Interior Drone/Sound Deadening

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Longroof79

Rocket Powered Basset Hound
G-Body of the Month
Oct 14, 2008
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Gainesville, Fl
I've used a product called Bonded Logic. It comes on a roll and is made up of shredded denim with a foil backing. I did the entire inside of the car...roof, floors, cargo area, etc. It was fairly cheap and is a good sound deadener/ insulator. I purchased it from JC Whitney some years back. I don't know if they still carry it or not. Home Depot was another source if I recall..
 
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500/600

Royal Smart Person
Nov 17, 2018
1,167
2,638
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West Virginia
I have the largest Dynomax mufflers available. It’s a combination of engine and road noise. Hitting potholes sounds bad. Thinking it’s the poly body bushings too...

My bad. I thought that you were talking about exhaust drone.
 

DSPbuilt

G-Body Guru
Jan 7, 2016
564
1,526
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Cape Coral, FL
I been driving my car around with open headers. I see the floor vibrating when it starts to drone. it is unbearable. My car has no carpet or sound deadener(Yes, I know obviously its going to be obnoxious).
I just ordered some cheap Amazon Kilmat sound deadener and going to order my carpet soon. I am also having my exhaust done next week. I doing something different because I don't want to have to do my whole exhaust twice. My car is going to be turbo by the end of the year beginning of next year. So I am having a custom 3" Y to a single 4" all v-banded with a resonator and Vibrant muffler. all stainless Tig welded.
 
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jlcustomz

G-Body Guru
Nov 22, 2011
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For exhaust drone, google the subject of j-pipes, or hertzholm resonators. It's simply a length of capped off pipe which reflects sound waves back & cancels certain tones. Doesn't cause any restriction , as no air passes through it. Late model factory mufflers can have these inside, so nothing new. Solo performance is one company that sells mufflerless systems with them.
 
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81_El_Homewrecker

Greasemonkey
Oct 26, 2015
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For exhaust drone, google the subject of j-pipes, or hertzholm resonators. It's simply a length of capped off pipe which reflects sound waves back & cancels certain tones. Doesn't cause any restriction , as no air passes through it. Late model factory mufflers can have these inside, so nothing new. Solo performance is one company that sells mufflerless systems with them.
I want to do one but have no idea how to figure out the hertz range of my drone...
 

81_El_Homewrecker

Greasemonkey
Oct 26, 2015
170
43
28
Yea, that's the confusing part for me. Could look at what others with similar engine/exhaust size may have done. I know there's formula's & phone apps. Others have kinda guessed & got an improvement.
I’m going to add an H pipe I think and see what happens. I guess they have other benefits aside from sound so could be a win win.
 
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axisg

Comic Book Super Hero
Jul 17, 2007
2,685
2,354
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YYZ
I went uber cheap with mine and used the foil backed bubble wrap from HD. You find it in the aisle with the water heaters. I did not want anything that sealed to the floor so I laid it out double on the DS and PS floors. And used 3m spray adhesive to stick it to the roof when I replaced my headliner. Also used adhesive foil tape ( real duct tape ) on the seams on the floor. It made a noticeable difference in both sound and heat displacement on the PS floor where the cat convertor resides. Before I could not hold a conversation with my cell it was so noisy. Afterwards it was no issue

 
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Kemper1976

Greasemonkey
Jul 25, 2017
172
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Topeka, KS
I have a Turbo LS with single 3.5” Borla XR-1 stainless exhaust the runs over the rear housing and exits in the stock location. after driving the car quite a bit the Highway drone really started bothering me.

I built a hemholtz resonator for my Cutlass that was 2.5” diameter and 3’ long. I welded it to my exhaust pipe just a few inches after the muffler then ran it towards the front of the car. It got rid of the drone immediately.

Prior adding this Hemholtz resonator, the exhaust drone at 2k was mind numbing

I’m sure there’s a formula to figure what length for what frequency but the rule of thumb is the resonator tube should be 1/2 the length of your exhaust after the muffler.


I also had a 2015 Chevrolet truck which someone added a huge single mafnaflow muffler that was 3.5” in/out. The drone made me avoid the highway at all costs.

I didn’t want to invest much to remedy the drone so I bought a $15 exhaust auger from Speedway, stuffed it inside my tailpipe and tack welded it in place. Cured the drone and made my exhaust quieter and all around better.

A little side note, I have no sound deadener other than the factory style pad that’s attached to the bottom of the interior carpet.

I’m sure there are some who could argue what I just mentioned, but this worked for me and I have nothing to gain by posting this. 👍🏼
 
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jlcustomz

G-Body Guru
Nov 22, 2011
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H or x pipe will give sound difference & a small power increase with the h pipe being deeper & the x the more powerful , scavenging, & canceling more resonance. Marginally, that is. Either one balances exhaust & allows both banks of cylinders to breathe through both mufflers.

On actual interior sound deadening, factories use multi component methods. Heavy stick ons dampens metal vibration, but not air transmitted noise & covering every last inch of surface usually is a waste. Foil or ceramic infused product helps heat. Any product that traps air particles helps insulate & trap sound movement.
 
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