I agree with slider have done it in the past and unless interior is out for other reasons its alot of work for little difference.

 

So, the head unit install, and sound deadening is done. Time to report back.

I suspect that there is a significant reduction in noise both from the engine, as well as that which is translated from the road to the cabin. I have to believe there is atleast a 50% reduction in overall road and engine noise. Interestingly, lower frequency tones, like that from the exhaust seem to enter the cabin per before, but higher frequency sounds seem to be considerably attenuated. All in all, an excellent upgrade. Mine was done by CarTunes Atlanta, and the deadening was achieved in the floor and around the backseats using 36 square feet of Stinger Roadkill Expert (http://www.stingerelectronics.com/pr...&CategoryID=12).

I will try to get an "after" dB metering tomorrow. A "before" was done by the shop, but only for idle, not for highway.

 

REMEMBER PORSCHE'S ARE Noisy ON THE HWY especially around 3500 rpm. i hope it came out well and your happy. Love to see Porsche's get love!

 

I understand so much the route you've just taken!

What I used to hear the most on the highway with a stock exhaust was a huge road noise. Not the engine. Noise obviously originating from the tires. First with worn pirellis, this noise was atrocious on bad roads. Later on, with new michelin pss, the noise became more bearable but I imagine it would not become much better while the michelin get worn too.

What I think is that you can not say that sound deadening on a 997 tt never works. I think it can work if you do it properly... If some people have poor result, well it might be that all what is needed to be done wasn't done (obviously). In the extrem, nothing prevents you to make it sound like a lexus, right?

Thank you for your usefull feedback (the link is interesting). I think there is a real need for this kind of work on this car.

David

 

If you're looking for top level sound deadening, secondskinaudio.com is unparalleled.

They have sprays, sludges, sticky mats, spray stick foams... anything and everything, all produced in house in small batches to the highest densities and qualities using the best technology available.

I don't work for them, but I've used their stuff before on a classi VW GTi and the difference was staggering.

On a car like a 911, tire noise is the major noise coming into the car, quieter tires will make the biggest difference.

The higher the frequency, the more likely it will be filtered out. The only way to remove noise, unfortunately, is to add mass. And it has to be all throughout, without gaps if you want the maximum effect, otherwise you may as well just damp the panels rather than block the sound.

Its like a closed window on a house off a busy street - its quiet when closed, but open it a tiny crack and its immediately over half as loud as if it was fully open. So unless you line the ENTIRE floor and doors and basically every panel possible completely, you'll be getting only 50% of the possible noise deadening effect. Its for this reason that the spray on dampers can be better on curved/hard to get to surfaces, although if you're really trying to silence you'll want to add more mass on top of that, espescially around the wheel wells.

Whatever the case, I REALLY doubt you'll get a 9dB difference even with a hundred+ pounds of deadener. Actually you definitely will not get differences like that. Maybe 5dB, MAYBE. Id guess 3-5.

 

Every 3dB is 50% less.

 

This is what I used, the product is indeed nice, but on my car did not notice much difference. I think it has to do with the car and installer (me) not the product. You would have to lay a $hitload of this down to make a difference though, that much is obvious.

I have a bunch of it left over, ordered too much. if someone wants it to experminent they can have it, just pick it up, not going to ship it. Im in SoCal.




=gushybear;3683886]If you're looking for top level sound deadening, secondskinaudio.com is unparalleled.

They have sprays, sludges, sticky mats, spray stick foams... anything and everything, all produced in house in small batches to the highest densities and qualities using the best technology available.

I don't work for them, but I've used their stuff before on a classi VW GTi and the difference was staggering.

 

50% less sound energy at a given frequency.... the reality is most people cannot hear a 3db change in sound level... it's fairly insignificant in perception.

gushybear is correct, mass is the key, at least as far as low frequency road noise is concerned. Higher frequency sound is easier to deal with but reducing sound levels across the 'problem' frequencies is all but impossible in our cars without a seriously engineered (think mass and vibration isolation) solution.

 

I agree that tire noise, especially old tires, appears to be a prominent source of noise; is spraying the wheel well one of the most important things to do then?
Does anyone have experience with this: does it work and what material is normally used?

 

I too have thought about Dynamat Extreme in my 2012 TTS. The PZeros are just so loud on the highway. I have a quote of $550 parts/labor from Gwinnett Sound. My biggest worry is having my interior removed/reinstalled.

 

In my earlier post I just referred to the result on my 996 TT where there was no perceptible difference after a very thorough application of Dynamat Extreme everywhere.

I would like to emphasize that I did a very good job. When I did the same procedure to my G35 a few years ago, the difference was amazing. It created an extremely quiet driving environment; so I know the stuff works. It's just that the OEM sound deadening from Porsche is not so easy to improve upon. They have already applied very good sound deadening to our cars before delivery and you will not be able to improve on it with Dynamat. Don't risk your interior on this - I've already been there - it won't make a difference.

 

Slider, this is a very interesting feedback you give us here.

It certainly shows that noise paths are probably not the same in a G35 and a 911. These 2 body shells probably require some different approaches.

May I ask you which surfaces you covered in your 996?

Where is the engine in the G35? Front or back?
Is there any insulation firewall at the front of the 911? Of the same effeciency?

Did you cover the interior from the inside only or also the outside (from underbody).

Did you have a "look" at the noise generated when you tap under the floor of your car? With the back of your hand? (Once you remove the plastic covers).

Which treatment did you apply to the doors?
Is there any seal between the shell of the door and the door panel? Any gap?

I imagine you covered the wheel wells, from inside of the cabin (where it's possible) but first of all from the outside to damp that huge unbearable road noise.

The main point - I guess - in sound deadening dampening is that if you miss ONE (1) path where the noise can go through, all your (hard) work loose its effectiveness.

I may be wrong but I believe the approach of the manufacturer was and still is to not use too much sound deadening mainly for weight reason. Is a Panamera as noisy?

 

The G35 has the engine in front.

I removed the carpet in the TT and put Dynamat everywhere. The carpet in the TT is easily an inch think in the rear - it's not just carpet - it has a very pliable rubber underlay for sound absorption. Sound deadening is not really the same as leaving an open window - it stops the vibration of the surface that allows the noise to go through (although an air opening world negate any benefit). I filled the rear with Dynamat under the carpet - no difference.

You will see that Porsche did put a patch of sound deadening material in the door. I filled the rest door with Dynamat and it made no difference.

It is possible I missed an inch here or there - maybe - but I've worked with the stuff enough to know that no amount of Dynamat will make a significant difference in a 911. If anyone has had any success in making any appreciable difference they can chime in now...