What thickness of sound deadening should I get???

[BoyDadCar]

Hey, guys, I'm pretty new to this forum and am not looking for speaker info but more sound deadening info. The brand I'm buying from has three different thicknesses of sound deadening material. The thicknesses are 5mm, 10mm, and 15mm.ive heard over 10 is too hard to bend a such to the body. Here's a couple of question regarding the material and size.

1. what thickness is best for my car? I have 6.5" inch punches and I have a 1991 Toyota mr2 which has little to no sound deadening and vibrates the **** out of me.

2. My problem is the car vibrates too much and has a pretty loud exhaust. anyone knows is open-cell foam or closed-cell foam better for my needs.

3. Again if anyone knows why do people put the open cell and closed cell layered on each other?

4. If there's anything you want to tell me just post it.

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[jt4x4]

First off: Cool car! I don't see many mr2's or Fieros where I live.

Thicker is better... and the same applies to sound deadener. Which products are you looking at? Are you trying to keep it light? Do you have a loud stereo or is your exhaust the only thing that makes your concerned with? Even 15mm is not worth the effort to install it in my opinion. I am slowly covering my interior with 70mm, and I believe other products are even thicker than that.

Make sure you check what the deadener is made of. You want butyl rubber. Asphalt products smell like... well... asphalt.

- Joe

 

[OldFartAudio]

Open cell foam helps to decouple from the vibration similar to a dual paned window. Sound hits the outer pane but loses energy between the two panes so very little makes it through. Closed cell is heavier and acts as a vibration deterrent to stop what does make it through the first layer. The butyl rubber foil backed stuff dampens by adding mass to the panel and impeding resonance. If you mainly trying to block out the exhaust I would concentrate on the firewall and engine bay. It’s a cool car. I would love a second gen.

 

[BoyDadCar]

thanks for the replies and compliments! I mainly want to block vibration and engine noise. I don't really care about the stereo. Ive heard you put open-cell foam and then closed-cell over for thermal and heat resistant. open cell is for high-frequency sounds and closed-cell is low frequency. Also open blocks vibrations. 15mm is the thickest I can get on wish and amazon is like 5mm. do you think 15mm is bendable enough to put on floor and roof? I think with the combination of 15mm and the 8mm it would do quite well.