Operation Run Silent (Second Skin Application)

[Herbst '71]

Ant is shipping the Second Skin package and I've been thinking of how the free product can best serve the Samba community. For the last few years I've learned more from the Samba than I have been able to give back. Then again, the countless hours I've spent on ratwell.com are all the more reason I owe the members of this community. Now, I think I finally have a chance to provide some information.

I got my hands on a decibel meter and I am planning on taking sound level readings before and after the Second Skin products are installed. I'm thinking the front seat, the middle seat and the rear bench at idle, 45 mph and 65 mph. I will post video of the results so that we will be able to hear the drop in sound and the decibel meter will provide solid numbers. I thought about testing after each layer is installed, but the results might be skewed due to the lack of interior or it might be perfect to keep everything out.

I also plan on looking at the heat barrier quality of the product. Basically in the rear cargo area. I'm still trying to find the best way to measure this with a thermometer. I thought about the engine bay, but with my luck the thermometer would end up in my cooling fan at 65mph.

When all is said and done I will post a full write up with pictures of each step. If there is anything I have not thought of that you want to know, please let me know.

As soon as the project gets under way, I'll start posting.

Thanks,
Rik
_________________
Rik
'71 Deluxe/1600 DP

"Fortunately my mistakes are serving as a warning for others."

[stupidsongs2]

Yay! Actual measurements! The Germans that designed our cars would be proud
_________________
'81 VW Rabbit Diesel 4-speed "The Liberalmobile"
'81 Mercedes 240d 4-speed
'77 Fiat 124 Sport Spider (sold)
'78 VW Westfalia "The Beast"

"Traveling in a fried-out Kombie,
on a hippie trail, head full of zombie..."

[dweller]

You could go ahead and post some 'before' pics, and get them out of the way. I'm sure most are familiar w/ the stock panels/insulation, etc. But some pics would start you off w/ what you have now.

good luck, am bookmarking to keep up to date as you get along.
dp
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77 Westie 2.0L FI ... slowly restoring bit by bit...

[second skin rep]

Here a re afew variables that can effect the db readings.
For comparison purposes

Asphalt vs concrete vs dirt road

Temperature (time of day is important too)

Location of microphone

gear at given speed

Al lthese things place a roll

For example, you can drive on 65 mph on asphalt on monday at 10 am when it is 90 degrees out side and get tottaly different readings on that same road at that same speed at Monday at 2 pm at 115 degrees outside.
Temperature can play a big roll, as can a few other things.
Just try to make sure that everything equal as can be when you take both sets of measurments.

ANT

[Herbst '71]

Ant,

Will take all of the above to heart. Same bat time, same bat channel, same bat temperature.

Thanks,
Rik
_________________
Rik
'71 Deluxe/1600 DP

"Fortunately my mistakes are serving as a warning for others."

[Herbst '71]

I finished the intial decibel tests and wanted to post the results. Video and audio will follow once I edit out some explatives. Some lady pulled out in front of us and we almost rear ended her. If we would have hit her, we would have atleast had proof on tape.

Common dB readings:

Normal Conversation - 60 dB
Motorcycle at 30 feet - 88 dB
Prolonged exposure to decibels 90 dB and above increase risk of hearing loss.
New York City Subway - 94 dB
Diesel Truck at 30 feet - 100 dB
Chainsaw at 3 feet - 117
Rock Concert - 120 dB
Jet engine at 100 feet - 130 dB

Test Vehicle:
1971 VW Bus Deluxe with Sunroof (Sliding Ragtop)
1600 DP engine
Bugpack Quietpack exhaust system
All interior panels covered with 1/4" foam and tweed
Floor carpeted/ 1/2" household carpet pad
Rear cargo area coated with cool patch
Engine bay insulated with 5/16" Reflectix Foil Insulation

Test Equipment:
Radio Shack Sound Level Meter (50 - 130 dB)

Test Conditions:
5:00 PM
91 - 94 Degrees F
Humid
All decibel readings were taken at head level from the seated position.

I ran my test circuit twice. Once with windows up and once with windows down.

Results:

Windows Up
At Idle: Front Seat - 87 dB, Middle Seat - 86 dB, Rear Seat - 84 dB
45 MPH: Front Seat - 93 dB, Middle Seat - 90 dB, Rear Seat - 94 dB
65 MPH: Front Seat - 94 dB, Middle Seat - 94 dB, Rear Seat - 94 dB

Windows Down
At Idle: Front Seat - 85 dB, Middle Seat - 87 dB, Rear Seat - 81 dB
45 MPH: Front Seat - 100 dB, Middle Seat - 100 dB, Rear Seat - 97 dB
65 MPH: Front Seat - 105 dB, Middle Seat - 103 dB, Rear Seat - 107 dB

Food for thought:
Every 6 dB increase doubles the perceived volume of the sound and a 12 dB increase quaduples the perceived volume of the sound.
Interior Noise of a new Mercedes CL Class meausred below 66 dB at head zone in the lab.

That's all I have for now,
Rik
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Rik
'71 Deluxe/1600 DP

"Fortunately my mistakes are serving as a warning for others."

[Ritter]

I'm surprised the your idle dB is so high. Looks like we'll all be deaf bus pilots at some time in the future.
_________________
-------
1978 westy 2L FI (needs a little bit less work)

[Caleb Melvin]

I can believe it, my bus it LOUD. Curious to see how it turns out...
_________________
My Current Project

BABES AND BAYS
(5/27/12 Update) | Send Me Your Additions!

[barefootwestie]

Very good job on getting those readings. I'll be tuned into this thread.
_________________
tangerinemoons.com
My Bus Restoration Blog
http://myvwbus.tangerinemoons.com/

1973 Westfalia
"Getting better....one repair at a time."

Other VW's owned through the years, in no particular order:
'67 Beetle,
'67 Ghia Hardtop,
'72 Ghia Convertible,
'72 Westfalia

[second skin rep]

Do you have any idea what frequency range youare testing for?
One thing to remember is that you are going to get lots of different levels of noise reduction at different frequencies.

You might kill 6-10 db at 800 hz and only 3 db at 250 hz
at 2000 hz you might bea ble to knock down 20 db depending on how things are applied.
Having a range of frequencies measured before and after is the idea way to get a better understanding of the total noise reduced.

ANT

[Herbst '71]

I'll look at the frequency ranges at work and then bounce the numbers of the meters capablilities. We'll recheck for another range of frequencies this afternoon. I let my daughter video the test run and when I went back and watched the video, it was stomach turning. Audio was awesome, but she had the camera pointed towards the side window. I now know how a dog feels looking out the side window. On to round three of the video.
_________________
Rik
'71 Deluxe/1600 DP

"Fortunately my mistakes are serving as a warning for others."

[Herbst '71]

I looked at the meters specifications and last night's test captured frequencies in the 32 to 10,000 Hz range. The meter has two settings so this afternoon I will take readings in the 500 to 10,000 Hz range. I am also going to see if I can scrounge up a meter that will let me select a tighter frequency range.
_________________
Rik
'71 Deluxe/1600 DP

"Fortunately my mistakes are serving as a warning for others."

[jmsmilin]

cool, bring it out to sno cap so we can check it out in person
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Der Schmutzige Süden.

(o\ ! /o) | o \/ o | (o)=|=(o) [o\|_|_|/o] \m/

[Herbst '71]

All of the sound deadening product has arrived. Everything but the spectrum arrived about a week after ANT made the announcement. The spectrum arrived yesterday.

My son and I have been installing damplifier along the side walls. Since I have never used any other sound deadening products, I cannot compare it to another brand, but I will say it is impressive. The biggest difference so far is in the sound of the slider closing. The empty trash can sound is gone. Now it closes with a thud. I've read other posts discussing this, but you have to hear it to get the full effect.

Lessons learned so far:

Cut damplifier into smaller measureable pieces. I had this idea that I could install it in full sheets. It is possible, but it gets ugly quick. I've been cutting it into 1' x 1' squares wherever possible and it has made a huge difference. More cutting, but way easier to install.

If you snag the wife's Pampered Chef tart roller (It has a nice six inch roller on one side and a 3 inch on the other) put it back before she catches you. However, the roller that ANT sent works fine too.

The wife is brining the camera back from her classroom on Friday so I will post some pics Friday evening.

I also have the second round of video for the before install road trip. I will post it as soon as it is edited.

The biggest negative to this project is I have only driven the bus once in the last two weeks.
_________________
Rik
'71 Deluxe/1600 DP

"Fortunately my mistakes are serving as a warning for others."

[VWBusNut]

Hi,

I have a Radio Shack meter and using it on the dbC scale I get readings similar to yours in the front seat of my 64DD camper. The dbC scale goes down to low frequencies which is where the majority of the problem lies. Using the dbA scale I get considerably lower readings, in the 70's and 80's.

I have done some frequency scans of my bus and the worst of the noise is below 500 hz.

I recommend using the dbC scale.

VWBusNut.

[deronmoped]

I should do some sound level tests in my Bus, now that I have a cast iron Buick V6 in it. That was the main reason I swapped that engine in there. I found the Bus unbearable to drive more then a hour on the freeway, this was even after I added lots of sound deadening material. It's a pure pleasure to drive now, around town the engine noises are almost nonexistent. On the freeway all the wind and road noises are now what is objectionable, replacing the front door weather stripping should help there.

The stereo sounds so good now

Deron.

[deronmoped]

OK, so I did the readings today in my Bus.

Buick cast iron V6, dual exhaust through headers and turbo mufflers. Stock cast iron headers and a stock muffler would be quieter.

Radio Shack meter, A and C weighting scales. "A" scale measures from 500 to 10,000 which is the range that the human ear is most sensitive to. "C" scale measures uniformly from 32 to 10,000, supposed to give indication of overall sound "feel". This is what the Radio Shack manual says.

Windows up, front seat.

Idle, A 65dB, C 90dB.
City street driving, A 72dB, C 94dB.
Freeway 65MPH, A 78dB, C 98dB.

Windows down you can add a couple of db's, this was from road noise. At idle it was actually down a couple of dB's.

What I believe makes my engine so quite is, it's cast iron construction (heads and block), hydraulic lifters and the low RPM's (around 1,500) I can run it at, driving on city streets. The noise it does make is from the lower tones of the exhaust system, which is not hard on the ears. The low tones do kill a little of the bass in the stereo though.

So if I was ever to go back to a VW engine I would attack the noise at it's source first. Probably the only practical ways would be to use real heavy wall exhaust pipe and a super quite muffler. Hydraulic lifters. Build the engine for torque, gear the transaxle as high as possible and keep the RPM's low.

Deron.

[second skin rep]

any updates on this project?

ANT

[davis911s]

Nice project but WOW you had high levels to start with.

I ran my test prior to installing B Quiet throughout, here is what I got

1973 VW Bus-
1.8 litre engine
single carb
Stock exhaust
no insulation only rear seat installed

idle 66spl
idle in gear 60spl
29km 70spl
45km 71spl
60km 76spl
75km 78spl
90km 81.5spl

high gravel section 83.5spl

I compared it to my wife's minivan on the same route

1998 Chev Venture

idle 46spl
40 km/hr 55spl
50 km/hr 59spl
70 km/hr 64spl
100 km/hr 68-69spl

Normal driving 61spl
high gravel section 90km/hr 74spl

I am not sure what hz my meter was reading, I will check that when I do my final readings using the same meter (I borrowed it from work)

I have not completed my install either but will post results also. I am doing the entire bus in Bquiet. Rear compartment is done including floors/ walls and over the engine.

I have the roof/ and the front cabin to do. I am thinking the front doors are going to make the biggest difference

Shawn
_________________
"I choose to use CAA on old cars with character...instead of car payments on a new car "

1973 Westfalia, Camper Special with 75 FI. Automatic 003 . Non-pop top
1977 Porsche 911S Targa, 2.7 L with 5spd
1992 Passat G60 Syncro Wagon (SOLD)
1975 Westfalia (SOLD)
1979 Westfalia (SOLD)

[Herbst '71]

Shawn,

This should work out well for the community. We will now be able to see the difference between the two products. Of course, there will still be variables (how much products was applied and where) but we should see which product offers the most cost effective sound deadening solution? Is there anyone out there who has used something other than Second Skin, or B Quiet? It would be intersting to bring in the Dynomat numbers and the home engineered solutions.

Rik
_________________
Rik
'71 Deluxe/1600 DP

"Fortunately my mistakes are serving as a warning for others."