M

mlwynn

Well Known Member
Hi folks,

There is a great thread on firewall insulation started by Dan Horton. Following his lead, I want to use a ceramic covered with SS foil. Looks like 003 is the ideal thickness. I have seen places where it is available, but only in 25' rolls. Did anyone buy one and would they like to sell me enough for my firewall? Maybe a source for smaller quantities?

Thanks,

Michael Wynn
RV 8 Finishing
San Ramon, CA
 
I buy heat treat wrap which is good for 2000 deg. but I don't think it is wide enough for what you want. I think the rolls are 18 inches wide. How wide do you need?
 
You can use foil widths less than firewall-wide by overlapping them at a fastener line:



Fold one foil edge, rivet the foil and insulator sandwich, then cover the seam with the ordinary aluminum foil tape used for sealing ductwork (solid aluminum tape, not fabric "duct tape"). The aluminum tape is for oil/dirt sealing in normal service. It will burn away instantly given a fire, but that doesn't matter. Actually it has a benefit; it creates a vent for any outgas from the insulator and vents it nearer panel center rather than near the firewall perimeter.

Terry, a test note; might want to take a another look at the addition of closed cell foam. Although the sheet insulator may keep overall panel temperatures well below the smoke and/or ignition temperature of the foam, you can still have a problem with point ignition sources. Some of my silly little tests included AN3 bolts through the firewall assembly, much like you would use to attach things to the firewall (battery box, for example). Those fasteners transmit heat by conduction....enough to glow red. If such a fastener or fitting was in contact with foam behind the firewall you could get ignition.

My own firewall is clean bare stainless and aluminum angle on the cabin side, not even paint.
 
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clips

Dan,

I have followed the firewall insulation test thread that you have intently worked on.
From the information on the thread, I have decided to use the ceramic blanket material (McMaster Carr). I had thought about using heave duty aluminum foil but I like the stainless foil idea. What I would like to do is make the encapsulated ceramic blanket panels to fit inside if the angle braces on the cabin side of FW. The only thing is, I want to attach them mechanically without the use of glues/adhesive. I had thought about using safety wire strung through small holes drilled in the angles spaced a few inches apart. But I really do not want to drill any holes in the braces. Not sure that would hold them anyway.

I was thinking about using some of these type of clips:
http://www.boltproducts.com/tinnerman/clips-u-type.html

...and use them to attach some stiff aluminum straps/strips across the angles to hold the insulation panels in place.
Do you, or anyone think that the barbed clips would damage the angles in a structural way? It would be rare that the clips and panels be removed once installed.
 
Barbed Clips

I wouldn't recommend the barbed style clips. They put pretty deep scratches in steel, let alone aluminum. IMHO these scratches would turn into cracks pretty quickly, given firewall vibration.

Dan Horton's solution of SS pop rivets is light, simple, and has little, if any, structural issues.

Mike
 
Sam, nice find! I notice they have some which are not barbed.

Do remember adding an insulator to the cabin side is a poor substitute for an insulator and stainless cover sheet on the engine side.

If you do choose cabin side insulation, stainless foil is totally unnecessary. An aluminum foil envelope is all you need.
 
DanH said:
Do remember adding an insulator to the cabin side is a poor substitute for an insulator and stainless cover sheet on the engine side.
Click to expand...

I just knew you were going to say that. I wish all of this hadn't been such an after thought. Else, I would have put it on the engine side (as you suggest) before I had all the stuff on the firewall. :(

I may go ahead and pursue the barbless clip idea for the cabin side. I just think they'll viberate off without something to hold them in place. I'll have to think on it a while.
 
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I told you wrong on the width of my heat treat wrap. It is actually 24-1/2 inches wide. It is a very high heat resistant Stainless foil I use to wrap tool steel in to keep the parts from carburizing during heat treating. It is supposed to be good for 2200 deg. F. I heat treat parts at 1875 deg. F. and the wrap does not burn through. You might check with local tool and Die shops or mold shops as most small shops that do their own heat treating will have some. I will caution you about handling it. You can use normal shears, even scissors to cut it but it will cut you like a razor blade. It is hard to handle without looking like you have been in a fight with a wild cat.
 
Firewall Insulation

Thanks for the tips, guys. I will plan the overlap per Dan's suggestions. I am thinking 1/8 or 1/4 Fiberfrax. Incidently Dan, thank you for the research. You may well save some lives.

Regards,

Michael Wynn
RV 8 Finishing
San Ramon, CA
 
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