Car Audio, who soundproofed there hood?

[TimmyB]

I am in the process of soundproofing my car for my car audio system. I just got 2 big bundles of roxul mineral wool insulation that I planned on filling the framing of the underside of my WK hood with. Then install mass loaded vinyl on the underside since I hear its the best soundproofing material for that application. From my research doing the hood will cut down on 1/3rd of the sound getting into the car, that comes from the tires and engine bay thru the hood then into the car from the windshield. They say doing the hood can cut down road noise about 3db, which is like doubling the amps power output. I dont really hear of anyone on here going crazy with soundproofing, so im just curious if anyone has done there hood and with what?

[sousa]

You gotta take pics and do a tutorial for those of use contemplating this mod.

[w87will]

I'd like to read your review if you decide to do it. I'd be very tempted to do the same to my jeep.

[suzieque]

I am in the process of soundproofing my car for my car audio system. I just got 2 big bundles of roxul mineral wool insulation that I planned on filling the framing of the underside of my WK hood with.
Roxul is good stuff, I use it right up against my exhaust system in my engine compartment to keep nearby hoses from heating up.

[TimmyB]

Roxul is good stuff, I use it right up against my exhaust system in my engine compartment to keep nearby hoses from heating up.


I got the idea for using the mineral wool because it withstands temps up to 1200 degrees they say and its used in buildings for fire safing and acoustical insulation at the same time, and it does not absorb water, well only something like 8% compaired to regular fiberglass pink insulation holding something like 1000x's its weight in water(basically a sponge). I saw on the dynamat site pictures of there hoodliner applied both only to the flat areas on the underside of the hood and also installed in a full sheet to replace the stock material under there. But I have not come across anyone filling in the framing. I have the hood liner off right now, and about to just break apart the mineral wool insulation and shove it through the holes and pack it with an extra wire antenna I have laying around.

The mass loaded vinyl looks like a great product to use. But I happen to have a few rolls of an EPDM membrane that is about 1/8" thick. My idea is to clean the underside of the hood then layer on the EPDM with contact cement so its about 3/4"s thick. Then put the stock liner back on. For the hell of it I bought a roll of that heavey duty tin foil that I might try to adhere over the membrane, to act as a heat shield like on the dynamat foil faced membranes. I was able to pick up some big plastic fasteners at AutoZone to replace the ones I broke removing the stock liner. I'll take pix as im doing it.

[suzieque]

I got the idea for using the mineral wool because it withstands temps up to 1200 degrees they say and its used in buildings for fire safing and acoustical insulation at the same time, and it does not absorb water, well only something like 8% compaired to regular fiberglass pink insulation holding something like 1000x's its weight in water(basically a sponge). I saw on the dynamat site pictures of there hoodliner applied both only to the flat areas on the underside of the hood and also installed in a full sheet to replace the stock material under there. But I have not come across anyone filling in the framing. I have the hood liner off right now, and about to just break apart the mineral wool insulation and shove it through the holes and pack it with an extra wire antenna I have laying around.

I have it laying tight up against my diesel exhaust, I pulled a piece away that had been in place for about 2000 miles, I could barely tell the surface was damaged.
I'm good friends with the Roxul sales rep, their demo includes floating the stuff in water and holding a torch up against it for hours. Its cheap, amazing stuff considering the outrageous prices for competitive heat wraps. I think you may have a problem framing or gluing it, I tried to glue it to the area above my spare tire to keep the wheel from chafing the WK, I couldn't get it to stick.

[TimmyB]

I have it laying tight up against my diesel exhaust, I pulled a piece away that had been in place for about 2000 miles, I could barely tell the surface was damaged.
I'm good friends with the Roxul sales rep, their demo includes floating the stuff in water and holding a torch up against it for hours. Its cheap, amazing stuff considering the outrageous prices for competitive heat wraps. I think you may have a problem framing or gluing it, I tried to glue it to the area above my spare tire to keep the wheel from chafing the WK, I couldn't get it to stick.


I mean im going to pack it within the hood framing, stuff it in there so its packed completely. Then glue the EPDM membrane to the flat areas. I work for a consulting firm and im on construction sites all day, I asked one of the subcontractors for some mineral wool and he told me to help myself to whatever I want. Thats why im trying these ideas, its all free materials I walk off sites with. Lol.

The mineral wool is amazing stuff, actually made from rocks, by products from making steel and iron I think. Thats why it doesnt burn. But it does break up fairly easily, just from carrying two 2'x4' squares of it I noticed it was breaking apart. From the uses I see they install it within the interior stud framing of buildings, just like the pink insulation.

A good site to read up on mineral wool and what its used for:
http://www.roxul.com/home

[TimmyB]

Here's some pix of what I did earlier. Well, me and a helper that was a big help. I packed the framing full of the mineral wool solid. Just knocking on it now i can tell its more solid, the metal doesnt vibrate as much.

http://i276.photobucket.com/albums/kk37/tdiglar78/DSC01926.jpg
Blurry pic of the stock liner removed.

http://i276.photobucket.com/albums/kk37/tdiglar78/DSC01928.jpg
My helper doing an awesome job stuffing the mineral wool in the framing. I wouldnt of gotten done tonight without her.

http://i276.photobucket.com/albums/kk37/tdiglar78/DSC01927.jpg
My big fingers packing insulation in the framing.


More to come, have the membrane to install next.

[w87will]

Its looooooking good.

[B.P.O.D]

looks and sounds good hehehe.... you are putting the liner back on the hood right?

[TimmyB]

looks and sounds good hehehe.... you are putting the liner back on the hood right?


Yes I am putting the stock liner back. It will add that much more soundproofing and heat protection im thinking, and also block most of the holes in the framing I packed the insulation into holding it in there. I cant believe how dirty the top of the hood liner was when I removed it, full of dead bugs and dirt.

http://i276.photobucket.com/albums/kk37/tdiglar78/DSC01925.jpg
Sorry for another blurry pic, I must of spilled some beer on the camera and it was drunk or something. Thats showing the top of the liner that goes against the underside of the hood, its filthy.

[Scottina06]

wonder how much weight youve added with this project?

[Chris]

Sound guys don't usually care about weight :) I bet that stuff is pretty light weight, but that in combination with all the other sound proofing added quite a few extra pounds for sure!

[TimmyB]

wonder how much weight youve added with this project?


Well I really am guessing here, but it seems a 2'x4'x3" piece of this mineral wool weighs about 5-10lbs. With what I packed in there, very solid so I couldnt fit anymore in, I used almost a full piece. So not alot of weight IMO. The hood goes right up with the piston thing on its own, unlike my rear cargo hatch that I completley filled the framing with expandable spray foam and I almost have to push the hatch up.

[Scottina06]

yeah...I meant overall. 50 pounds maybe?

[TimmyB]

yeah...I meant overall. 50 pounds maybe?


Oh, with EVERYTHING, all 4 doors, cargo floor, cargo door, and now the hood. Yea 50lbs sounds about right. I'll look up the specs for the membrane I used and try to get a number. But with soundproofing its all about mass loading the vehicle to absorb the noise. And so far its def working with all i have done. The car is alot quieter.