Sound Insulation

[Revvv]

I know that sound insulation isn't a normal addition to a performance car. Insulation adds weight, and weight affects performance. Noise is expected, and usually enjoyed.

However, I need to lower the decibel level in my car. My daughter is sensitive to noise, but she enjoys riding with me from time to time. I'm not worried much about the minute amount of weight that would be evenly distributed throughout the vehicle. I would like to cut the volume of the exhaust, rear end, transmission, etc.

Before anyone suggests it, changing the exhaust is not wanted. The exhaust flow is perfect, as well as the tone. The volume outside of the car is not obnoxious (you will go deaf inside). I was able to see an increase in performance across the board for my application, and I don't want to change anything if I don't have to.

The exhaust system is a full Borla S-Type (Stinger) system with an H mid / downpipe.

[eville]

https://www.sounddeadenershowdown.com/

Good read.

[Tsaints1115]

You gave your own answer.

Do it for your daughter. You're not building a race car so 50# of sound deadener won't make any difference to the seat of the pant's feel of your cars performance.

[Revvv]

You gave your own answer.

Do it for your daughter. You're not building a race car so 50# of sound deadener won't make any difference to the seat of the pant's feel of your cars performance.

...but what are you guys using? What is a good suggestion. I've already made up my mind that the car needs sound insulation.

[dhutton]

I use Dynamat followed by a layer of Thermozite.

Don

[John McIntire]

I'm interested in hearing everyone's input. I've been eyeing up this company Flatline Barriers, but can't get anyone's take on it.

Let the suggestions flow!

[WallaceMFG]

We have put Lizard Skin in several vehicles, that stuff really works. We used both the sound and heat products. We also use Dynamat in the doors and areas we don't want to spray Lizard Skin.

We had one car that was driving before we put in the Lizard Skin, the floor in front of the mufflers was hot enough that you could feel it through shoes. After Lizard Skin, you could barely tell there was anything hot under there. Sound levels knocked down quite a bit too. Highly recommend.

I might have missed it, but does your car have full tail pipes out the back or turn downs? If it does not have tail pipes, put some on. That will get rid of most or all of the interior drone without affecting the overall sound much. My Rustang went from needing earplugs on the highway to dead quiet inside just by adding tail pipes.

[77thor]

Another vote for Dynamat Extreme... It makes a huge difference. Works great!

And the doors close with a "thud".

[Revvv]

We have put Lizard Skin in several vehicles, that stuff really works. We used both the sound and heat products. We also use Dynamat in the doors and areas we don't want to spray Lizard Skin.

We had one car that was driving before we put in the Lizard Skin, the floor in front of the mufflers was hot enough that you could feel it through shoes. After Lizard Skin, you could barely tell there was anything hot under there. Sound levels knocked down quite a bit too. Highly recommend.

I might have missed it, but does your car have full tail pipes out the back or turn downs? If it does not have tail pipes, put some on. That will get rid of most or all of the interior drone without affecting the overall sound much. My Rustang went from needing earplugs on the highway to dead quiet inside just by adding tail pipes.

I'm running a full exhaust with rear exit.

[kush69]

Check out second skin luxury liner pro mass loaded vinyl defintly heavy but blocks sound very well.

[Gmachine1911]

I used Dynamat Extreme which works awesome, but the cherry on top is adding a layer of 1/4" Dynaliner on top of the Dynamat Extreme. I can tell you, in my experience, adding the Dynaliner made as much or more difference in the sound deadening as it did with just the Dynamat. The two work well together as the Extreme blocks heat and takes out the "tinny" sound while the Dynaliner further knocks down the noise and adds very little weight in the process. Good luck!

[minendrews68]

I bought a box of Killmat. looks just like all the other Dynamat type products but considerably less expensive. I used it inside the doors so far to take the "twang" out of the doors. Seems to work pretty good.

[slimjim]

This may be on the expensive side but I like the look of 'membrane' from restomod air, it appears to be a 2-in-1 version of butyl and rubber. might even save you some coin if planning to buy the 2 products separately. I've started with raptor liner and will probably apply something like this over the top.

[chuckd71]

Have tried several things but might give membrane a shot for the simplicity of it.

[Chad-1stGen]

I honestly doubt you will see any difference in decibel level from the exhaust with the addition of sound deadener. And definitely no difference in rear gear whine. Sound deadener reduces the panel harmonics / vibrations where it is placed. Generally, those aren't caused much by exhaust or ring gear whine.

I didn't notice much difference in either of those when I pulled a bunch of sound deadening and foam insulation out of my 68 Camaro. The interior got a tiny bit louder from road noise. But IMO the loud exhaust drowned out most of the benefit of the sound deadening I had previously added. That and the increased wind noise these cars tend to have over modern cars.

[vette427-sbc]

https://www.sounddeadenershowdown.com/

Good read.

This.
One product alone is not going to help you. You need to evaluate where the noise is coming in (besides the windows). Having taken apart more than a few Mercedes, Bentley, BMW, etc... They all share a common sound deadening formula. Thick foam with a mass loaded vinyl on the floors, firewall and rear seat bulkhead. The sheetmetal is not covered 100% in damping tiles, but more like 30-50%. Thinner areas like doors and roof that cannot use the thick foam and MLV formula will have the CLD tiles, 3m thinsulate and the MLV. Every car is different, different panel shapes resonate differently, and will respond better or worse to each method. For our hobby, its more of a trial and error than an engineered solution

[LS1-IROC]

Last winter I did my whole floor pan with the CLD/MLV and ensolite foam. Pretty much the same approach as SoundDeadnerShowdown spells out. It made a big difference in noise level inside the car. Very pleased with it.

[Revvv]

Great ideas. If anyone has anything else feel free to share.

[vette427-sbc]

Not related to exhaust noise, but many new cars have some kind of wind noise gasket on the front and rear door edges. Take a look at the next newer bmw or Mercedes you see (probably a bunch of other cars too, I just happened to notice on slot of their models), the fender to door and door to quarter (or rear door) gaps have a piece of weather strip that they seal on... helps with wind noise and vehicle aero

[shelteredchevelle]

I did a major stereo in my '17 Raptor and completely gutted it to do the install. We applied about 300 pounds of Focal B.A.M. xxxl mat to the roof, floors, back wall, firewall, outer door shell, and inner door panels. It is pretty amazing the lack of noise inside the cabin and just about zero vibration, even with the stereo at close to full throttle. Talk about creating a vault, the doors feel like they're lead lined. Not cheap, but very good stuff.
If I was chasing the OP's problems, I might use a combination of lizard skin products with some kind of mat on top to eliminate static noise.