Possible Floor Insulation near Exhaust

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Jun 1, 2015
Denver, CO
Hi! New to the forum and happy to be here!

After a long cross country drive in my 97 LX450, I was shocked to find that the inside of my bag which had been lying flat on the passenger floor was too hot to touch, i.e. 140-150 °F. I'm running a stock FZJ80 with factory exhaust and cat converters under the passenger floor- nothing modified here. I've read extensive threads here and elsewhere on adding insulation such as foil-backed butyl and foam insulation but can't seem to find much about adding a radiant barrier outside the vehicle. I'm hoping for a way to add some insulation between the exhaust and the passenger floor to try and prevent the heat from entering the cabin.

I'm thinking of adhering something to the outside of the vehicle, under the floor pan, like the Thermo-Tec 14100, a 6mm fiberglass insulation with foil backings or the Thermo-Tec 13575, a thin aluminized silica foil.

Apart from the insulation falling or tearing off, do you think this would help to reduce the heat inside the cab? Any cons or drawbacks that you can think of, or should I just opt for the interior foam insulation under the carpet?

I have had the same issue and my good friend, fellow mudder jfz80 has also experienced the same thing.

Here is what baffles me... in the winter, i have no issues at all. It only happens on hot days, mostly summer. I am literally thinking it has to coincide with road temps. If i'm driving across hot black top then my center console and floorboards and transmission tunnel get hot as can be. It will even cause my iPhone to shut down because of overheating. Just to confirm this fact, on a long road trip this past spring, on sunny days my floorboard and center console would get really hot. Driving down the same stretch of highway, as a rain storm came and it clouded up, temps dropped, my heat issue went away. After the rain stopped and it remained cloudy, my heat issue was still not an issue. As the sun came back out and the outside temps heated up, so did my center console and floorboards.

I put down a little bit of insulation in the past and it didn't help. I'm considering another insulation that might be of higher quality.
You could wrap the cat/exhaust in exhaust wrap - that should help.
i have a magna flow down pipe, aftermarket single cat and a magna flow muffler.... My water temps are perfect.

I'm telling you, it seems crazy when the floor gets hot and the only thing that is consistent is the outside temps and sunshine... weirdest thing.
You could wrap the cat/exhaust in exhaust wrap - that should help.

Do NOT do that!! Unless you live in the SW and never see snow and salt! I did that once and it rusted my system out in 2 years. If you don't go off road and you don't have snow/brine where you live, then sure. That stuff acts like a sponge and holds moisture and debris against your exhaust which will eat it out.
I've done a few things that have decreased the heat in the cabin a bit, but not dramatically. I applied Hushmat Hoodliner, which has a higher temp adhesive, to the underside of the passenger floor and transmission tunnel. It was NOT worth the effort. It started out as a job to replace the rear heater pipes, so the cat heat shields (1996 FZJ80) had to come down, then the second section of rear heater pipes come out. At that point I was looking at the floor pan, so I began to manually remove the dealer applied undercoating using Terpentine. That worked well and did not affect the painted/primed floor. Cutting and applying the Hoodliner was a real bear; like a giant upside down jigsaw puzzle, hours and hours of work. I also had the AC pipes out that fit on the US passenger side (right) firewall, so started up at that level and brought the hoodliner to just past where the rear heater sits. Then over the transmission tunnel, both sides, from the bellhousing to the transfer case.

The job actually isn't done, haven't reinstalled the cat heat shields yet. What I found however is that there is less vibration for sure coming through/from the floor, but once the floor (steel) gets heat soaked, there is almost the same amount of heat coming up into the cabin. Using an IR Thermometer pointed at the floor directly above the cats the temps did drop maybe 10-20 degrees F', from 140'F to 120-130'F. So from that experience I would say all that work was not worth the effort.

What I would put my time and money into would be more layers of heat reflective barriers laid down under the carpet, or use one of the products that are sprayed on the entire floor. I have used the Thermozite padding and that does work to some degree; however I used the single sided foil version. There is a dual sided foil option that might work even better. One thing I noticed about the Thermozite is that the foil coating does not handle abrasion very well by itself, but once the carpet and carpet padding is put back down it should hold up well. There are industrial strength heat reflective products out there but they are very expensive per square foot, not worth it in my opinion.

The cats can get up to 500'+ and the pipes going into the muffler get up to 400'+F, that's a lot of heat only inches from the floor. There are also heat reflective materials that are not absorbant that should work well that are connected to (around or above) the cats and pipes, but again, the products that work are fairly expensive.

Much of the heat IME comes up via the transmission tunnel directly back from the engine. Others have reported that a body lift helped decrease heat in the cabin afterwards possiblly due to more air flow in the tunnel area. FWIW.
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This post is from THIS thread when I re-routed and changed the cat and muffler.
The exhaust mod has been great in so many ways. -

After several days of wheeling Moab and the surrounding area I can fully endorse this set-up. I smashed the main cross member, hit the transfer-case skid plate hard, scrapped the rock rails. I can tell without question the stock exhaust would have been a problem, possible not even there after Moab :eek: No rattles, no damage, no vibrations, no issues at all. I have zero concerns about my exhaust at this point forward when wheeling.

I was with several other 80, early models, late models, stock exhaust, modded exhaust, single cats, and dual cat. A couple of times I took some IR temp readings of the passenger floor and the cats. My cat was at 200° max while others were double some as high as 465°. My floor temps saw about a 5-10° difference between drivers and passengers. While other 80 passenger temps were up to 25° hotter then mine. Keeping in mind my cat is 3/4" from my heat shield much less then stock.

The muffler is as quiet if not more quiet then the stock muffler with about 10-15lbs less weight.

All said one of the my best most effective mods.

The exhaust mod has been great in so many areas.
Phil, i have the same setup... at least the cat and the pipe going over the frame...

I don't know what else to think at this point. I don't believe i'm running rich or have an exhaust leak causing high exhaust temps.
Phil, i have the same setup... at least the cat and the pipe going over the frame...

I don't know what else to think at this point. I don't believe i'm running rich or have an exhaust leak causing high exhaust temps.

Wow Im not sure what to say its not like a live in cooler climate

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