Sound Deadening & Exhaust Droning

[Smkymts]

Heres a issue I haven't seen addressed.

Sound Deadening

I know many of the members have tried to address this in their own Camaros and other cars. I have scoured the internet and spoken to many a Custom stereo shop and their seems to be many different takes on how to solve this issue. I want this to be the place where alll sides are discussed in a friendly matter.

First,there needs to be some clarification because there seems to be at least three totally different reasons for sound deadening.

There are those who want the mobile music factory and desire the best/purist sound.

Then there are the ones like me that have increased there horsepower and exhaust and now suffer with exhaust droning and excessive road noise in low gears/RPMs.

And then those that want both.

These are two totally different types of noise. And from what I have read require to different ways to attack the issue.

The typical Stereoaphile shop recommends using a Product Like RAAMmat, Dynamat, RoadKill, B-Quiet, second skin, FatMat, Hushmat, spray on material, expanding foams and even materials for roofing from the local Home Depot.

But even this group is divided with those that say you only need to cover 25% of the area in the material and those that say you not only need to cover the entire area in material but are better off doing it multiple times. The more you add, the heavier your car gets and all of us know that weight kills race times and needed repairs may require removal or interfer with proper fitting of panels.

Now I have heard that this works and doesn't work. And those that say it works great and the proof is there when you feel the heavy doors close "THUD". But many have found that their stereo sound great but they still hear road noise and exhaust droning.

The other group says that in order to control road noise you need a close cell foam (CCF) like an ensolite foam material or a batting material like the material you get from your dryer lent trap. The down side to that material is that it can hold moister and smell.

This issue even has a language all to itself. CCF- Closed cell Foam, CLD- Constarined Layer Damper, MLV- Mass Loaded Vinyl, Resonance, Substrate, Frequency.

See Sounddeadenershowdown.com, but even they want to sell you something. I want real world experiences on what has worked and not worked for you.

For me, I want to quiet down my roadnoise and exhaust drone. Its going to me hard because I have complicated my problem because I have a convertible. I know it is never going to be quiet, but I want to low the amount of noise in the cabin while I cruise. Please help and share with all the members.

Don't make this a vendors sell speech or mine is better because.
I want those who have used various types to share.

[CWI]

All I can say from experience is that I have covered about 80% of my trunk area with Dynamat so far and there is a slight decrease in the drone, it's still there but doesn't seem to resonate as bad. I have cam, intake and headers with Flowmaster Super 44s. Definate drone problem.

I am now working 7/12's so don't get much time to work on my system, us it's been wet this week and I don't have an indoor work area. I am focusing on the trunk first so I can get amps and subs in. Next will be doors then the floor areas. I will be using Dynamat and Dynaliner with heavier Dynaliner in the trunk in an attempt to lower the drone inside.

I don't know what all products people have tried. I'm sure people have tried a lot of different things with good and bad results. I did order some foam pad called gym rubber, it's a dense, flexable, closed cell foam that should be very similar to dynaliner, maybe a bit more dense. Gotta try it, Dynaliner price is rediculous and this stuff is a third the cost and free shipping. Feel free to check it out at the Foam Factory online. I will post my thoughts when I get it.

[ckaram]

Do a search. There's great pics, DIY's, and info on this site regarding what others used to quiet exhaust drone. I myself used FatMat in the trunk of my 2010 to help take the edge off a catback system. It helped.

[myold88]

I was suprised that my new Camaro had absolutely no unibody insulation from the factory. The first thing I did was install Dynamat & Raammat (do a search) products from the front seats to the rear bumper of my SS. I did the floors, 1/4 panels, wheelhousings, etc everywhere I could reach from the doors back. This is a very inexpensive job and only takes a few hours.
Even with my Solo Axle Back exhaust my Camaro is now wisper quiet inside. I posted this here a couple of times but few camaro5 members seemed to be interested:
Photo during install- Peel & stick material is then covered with the supplied finish cloth and buttoned up with stock trim.
Photos are before Rollong Out mats and adding finish cloth/pad supplied with the Dynamat.

[MikeYoungSS1]

Best I can tell you to do is the tap test. strip your interior of the plastic panels and then tap the metal in the thinnest areas, (area under the middle console, wheel well in trunk, spare tire area, area under the rear windows) listening for hollow sounds. If it sounds hollow or otherwise thin then add deadener. If it sounds like metal (deeper sound) then don't. You'll be able to hear the difference.

[TeamTCA]

More, less, what brand?? Pretty much personal opinion. There are those that swear by their particular brand that they either sell or use more than others. Although there are some differences between materials, the bottom line is always- the more material you use IN THE RIGHT PLACES, the "quieter" the interior will be. Fact. Most commonly there are the "peel & stick" mats, different thicknesses, with or without foil, etc AND then you have the sprays. Make no mistake- the MAT is the best and most effective. Any of the sprays also work but are designed for areas that you can not normally get MAT. I have done dozens of cars over the years and used both, sometimes one or the other.

Main thing in an already heavy car is that virtually NO deadener was installed in these cars from the factory. Thicker the mat you add for better effect the more the weight you just added to the car. It's a catch 22 so you have to sacrifice a tenth or two to quieten these cars down. Doors, floor, and trunk area will make the most impact. It takes over 100sq ft easily to cover the car. I have used over 200sq ft in mine and added right at 100lbs in weight (but I used Dynamat Superlite- which is thinner and yes lighter) including 1/2" Dynapad under the carpet (entire front area). I have Flowmaster catback exhaust which already has a pretty low tuned freq to it and my car is still fairly loud inside, but only from the exhaust note. Overall road noise is much quieter but you also have to understand that there is alot of glass to deal with too that you can't do anything with.

You can definitely quiet the car down by applying almost any kind of damping mat but the addition of thicker foam pads helps even more. The doors will be the most noticeable from day to day "road noise". The rear area will affect the exhaust droning more but it will be difficult to completely eliminate it. Just my two cents...

[justa25thTA]

search helmholtz to get rid of the drone, then worry about the sound deadening

[buffaluphagus]

Just got done installing raammat and gym rubber in my trunk. Did nothing to quiet interior from exhaust drone.

[CWI]

Originally Posted by justa25thTA

search helmholtz to get rid of the drone, then worry about the sound deadening

Originally Posted by buffaluphagus

Just got done installing raammat and gym rubber in my trunk. Did nothing to quiet interior from exhaust drone.

Also check out j pipes, it's an extra j shape peice of exhaust pipe that ties into your existing exhaust in front of the mufflers if you have them. It works without mufflets too. Steve at Solo makes them adjustable lengths to eliminate the drone frequency. I will be doing this option for $185 shipped once I determine the frequency my system is emitting so he can make the proper length.

Dynamat style products will only help a little on drone however help a lot on accoustics. I've been studying!

[KMPrenger]

As others here have said...using the helmholtz or "J" pipes i the key to killing drone. You have to figure out at what RPM the drone is worst and then cut the helmholtz pipes to the right length for it to work.

After that, you won't need any mats in the back to help kill the drone, but I hear it will certainly help the stereo a lot.

This is your answer.

[LBV]

The best stuff will be the thick foam MLV stuff . it weighs a ton and I'm sure I added about 80 lbs to my trunk and rear seat area but it did help ... not as much as one would hope but the drone is gone ... more of a slight moan now.

If you can though, do the j-pipes ... with my Borlas there's just no room.

[Fraxum]

Originally Posted by Smkymts

Heres a issue I haven't seen addressed.

Sound Deadening

I know many of the members have tried to address this in their own Camaros and other cars. I have scoured the internet and spoken to many a Custom stereo shop and their seems to be many different takes on how to solve this issue. I want this to be the place where alll sides are discussed in a friendly matter.

First,there needs to be some clarification because there seems to be at least three totally different reasons for sound deadening.

There are those who want the mobile music factory and desire the best/purist sound.

Then there are the ones like me that have increased there horsepower and exhaust and now suffer with exhaust droning and excessive road noise in low gears/RPMs.

And then those that want both.

These are two totally different types of noise. And from what I have read require to different ways to attack the issue.

The typical Stereoaphile shop recommends using a Product Like RAAMmat, Dynamat, RoadKill, B-Quiet, second skin, FatMat, Hushmat, spray on material, expanding foams and even materials for roofing from the local Home Depot.

But even this group is divided with those that say you only need to cover 25% of the area in the material and those that say you not only need to cover the entire area in material but are better off doing it multiple times. The more you add, the heavier your car gets and all of us know that weight kills race times and needed repairs may require removal or interfer with proper fitting of panels.

Now I have heard that this works and doesn't work. And those that say it works great and the proof is there when you feel the heavy doors close "THUD". But many have found that their stereo sound great but they still hear road noise and exhaust droning.

The other group says that in order to control road noise you need a close cell foam (CCF) like an ensolite foam material or a batting material like the material you get from your dryer lent trap. The down side to that material is that it can hold moister and smell.

This issue even has a language all to itself. CCF- Closed cell Foam, CLD- Constarined Layer Damper, MLV- Mass Loaded Vinyl, Resonance, Substrate, Frequency.

See Sounddeadenershowdown.com, but even they want to sell you something. I want real world experiences on what has worked and not worked for you.

For me, I want to quiet down my roadnoise and exhaust drone. Its going to me hard because I have complicated my problem because I have a convertible. I know it is never going to be quiet, but I want to low the amount of noise in the cabin while I cruise. Please help and share with all the members.

Don't make this a vendors sell speech or mine is better because.
I want those who have used various types to share.

Have you tried Helmholtz? Those that have swear by it. I do not think matting the trunk will cure drone.

Just sayin.

[CWI]

Originally Posted by LBV

The best stuff will be the thick foam MLV stuff . it weighs a ton and I'm sure I added about 80 lbs to my trunk and rear seat area but it did help ... not as much as one would hope but the drone is gone ... more of a slight moan now.

If you can though, do the j-pipes ... with my Borlas there's just no room.

Solo j pipes are in my near future, as soon as I find out my frequency target. Most likely will order from Steve at Solo. I like that they are adjustable to fine tune them. I would make my own if I had a shop, pretty simlpe design and not hard to fab.

[SSE 4 2SS]

Originally Posted by Smkymts

Then there are the ones like me that have increased there horsepower and exhaust and now suffer with exhaust droning and excessive road noise in low gears/RPMs.

This exhaust drone can be fixed pretty simply. As was mentioned before, check out the Helmholtz fix.

This "exhaust drone" is caused by sound waves traveling through the exhaust pipes and the larger or close proximity sheet metal panels picking up the vibration and amplifying it through the car body.

The fix is a Helmholtz chamber. This is basically a section of pipe welded on pretty much anywhere in the exhaust system, though for space considerations they are usually located right around the muffler.

The length of the chamber is critical.

Here is a nut shell is how they work.

You have sound pulses traveling through the exhaust. If you install a properly sized chamber, the sound waves are split with some of it traveling out of the exhaust as is normal, and some of it traveling up the helmholtz chamber. When the sound waves hit the capped end of the chamber, they bounce back, at the same frequency as those traveling through the exhaust pipe. When the waves from the chamber reenter the exhaust stream, the sounds waves colliding at the same frequency cancel each other out.... Thus, no drone... or substantially less....

The easiest way to determine the proper length is to get in your car, and find a fairly long stretch of highway... Accelerate up into the top gear.... or manually shift it up...

Hold it in that gear and slow to approximately 50 mph... You should be very low in the RPM range.... Accelerate in steps, maybe three to five mph per step... Then cruise in that step... Note the drone level.... again accelerate 3-5 mph... then cruise at that rpm level... do this until you have reached a level where the drone is the worst and continue on until little or no drone is noticed... Make a note of where the loudest drone was... then use the attached chart to determine the proper length for your chambers... My drone was worst at 72-78 mph and about 1800-1950 RPM....

The pic below is of a typical Helmholtz chamber.Again, the location of it does not matter, and it needs to be fairly close to the same diameter, at least not any smaller. The next item is the chart for determining the length needed based on the RPM of the worst levels of exhaust drone.

As for the Stereo related sound stuff... it's not in my area... Others can help you with that...

Hope some of this helps.