Fiberglass For Firewall

BBShark

Garage Monkey
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I had to cut a corner of the footwell out of my car for header clearance. I'm thinking that I will have 1/2 inch clearance between the glassed in cutout of the footwell and the header.

Is conventional glass fiber with epoxy heat resistant (enough for this)?
 
Just did a quick check of some of my tables - and the max I see for "run-of-the-mill" Epoxy is around 200 degrees F.

McMaster sells some sheet (already laid-up) that is Flame retardant and good to 140F.

Specialist resins go up in heat range - and so does cost.

From FiberGlast:
#3300/3330 High Temp Tooling Epoxy can be used with #1096 High Temp Epoxy Surface Coat. When used together, High Temp Epoxy Resin and High Temp Epoxy Surface Coat can create tough, durable, heat resistant tools.

Mix Ratio (by weight) – 100:22
Pot Life @ 77°F – 150-180 minutes
Color – Amber
Maximum Service Temperature – 350ºF

$150 a quart...
There is a detailed post cure needed and may not be too practical.

A piece of sheet metal with a Jet-Hot Coating?

Sounds like an interesting challenge. Not much help there - Good Luck!

Cheers - Jim
 
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I have successfully used DEI Floor and Tunnel shield. It has a metal outside, a heat resistant material on the inside, and is sticky backed. It is less than .25 inch thick and molds fairly well.

Pappy
 
I could do something like vette427sbc did. That material looks like foil.

I stole his pic
45bfb1a171966f.jpg
 
Here are photos of the heat shield I referred to above. I covered the whole thing with the gold reflective, then I added the DEI Tunnel Shield to the bottom half (closest to the exhaust). The Vipers have a lot of trouble melting the plastic fuse box, especially when driven hard on track. I have had no issues since adding the shielding. The bottom part of the shield is .75 inch from the exhaust manifold.

Viper Heat Shield 1.jpg

Viper Heat Shield 4.jpg
 
I will give the DEI Tunnel Shield a go. Here is a picture of the footwell cutout I need to clearance.

45c03c037080a5.jpg
 
I called West Systems about the resistance of fiberglass to heat from the headers and was told that 1/2" clearance would be OK. The tech guy I talked to has a 71 Corvette. He did tell me that I should use epoxy resin (to bond to the polyester floorpan) and woven fiberglass mat. I will also use the DEI tunnel insulation.

After checking the underbody clearance with the completed chassis, turns out I will have to cut out the top of the tunnel to clear the taller Tremec transmission anyway. So that is another area that I will have to insulate. Planning on an aluminum cover there.

Might be easier to cut out the whole tunnel!
 
I ended up buying the DEI tunnel shield. When it came I noticed there isn't an adhesive backing. DEI sells a spray adhesive but it is "rated" at a max 160 degrees. Probably OK in the tunnel but not 1/2" away from the header.

Anybody know any high temp spray? Maybe epoxy it on?
 
Got a link for the one you bought? I did the DEI tunnel shield in my.... tunnel, and it had an adhesive backing. Not anything I would trust to keep it affixed by itself though. I also mechanically fastened mine using the factory clips and starter cable studs.
lmore2855.jpg
 
I ended up buying the DEI tunnel shield. When it came I noticed there isn't an adhesive backing. DEI sells a spray adhesive but it is "rated" at a max 160 degrees. Probably OK in the tunnel but not 1/2" away from the header.

Anybody know any high temp spray? Maybe epoxy it on?

I have a piece of DEI tunnel shield in my hand. It has an adhesive backing and a thin plastic film you have to peel off. Their add says the adhesive is good to 450 degrees. I also use their heat tape around the edges to keep moisture from soaking into the shield material.

Pappy
 
This is what I bought:

Design Engineering (DEI) 050506 Heat Shield Material
This Design Engineering (DEI) Heat Shield Material is made of 10 mil aluminum bonded to a layer of high temperature resistant glass fiber and withstands temperature up to 1,750 degree Fahrenheit.


Never saw that it didn't have adhesive backing until I received it. Searching around looks like I should have ordered DEI 050502
 
I used the DEI heat shield. Nice stuff, conformed well to the cutouts I had to make to clear the headers. Ended up cutting a pretty good chunk of the passenger side floor but not to bad on the drivers side. Thats a good thing because the gas pedal is right above.

45d3ee4f8d27fc.jpg

Next is cutting out the top of the tunnel to clear the transmission.
 
Just trying to keep up here. What transmission are you planning to use?

I am using a Tremec TKO500. The footwell clearance was the result of my desire to keep the header collectors even with the bottom of the oil pan (for no other reason than I don't like the look of headers hanging down under the car).
 
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