I am going with a closed cell foam, for sure. My question is whether it is worth it for me to use a liquid damper like eDead v3 in addition to my eDead v4?
I have a stock stereo in my '04 Z and basically just want less road noise -- thats it!
IMO you don't need foam for the entire car. I'm only using foam on the wall behind the seats, some of the cargo area and the doors.
I used Overkill Pro from secondskinaudio.com I got 3 sheets of the stuff and that's plenty for me to do the areas i described. (sheets are 4.5x5' i think)
depending on your application, standard overkill might be better. i'm only using pro because i have a borla stinger system and the resonation at cruise is a little annoying.
I guess I'll go with a 1 gallon bucket of the liquid stuff and 50sqft of foam.
One thing I've noticed is that there are two companies I know of (RAAM and Second Skin) that use a 1/8" thickness for the closed cell foam, and only one that uses 1/4". Any reason why 1/8 seems to be more popular? Do you think the 1/4 would do a better job? It's twice the price, but also twice the thickness... not sure if that extra 1/4 will really make a difference though. I don't mind paying if it really is twice as good (or thereabouts).
Doing some research I've found that yes -- Noise Reduction Coefficient (NRC) is directly related to material thickness. Doubling the thickness typically results in doubling the NRC until you get to 1/2", then the NRC increase is about 75% of the thickness increase.
However I'm also noticing that anything less than 1" and it's basically pointless to even do it. The NRC is so low on even 1/4" (about .18) that it would be difficult to notice a difference in the cabin. 1/8", as RadioFlyer said, is practically nothing (NRC = .09). An NRC of 1 is the best noise absorption there is.
It doesn't start to get good until 1" (NRC = .73). This is for closed cell foam, or CCF, which as it turns out, is not very good at blocking or absorbing sound (doh!). I am trying to find better alternatives. The reason CCF is so popular is because it is well suited to an automobile environment -- doesn't collect water so it won't mold or develop mildew, and also fairly resistant to heat up to about 200*F or so. It's also fairly light. What it is best at, is actually blocking thermal transfer, or heat! Interesting stuff... I'll post up further findings if anyone is interested...
Damn... no doubt that is the "End all" of sound deadening, but at 1-3/8" thick and $10/sqft, I don't think it's the right balance for us... But still, it would be nice.
Also notice how it has 1" layer of the CCF, I think that is the minimum thickness before it really becomes "worthwhile" to use that type of product... 1/4" feels almost more like a gimmick! And 1/8" is a cruel joke!
Corvette Store
Road Noise: Necessary to use a damper?
with all of the above. 
