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    1. #1
      Join Date
      Sep 2016
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      LA - Lower Alabama
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      Current recommendations for sound deadening and insulation

      what's the current guidance on sound deadening and insulation for a protouring car? In the process of relocating my battery to my trunk, I ended up tearing out my interior and coating my floor plans, and I figure I might as well put in something to help keep it quiet and cool.

      Not it sure if it matters, but this is a 1969 camaro.



      Thanks for the help!


    2. #2
      Join Date
      Jul 2011
      Location
      Nashville/ Tampa
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      I'm sure you'll get a thousand different answers here but car audio forums will have lots of better information. Some of those guys actually test stuff and people doing SPL competitions and etc are more knowledgeable than us hobbyist types. Having used a variety of stick on products in the past, moving forward I'm going to use dense non-adhesive products for floors. Makes changing seats, trans, etc easier.
      For practical purposes it seems unlikely you'll notice a huge difference between brands once you get to a certain minimum quality level.
      https://www.instagram.com/gen_v_lt1_chevelle/


      Do not buy anything from Frankie's Used Auto Parts. Ever.
      Chevelle ̶a̶l̶m̶o̶s̶t̶ ̶f̶i̶n̶i̶s̶h̶e̶d̶ L92/200-4r now Gen V LT1 and T56- https://ls1tech.com/forums/conversio...nvertible.html

    3. #3
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      Sep 2005
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      I have always used DynaMat Lite or RamMat

    4. #4
      Join Date
      Sep 2016
      Location
      LA - Lower Alabama
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      560
      Quote Originally Posted by chuckd71 View Post
      ...... Having used a variety of stick on products in the past, moving forward I'm going to use dense non-adhesive products for floors.......
      Can you give me an example? Are you referring to something like a spray-on (or roll-on) material? Like bedliner or lizardskin?

      Quote Originally Posted by BMR Sales View Post
      I have always used DynaMat Lite or RamMat

      DynaMat was on my shortlist, but I'll need to check into RamMat. Thanks for the info!

    5. #5
      Join Date
      Jul 2011
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      Nashville/ Tampa
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      I don't have the box in front of me but I have used a what I think is called Stinger roadkill in floors and like it. Two layer closed cell foam and butyl combo.
      I've used Rammat, dynamat (thin crap), dynamat extreme (better), dynalite or whatever it is now, peel in seal back in the day and spray on (only in places I couldn't put something worth using) and really I couldn't tell you which is which in terms of the results, at least with adhesives. Can someone in a competition car tell? Maybe. Can Joe Average driving down the road in a 50 year old rolling brick? Doubt it. Just IMO. To really do it right you need multiple layers of multiple things, and full disclosure I haven't taken the time to do it 100%, $1,000 correct.
      In my experience a spray or roll on product isn't going to do much except maybe take some of the tinny metal sound out. I'm actually putting in some leftover damplifier right now, expecting very little out of one layer in a convertible, I just want it out of the garage.
      Grain of salt with all of this, I haven't done anything close to being serious about this since high school helping friends out.
      https://www.instagram.com/gen_v_lt1_chevelle/


      Do not buy anything from Frankie's Used Auto Parts. Ever.
      Chevelle ̶a̶l̶m̶o̶s̶t̶ ̶f̶i̶n̶i̶s̶h̶e̶d̶ L92/200-4r now Gen V LT1 and T56- https://ls1tech.com/forums/conversio...nvertible.html

    6. #6
      Join Date
      Sep 2010
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      Beach Park IL
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      50% to 100% coverage of a "mat" product. I use Boommat or Dynamat.

      Then 100% coverage of DEI UnderCarpet lite. Done.
      Donny

      Support your local hot rod shop!

    7. #7
      Join Date
      Dec 2008
      Location
      Detroit
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      A closed cell foam/foil butyl combo would work the best. If you choose to do foil with butyl based solution, pay attention butyl AND foil thickness. I used Damplifier Pro from Second Skin Audio. Very happy with product and adhesion.
      Big dreams, small pockets....

      Chris--
      '72 Cutlass S LSA/T56 Magnum
      Bowler Performance, Rushforth Wheels, ATS, Holley EFI, KORE3, Ridetech

      Project Motor City Madness

    8. #8
      Join Date
      Feb 2013
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      799
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      You'll see sound proofing way overdone and done incorrectly both here and on car audio forums.

      As background, I used to be engineering support for BMW and Mercedes NVH applications. Basically, molded carpet with other layers to reduce road noise and vibration.

      To really cover all your bases, you'll need a damper, a decoupler, and a barrier (sticky mat, closed cell foam, and mass loaded vinyl). A lot of people seem to stop at damping or try to get it to do all the work. It won't get you all the way.

      Pick your favorite brand of butyl based damper. Stinger was the last one I used and it is more than adequate. Cover 50% - 75% of the intended sheet metal. More doesn't really help you but might make you feel better. Automakers usually apply something to serve this function directly to their own sheet metal and paint over it.

      Decoupling the floor from you is just foam that isolates you from sound/vibration. Closed cell foam doesn't absorb water and works well. 1/4" is common as your car wasn't designed for the 4"-6" layer in modern luxury cars. Noico liner works well, is adhesive, and you can find it on Amazon.

      The mass loaded vinyl is the last step and is where the real magic happens. You can find car audio brands but just buy a roll of 1 lb/ft2 of acoustic mass loaded vinyl. It is automotive grade and is what is used by BMW/Mercedes. Amazon has it and it will be expensive to ship. It is MASS loaded vinyl. Cover everything that you can with this. For curves/corners/compound angles you'll need a cement for it called HH-66 Vinyl contact cement. Basically just build a tub of you floor pan out of this material with the necessary bolt holes for seats, etc. For OE applications, this is molded between the foam and carpet.

      That's it.

      This guy is the closest I've seen to OE automotive, https://www.sounddeadenershowdown.com/, but still a little pricey on his materials.

      Do all of the above and you'll be able to have conversations in a normal tone of voice with your passengers.

    9. #9
      Join Date
      Aug 2015
      Location
      charlotte
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      I'm approaching this stage and have already started purchasing the basics, I plan to use a "mat" product, undecided which one, and the NOICO closed cell liner, I can get it nice and cheap.
      I see some people go this route: Epoxy, seam sealer, raptor liner or por15, then sound deadening materials.
      Is the raptor liner going to add anything at this point or is it just personal preference? I was leaning towards applying sound deadener to the SPI epoxy floor, Is there a problem with this?

    10. #10
      Join Date
      Sep 2016
      Location
      LA - Lower Alabama
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      560
      This is an interesting topic, though not one I'd put much thought into. The home theater guys tend to agree that sound control comes down to mass. Attenuating high frequency stuff is easy, but controlling low frequency energy really boils down to mass. You can add a constrained damping layer (or whatever it's being called now) to improve performance.

      What's most interesting about this discussion to me is spray foams (open or closed cell) have been shown to perform poorly with regard to broad spectrum sound control. They work fine for high frequency content, but just about anything does. Spray foams work great as thermal barriers, and maybe that's the piece of the puzzle they're providing here. I suppose there's also the issue of panel movement here, and I can see where spray foam products would help there as well.

    11. #11
      Join Date
      Feb 2013
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      Quote Originally Posted by AU Doc View Post
      This is an interesting topic, though not one I'd put much thought into. The home theater guys tend to agree that sound control comes down to mass. Attenuating high frequency stuff is easy, but controlling low frequency energy really boils down to mass. You can add a constrained damping layer (or whatever it's being called now) to improve performance.

      What's most interesting about this discussion to me is spray foams (open or closed cell) have been shown to perform poorly with regard to broad spectrum sound control. They work fine for high frequency content, but just about anything does. Spray foams work great as thermal barriers, and maybe that's the piece of the puzzle they're providing here. I suppose there's also the issue of panel movement here, and I can see where spray foam products would help there as well.
      Foam should really only be used to decouple, which is why it's always there in OE applications between the damping and mass layers. OE foam is also mass loaded but no where near the density needed to function as a standalone solution.

    12. #12
      Join Date
      Oct 2011
      Posts
      696
      Justjohn, are we supposed to use all 3 layers everywhere or just the floor, trunk and firewall? What about the roof, all 3 layers also? What about inside doors? I doubt you can fit all 3 layers inside a door. Also what about rear package tray, outside door like immediately behind door panel? Lastly, after all 3 layers are in the floor pan can we put molded carpet or do we need some padding between 3 layers then padding then carpet?

      Thanks!

    13. #13
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      Feb 2013
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      Quote Originally Posted by joeko23 View Post
      Justjohn, are we supposed to use all 3 layers everywhere or just the floor, trunk and firewall? What about the roof, all 3 layers also? What about inside doors? I doubt you can fit all 3 layers inside a door. Also what about rear package tray, outside door like immediately behind door panel? Lastly, after all 3 layers are in the floor pan can we put molded carpet or do we need some padding between 3 layers then padding then carpet?

      Thanks!
      The more surfaces you cover, the more noise you block. Sound is basically just treated as radiating from everywhere so you are essentially just building a dam to keep it out. The short answer is nothing else is needed between your sound proofing and the carpet. The decoupling layer is doing that for you.

      For the guys who are spraying with Rhino Liner, that is essentially acting as the damping layer and they probably don't need additional butyl because the coverage is so thorough.

      When I did my Wrangler it was a good case study because it comes from the factory with basically nothing. A few patches of damping material here and there to keep it from ringing like a bell. I did the entire floor and all 4 doors with butyl, closed cell foam, and MLV. It is not uncommon in the aftermarket and can be fit under door panels. When I get around to it I'll put a Moll panel on the rear gate and put the same thing under it. As it is, people in the rear seat can now hear and participate in conversations going on in the front seat. You can have phone conversations on the highway. I kind of have an audio thing going on with it too.

      If I were doing my Impala doors (which I will at some point), I'd put the butyl on the outer door skin and the foam/MLV under the door panel.

      Basically, the more you cover, the quieter it gets. When I was at IAC (part of the automotive interior division spun off from Lear), the Detroit sound lab had a front/rear roller dyno as a road simulator. The OE gave us interior noise level specs to meet. From there, we covered all the glass in MLV and used arrays of microphones to measure transmitted sound inside the vehicle. That is how "leaks" were pinpointed and addressed with additional sound proofing.

      From a strictly automotive performance perspective, none of this is ideal. It's not uncommon to add 75+ lbs to a vehicle with the goal of making it comfortable on the inside. Since I'm really after more of a GT vehicle, it's a trade off that works for me.

    14. #14
      Join Date
      Oct 2011
      Posts
      696
      Thanks for the info, so your saying if I spray some bedliner underneath the vehicle, I will not need the layer of butyl on the floors? I am using defender pro, I think it's pretty comparable to rhino

    15. #15
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      Sep 2016
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      LA - Lower Alabama
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      Quote Originally Posted by JustJohn View Post
      ........
      This guy is the closest I've seen to OE automotive, https://www.sounddeadenershowdown.com/, but still a little pricey on his materials.
      ......
      I'm finally getting close to putting my interior back In my car. So I'm putting some thought into this again. I double checked the prices based on what I found on Amazon with a few quick searches, and it looks like https://www.sounddeadenershowdown.com/ pricing is about the same as buying the stuff separately. Maybe even a little cheaper. It's certainly cheaper than the custom cut dynamax extreme kits for my car.
      Dude are you made of leprechauns? Cause that was awesome!

    16. #16
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      Apr 2001
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      The City of Fountains
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      15,971
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      Quote Originally Posted by AU Doc View Post
      I'm finally getting close to putting my interior back In my car. So I'm putting some thought into this again. I double checked the prices based on what I found on Amazon with a few quick searches, and it looks like https://www.sounddeadenershowdown.com/ pricing is about the same as buying the stuff separately. Maybe even a little cheaper. It's certainly cheaper than the custom cut dynamax extreme kits for my car.
      I've bought stuff from him and it works well. However, the mass loaded vinyl is really...really...I mean, really heavy. I would think long and hard about when to actually use it. Remember, at the end of the day we're playing with old cars. These aren't hermetically sealed modern BMWs. We also want maximum performance, and weight is our enemy.

      Andrew
      1970 GTO Version 3.0
      1967 Cougar build
      GM High-Tech Performance feature
      My YouTube Channel Please Subscribe!
      Instagram @projectgattago
      Dr. EFI
      I deliver what EFI promises.
      Remote Holley EFI tuning.
      Please get in touch if I can be of service.

      "You were the gun, your voice was the trigger, your bravery was the barrel, your eyes were the bullets." ~ Her

    17. #17
      Join Date
      Sep 2016
      Location
      LA - Lower Alabama
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      560
      Quote Originally Posted by andrewb70 View Post
      I've bought stuff from him and it works well. However, the mass loaded vinyl is really...really...I mean, really heavy. I would think long and hard about when to actually use it. Remember, at the end of the day we're playing with old cars. These aren't hermetically sealed modern BMWs. We also want maximum performance, and weight is our enemy.

      Andrew
      That's a good point. It's about 150 s.f. to do a car, and that stuff is about 1lb/s.f., correct? So another 150 lbs to the scales. I suppose the question is whether or not it's worth it for a car that will spend 95% of it's life cruising around town and up and down the interstate, and the other 5% of its life on a track. I wish I could say those numbers were reversed, but unfortunately, the good Lord decided to make me good looking instead of wealthy

      Still. Lighter is always going to be better. Even on a cruiser.
      Dude are you made of leprechauns? Cause that was awesome!

    18. #18
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      Sep 2016
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      LA - Lower Alabama
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      560
      EDIT: Double Post
      Dude are you made of leprechauns? Cause that was awesome!

    19. #19
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      Apr 2001
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      The City of Fountains
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      Cruising around town the difference is negligible, at least for me, because I generally have my windows down. There is a bigger difference on the highway, especially with the windows up. The exhaust also plays a major role. If it's loud to start with, it is very difficult to deflect all of the sound.

      Personally, I would put sticky stuff on the roof, firewall and inside the doors, then assemble the car and see how it goes. If it is too loud, start on adding other stuff to the floor. I would also recommend some kind of heat blocker for the front of the floors right away. The heat from the exhaust will definitely come through, especially when just cruising around town.

      Andrew
      1970 GTO Version 3.0
      1967 Cougar build
      GM High-Tech Performance feature
      My YouTube Channel Please Subscribe!
      Instagram @projectgattago
      Dr. EFI
      I deliver what EFI promises.
      Remote Holley EFI tuning.
      Please get in touch if I can be of service.

      "You were the gun, your voice was the trigger, your bravery was the barrel, your eyes were the bullets." ~ Her

    20. #20
      Join Date
      Feb 2013
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      799
      Country Flag: United States

      Modern noise, vibration, heat (NVH) control.

      This keeps coming up so I decided to summarize some of the information from my previous career. I used to be involved in the manufacture of interior acoustic control for BMW and Mercedes. The plants in Greenville, SC and Tuscaloosa, AL are supplied from Greenville and Spartanburg, SC. During that time, I had regular meetings at the BMW facility as well as travelling to the development center in Stuttgart for Mercedes to work on upcoming models. Here is a summary of the whole process from my former company:

      Interior component prototypes for interior noise reduction are developed in a pre-production vehicle on a dual axle dyno which can accommodate speeds up to 125 mph. Exterior transmission surfaces, like glass, are covered with 1 lb/ft^2 mass loaded vinyl to block sound from surfaces not being studied. During the dyno runs, noise levels are measured inside the car by an array of microphones arranged on a grid. The array is aimed at various places in the interior to determine where most of the transmitted noise is coming from. This is to determine where to apply sound damping material and is mainly a cost cutting exercise. The materials used are relatively expensive and even luxury automobile producers do not overspend on construction. The effective hobbyist approach is to cover as much as is feasible.

      Here's what BMW and Mercedes do:
      Damper is applied directly to the body at the factory under the paint. It's butyl-based and not that much, about 50% - 75% coverage max. If you've ever pulled carpet from a new vehicle you've seen it. Just some "thicker" material here and there that was painted over in the factory color. It's enough to get rid of resonance, nothing more. I think that is often misunderstood about damping material but the most easily demonstrable. A bell does a good job of resonating and is described as ringing. Apply damping material to the bell and it no longer resonates. I think Dynomat uses this as part of their marketing. If you ring a damped bell, the initial sound is just as loud as before but there is no resonance. It's just a thud. Good, but there's more to NVH control.
      For the interior carpeting, what most people do not realize is that it is several inches thick in modern (luxury) cars. Roughly 4-6 inches and just the carpeting can weigh 50 - 60 lbs. The car has this designed in and here is the composition:
      1. Isolation layer of mass loaded foam. Exactly what it sounds like, it is a two part molded foam, mixed at the molding process and loaded with a carbon-based material to add mass. This layer isolates the interior from exterior vibration and keeps the thud of the damped car body from being transmitted to the passengers. I just recently found this commercially available in the aftermarket. A good compromise material is closed cell foam. It does not absorb water and is available in rolls and sheets.
      2. Mass loaded vinyl. 1 lb per square foot and about 1/8" thick. This is molded on top of the foam and blocks transmitted sound waves. This is the screen that keeps out ambient noise, especially the higher frequency sounds that most people can here. This should cover everything you can get it to cover with as few gaps as possible. By definition, this stuff is heavy and is not cheap to ship.
      3. Carpet. I feel like this is self explanatory.

      For the firewall pad, it is mass loaded foam and mass loaded vinyl.

      That's all there is to it if you are aiming for a quiet ride. Damping the sheet metal, isolating the interior, blocking sound. The materials to do these three things are well established and readily available.

      I put a high end stereo in my Wrangler a couple of cars back and went through this exercise. From the factory, a Wrangler has some damping and some carpet. Conversations with the back at highway speeds are not feasible. After adding 75% coverage Stinger butyl damping, NOICO closed cell foam and mass loaded vinyl (it's all on Amazon), I achieved a 6db reduction in ambient noise (3db is percieved as twice as loud).
      Doing more than the above is a fun over-engineering exercise but will only add (more) weight and not really improve the results.

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