I'd like to hear from any of y'all who've tried the DEI Boom Mat stuff,

either the acoustic material or the spray, especially as a sound barrier on the 914 firewall

many yrs ago Like 1977) i tried the then "hot ticket" spray-on rubberized vinyl stuff in my sixer engine compt - but it eventually flaked off in sheets and was not all that effective on noise - so I put in a oem hair pad to cut the noise - that pad weighs 35 lb as i recall

since i am about to remove the current 2.7 engine, I'd like to update the sound deadening while i'm in there

(I have used DEI's 050502 on the tunnels of my miata & MG, and it is an effective heat barrier there against hot exhaust & CATs)

TIA

Sounds a bit pricy for what you are getting to me

Try Second Skin, you get the same thing if not better, and its half the price. I used it in my car on the firewall and under the seats. Works awesome, I am very happy with it. Check my blog for lots of pictures of it.

website

SECOND SKIN

My firewall

Click to view attachment

and the floors

Click to view attachment

Back in the day we used to get "Ice Mat" from the roofing supply store. It's rubberish, sticky back, comes on rolls and is cheap. Put 2-3 layers and it works just as well as the expensive sound deadeners. But a fraction of the cost.

How much would you estimate 2 layers weighs?

I just recently installed Raamaudio products.

Great value and just as good as competitors.

http://www.raamaudio.com/

This came recommended by a few auto shows....

http://www.lizardskin.com/sound-control-insulation.html

re: ice mat

- that stuff is sold on various size rolls at your local HomeDepot & Lowes

- it works great on a lot of things, including RV roofs - durable for years, imle

i did not think about that as a firewall choice but it might work - i actually have a roll of it

what i really want is lightweight effective sound deadening material to use on the engine side of the firewall in place of the thick oem jute pad

- i want to first kill the heat and noise on the outside

and to do that job while the engine is out




.

I used it in an in house sub. very nice!

It was my understanding that the automotive stuff is expensive because it is not supposed to trap moisture. Household products are generally not recommended in automotive applications because they trap moisture, which promotes rust.

yep. I shot the sound layers and then the thermal layers of the lizard skin. it is probably 2 credit cards thick. Good stuff. I will be adding a little bit of boom mat to iron out the raised sections in the back pad and the floor. seem like a good filler....

I know Zach & myself have both used RamMatt. It used to come in a roll & now is in squares.

I would be careful about stuff that you would buy at a Home Depot - it's probably Asphault based. I have heard of peoples cars smelling like Tar when it gets Hot

This stuff is the same butyl rubber with aluminum face as the "auto" stuff, but cheaper per sq ft. Lowes - Peel & Seal Mastic Roof Coating. It's job is to lower the vibration frequency of metal to something people can't hear.

Next, in Socal is... soundproofing.org. They sell the Mass Loaded Vinyl with and without the foam for much less than the "auto" dedicated places. This reduces the sound that passes thru. The also have an engine hood liner, but it's thick. Lastly is their "Fire retardant blanket", for thermal insulation and some sound absorption.

The factory basically used a MLV with insulation on the engine side and MLV covered by the foam back pad in the cabin, totally ignoring all the sound that reflected off the tarmac under the seats.

That's my $0.02 for quiet cabins.

You can also get a sound deadening mat from McMasters Carr. I thing a 4x4 sheet was 32.00? Cant remember. Works great for Sound / Vibration dampening. Iv used it to quiet the sheet metal on cnc machine tools and in my rabbit diesel. good stuff but not as ply-able.

On the vanagon I used B-quiet rolls and glued the wool carpet under lay on top of that. Made a huge improvement! That is like the factory sound deadeners in the late model vw's .

The stuff from lowes WILL smell like roofing tar on a hot day. The duct seal will not but its to thin to work on vibration .



Jcl

The butyl rubber stuff is most effective at lowering the resonant frequency of the panel. The best stuff to use is foam backed mass loaded vinyl. Just be sure to completely cover the firewall...any holes greatly reduces the effectiveness.

many thanks for the experiences & sources

fyi - there is a parallel thread posted after this one

- topic is dynamat - same issues

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You guys that keep talking about the Crap from Lowes & Home Depot are Wrong! The reason is sold at the Boxes is because it's cheap & it's for Roofs. Use it if you want but you've been warned

^^
How is the aluminum face different? How is the butyl rubber different? How is the manufacturing process different?

I can't tell the difference between it and the stuff Nissan put in my Infiniti, so please justify your comment.

Engineering doesn't pertain just to Jets & Bridges.

Because a 1939 Penny looks like a 2012 Penny doesn't make it the same.

I was involved for over 10 Years dealing with Home Depot & Lowes - they squeeze every Vendor to get the lowest Cost possible. As a result, the Vendors make their shit cheaper & cheaper - Ever hear of Chinese Drywall?

The Fact is that what you are looking at in Home Depot is a ROOFING Product. It was not engineered for Sound Insulation. If I was looking for a Roofing Product I would shop at a Roofing Supply House not Home Depot. If I want Car Sound Insulation, I'm going to buy the Stuff that was made for that purpose.

As I said before if you want to go CHEAP, go for it, but don't bitch - But do come back and say you were wrong and advise peeps to buy the right thing

Boom Mat works great for noise and heat. My brother hooked me up with two boxes for my truck cab and it worked great but I wouldn't want to pay for it and for the 914 the extra weight not my choice. If your local and you want it PM me and I can get for you at cost.