My Side Sill Just Caught On Fire!!!!!!!!!!!

[Motor City Mad Man]

My insulation on both side sills has fallen apart literally in a probably 8" X 8" or so area right near the cats on both sides. I recently installed hi-flow cats to cut down on the heat problem and tried a homemade side sill insulation repair since you can't buy the insulation separate from the side sill itself. And the sills cost like $3,000 or more a piece. So I bought some Thermo-tec 2000 degree heat shielding for $50 made specifically for catalytic convertors and exhaust systems and stapled it into place on top of the old insulation. I had my doubts about whether it could handle the heat, so I only put one side on to test it. Well I thought it would work but I was concerned it may only be for radiant heat. The new insulation rested right on the cat though since it is kindof a tight fit. I let the car idle for 10 minutes and that's when I noticed smoke billowing from all under my side sill. I must have set a record for time to take of a side sill on a Viper. I could just picture my baby and my garage going up in flames. Upon investigation, the area of the heat shield that rested directly on the cat had charred and was still smoking. Whew, at least I didn't start the car on fire. So I guess I will have to take the advice on someone else on this board who suggested I use boiler quartz insulation and cover it with a thin layer of metal. Any other ideas out there? The stock heat shield has completely fallen apart in that area and the side sill itself is exposed to all that heat. I am running without the sills on for now until I find another way to fix the heat shield. Whew, almost had a heart attack when I saw all that smoke, and at my young age.

Question, I also bought a header heat shield from thermo-tec made out of what looks like the exact same material and am wondering what the hottest part of an exhaust system is: the headers or the cats? On the one hand the headers are the closest to the engine but on the other hand with the way a cat works I could see possibly being the hottest part too.

 

[Roland L-Ocala FL]

Sean,
That is one hot Viper you got there! Hope you can solve the problem, maybe Jon B or Sean Roe can jump in here with some advice on how to shield the side sills from heat. If anybody has the stuff to do it with, they should.

 

[shifter]

I've used the thermo tec wrap on headers that glow red from heat without igniting it. They smoke a bit at first, but never have caught on fire.

In my Viper I have the Thermo tec wrap on the exhaust from the collector up to the cat inlet. Been on there for 2 years with no problems. I had thought that aside from increasing the gas velocity during the transition from the stock pipe to the 3" Borla, it would keep the sills cooler. Can't say that it had a large effect on the sill temperature and I have no way of knowing if it added anything to performance by keeping the velocity up.

I also have heard that you shouldn't put the wrap on the cat itself, not due to flammability, but it will keep the cat at a mucgh higher operating temp which can prematurely destroy the ceramic internals.

The other down side is that under certain conditions the wrap can accelerate the corrosion of the pipes/headers. If you are in moist climates or get the headers/pipes wet regularily, the wrap helps trap moisture on the bare metal, contributing to corrosion. Again, I've never had a problem, but I haven't had a wrap on any parts more than a few years in wet situations.

Hoep this help. This is from my observations and experience.

I'd also give JonB, Sean, Chuck etc a call.