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Sound Deadening Suggestions for exhaust drone

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Location
Scranton
#1
So I recently installed my mbrp exhaust and the exterior sound is great but holy cow is the drone bad from 3-4k in the cabin[bash]. Its so bad that my ears ring after driving for a little while. I heard from various other forums and research that an aluminum based insulation lined in the trunk may quiet the noise and vibration coming into the car. I know theres stuff such as dynomat and some cheaper alternatives like peel and seal but I don't want to spend the money/time and still have the noise afterwards. Any suggestions/input would greatly help, otherwise I might have to ditch this exhaust [}(]
 


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Location
Baton Rouge
#2
Peel and seal and the asphalt based alternatives (like FatMat) are just mass loaders. Meaning... all they do is add weight to whatever you're applying it to and that in turn lowers the resonance of the panel (ideally to below audible thresholds). Problem with that is that you have to add POUNDS and pounds of the crap to accomplish this.

Well designed butyl based CLD's (Constrained layer damper) actually absorb the vibrations and turn it into low level heat. This means you can get more efficacy with less added weight. Well designed products would be stuff like RAAMmat (@RAAMaudio) and Sound Deadener Showdown and Second Skin. Be forewarned that properly designed CLD is not cheap, but as was mentioned... it's actually a better bang for your buck since 25% coverage of a CLD is cheaper and more effective than 100% coverage of the cheap alternatives. Bonus is it's also less weight.

I've never treated for exhaust drone before so I don't know how effective CLD is for those frequencies. But what is normally used to treat road noise frequencies is MLV (mass loaded vinyl). This is an actual sound barrier. It's also very heavy. As in ~ 1lb per square foot. It has to be this weight to be effective.
 


D1JL

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#3
Where you need to do this in the spare tire cavity.




Dave
 


RAAMaudio

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#4
Having shipped tens of thousands of orders for RAAMmat and PS Ensolite all over the world and helping thousands with exhaust drone issues I have a pretty good idea of what you will need to do.

1) Fix it at the source if it is that loud no deadening can cure it as there is a huge amount of acoustical energy involved. Any exhaust that creates excessive drone is simple not a well engineered, if engineered at all, product. You will need to add a resonator or bigger muffler or whatever is lacking in the system to cure it.

2) To make it better with deadening instead of modifying or replacing the aftermarket system or make a marginally noisy one just right for for some it depends on personal preference and just how loud it is.

Properly placed actual sound deadening mat and foam like Ensolite can help a great deal as well as adding in some egg crate real acoustical foam in qtr panels, under dash, under seats, in the tire well where there are empty spaces, etc...can help as well but they also can absorb moisture so use at your own risk.

How to guide will show you how.

http://www.raamaudio.com/pages/How%252dTo.html

Vehicle fitment guide will give a good idea of materials per area though the qtr panels are smaller than most vehicles.

http://www.raamaudio.com/

Package #1 is the best value and will do all the needed areas and some extras like under the dash to make the whole car a much more pleasant place to spend your time.

Forum members get a $10 discount on Package #1, 1 pack BXT II RAAMmat and 3 yards PS Ensolite, discount code is raampack1

These are world class products, you can pay more for more highly advertised or nicer packages or "specialized" super thick marketing schemes, etc...but you cannot buy better quality;)

You have my word on that and you can Google up RAAMmat or RAAMaudio:)

Rick
President and Founder
 


RAAMaudio

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#6
One of the very few companies that actually fully engineers their parts makes the best exhaust you could get for Subaru cars, Cobb, NO DRONE and great gains, perfect fit, never a problem later on.

How many insanely loud Subarus have you heard on the streets? They have insane levels of drone as well.

I was going to build a 2.5" system and had all the parts on hand but was convinced I need to go to 3" so I spent the time figuring out the parts to use like 5" diameter 18" long SS packed resonator from Vibrant, the biggest one I could fit. I was able to use a smaller muffler, Borla, SS packed, because I installed a big cat as well but later did a cat delete and it is still a great system, no drone.

I did add in a V-BAND muffler delete straight pipe for the track that makes it a great deal louder so I can hear it better which helps when driving all out as I tend to do.

For a stock turbo or possibly Cyborg a 2.5" system is likely all that is needed but I am going bigger turbo as always planned so 3" is best but the Cobb maybe the best for most owners.

I am not an engineer or exhaust manufacturer, just DIY builder, so why do most companies sell drone filled exhausts when I could figure it out and I have the freest flowing system on an FiST as less bends, less angle, ported each fitment, straight flow single in and out muffler....????
 


lessard.dcj

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#7
I have crazy drone some days and none on other days. Wtf. I noticed that the exhaust tips touch ever so slightly on thright side of bumper when i push it over i think it kills the drone. Next time it is happening im going to pull over and test this. My trip back from Montreal this past weekend almost made me burn my car. No lie.


I am not an engineer or exhaust manufacturer, just DIY builder, so why do most companies sell drone filled exhausts when I could figure it out and I have the freest flowing system on an FiST as less bends, less angle, ported each fitment, straight flow single in and out muffler....????

True story. If you make it i will buy it lol

Ps

Raam get back to work
 


RAAMaudio

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#9
A drone caused by parts touching is the resonate frequency of the part effecting what it is touching so making sure the part does not touch is the cure and usually pretty easy to take care of. Sometimes bending a hanger on the exhaust is at that is need.

Not only drone prone but some of the exhausts I have seen over the years have very restrictive mufflers, couplers that are not lined up well, etc...mufflers....sheesh, I have seen one that was so bad it had to be probably worse than the stock system.

---------------------

This remodel project has turned into a monster eating up my time and energy, I was supposed to be home weeks ago and today I missed my sweet wife's birthday:(

Word of advice, never buy $2 sq ft, 11 different pattern, Lowe's Porcelain tile...what a friggin nightmare it has been.

I could of finished my EFR turbo build including designing and building a bad arse tubular manifold, and all the other parts, tuning, etc.....in just dealing with tile issues, guess what is more fun!
 


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