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Discussion Starter · #1 ·
My fiberglass floor (Rhino lined inside) above the muffler is getting HOT (too hot to even set your feet on). My muffler is about 2" away from the floor now. I DO plan to put some heat shield material (design TBD).

My question is how hot can fiberglass get before damage or failure happens? What kind of failure would happen? Melting, burning, fire?

If it's just foot heat to be worried about, that's really not a problem right now (kids feet don't touch the floor in back).
 

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It's going to start to blister, check and crack over time. A lot of it depends on how much moisture can be induced in to the laminations when cracking/checking occurs. I'd sure put some heat shielding above the muffler to mollify, if not deflect the heat.

I'm wondering if you've got clearance for it, if a piece of Dynamat (or similar) may not be a good idea.
 

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Your question aroused my curiosity, so I did a quick Yahoo search and found this resin manufacturer's site:

http://www.poliya.com

There I found a spec on one of their polyester resins that says "Heat Deflection Temperature - 124 degrees C." That's about 255 degrees F! HDT is defined as a temperature at which a sample loses a certain amount of beam strength.

Unfortunately just that one web site lists dozens of resins. Without knowing the manufacturer and specific product used to make your tub, you can't know exactly what the temperature spec will be.

Also, that test doesn't address the long-term affects of elevated temperature. Still, at 255 degress it hasn't yet caught fire. But fiberglass WILL burn vigorously if it gets hot enough. When the fire burns out there's nothing left but a pile of glass fibers.

Maybe you can look around at that site or another to find a kindling temperature.
 

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If you can not hold your hand on the fiberglass it is to hot. You will dry out the oils in the glass and it will break or shatter very easy.
Had a lot of experience with boats and fiberglass. Even exposure to the hot sun for a few years will dry out glass and then the cracks set in AND THEN, & THEN poof worthless boat.
If there is a good Corvette repair shop near you, stop and talk to their best and oldest glass man, a few minutes over coffee or a beer will be well worth the time.
 

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Discussion Starter · #5 ·
Thanks for all the info, I think I saw that flowmaster themselves make sheet metal heat shields to attach to the muffler instead of putting material on the floor. Problem with the stuff I would attach to the floor is that they don't attach with adhesive, you have to use fasteners, and I don't want to add any more floor holes than necessary.
 
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Hey Matt,
The best way to attach it is to make it long enoug to go over the ends of the muffler....you can then use a pipe clamp as a mounting point for the shield...

I'm making a couple of shields now for mine out of 16G SS....The key to good performance is to have enough air gap between both the muffler and body for good air flow....
 

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Discussion Starter · #7 ·
Please post up a pic (before and after mounting if you can). I'd like to see it for ideas!!
 
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