This provided enough material to line the entire tunnel, a small area on the bottom of the fuel tank and the underside of the OEM heatshield above the rear muffler. I planned on removing the OEM shield and simply lining the underside of the trunk, but on my NB the bottom of the trunk is a conical shape. Cutting out all the necessary cone-shaped pieces to cover the area would have been a pain in the ass, so I just covered the bottom OEM shield. Not shown clearly in any of the photos, I cut out 2 circular pieces of material, one 1/2" larger then the other, and made a donut to fit under the large shifter boot. This should extend the life of the boot and block any heat from entering through the boot.

To protect the gearbox from heat radiated from the downpipe the DEI sales guy recommended header wrap. I did not want to go this route for 3 reasons. First, removing an FM downpipe is a pain in the ass. Second, I have has bad experience in the past with wrapped headers cracking and blowing out welds from the contained heat. Third, with a wrapped pipe, heat still radiates from the pipe. Not nearly as much, but because the tape contacts the pipe, heat transfer inevitably warms the tape as well. I wanted to use something with an air gap between the pipe and the material to block the radiated heat. I decided on DEI’s Titanium Pipe Shield. Probably over-kill for this application, but let’s face it, anything worth doing is worth over doing. I used a 6”x2’ Pipe Shield #01041 on the downpipe. This length fit perfectly between the upper and lower O2 sensors on the downpipe. I positioned it on the downpipe to block heat going to the transmission. Additionally, I used a 6”x3’ Pipe Shield #010452 on the mid-pipe. I positioned this piece on the top of the pipe to block radiant heat from the cockpit and drive shaft. This covered the top half of the midpipe from the junction with the downpipe, over the cat and back to the end of the transmission tunnel. All the materials were bought off Amazon.com.

So far, I have only driven the car on a 20-mile route. During and at the end of the drive, I felt no heat rise to the hand brake area. I am confident I’ll have the same results on my next day-long drive. I cannot say I notice any reduction in sound with the Floor and Tunnel Shield, but that was not part of my objective.

I have the floor and tunnel sheildmon my car. Just up in the footwell area over the trans and that made a huge difference. Great product, adhesive is good and it is easy to shape and cut. I still need to get around to doing the rest of the tunnel. The pipe sheild looks good, I will look into that once I build an exhaust.

Ken

Props for the write up. I was just doing a bunch of research on this subject and pretty much gave up because of all the various opinions and crap available. This stuff looks better than the other stuff, so I'll go this route.

Why is everything under your car so fresh and so clean?

Nice work. I added shielding inside the cabin for my right leg, but I was wondering how to get the heat soak along the shifter and next to the seat down. I have a header wrap on my cheap ebay header, so no biggie if it dies.
I'll try the same approach to shield the diff as advised per the diff/trans cooler thread. I got rid of the stock heatshield on the aftermarket catback exhaust, and I want to keep the diff temps down without a cooler.

Looks great! Its always nice when you do something on the car when it actually makes an appreciable difference, makes the time invested totally worth it. This will definitely be something I do on my car in the near future because the tranny tunnel is like a little oven on longer drives in my car.

Hate to revive an old thread, but after spending hours of looking around with the G00gz, I couldn't find many folks using that DEI Pipe Shield. How has it held up long term?

I have the DEI Form-A-Shield on basically the entire exhaust from the collector on my header all the way back past the diff. They recommend only covering about 75%, so I have about the top 75% covered. It's attached with either safety wire or the stainless zip ties. I've had it on the car for about the last 4 years and have no issues. My entire exhaust is 304SS and I have a flex joint in the mid pipe.
The front half of the header is DEI titanium wrap (from the primaries to the collector) and I used the DEI floor and tunnel shield on the entire trans tunnel.
The floor and tunnel still get warm, but my shoes don't melt and I don't burn myself if I lean on the trans tunnel after a track session with short sleeves. So chalk it up as a win.
I've had a couple offs over the years and the form-a-shield doesn't get shreaded like the header wrap if you beach yourself in a gravel trap.

I was specifically wondering about the pipe shield that mounts the material on standoffs. FM sells it:

https://www.flyinmiata.com/media/cat...1577121992.jpg

I've used one for some years, but it is a pain to handle if on a RB header (not easilly removed).
I guess it shielded some but I have too little air in between anyway.

I was trying to avoid having to drop the transmission (or at least minimize time under the car). It sounds as if just buying insulation to shield the car from the inside might do me better.

From one Bryan to another.

Unfortunately, you will want the heat shielding underneath the car, rather inside it, to prevent heat from entering the cabin in the first place.







I installed the DEI Pipe Shield at the same time as the Floor and Tunnel shield so cannot verify the effectiveness of solely the pipe shield. As many of you know with an aftermarket header, and no carpet the floor and transmission tunnel becomes uncomfortably hot as the header is literal inches from your right foot.

Heat shielding installed. I did end up pulling the transmission to install the adhesive backed tunnel shielding. Although it was possible to install the pipe shield on the header in car without disassembly of anything.

Pipe Shielding on the header, strategically positioned where it comes closest to the transmission tunnel and my foot.

https://cimg6.ibsrv.net/gimg/www.mia...c45422e2c9.jpg

Floor and Tunnel Shield.

https://cimg8.ibsrv.net/gimg/www.mia...4f27728ba0.jpg

I did a little A to B testing controlling as many variables as possible, driving same route, similar ambient temperatures and concluded with the following. (20 minute drive in town, alternating load, 86*F)

No heat shielding at all.

151.3*F

https://cimg3.ibsrv.net/gimg/www.mia...6df753f3db.jpg

DEI Pipe Shield and Floor and Tunnel Shield installed.

115.6*F

https://cimg4.ibsrv.net/gimg/www.mia...1c1c9eaee4.jpg

Delta of 35.7*F after a short drive. I would chalk that up as a win. I believe any sort of quality and well implemented heat shielding is worth the effort. It pays dividends in driver comfort.

The Pipe Shield does seem like a quality product and only time will tell how it holds up but has been great thus far. The air gap between the woven fabric and the exhaust (air is a fantastic insulator) does help cut down on heat.

I recently tested both again at Thunderhill in July, read 105*F, and dare I say that the cabin was actually a pleasant place to be relatively speaking.

TLDR: The pipe shielding, aside from fumbling with a few clamps, is well worth the effort.

Bryan Z,

How did you prep the transmission tunnel for the adhesive backing?

Thanks,

You can add one more product if you want further improvement.

Black material is Hushmat (sound & heat blocking), whereas the silver material is the less expensive Kilmat (sound attenuating only).

Made a big difference in my car which doesn't have A/C.

https://live.staticflickr.com/65535/...451c1905_b.jpg

Engine degreaser, brake cleaner, Simple Green and Scotch Brite pad along with a bit of elbow grease.

I prepped it as best as I could to give the glue something to adhere to.

https://cimg2.ibsrv.net/gimg/www.mia...2852c15cfc.jpg

The other thing is that you don't really need to get all of the tunnel spotless. The adhesive is pretty effing sticky. And it's malleable, so once you press it into shape, some reasonable amount of adhered area will keep it in place—it retains its shape once positioned, doesn't flop.

Sorry for the time to reply. The pipe shield has held up well. Of the two pieces I used, I'm still using one of them. The other had to be replaced because 3 of the rivets pulled out of the material. I do not hold this against DEI because the exhaust on my car had been R&R many times in the past few years. Handling of the material caused the failures. The tunnel shielding is adhered as well today as it was when I started this tread. Truly great stuff. I did all this work with the transmission and downpipe installed in the car.

Thank you for your replies, guys! I might have to pick this up. I just finished covering the muffler heat shield in DEI Reflect-a-Cool and was pleased to find that the contents of my trunk were no longer getting hot to the touch after a short trip. I have some Reflectix I'm planning to put in inside the cockpit, too.

Very neat application, can't say I thought about this type of insulating before.