Sound deadening or barrier... Exhaust drone and noise control.

[Luisv]

About a month ago I did a muffler delete on my 2002 GTS. I love the new exhaust note. More of a growl instead of the hum the stock exhaust gave is the easy description of the change. Definitely keeping it. What I would like to do however is control a bit of the noise, vibration or drone in the cabin. I love the new sound of the exhaust, but at certain RPM while cruising the sound is too loud in the cabin under cruise.

I have read mixed reviews about the effectiveness of mass loaded vinyl (Dynamat, for example) for the control. In some places I've read that closed cell foam is the better option. Some say a combination. I've read this in many places about many cars but little with regards to what is best in a Viper.

What's the opinion out there? What have you seen done in Vipers?

I am not looking to make the Viper as quiet as a Luxury Sedan (Kind of defeats the purpose) but I would like to attenuate the cabin drone and noise a touch. Mostly concerned about cruises I do regularly.

 

[Steve M]

You would probably need to do a 2 step process...one to reduce panel vibration (that would be the Dynamat type of adhesive backed butyl rubber) followed by some sort of mass loaded vinyl to address the actual noise. The stick on stuff does not stop sound waves...it just keeps the sheet metal from vibrating. The MLV (like Second Skin Audio's Luxury Liner Pro) can actually stop sound, but the stuff is very thick, and very heavy (I have quite a bit laying around that I just can't bring myself to install due to the weight).

You can always try a Dynamat type stick on product first and see if that helps at all. Panel rattles account for a lot of noise in cars, so it is a good place to start. You don't need to cover every single square inch either...just enough to stop the panel from vibrating. Tap around on the sheet metal, find the places that sound the loudest, put down a square of Dynamat and try tapping it again to see if it stops. Keep working around the car until every time you tap sounds like a nice solid thunk instead of a hollow, drum like sound.

 

[eucharistos]

do you do straight pipe for your muffler del?

adding an x-pipe should greatly reduce the drone rpm range.

for me, i get a slight drone btw approx. 2100 and 2250 rpm which is easily avoided by gear choice. (also less drone in an rt, but still there especially with the hard top on)

 

[Dom426h]

adding an x-pipe should greatly reduce the drone rpm range.

I had the X-pipe on my full B&B system and she had plenty of drone.
On a stock system like the OP it might be worth a try though.

for me, i get a slight drone btw approx. 2100 and 2250 rpm which is easily avoided by gear choice. (also less drone in an rt, but still there especially with the hard top on)

My drone no matter how much i switch around my exhaust setup starts around 1200 and peaks at 1500 then falls off quick. The only thing that has remained constant is my B&B headers and everything is 3" to the outlet. I think that stock vs aftermarket header, and stock2.5" pipe vs 3" pipe is what mainly changes the drone range.

 

[Cobraken]

Just out of curiousity, why would you want to subject others to a noise you yourself want to diminish?

 

[Dom426h]

Cobraken, I see what your saying, but its not like that. The deep tone of the drone and its decibel level can be damaging to the users eardrums (according to OSHA blablabla). This is because the low frequency soundwaves are a large wavelength that get bounced back and forth inside the cabin eventually lining up causing an amplification of decibels at a particular frequency.

Outsiders are not subjected to this effect. They are hearing a larger range of sound frequencies than what you hear in your car.
Large frequency range / Minimal amplification is better for your ears than
Small frequency range / Maximum amplification.

 

[Luisv]

do you do straight pipe for your muffler del?

adding an x-pipe should greatly reduce the drone rpm range.

for me, i get a slight drone btw approx. 2100 and 2250 rpm which is easily avoided by gear choice. (also less drone in an rt, but still there especially with the hard top on)

I do have an X-pipe. I also went to 2.5" pipe. I essentially had a 2.25" to 2.5" coupler put in to bring the muffler delete portion up to a 2.5" from the 2.25" that is there in factory. I did this in anticipation of, perhaps going to 2.5" from the cat back. Currently the stock is 2.5" out of the cat, reduction to 2.25" through the stock sill mufflers. If I do something it may be a 2.5" sill muffler in the future making it 2.5" all the way through.

Bottom line, the x-pipe is in there....

Just out of curiousity, why would you want to subject others to a noise you yourself want to diminish?

I want a more throaty, deeper, tone. I also wanted louder. The problem is the reverberation in the cabin is amplifying the noise. This is not the case, for example, in a supercharged Charger SRT8 I have with a Corsa system. One reason is there is more "material" between me and the exhaust in the Charger. A huge trunk, rear seats, more sound deadening than the Viper, a metal body vs. the composite, etc dull the noise a great deal. The exhaust note is awesome outside the car. It is not unpleasant outside the car. It is not earth shaking by any means... inside however, it is louder and the reverberation in the car make it louder still at certain RPM... Again.... I don't expect this to be a Luxury Sedan, quiet type of ride... but right now we need to tone it down....

BTW... this setup is no different than side pipes.... It is just that the path to the rear is creating the echo in the cabin that I'd like to tone down a bit.

 

[Luisv]

You would probably need to do a 2 step process...one to reduce panel vibration (that would be the Dynamat type of adhesive backed butyl rubber) followed by some sort of mass loaded vinyl to address the actual noise. The stick on stuff does not stop sound waves...it just keeps the sheet metal from vibrating. The MLV (like Second Skin Audio's Luxury Liner Pro) can actually stop sound, but the stuff is very thick, and very heavy (I have quite a bit laying around that I just can't bring myself to install due to the weight).

You can always try a Dynamat type stick on product first and see if that helps at all. Panel rattles account for a lot of noise in cars, so it is a good place to start. You don't need to cover every single square inch either...just enough to stop the panel from vibrating. Tap around on the sheet metal, find the places that sound the loudest, put down a square of Dynamat and try tapping it again to see if it stops. Keep working around the car until every time you tap sounds like a nice solid thunk instead of a hollow, drum like sound.

OK... so now I am confused... Isn't the Dynamat the mass loaded vinyl? I know that does the vibrations... but wouldn't the closed cell foam handle the attenuation of the sound? If that is the case.... how thick? 1/8"? Thicker?

 

[Steve M]

OK... so now I am confused... Isn't the Dynamat the mass loaded vinyl? I know that does the vibrations... but wouldn't the closed cell foam handle the attenuation of the sound? If that is the case.... how thick? 1/8"? Thicker?

The Dynamat peel & stick product is butyl rubber with an aluminum constraining layer. The only thing that product does is reduce panel vibration.

Closed cell foam can attenuate some sound, but the frequency ranges I've seen are 15kHz-20kHz...far above the bass tones you are hearing.

Something like Second Skin Luxury Liner Pro is a mass loaded vinyl (Dynamat might have a similar product, I'm not sure), and that is what is specifically designed to stop sound waves. If you want attenuation, that is what you want. The stuff I have is 1/8" thick (feels thicker than that though), and weighs 1.25 lbs/sq ft.

 

[eucharistos]

I do have an X-pipe. .....

thanks for the reply, i am satisfied with the sound of mine and am thankful the drone is not in my cruising rpm range.....there is a solution out there for you

iirc, dave6666 did a write up on his dynamat install

 

[cubican]

The dynamat will not help with the drone a Corsa exhaust will .

 

[Luisv]

The dynamat will not help with the drone a Corsa exhaust will .

Love the Corsa systems. Have one in the Charger. Great for cruising. Quiet with no drone when normally driven and louder on full throttle. Great for the Charger and the way I use it. Like the "sleeper" mindset with the black 4 door sedan. However, the Viper is far from a sleeper car. A bit tough to not assume the performance is there with the car. I want the tone. The stock system attenuated the exhaust way too much, IMHO. I wanted to see what the muffler delete would do first. I love the sound of the delete. The only problem I have is the amplification in the cabin. I am certain it does not require an $1,800 solution.

I've got an order in for some butyl mat now for a '77 Vette we are restoring. I will see what that resolves. If I feel it requires more.... I'll go from there. I just wanted to see what if anything had been attempted before. From what I have seen...it has only been Dynamat or equiv.

I'll fill everybody in....

Thanks for the feedback though...

 

[JKVIPER]

The dynamat will not help with the drone a Corsa exhaust will .

I agree. I did the dynamat thing on my 01 GTS to quiet down the drone of a Borla, event put extra mufflers on it, finally ditched it and went with a Corsa. Sounded great after that.

 

[100_]

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I installed Dynamat Extreme and it quieted my 97 GTS considerably. It was extremely easy to put on. I also installed an extremely lightweight thermal blanket on the walls of the transmission and the mufflers. You can buy a Dynamat knockoff at Home Depot at the fraction of the $200 I paid to cover the trunk and cockpit. You can always roll down the window to hear more of the engine. Buy a $5 roller and just start rolling it on.

 

[Zentenk]

You will need to fab up a hertz resonator like this:

http://www.performancetrucks.net/fo...xhaust-resonator-tube-eliminate-drone-489463/

The Corsa mufflers have a similar system built within.

 

[Luisv]

You guys are complicating this way too much... My goal was to get a similar sound to side pipes. However, since the 2002 GTS runs the exhaust to the rear, the exhaust creates a drone in the cabin.

There is a drone... It is not stopping me from driving the car... Don't want a Corsa... Wanted a bit more growl... If I wanted a Corsa, I'd have gone that way...

The main culprit is the shape of the rear end of the car. The exhaust runs directly below the spare tire space. That is simply acting like a sub. Eliminating the vibration with a vibration damper like Dynamat or Second Skin Damplifier, will take most of the drone out. If I want a bit more quiet in the cabin, I will add a mass loaded vinyl... This will kill the volume as opposed to the drone which is a bass sound.

I have not done it but will be soon.... I'll see what I can do for a before and after video or sound clip....

 

[Westxsrt10]

CORSA..... go ahead and apply 2 layers of Dynamat. ( did 2 layers of Dyna and it did almost nothing for DRONE.)

You guys are complicating this way too much... My goal was to get a similar sound to side pipes. However, since the 2002 GTS runs the exhaust to the rear, the exhaust creates a drone in the cabin.

There is a drone... It is not stopping me from driving the car... Don't want a Corsa... Wanted a bit more growl... If I wanted a Corsa, I'd have gone that way...

The main culprit is the shape of the rear end of the car. The exhaust runs directly below the spare tire space. That is simply acting like a sub. Eliminating the vibration with a vibration damper like Dynamat or Second Skin Damplifier, will take most of the drone out. If I want a bit more quiet in the cabin, I will add a mass loaded vinyl... This will kill the volume as opposed to the drone which is a bass sound.

I have not done it but will be soon.... I'll see what I can do for a before and after video or sound clip....

 

[cubican]

Enjoy the drone!!!! is not going away with any amount of dynamat. If the Drone is a problem now it will drive you nuts later. One word CORSA

 

[Zentenk]

I was on a mission a few years ago just to get the special Corsa mufflers but the websites selling it looked too shady.

 

[Grisoman]

You guys are complicating this way too much... My goal was to get a similar sound to side pipes.

Do a side pipe conversion then?

 

[Luisv]

Do a side pipe conversion then?

Did not want to alter the lines of the car.

I wanted the sound similar to the side pipes. Side pipe vipers have the sill mufflers with no secondary cans like we have in the rear exhaust cars. Without going to the side pipes, eliminating the rear can would get me close.