When I do my 3800 sc swap do I really need the firewall insulation? Or can I use undercoating as a sound deadener? My insulation is pretty much shot and falling apart.

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It's a CAR, now drive it!!

http://community.webshots.c...rx32?vhost=community

quote Originally posted by NightMare Cruiser: When I do my 3800 sc swap do I really need the firewall insulation? Or can I use undercoating as a sound deadener? My insulation is pretty much shot and falling apart.

SOMEONE on here sells replacement firewall insulation. I don't remember who... but I do know that it makes a pretty substantial amount of difference in heat and sound when it's working. If your insulation is shot and falling apart, you probably won't notice too much of a difference when you remove it... but if you put some new stuff in, you'll probably see an improvement.

I always tore it all out and threw it in the dumpster. It didnt make any noticeable diff in heat or noise to me. It looked nasty at car shows and held water that made stuff rust. Clean and painted firewall looked better to me. IF its in great condition and you want your car pure stock, you could leave it in.

Before I made my current car into a full race car, I have a 3.4l in it as my daily driver. I ran no insulation with no problem. I even took the interior out and used just floor mats. However the fire wall will get hot and warm to touch from the inside. I assume even with the interior in it will get warm. But there was no damage and not enough heat to hurt the ECM or any electrical components. I think your fine with out it. And even in our race cars we have no insulation. And were beating the hell out of the cars.

Cool. Something to look into. Unless someone has a good one for sale...

Rip it out!!! Check out my clean engine bay in my build thread in my sig!

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86 Fiero GTX project soon to tear up the street, My build thread! 3800sc, interior, wheels and more! https://www.fiero.nl/forum/Forum1/HTML/089483.html

quote Originally posted by IanT720: Rip it out!!! Check out my clean engine bay in my build thread in my sig!

Great Build!!
Does your firewall get hot?

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It's a CAR, now drive it!!

http://community.webshots.c...rx32?vhost=community

The inside of the firewall has a thick rug and jute padding layer on it so that 1/4" of fiberglass shouldn't make much difference in sound, heat or noise. I am of the opinion though that the fiberglass on the wheel wells does reduce noise a bit. I dislike the look of that old dirty flaking fiberglass and have removed it but thinking about spraying sound deadening material on the inner metal wheel wells under the plastic well liner.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

quote Originally posted by NightMare Cruiser: Great Build!! Does your firewall get hot?

Thanks! Don't know yet I'm not finished haha, I expect it to be but you could always insulate in the cabin under the carpet behind the seats, that would be much better.

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86 Fiero GTX project soon to tear up the street, My build thread! 3800sc, interior, wheels and more! https://www.fiero.nl/forum/Forum1/HTML/089483.html

REFLECTIX nsulation works great and looks good on the firewall. I have used it for years with zero problems.

I have been driving mine without insulation for over a decade and two engines. The back window always got warm no matter if I had the insulation or not.
I couldn't feel the rest getting hot or not, the interior parts kept that in check, I guess.

-Dave

I bought this:

http://www.ebay.com/itm/SAL...em20cc092fba&vxp=mtr

Looks and feels like a really good product. I've not installed it yet. Sorry no pics or reviews.

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Jonathan
23K mile '85 notchie - Still under construction
https://www.fiero.nl/forum/Forum2/HTML/121056.html
I'm not a mechanic but I play one in my garage - me
Power tends to corrupt, and absolute power corrupts absolutely - Lord Acton
Those who hammer their guns into plows will plow for those who do not - Thomas Jefferson
The tree of liberty must be refreshed from time to time, with the blood of patriots and tyrants - Thomas Jefferson

One thing is that is not often mentioned is that the firewall has a separate outer wall that runs about half way up . It's a partly hollow wall.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

I wonder if you could use Great Stuff expanding foam by spraying it in a hole to fill the hollow space between the panels. I dont think theres anything inside it at all.

with my exhaust routing (so I could keep the whole trunk space) I ended up having to use a heat barrier for the trunk side. As long as I was putting it in for that, I just installed it both front and rear of the engine bay. It just depends on how hot things get while driving.

Charlie

When my first Fiero was totaled, the back window was broken out. The car could still move under its own power so I limped home after dark to avoid paying for towing. The heat that came in through that broken window was incredible. I kept checking my hair to see if it was on fire! I'd guess that the rear defroster is the Fiero's most useless option. In short, I'd recommend some sort of insulation or you will need a very good AC system.

Jonathan

Ripped mine out for a 3800 swap, no problems with heat. I think its a matter of preference, but If its really deteriorated like mine was definitely remove it for safety reasons, I took a lighter to some of the really nasty pieces and they caught on fire!

Whole heartedly agree.....It does make a nice radio antenna though. Lots of newer cars have discovered that too. I did it 15 years ago.

"I'd guess that the rear defroster is the Fiero's most useless option."