Engine Room Sound Insulation

[Beersmith]

I am looking at getting some Soundown foam to insulate my engine room. I am a bit confused by the difference between these two products:

Soundown Composite Insulation Vinyl Foam Sheets

Soundown Acoustic Absorption Foam

The second is much cheaper than the first, even at the same thickness. What are you getting with the vinyl foam sheets that the acoustic absorption foam doesn't have? The only thing I can figure out is the "barrier" feature, but that appears to be nothing but odor control, is that correct? Would I be extremely unhappy if I got the cheaper foam?

[GordMay]

Acoustic insulation materials work by two processes:
Absorption of sound energy, which dissipates sound as heat energy,
and
Reflection, which reflects noise away from a location where quieting is desired.

Acoustic Insulation operates on only the absorptive principle, while Vinyl Foam Composite utilizes both absorptive & Reflective processes.

Diesel engines generally emit higher sound pressures in the lower frequencies.

➥ http://www.soundown.com/Section%202%...orp%20Foam.pdf

➥ http://www.soundown.com/Section%202%...nyl%20Foam.pdf

[HopCar]

The more expensive sheet is made up of four layers. There is a thin mylar like surface layer over a layer of foam. Then you have a layer of very dense plastic which is over another layer of foam. It is the dense layer that takes out the deeper sounds of a diesel. It is much more effective than the less expensive stuff, especially with a diesel engine.
Years ago they actually used a layer of sheet lead between the layers of foam. The dense plastic seems to work just as well and is easier to work with.

The less expensive stuff is only two layers, mylar over foam.

Don't count on adhesive alone to hold this stuff on an overhead. You really need to use mechanical fasteners as well.

If you have any questions, you can call me at work. I recently installed this stuff on my boat.

[Beersmith]

Thanks so much for the info!

[GordMay]

Originally Posted by HopCar

The more expensive sheet is made up of four layers. There is a thin mylar like surface layer over a layer of foam. Then you have a layer of very dense plastic which is over another layer of foam. It is the dense layer that takes out the deeper sounds of a diesel ...

Called “Mass Loaded Vinyl” (MLV)

[hogfighter]

I know that this thread is a little old, but I went on down to the Soundown store in Ft. Lauderdale last week and checked out both of these sheets. Really no comparison.....the "more expensive stuff" was head and shoulders above the regular foam. The Vinyl/Foam Barrier Composite was self -adhesive, quite a bit heavier, simply seemed much more quality. I bought a sheet and am presently installing it in my generator bay. Easy enough to work with, make sure to screw holds into any part that is applied to the ceiling. If you care, I'll let you know how it sounds (or doesn't sound) when I'm through.

[HopCar]

Here are the installation instructions: http://www.soundown.com/Section%203%...structions.pdf
I tried to use screws to fasten it to the overhead but the screws just kept tearing it. Use their pin fasteners. They are easy to use and work great. I like to use a few on vertical surfaces as well as overhead. Be sure to tape the raw edges with their reinforced mylar tape.

[DeepFrz]

If you care, I'll let you know how it sounds (or doesn't sound) when I'm through.

Yes, please...

[hogfighter]

It's been a little while, but I finally installed all of the sound insulation around my generator compartment. I used the Vinyl/Foam Barrier Composite with self-adhesive backing from Soundown.

All in all, it did a good job reducing the noise from the generator. My compartment is oddly shaped (doubles as a cupboard / seat in the main salon), so it was nearly impossible to completely cover every inch...which I suspect would have made the sound even better. Even so, we played poker last night while sitting on the generator and wasn't bothered by the noise.

I liked the adhesive backing...the stuff is impressively sticky. Although far from cheap, I would use this insulation again. If you are able to completely cover the entire compartment, I believe that you would really be impressed. Hope this helps!