Sound deadening material

[DonRW2007]

Has anyone used commercially available sound deadening material in their Rover or other vehicle? Looks like there are a number of options and brands out there. I was considering lining the underside of my hood; I figure a good deal of road (and obviously engine) noise could be eliminated. But, I wonder if it is really effective unless one goes all-out and installs in door panels, floor, etc. Any experience or comments appreciated. DRW

[Savannah Buzz]

As part of your research you might consider a trip to the junk yard. Not to get material, but to see how the various high end cars applied it, it turns up in lots of spaces. As you said, in doors, under glove boxes, etc.

[Mountain Goat]

Originally Posted by DonRW2007

Has anyone used commercially available sound deadening material in their Rover or other vehicle? Looks like there are a number of options and brands out there. I was considering lining the underside of my hood; I figure a good deal of road (and obviously engine) noise could be eliminated. But, I wonder if it is really effective unless one goes all-out and installs in door panels, floor, etc.

Any experience or comments appreciated.

DRW

I should preface this with I run a professional installation service so I've used a variety of products.

Look into Second Skin Audio (Sound Deadening Materials for Noise Reduction from Second Skin) and Sound Deadener Showdown (Sound Deadener Showdown - Your Source for Sound Deadening Products and Information) both make good quality products. SDS has great info on their site as well. I recommend thorough reading on diymobileaudio.com and mobilesoundscience.com, there are some excellent threads on the science behind it all.

Basically you have three types of material - damping, absorption, and blocking. Damping is the only type commonly used, such as Dynamat. People throw layer after layer in cars and but it's usually misused. You need damping material in large flat areas prone to vibrations and flexing. In extreme cases you may need to add physical bracing as well.

Absorption material is not often practical in a car because of the thicknesses required, but an example is the thick foam on the walls in some recording studios.

Blocking material is heavy and stops airborne noises. Examples are lead, mass-loaded vinyl (MLV), and concrete. Mass-loaded vinyl is the most commonly used. It is generally applied on the entire floor area, the seams sealed with some type of glue, and decoupled with foam (just means it is spaced from the floor so it can behave independently from the floor). It can also be applied inside doors but this is trickier.

In short there is a huge science to sound deadening. Take your time to learn as much as you can first and you will avoid unnecessary and fruitless purchases.

And I agree on the luxury car comment. The most common theme I've seen working on luxury cars is multiple layers of varying materials (foam, MLV, different type of foam, more MLV, etc.) and very airtight construction. So that should give you a good start. Feel free to shoot me a PM if you need any direction.

[slanginsanjuan]

i used an 1/4 inch insulation i bought on ebay between the old and new floors. I noticed an immediate benefit in heat and noise. i'll add more behind the headliner and probably the hood.

i think it would definitely help although you would need to do it extensively.

[Mountain Goat]

Originally Posted by slanginsanjuan

i used an 1/4 inch insulation i bought on ebay between the old and new floors. I noticed an immediate benefit in heat and noise. i'll add more behind the headliner and probably the hood.

i think it would definitely help although you would need to do it extensively.

What is that insulation made of? If it's the same type I've seen (foam or fiber based), it's only marginally effective for noise compared to properly applied acoustical products.

[Disco Mike]

Don, you are probably the first person I have hear mentioning concern of too much noise from the engine compartment. For the most part it is just about dead silent. My concern about you trying to muffle some sound is you will cause the engine compartment to get even hotter then it already is and then you will have problems.

[Mountain Goat]

Good point, Disco Mike. I can hear my rod knock and my ticking exhaust manifold when I accelerate hard, plus a slight bit of drone from my Magnaflow, but otherwise I don't even notice the engine. Hardly any engine vibrations even make it to the cab.

[slanginsanjuan]

Originally Posted by Mountain Goat

What is that insulation made of? If it's the same type I've seen (foam or fiber based), it's only marginally effective for noise compared to properly applied acoustical products.

yes fiber and foil.

well according to the manufacturer it's awesome.

i don't think so...but i do think it helps and has quieted down the truck as I removed all the padding and carpets.

i know it has reduced heat.

i also know you're a pro and there are going to be lots of better products and procedures. For the costs and requirement, it worked just fine.

[Mountain Goat]

Originally Posted by slanginsanjuan

yes fiber and foil.

well according to the manufacturer it's awesome.

i don't think so...but i do think it helps and has quieted down the truck as I removed all the padding and carpets.

i know it has reduced heat.

i also know you're a pro and there are going to be lots of better products and procedures. For the costs and requirement, it worked just fine.

Not meaning to be critical, I was just curious if it was a different material from the one I mentioned. If you're first priority is heat retention or rejection and you accept the slight noise reduction characteristics as a minimal side effect than yeah it's great. I simply wanted to point out that according to the conventional math, 1/4" of anything porous (foam, fiber, etc.) is far too thin for absorption within the audible range. I have successfully used 1/4" foam before to stop panel squeaks and vibrations.

I also agree with Disco Mike though, you should probably not do any extra sound blocking under the hood because you risk trapping too much heat, and possibly covering up more serious problems that you should be able to hear.

[hilltoppersx]

im sure you are all well aware that the padding under the hood is not only for noise but fire suppression.

dynamat hoodliner is not a fire suppressor. the factory padding is made to smother the fire when the plastic plugs that hold it in place melt from excessive heat.

not saying you shouldn't remove it or replace it just stating fact.

FYI i tore mine out because it was falling out.