YNOT2K

i did the FrostKing mod - http://mikemercury.home.att.net/sound.htm

i took "before" and "after" readings with a radio shack noise level meter. http://www.radioshack.com/product/in...ductId=2103667

i took average noise readings for 15 second samples:

at idle
30 mph on city street
WOT on freeway onramp (that one was fun!)
70 mph on freeway

i used the A-curve weighting - used to measure average noise level of an area, and set the response time to FAST (.3 seconds between samples). you can read all about the unit and what it can do here - http://rsk.imageg.net/graphics/uc/rs...2055_PM_EN.pdf

here are the results:

at idle
before - 63 dB
after - 63 dB

30 mph on city street
before - 72 dB
after - 71 dB

WOT on freeway onramp
before - 82 dB
after - 82 dB

70 mph on freeway
before - 80 dB
after - 80 dB

testing procedures were as close as i could get them before and after - same streets, same time of day, same location and positioning of the noise meter, etc.

i'm finding it very difficult to "hear" a difference either. because of the work involved in this mod i think my sore, old body tells my brain to tell my ears that it's quieter now than it was, but my brain knows better.

i've been wanting to contribute some meaningful information to this great forum. i hope you find this information useful.

take it easy,

jeff

peter pan

Wow really no difference in interior sound levels

Z06ster

Jeff,

Thanks for taking the time to do this study. If I am reading your thread correctly, I am sad to hear that this mod did not reveal better results... I would have expected better. I did an extensive Sound deadening mod with Second Skin Audio Damplifier Pro and Overkill standard. It definitely made a difference for me, but I wished I had done a before and after study as you did to quantify the results.

http://forums.corvetteforum.com/c5-g...os-photos.html

nextime

Thanks for the info, looks like I wont be wasting my time doing this now.

csexton

Thanks for the info

Chuck

Patches

We have two '02 C5 coupes - mine with the FK mod and the wife's without. There is an obvious difference in how quiet the interiors are- mine is noticeably better. I have h/c/headers/Ti's while her's is just intake,exhaust and headers. In mine, the sounds from outside including bumps to the suspension are muffled and distant-sounding while external sounds in her's sound sharp and more immediate. Also, I gave her my HD rear cargo mat when we bought her's so she has that extra padding in the rear hatch area. I am planning on adding the FK to her's this spring.

Just as another data point, someone posted this here a while back from a mag.

intoc6s

Maybe....it helps when the car is a loud car to begin with. Meaning, if the OPs car is quiet , like a stock car, there won t be much change.(i didn t catch his mods) But in a car with 1 7/8 headers , offroad catless x-pipe and straightpipe cat-back, It might really make a difference...Just a thought.

It says in his profile that its a stock car. I just checked. Maybe this is it.

JEEP/C5

I wonder if your db meter measures fractions (like .5 or .25 of a db). You could have possible dropped .5 db and the meter shows the same reading as before until it drops to .6 db?

Not sure on the ratio but 1 db is quite a bit of change. If I remember my stereo 101 from the 80's it take 10 x the wattage to make a stereo twice as loud (for instants you cannot double a 250 watt amp to 500 watt amp and expect twice the volume - It would take 2500watt amp). Not sure what the db ratio is but it seem like 3 db is twice as loud as 1 db? Or maybe it was 6 db? (Im sure somebody out their knows).

Plus the db meter is measuring across the whole spectrum of frequencies (20 to 20000 hz or more) so the wind noise and squeaks may no longer be heard by the human ear (so its quieter to us) but the lower frequency are the same db so the meter shows not changes.

I did the front king mod with a some dynomat extreme in the front and back. I double up the FK in spots and I noticed a nice change and am very happy with my results. I may have only realized 1 db across and most speeds but it was enough for me esp. for the minimal effort and cost.

Just thought I would throw that out there. I am sure there is somebody out their that know much more about db than I do.

Corvette Don

I noticed a big difference in mine but I had straight pipes on at the time.

CCA Corvette Parts

Did you stuff the frame rails?

Peace
Chip

00 Rooster

jrprich

Which frame rails

tlc0706

Mine is a Z06...In addition to back, put double in back storage bins and behind seats/ removed tailights and coated outside of tub/ removed rear wheel liners and covered area protected by liners/ stuffed and sealed off gas tanks filler tube/ added a good partition. Don't have a meter but, can hear the radio now at normal levels......Very happy w/mine

CCA Corvette Parts

If you take out the rear wheel wells, about 10 screws, you will have access to the rail area on the front side of the wells.

Much of the sound travels up the rails. Stuffing these eliminates a lot of sound...

Peace
Chip

jrprich

Yep, I have been nervous about doing that as keeping the fiberglass dry while still retaining it's ability to insulate sound seems a difficult trick

CCA Corvette Parts

Stuff sealable sandwich bags. That way any water that needs to can travel around the bags.

You don't need to pack them in the rails, just take up about 60 to 70 percent of the volume...

Peace
Chip

YNOT2K

i know there is something like this in a C6 Z06 - watched a vette buddy take out his fender wells and there was a bag of insualation in there about the size of sand tube.

tlc0706

I jambed several pieces of pipe insulation in that area...then sealed off with FK ...

jrprich

Interesting......looked at the parts diagrams on gmpartshouse.com for that section on the C6 Z06......nothing listed

Kale

If your mid and low frequency road noise is higher than your high frequency road noise, a DB meter will not measure a difference. Frost king lacks the thickness or mass to block these frequencies (about 1lb/square foot is required)

A real time analyzer will show a difference probably starting around 15k.

When I tested a couple of materials, using a speaker in a wood box with an open side, and the material over the open side, there was no sound reduction by frost king under about 10k. But it was quite noticeable over 15k or so.

The sound source was pink noise - 20-20khz all at once.

I should do this test again, now that I have some better material on hand.