Sound insulation -



Sound insulation -

Postby DorianL » May 5th, 2014, 5:21 am

Hey guys, here's another one way out there


I'm trying to get things as quiet as possible in my KG. I put down anti-rattle… Dynamat. The Dynamat has a good reputation for keeping yer car from sounding like a tin can.

The problem is that after that things get confusing for sound barrier. All of it is VERY inconsistent and UNCONVINCING. I read that you need to closed cell foam (CCF) and mass loaded vinyl (MLV). The first is used to prevent sound transmission between panels/trim, etc. (hydrophobic) and the other is sound absorbing. Even considering the geometric way in which sound is measured (db) the improvements seem marginal. 2-3 db at all frequencies. Hmmm - none of it is convincing.

All of this interests me because I want a quality sound system.

Anyone have any experience here?
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Re: Sound insulation -

Postby grumpyvette » May 5th, 2014, 9:32 am

your human Hearing range usually describes the range of frequencies that can be heard by humans,The human range is commonly given as 20 to 20,000 Hz, if you want to reduce the "NOISE" you either ABSORB, REFLECT,DISSIPATE, OR CHANGE THAT FREQUENCY to one well above or below that range.
changing the frequency, is done by changing the way a component vibrates, or absorbing and muting the vibration.
several stacked layers such as a spray on coatings, expanding foam, in hollow areas, a heat barrier,adhesive mat ,a thin compressed carpet backer glued to that surface,and a layer of carpet glued to that (all having vastly different natural harmonics )on the inside of the cab , and in some cases an adhesive heat barrier with a ceramic foam backing on the outside fire wall can make a huge difference, in sound transmission levels inside the car.
from an engineering stand point most sound in a car is the result of transmission of vibration, your dealing with it by either absorbing, or mechanically adding barriers,or reflecting the vibration, effectively increasing the distance from the source.
when you change the rate at which a material vibrates by changing its natural harmonics , either by physically changing its ability to vibrate (example adding rubber bushings and spacers) or adding braces that reduce the components ability to vibrate in the frequency we can hear you effectively reduce "NOISE"
WHEN YOU ADD A LAYER OF INSULATION, you effectively reduce the ability of the original vibration frequency too easily be transferred thru two dis-similar surfaces with widely different harmonics, kind of like if you had a tuning fork , it vibrates at a set frequency, place your finger tip on one side and you destroy the ability of the harmonics to propagate, to the surrounding area , as your disrupting the ability of the fork tines to vibrate at equal frequency's.
theres expanding foam, to be used in harder to access areas, heat barrier used near engine, drive train and exhaust, rubber mats and spray on coatings, for interior surfaces, and of course carpet backing and carpet.
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http://www.modsandrods.tv/2012/02/07/au ... -products/

http://stp-atlantic.com/articles/carsoundproofing/DIY/

READ THIS LINK ALSO
viewtopic.php?f=89&t=2004&p=5314#p5314

http://www.thefoamfactory.com/acousticf ... riers.html

http://www.eastwood.com/autobody/sound- ... E=MN060110

http://www.tmsoundproofing.com/mass-loaded-vinyl.html

FOR SOME INSULATION YOULL WANT CONTACT CEMENT
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http://www.centralvacuumstores.com/Cent ... 7AodHhwAAQ
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Re: Sound insulation -heat insulation

Postby grumpyvette » May 5th, 2014, 9:46 am

http://www.secondskinaudio.com/

http://www.autobarn.net/thalheba.html

http://www.autoanything.com/exhausts-mu ... shield-mat

http://www.cascadeaudio.com/car_noise_c ... rriers.htm

http://www.vichubbard.com/auto-part-det ... 00507.html

http://www.advancedenergyhome.com/radia ... r_coat.htm

http://www.vintageair.com/08/catalog08/ ... 34%20f.pdf

http://www.sounddeadenershowdown.com/

http://www.quietride.com/heat-shield.htm

http://www.ecsautostores.com/spray-onsoundbarrier.aspx

http://www.lizardskin.com/

http://www.ziebart.com/sound_barrier.php

http://www.stockinteriors.com/HeatSound.asp?ItemId=4783

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viewtopic.php?f=56&t=1507

viewtopic.php?f=56&t=1730

viewtopic.php?f=56&t=1503

viewtopic.php?f=79&t=1068&hilit=hangers

viewtopic.php?f=56&t=495

properly installed heat and sound reflective barriers can do a good deal to make the cars interior more pleasant, Id see no reason NOT to install something similar in a STREET car application. be aware that theres a huge difference in how effective the different manufacturers products are and its usually best to spray a flexible rubber glue or tar like coating on metal surfaces before adding a foam or plastic sheeting fire barrier,or reflective metallic film as this tends o absorb vibration and hold the upper layers in place, but read and understand the installation instructions
naturally reduction of the source of the heat or noise will also help.
if your getting significant (TIRE NOISE) Id sure find out if its BEARINGS,SUSPENSION , BRAKES or TIRE TREAD DESIGN RELATED, and IF its HEAT or EXHAUST noise Id suggest installing a well designed exhaust system if the proper size, and adding a (X) as close to the collectors on the headers and possibly an (H) back near the exhaust pipe muffler entrance points and extending the exhaust tips from the muffles to several inches past the rear bumper on the car


shop carefully, you can buy complete insulation and carpet kits for most corvettes or muscle cars with several different types of sound and heat barriers and types of carpet
http://www.stockinteriors.com/AutoCarpe ... ModelId=69
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
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Re: Sound insulation -

Postby mathd » May 5th, 2014, 11:15 am

DorianL wrote:Hey guys, here's another one way out there


I'm trying to get things as quiet as possible in my KG. I put down anti-rattle… Dynamat. The Dynamat has a good reputation for keeping yer car from sounding like a tin can.

The problem is that after that things get confusing for sound barrier. All of it is VERY inconsistent and UNCONVINCING. I read that you need to closed cell foam (CCF) and mass loaded vinyl (MLV). The first is used to prevent sound transmission between panels/trim, etc. (hydrophobic) and the other is sound absorbing. Even considering the geometric way in which sound is measured (db) the improvements seem marginal. 2-3 db at all frequencies. Hmmm - none of it is convincing.

All of this interests me because I want a quality sound system.

Anyone have any experience here?


DB is a logaritmic expression of the ratio of two power level
db = 10xlog10(p1/p2)

3db is twice the power level. or since this is a reducion -3db - half the power level (50%).
i just mean, -3db do not sound like alot, but its not that small.

-2db is 62.5%.
Last edited by mathd on May 5th, 2014, 7:10 pm, edited 1 time in total.
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Re: Sound insulation -

Postby DorianL » May 5th, 2014, 4:14 pm

mathd wrote:2db is 62.5%.


Ummmm WOW :shock: :shock: :shock:
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Re: Sound insulation -

Postby mathd » May 5th, 2014, 7:07 pm

DorianL wrote:
mathd wrote:2db is 62.5%.


Ummmm WOW :shock: :shock: :shock:

well not 62.5% of reduction.
62.5% remaining of the total level.

its a 37.5% reduction for -2 dB.

But am a little confused, am thinking your looking for a lesser/reducing, but am not sure, did you mean the other way?

Sorry for my english :/.
When writing in english.. sometime i confuse myself,, ahh i hate when am stupid.
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Re: Sound insulation -

Postby grumpyvette » September 21st, 2014, 8:34 am

you'll occasionally find adding a heat reflective barrier or insulation, between things like coolant lines, trans fluid or oil cooler lines and surfaces like oil pans where the headers almost make physical contact,and of course electric wiring from heat sources like hot headers becomes MANDATORY in confined engine compartments.
covering a starter or an ignition control box to reduce heat soak can significantly increase durability

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http://www.zircotec.com/page/aerospace_defence/56

http://industrialcoatingsworld.com/news ... e-properti

http://www.thermotec.com/products/all.html

http://www.summitracing.com/parts/the-14150/overview/

http://www.directindustry.com/prod/ning ... 88629.html
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
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Re: Sound insulation -

Postby DorianL » September 24th, 2014, 3:50 am

Interesting - I learned something else... but I am not totally convinced about it.

Apparently on ACVW (Air-cooled V-Dubs) a lot of noise comes from the carbs.

Once you accelerate, or otherwise open the throttle (highway driving), the intake makes much noise.
When your exhaust is open, it makes the most noise, due to the escaping explosion, so, obviously, street cars run mufflers.
Once the exhaust is muffled, the intake becomes the second-largest source of sound.
There is the rush of incoming air, but also some combustion noise from the overlap cycle, where both valves are open.
The shape of the intake tract also helps to funnel the internal noises up and out. Long story short, once you have a muffler on your car, enclosing the intake is the best thing you can do to quiet down your car out on the road.


Indeed I seem to get this burble-popping sound (through the carb) on acceleration.

The recommended treatment is:
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Pricey tho and doesn't necessarily fit a Karmann Ghia with a rain tray.
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Re: Sound insulation -

Postby Indycars » September 24th, 2014, 7:04 am


To test you might build something out of corrugated cardboard. If you have
any of the sound deadening material left over, line the box with that and go
for a test drive.

Rick
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Re: Sound insulation -

Postby 87vette81big » September 24th, 2014, 10:30 am

Its True Dorien.
A large part of drive by noise is caused by intake air flowing freely into carburators & EFI Throttle bodies unsilenced .
Its why the 2nd generation Trans Am only recieved A true functional factory shaker hoodscoop from 1970-72 model years.
Stand on the gas pedal & the rear trap door opened a full 90 degrees and high pressure air from the winshield base drawn in with great HP & Torque Increases.
Come 1973 it had a pop riveted plate on the backside of the scoop.
During the 1973 SD455 Early production road tests the pop riveted plate was removed and 7db more WOT Drive by road noise recorded with standing decibel meters on Tripods.
Also a 3-4 mph increase in 1/4 mile trap speed recorded.
Pontiac was sneaky & hated the EPA.

Come 1977 the pop riveted steel plate was gone.
A 1-piece molded fiberglass upper scoop.
But its easy to hacksaw out .
Pontiac made the outline to cut easy.
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Re: Sound insulation -

Postby bytor » September 24th, 2014, 10:33 am

Do a Internet search on "intake resonator" You may be able to put something using this concept to help with the intake noise.

http://www.ehow.com/info_12156112_air-intake-resonator-do.html#ixzz2ZhcM3BGS

There's is some science and math involved but you could play around with some temporary tubing routing and design to see if you get any improvements.

http://www.brighthubengineering.com/machine-design/84316-how-intake-resonators-improve-volumetric-efficiency/

Most production cars today have all kinds of boxes and strange looking bumps and tubes on their cold air intake systems. Here's an example that was on my Pontiac G6. Very odd looking but it was used to control the sound the intake make. If it was replaced with a section of pipe, the engine was much louder.

downsized_0325001804.jpg
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Re: Sound insulation -

Postby NOT A TA » September 24th, 2014, 12:14 pm

WARNING! Anyone in a warm climate or planning to visit a warm climate should NOT use Eastwoods Thermo-coustic sound deadening/heat mat. One of my customers installed it in his 68 Mustang while I was working on other things and the next time I went to work on the car I found a huge mess. Even though the temps in the garage don't hit the 140 fahrenheit maximum service temperature listed in their sales info the product is melting and flowing to the lowest points. As time goes by it's puddling in the footwells and other low areas. After a while I expect it to flow down off any surface that isn't horizontal leaving just the aluminum skin. You wouldn't believe how aggrevating it is to work on the car now because it's leaking out of every little crevice it can onto the frame, suspension, etc. end eventually the floor. It's sticky like urethane window sealer and gets on everything then smears into skin, clothes, shoes, tools, and gets transferred everywhere.

It's warm here in South FL but the temp in the garage doesn't get anywhere close to 140 even when the doors closed so it shouldn't be doing this. I can only imagine the embarrasement on a hot summer day when he pulls the car into a buddys nice concrete driveway and it drips sticky goo on it. He's installed about 300.00 worth of it in the car and removing it would be a royal PIA so nothings been done about it yet. I think he should use dry ice to harden it up and use an air powered needle scraper and putty knife to remove it while he can. We'll see what happens.

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Re: Sound insulation -

Postby 87vette81big » September 24th, 2014, 3:56 pm

Wow what a mess '70 Bird Man.

I took all the sound deading insulation out if my '70 TA Aound 1996.
I left just the inside Firewall pad in place.
Weight saving measure.
Reinstalled the Black Tweed Carpet.
I could care less about interior noise myself.
Race Car is my Motto.
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Re: Sound insulation -

Postby NOT A TA » September 24th, 2014, 10:23 pm

87vette81big wrote:Wow what a mess '70 Bird Man.

I took all the sound deading insulation out if my '70 TA Aound 1996.
I left just the inside Firewall pad in place.
Weight saving measure.
Reinstalled the Black Tweed Carpet.
I could care less about interior noise myself.
Race Car is my Motto.


I'm with ya on that! Removed the factory deadener out of my 70 bird about 10 years ago and only put in a light weight heat barrier on the firewall when I removed the stock firewall pad recently. I'm keeping the repro loop carpet.
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Re: Sound insulation -

Postby DorianL » September 25th, 2014, 2:10 am

Wow - lots of interesting stuff here. I like the idea of fabbing and experimenting with sound deadener and corrugated around the carbs. I'll test that out to see if it makes a difference.

I'm with you on the noise control - however the initial design was to be a daily driver for Mrs. D. Tho' she has yet to drive it with some regularity. :roll:

Some other projects: move the batt and ignition under rear bench to clean up the engine bay... and further noise insulate.

Come 1973 it had a pop riveted plate on the backside of the scoop.
During the 1973 SD455 Early production road tests the pop riveted plate was removed and 7db more WOT Drive by road noise recorded with standing decibel meters on Tripods.
Also a 3-4 mph increase in 1/4 mile trap speed recorded.
Pontiac was sneaky & hated the EPA.

Come 1977 the pop riveted steel plate was gone.
A 1-piece molded fiberglass upper scoop.
But its easy to hacksaw out .
Pontiac made the outline to cut easy.


VERY cool tidbit...
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Re: Sound insulation -

Postby grumpyvette » September 25th, 2014, 7:44 am

KEEP IN MIND YOU MAY NOT ALWAYS WANT TO REDUCE THE SOUND, IN FACT ONE FACTOR THAT MAKES THE USE OF A DUAL QUAD SETUP ON A BIG BLOCK, is that three stage sound as the various stages of the throttle blades on the carbs open .
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and there are cold air duct hoods that make routing cold air to the engine efficient
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AND SOME GUYS LIKE TO DISPLAY THE INDUCTION SYSTEM
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viewtopic.php?f=55&t=8961&p=31945&hilit=+clear+filter#p31945

viewtopic.php?f=55&t=444&p=41586&hilit=dual+quads#p41586
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