While pondering building a replacement battery tray to replace the rust-eaten factory unit in my '86 GT, and looking for locations to secure it, I noticed that the front and sides of the engine bay are covered in the type of insulation normally found under the hoods of lesser automobiles. The purpose for this insulation, other than on the front wall, eludes me. Seems like it would best serve to trap water and assist in the rusting process, and that it could be replaced with a coating of some product like Lizard Skin (I promise this is not an endorsement or advertisement!) after the new battery tray was installed. Unless there's something I'm missing, which is entirely possible. Any input on this topic would be greatly appreciated. Thanks in advance - Chris
[This message has been edited by CSM842M4 (edited 03-16-2019).]
I noticed that the front and sides of the engine bay are covered in the type of insulation normally found under the hoods of lesser automobiles. The purpose for this insulation, other than on the front wall, eludes me.
I believe it's primary purpose in the engine bay is for sound deadening. It's secondary purpose is to irritate the skin of anyone working around it back there.
Think I gotta go with Patrick here, if only from a personal historical standpoint. All other responses also bear their own merit, though. And it sounds like it won't hurt a thing to pull it. It will pain me to alter the VERY stock nature of this particular car, but since I'm not putting a stock battery tray back in it, I guess I'm already going to do that... If I can remember to take pictures AND figure out how to upload them, I'll happily share the results.
I chose to take it all out and repaint the engine bay. The insulation plugs or restricts ventilation holes on each side. But I will say that the side may be for sound insulation, the front and rear need to have a good layer of insulation. I have seen luggage with melted and burned spots from being in the trunk.
I plan on replacing mine with new and doing tha wall between the engine compartment and the trunk as well. I am also insulation the exhaust system. Keeping the trunk cool and the passenger compartment quiet is a priority for me.
...the front and rear need to have a good layer of insulation. I have seen luggage with melted and burned spots from being in the trunk.
With the trunk getting that hot, I'd be wondering if the factory metal heat shield between the muffler and trunk was missing (or damaged/incorrectly mounted and jammed up directly against the trunk).
With the trunk getting that hot, I'd be wondering if the factory metal heat shield between the muffler and trunk was missing (or damaged/incorrectly mounted and jammed up directly against the trunk).
On my last 2 engine swaps I doubled up the stock heat shieds. I used a heat reflecting insulation on the inside of the trunk under the carpet. Through the years of searching wrecking yards for parts, I have seen several melted trunk carpets from the exhaust. The factory sound insulation under the carpet is discolored from heat.
On my last 2 engine swaps I doubled up the stock heat shields. I used a heat reflecting insulation on the inside of the trunk under the carpet. Through the years of searching wrecking yards for parts, I have seen several melted trunk carpets from the exhaust. The factory sound insulation under the carpet is discolored from heat.
Did the same here. The heat shield with insulation under the trunk carpet keeps the trunk much cooler. As for the all that fiberglass insulation around the engine compartment; if you remove it you will hear more engine and exhaust noise. This is especially so if you have a short exhaust system for a swap..
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, 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 "
Originally posted by Patrick: I believe it's primary purpose in the engine bay is for sound deadening. It's secondary purpose is to irritate the skin of anyone working around it back there.
Had to revive this old thread to say 'Good one, Patrick.' No more scratchy arms, out it comes ...
On my 3800SC install, I removed all of the stock insulation, and replaced it with 1/4" thick Mighty Matt insulation. Very impressive stuff, easy to cut and mold to shape. Attached it with spray contact adhesive, and Aluminum Duct Tape to seal the edges. I left the fenders blank, but did cover the outside of the trunk. For sound deadening on the firewall, I installed RAAMmat BXT II. It has excellent adhesive properties in heat, and does a good job of sound insulation. Install the MightyMatt over the Raammat to help protect it from the heat.
------------------ '87 GT , '00 3800 Series II SC, 4t65e, Vue Power Steering. (SOLD)
I threw it away on all my Fieros. Its just a dirt and water collector. I never had a problem with items in trunk, although I wouldnt carry groceries there. I like to hear my engine myself. If quiet is a necessity, just put sound deadener like DynaMat on the inside, under the rear panel carpet, in the doors, and under the carpet. If you want quiet, buy a Cadillac, not a 'sports' car .
" I bought my Ferrari for the comfortable, quiet ride."
Sorry robymon & Vicophine, I've been out of town and haven't looked at the forum.
I found the receipt for the insulation (OReilly Auto), but the receipt was too smudged to read the part number or brand. It came in sheets about 48" by 24" and cost $84 before taxes. This was enough to do the complete firewall. You would have double this to do the trunk. It has a glue backing that makes it easy to install. The engine was out of my car when I installed the insulation, which made it pretty easy. It would be tough to do with the engine in place.
Good luck
------------------ ____________________________________________ "Of all the things I have lost during my lifetime, I miss my mind the most."
I have a similar issue with my 88GT and have been searching the forums to see what people have chosen to do. I absolutely want the original gone, but I hate to put something shiny in there when it was black originally. The black insulation I've seen looks to be for sound only. I'm more concerned with heat. Anyone looked at it from that perspective and has a recommend? Some of the threads are 5+ years old now and I'd like something that's up to date.
Thank you,
David gone: 84 SE, 84 base auto, 85GT here and in process: 1988 5speed GT
With the trunk getting that hot, I'd be wondering if the factory metal heat shield between the muffler and trunk was missing (or damaged/incorrectly mounted and jammed up directly against the trunk).
With the short exhaust system most of us 3800SC engine swap guys use the trunk gets very hot even with the heat shield. Eventually I will put some ceramic stove insulation between the shield and the trunk. It got so hot in there it distorted a small wheeled carry on a bit but it didn't harm the rug.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, 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 "
Mine is all ripped out right now, but I plan on using sound deadening material on the firewall. I don't need any heat shielding properties, so I can use any decent sound deadening material.
I believe it's primary purpose in the engine bay is for sound deadening. It's secondary purpose is to irritate the skin of anyone working around it back there.
LMAO!!! Tell me about it.!!! I learned to hate that stuff!! But mine was still in good shape, so I kept it, for whatever it's worth...
As you look to replace the engine bay insulation, make sure it is designed for the application. There has been at least 1 3800 swapped Fiero burn to the ground because the aftermarket insulation came free and drooped down and rested on the exhaust.
Not all insulation products are designed for direct contact to an 800+ degree surface. I much prefer steel heat shields with a proper air gap for this reason.
Sides are to block noise. From road noise to engine noise to damped the Strut Towers sheet metal acting as sound boards to echo and/or amplify any noise like guitar violin etc. bodies.
Firewall blanket and interior trim block engine heat and noise getting thru the wall. That's why many replace the firewall blanket w/ better material.
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Originally posted by Rickady88GT: I chose to take it all out and repaint the engine bay. The insulation plugs or restricts ventilation holes on each side. But I will say that the side may be for sound insulation, the front and rear need to have a good layer of insulation. I have seen luggage with melted and burned spots from being in the trunk.
GT have "extra" vents that doesn't add much air flow but many think side insulation can block airflow. If anything, the Strut tower and hardware block most of the extra venting area over that.
"But engine bay is too hot" Very unlikely... see Fiero Engine bay vs Heat. //www.fiero.nl/forum/Forum2/HTML/141784.html Isn't hard to make temp recorder but need more parts then just ardinuo board that most won't buy for 1 time project. Can buy a temp meter w/ long thermocouple(s) so a helper can read while driving but most won't buy for same reason. (I have both and rarely use them and need to remove batteries to protect them.)
Hot Trunk... This often involves another "insulation type..." Heat Shields.
Many Shields are missing because some fool took them out or rotted and fell off. Shields block Exhaust IR heating whatever behind. Shield try to get hot but thin metal and airflow to 1 or both sides it can't get hot to pass heat to things protected.
2 large Shields front and back. May depend on engine have more too. Trunk wall for 4 cyl has 2nd smaller shied w/ a hole or knockout where AT dip tube goes thru. Haven't seen a V6 in decades to see if has same, different or no shield. If there, bolted to the wall w/ 3 or 4 self tappers only at top of the shield. If V6 had No Factory shied there then the mounting holes have no damage/treads by the bolts.
Even w/ all shield in place... Don't keep cold/freezing foods in the truck even for a few miles. Between engine/exhaust heat and sun/weather heating the trunk will melt frozen food fast, worse in "summer." Engine heat the trunk but weather > 80-90° and trunk heat doesn't go out fast or not at all. People put MSD box etc in the truck can have problems too. Hot trunk w/ parts that generate more heat is a bad idea. (Weather Heating and people trapped in a trunk for whatever reason is why newer cars have latch release pull knobs etc. required by DOT/NHTSA.)
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
Reviving this thread, because I'm curious if anyone came up with an alternative for the insulation?
I removed mine at one point back when my Fiero was running well, and it made a noticeable increase in sound in the cabin. It wasn't all good noise either... like, it didn't give a throaty roar inside, it was just louder, and I also definitely noticed increased road noise (like Ogre said). The only reason I removed it was because it was getting so ragged by ~2010, that it was starting to fall apart, and I just figured it was better not even being there at that point. It had enormous tree fasteners that I kept just in case I decided to replace it with something.
Like the OP on here, I was thinking about going with Lizardskin or something like that. Curious if anyone has done anything? Advance Auto sells rubber spray, which essentially does the same thing... and you can paint over it too. I did the entire undercarriage of my 1973 VW Bus, but not sure I want to do that in my Fiero's engine bay... looking for a classier solution.
Oooh, that looks decent... it's VERY inexpensive too. I wonder what the weight is per square foot?
Lots of positive comments... though it says hood, so I don't know how well it would be to place it right on firewall inside of the engine bay facing the engine... but it does show someone with direct fire up against it, haha.
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Originally posted by Mike in Sydney:
Dynamat. Pricey but good.
I have a ton of this that someone gave me years ago... I've got to find it, but I assume this was mostly only for the inside?
The thermo tec stuff is nice. It’s tough to cut…..I couldn’t burn it with just a lighter. They also sell the spray adhesive that is high temp. I only used it in spots that had a tight bend….but if you cut the brackets right it won’t fall off. At the moment I have not started the car after rebuild so I have no comment on heat and sound..
I have a template for the back firewall for cutting out insulation. If anyone wants to borrow I would be more that happy to send to you if you are willing to return if completed your project. I have loaned the template to several members in the past. I fact, I believe the template made it's round in Canada a few years back.
Beside many things you could replace OE insulation will easily burn in the engine bay... A lot of stuff will hold water, oil, etc or dissolve expose to any chemicals. Often then falls off in pieces on the Cat etc that can burn even flame safe insulation. Like fall on Exhaust pipes and Cat that runs > 600°F normally. If Burning oil, running too lean or rich, or other problems w/ a Cat can see Exhaust Temps > 1000°F.
Quick Example: Spray Rubber Undercoating/anti-noise products, Pro or DIY installed, can dissolve getting hit by leaking/spilled gas, oil, and other solvents. May not come off right away but gets weak and fails often at worse time.
"Fire Proof" stuff often have limits and will burn if sees exhaust hitting from a leak or fall on pipes. Like "Fire Proof/Safe" stuff often will burn but self extinguish when another heat source is removed. Most kid cloths, "Plenum Rated" wiring, FR4 etc circuit boards and way more do this. Even DuPont Teflon, Nomex and Kevlar will burn but needs a lot of heat to start. (Or High O2 levels...)
Yes, OE stuff is a pain after 20-30+ years... but does things many other materials fails... Like Most times OE Side "Insulation" holds dirt and looks bad now but not polluted water to rust the strut towers. If it does is because Way dirty and that dirt hold the water. Doesn't hold a lot of oil either unless oil leaking on it for months to years allowing oil and dirt to buildup.
I have used the thermotec material myself, it is good up to 2000*F, and does a great job with heat. I have no carpet or trim in my interior asides from the center console stuff, dash, and door panels, and the firewall would get HOT after pulling the nasty stock insulation out. I have no AC so this was an extra big problem. The Thermotec worked great.
Only recommendation I have is to find a good way to retain it at the top, even aluminum tape would work fine.
If you’re talking about the top where it folds underneath….mine had those big head plastic rivets across there. Same ones that hold the trunk carpet in place. I believe there were 3.. Thermotec has the high temp spray glue….seems to hold pretty well.
I have a template for the back firewall for cutting out insulation. If anyone wants to borrow I would be more that happy to send to you if you are willing to return if completed your project. I have loaned the template to several members in the past. I fact, I believe the template made it's round in Canada a few years back.
If you’re talking about the top where it folds underneath….mine had those big head plastic rivets across there. Same ones that hold the trunk carpet in place. I believe there were 3.. Thermotec has the high temp spray glue….seems to hold pretty well.
I use the three big push plugs as well as aluminum foil tape to retain the top folded edge, and also the bottom. No glue, the stock attachment standoffs retain then insulation well if the insulation is "tabbed" to fit under them.
It's really not bad making a template with some thin cardboard, that is what I did. I used the dirty thumb trick where you put your cardboard over the feature or edge you need to cut around, and rub your dirty thumb over it and the outline will show up in grease. Doesn't need to be perfect, you can add masking tape or duct tape etc to fix any mistakes or make any holes that are too large or offset to line up properly.
I think I used cereal boxes and made the template in pieces that I taped together at the end once they all fit.
I have used the thermotec material myself, it is good up to 2000*F, and does a great job with heat. I have no carpet or trim in my interior asides from the center console stuff, dash, and door panels, and the firewall would get HOT after pulling the nasty stock insulation out. I have no AC so this was an extra big problem. The Thermotec worked great.
Only recommendation I have is to find a good way to retain it at the top, even aluminum tape would work fine.
LOL! I'm going to be in MA next week... going to be driving through "Woosta" MA as I visit my old prep middle school in Deerfield, MA.
Gonna hit all the typical spots... night on the town in Greenfield, the Yankee Candle Company... Salem, Plymouth Rock, Chappaquiddick... where I'll tell my daughter about this guy named Ted Kennedy, and then after a quick jaunt to Acadia National Park in Maine, I'll head back for some sausage at Faniel Hall!
