[porsche]

So now the question is, compared to other cars, is the 968 louder on the outside? And what does the RS Barn exhaust sound like <img src="/forum/images/smilies/968/wink.gif" class="smilie" alt="" />

[/quote]





I participated in the 968 Forums RS Barn Exhaust Group Buy and installed it on an entirely stock 968 Coupe.

   



To answer your question on how the RS Barn exhaust sounds:



It is nearly as quiet as the stock exhaust, although the tone is a bit deeper. Thankfully, the RS Barn model does not add any resonance in the cabin (thank you Pete!!!!!!!).



A huge benefit is that the RS Barn exhaust is 38 pounds lighter than the stock exhaust (yea!), and has a great "sports car" tone during hard acceleration, but shuts the hell up when you're cruising. As such, I was absolutely 100% delighted/happy with Pete's RS Barn "upgrade."



Porsche

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[RickP]

[quote name='cdtscout' post='31446' date='Feb 24 2007, 08:05 AM']Rick,

The liquid product: eDead from Elemental Designs $50 per gallon. I also used some of their "Mat" materials for sound insulation and sound deadening. I used it most anywhere I could..... rear deck/hatch; doors; side panels; entire floor under the carpet (the carpeting was a real pia to remove....I have never seen so much glue); front plastic inner fender wheelwell inserts (liquid only);under the hood. This process has not muted/eliminated the 968's desirable engine sound/music....but has really muted the road/tire noise/droan.

Craig[/quote]



Craig,

Is the liquid brushed on? Does it stay flexible or does it get become hard? Sounds like you really went all out. My stereo sounds great when stopped, not boom boom but clean and nicely balanced, and becomes crappy with the road noise at highway speed.



Seems like the RS Barn exhaust's weight savings would be a great way to offset the extra weight of the sound insulation, but may be detrimental to my gas mileage <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" />

Thanks,

Rick

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[SILVY968]

I would rather listen to the exhaust note than the trans axle and tire noise coming from the trunk. The way the fold down portion of the trunk/rear seat backs are designed, you can hear everything in the rear of the car.



When I installed Flash's brace I decided to get belts and not put the cubbies back. This works out great for my 10 year old when we have another friend travel with us, but I have noticed that without the cubbies the rear noise has increased.



I have ordered 12 square feet of Dynamat Extreme # 10435. I plan to cover the flat surface of the trunk and if any is left over, fender sides or tool pockets. The material does not have to cover 100% to have an effect. I'll post my results on the noise pollution change.



For those who are weight conscious, (flash) the total weight increase over the rear wheels is 5.4 pounds. The Dynamat extreme material weighs .45 pounds per square foot. I have removed the jack, spare tire and cab ballast weight and replaced them with a AAA card and a can of flat fix.



If any are interested in trying Dynamat in either the rear for sound reduction or the doors for improved audio, a search @ amazon.com will find # 10435 for only $ 49.90, a 45% discount from list.



Brian

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[flash]

lol - funny you should mention that - i have been considering using dynamat, and ditching the oem carpet and replacing it with new carpet without the very heavy foam - i think i could come out 5 lbs ahead in that area alone



similar plans elsewhere in the car - they used very heavy materials - there is better stuff out there now

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[Cloud9...68]

[quote name='SILVY968' post='31501' date='Feb 25 2007, 01:11 AM']I would rather listen to the exhaust note than the trans axle and tire noise coming from the trunk. The way the fold down portion of the trunk/rear seat backs are designed, you can hear everything in the rear of the car.



When I installed Flash's brace I decided to get belts and not put the cubbies back. This works out great for my 10 year old when we have another friend travel with us, but I have noticed that without the cubbies the rear noise has increased.



I have ordered 12 square feet of Dynamat Extreme # 10435. I plan to cover the flat surface of the trunk and if any is left over, fender sides or tool pockets. The material does not have to cover 100% to have an effect. I'll post my results on the noise pollution change.



For those who are weight conscious, (flash) the total weight increase over the rear wheels is 5.4 pounds. The Dynamat extreme material weighs .45 pounds per square foot. I have removed the jack, spare tire and cab ballast weight and replaced them with a AAA card and a can of flat fix.



If any are interested in trying Dynamat in either the rear for sound reduction or the doors for improved audio, a search @ amazon.com will find # 10435 for only $ 49.90, a 45% discount from list.



Brian[/quote]



Let us know how it works out. You're right, it's a very small amount of weight, which would be a reasonable trade-off to cut down on the infernal droning this car makes. It's interesting that your cab is also noisy; from the other posts, it appeared that cabs were largely immune to the road noise issue. Must be the elimination of the cubbies, as you say. Good luck!

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[SILVY968]

When the top is down the sound of the car changes. With the top down you get exhaust noise and engine noise, but no rear end noise. It is obviously still there but it is overpowered by the louder sounds.

With the top up the lower exhaust noise is much lower and the trans axle noise seems to be contained by the top and focused forward to the driver.

I prefer driving with the top down for the sound and for the openness. Having had other P cars with solid tops, I much prefer the cab. I doubt that I will ever get another P car unless it is a cab.

Even though I live in rainy Seattle...when it's clear, it's amazing to drive!

Brian

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[Renalicious]

[quote name='porsche' post='31494' date='Feb 24 2007, 06:48 PM']To answer your question on how the RS Barn exhaust sounds:



It is nearly as quiet as the stock exhaust, although the tone is a bit deeper. Thankfully, the RS Barn model does not add any resonance in the cabin (thank you Pete!!!!!!!).



A huge benefit is that the RS Barn exhaust is 38 pounds lighter than the stock exhaust (yea!), and has a great "sports car" tone during hard acceleration, but shuts the hell up when you're cruising. As such, I was absolutely 100% delighted/happy with Pete's RS Barn "upgrade."



Porsche[/quote]



Great! I like the sound of the stock exhaust, more or less. So it's good to know the rs barn version is similar. As long as it doesn't make the car sound like a farty ricer hehe. Not that I assumed it would, but you know <img src="/forum/images/smilies/968/wink.gif" class="smilie" alt="" /> Throw in the air-box mod and I'll be good to go! Can't wait to hear what that sounds like (Anyone in Vancouver / Seattle area have both? Lets go for a cruise!)



I'm hoping to go to some private location one of these days with my sound recorder and capture what this thing sounds like stock, then when I upgrade do it again and compare.



I am considering doing some sort of sound proofing as well, since now I know it's not my tires that are so loud. Figure I can take the spare tire and jack too while I'm at it, especially around the city.

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[cdtscout]

[quote name='RickP' post='31496' date='Feb 24 2007, 11:27 PM']Craig,

Is the liquid brushed on? Does it stay flexible or does it get become hard? Sounds like you really went all out. My stereo sounds great when stopped, not boom boom but clean and nicely balanced, and becomes crappy with the road noise at highway speed.



Seems like the RS Barn exhaust's weight savings would be a great way to offset the extra weight of the sound insulation, but may be detrimental to my gas mileage <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" />

Thanks,

Rick[/quote]



Rick,

You can brush it, roll it or spray it with proper spray nozzle... I have only bushed it or rolled it. Seems to stay flexible.... I live in the Norh East and I have not seen any cracking, flaking or any other issues. In some areas, the rear spare tire area in particular, I placed some of the "mat" material down then placed a coat of the liquid over the mat material. During some of the down-time this winter, I have applied the liquid on the back-side of the plastic front fenderwell inserts to further reduce the tire-noise. Again, even when applied to a flexible component....it seems to adhere just fine...time will tell.

Craig

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[Cloud9...68]

[quote name='cdtscout' post='31565' date='Feb 26 2007, 09:21 AM']In some areas, the rear spare tire area in particular, I placed some of the "mat" material down then placed a coat of the liquid over the mat material.[/quote]



I was wondering about the spare tire cavity as well. I don't know how the spare is situated in a Cab, but I wonder if the round (disk-shaped, actually) hole the spare lives in contributes to the road noise, which then gets bounced around in the acoustic chamber from hell known as the rear hatch area. Not that I would advocate trying this because of the mess it would make, but I wonder what impact removing the spare and filling the cavity with some sort of spray foam would have on the noise level. I wonder if there is a product like this that would be relatively easily removable, in case if a change of heart, and wanting to go back to having a spare. I know that "Great Stuff" stuff they sell at Home Depot is miserable, but that's the general idea I have in mind...

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[SILVY968]

Cloud 9..68



If you want to see what the sound would be like without filling the spare tire well with GREAT STUFF, ( a real nightmare to remove, and not all that dense),try filling the cavity with R-19 fiberglass insulation or rock wool insulation (even better as it is more dense). If there is paper on the insulation, remove it. Stuff in as much as possible and as firmly as possible. Cover with sound board ( like sheet rock but made up of bits of cardboard-like stuff. Duct tape the board down over the opening. If you like what you hear you can cut a piece of sound board using the trunk carpet as a template. Screw it down with large flat washers or an aluminum strip along the edges and across the middle. If you do not want to risk drilling into wires or lines, you might try duct tape all the way around. This should effectively remove the tire well as a sonic transfer unit and remove its ability to act as a resonating chamber.



If you try it let us know. I may also give it a try, as my wheel well is empty, when I install the Dynamat.



Brian

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[flash]

ruh roh - next step is to seal it up airtight, make the top surface a membrane, and turn it into a bass trap - based on the size, should be good for 10db or so reduction at about 60hz

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[Anchorman]

Whatever that means... <img src="/forum/images/smilies/968/wacko.gif" class="smilie" alt="" />

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[flash]

lol - sorry - that was mostly for brian's benefit



a bass trap is like a roach motel for low frequency sound

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[Anchorman]

That part I sort-of got. It was the 10db reduction at 60Hz that started throwing me (although, if I think about it long enough, I'll probably remember what that means, and realize that it's good - right?).

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[Cloud9...68]

[quote name='SILVY968' post='31611' date='Feb 26 2007, 11:08 PM']Cloud 9..68



If you want to see what the sound would be like without filling the spare tire well with GREAT STUFF, ( a real nightmare to remove, and not all that dense),try filling the cavity with R-19 fiberglass insulation or rock wool insulation (even better as it is more dense). If there is paper on the insulation, remove it. Stuff in as much as possible and as firmly as possible. Cover with sound board ( like sheet rock but made up of bits of cardboard-like stuff. Duct tape the board down over the opening. If you like what you hear you can cut a piece of sound board using the trunk carpet as a template. Screw it down with large flat washers or an aluminum strip along the edges and across the middle. If you do not want to risk drilling into wires or lines, you might try duct tape all the way around. This should effectively remove the tire well as a sonic transfer unit and remove its ability to act as a resonating chamber.



If you try it let us know. I may also give it a try, as my wheel well is empty, when I install the Dynamat.



Brian[/quote]

What you're suggesting makes sense. Any idea where to get rock wool insulation? Does Home Depot carry it? And what about sound board? Who might carry this? An auto stereo installation shop perhaps?



Once the insulation and sound board are in place, would you cover the who thing with Dynamat, or is this overkill (though I can't imagine anything done to reduce the droning from back there to be overkill)? Thanks for the suggestions.

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[SILVY968]

[quote name='Cloud9...68' post='31750' date='Mar 1 2007, 05:45 PM']What you're suggesting makes sense. Any idea where to get rock wool insulation? Does Home Depot carry it? And what about sound board? Who might carry this? An auto stereo installation shop perhaps?



Once the insulation and sound board are in place, would you cover the who thing with Dynamat, or is this overkill (though I can't imagine anything done to reduce the droning from back there to be overkill)? Thanks for the suggestions.[/quote]





Cloud9...68



Instead of rock wool use Mineral Fiber Insulation (MFI). It is available from dealers for AURALEX. Here is the link. http://www.auralex.com/sound_isolation_mfi...olation_mfi.asp

Locate a dealer and get some, or use the photo/data on the link and see a local home builder supplier carries it. If it proves too tough to locate you can use R-11 fiberglass with the paper removed. It is not as dense, but will provide very good results.



Sound board should be easier. It is also called fiber board. It is made by Cellotex and is called cellotex insulation board. It is used in construction between walls. A web search may locate a supplier in your area.



I would cover the metal surface of the trunk, as outlined by the rear, removable carpet mat with Dynamat. The board would not require Dynamat.



Mine comes in mid week so I guess I'll Dynamat the trunk o the weekend and post the results. I have some of the MFI and cellotex at the office that was left over from a studio job. You idea for the tire well sounds very interesting. Now the question is how much do I really use the 2 side pockets beside the wheels? These must also contribute to the noise leakage as well as the "drone"

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[flash]

i really don't think any of that is going to do anything appreciable in a car - the problem is the source of the noise - it isn't like the inside of a studio, where you are trying to kill reflective sound - you are trying to kill sound that is emanating from outside the car, and vibrating the membrane (sheet metal of the car) - it is at such a low frequency that you will need to add mass, or another mechanism to dissipate the energy - this is exactly like trying to isolate one room from another - you need dead air and lots of mass to do the job



lining the wheel well with dampening materials is fine, but you need to seal it up, and add another heavy mass membrane



lining alone, whether fiberglass or dynamat, will kill the noises above 400hz, which will make it quieter overall, but it won't do anything for low frequncy sound, which is the bulk of the "drone" sound



it will be nice and quiet inside the wheel well, but the rest of the car will be unaffected



a cab will benefit a bit from this, because it has a trunk, but a hardtop will not



been there - done that



you'd be a lot better off getting some lead sheet and lining the entire back end of the car

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[RPM]

Flash, I think I am still confused... your car has roaches?



<img src="/forum/images/smilies/968/rolleyes.gif" class="smilie" alt="" />

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[flash]

roflmao - yeah yeah - that's it



by the way - i wasn't trying to rain on anyone's parade - sound is tricky stuff, and isolating it is not easy - brian knows well how hard it is to make any real difference in a studio - cars are even tougher than studios - the 2 different areas (inside and outside) of noise generators are dealt with very differently, and there is no real easy way to handle the rumbling and droning stuff wihout a lot of money and added weight - you can make it quieter overall though, and take the edge off of some of the extranious noises in the car



in a hardtop, the best place that could help with dampening sound is the only place you really can't do anything - that danged hatch - it's a near perfect acoustic amplifier - because of the hatchback, you get a lot more low frequency sound going on in a hardtop than a cab, and because of the roof, a lot less mid and high frequency sound - the trunk of the cab creates a baffle chamber, lowering the low frequency levels, but the soft top does us no favors in mid and high frequencies



the perfect solution would be a coupe, where you had a near vertical back window, and a real trunk - i still can't figure out why they never made one - would have looked cool - oh well - another conversation for another day



good luck on the lining

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[RickP]

Line it with LEAD???? Oh My!!!



Driving to work this morning I heard low frequency along with mid and fairly high depending on what kind of surface the construction people happened to have on the road at that particular spot. Gonna try the dynomat cause any improvement I can make will be beneficial. Has anyone tried two layers of dynamat instead of just one, and was it a help?



Rick

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