I want to thank all of you for your patience while I finished this project. I live at 9000 feet, and with all the rain and snow, I haven't been able to get out with the car until just a few days ago. It's been a long work in progress; the car has been apart and back together six times, but by Jove, I've got it!

I did the full treatment so those of you with sound systems would have some results to look at also. Let's get to the hard facts: net weight gain 24 pounds. That is 4 gallons of fuel, your spare tire, a Hawker battery and your jack, a few inches of flab, or a lightweight exhaust, your choice, as far as keeping to the factory weight. In reality, I don't believe anyone will notice the difference.

Subjective notes: the first thing you will notice is the quiet at idle. Keep in mind I did this with a 2002 running factory exhaust. In the trunk (boy is it cramped in there!) it went from 85 to 58 db. At the driver's seat with the top up, we went from 69 down to 60 db. It is hard to explain, but the car sounds "solid". Turn on the sound system-whoa! The dampening in the doors clarified and extended the mid-bass so much that I think before overkilling the amps one needs to evaluate this one improvement by itself. I am using the stock head unit with Kenwood dual mags, and it sounded like a whole different setup.

Let's go for a road test! I used the same road for all the before and afters, running S02 tires. Put the pedal to the metal and run to redline in first gear. Huh? it must not be revving, because the SPL dropped from 93.3 db to 80.6! Second gear, from 94.5 to 85 db. Third gear at 60 mph, from 84 to 81 db.

Although the car felt solid before, this makes it feel like it was seam welded. All the little mechanical pop, whirrs, rattles, and whines are gone. There is no, and I mean no, road noise, tire, gear, or otherwise, apparent from the rear end. So much so that now I can hear the top rattles others have mentioned. Moving right along; 4th gear gets us from the previous 81 db at 60mph down to 77.3, with the top down! But you all want to know what happens at speed, right? In sixth at 60mph, top up, we get 76 db, and an amazing 82 at 80mph, down from 87!
But the test I found most revealing was a coast down from 70 mph. Before the soundproofing, when you put in the clutch and let the engine idle, although the thrashing went away, there was no reduction in the actual Sound Pressure Level. Now, we see a 4 db reduction. Since 3 db is considered a one half reduction in perceived levels, this is great.
Other excellent posts have referred to the human ear's sensitivity to certain frequencies being more acute even though the SPL is the same. That is where this setup is so great. More than the meter measures, those annoying noises have been made to go away. The first time I went to pass a string of cars on a stretch I always run, I listened for the engine sounds, as always, to tell me when to shift. Not. The rev limiter banged away, something I've never done, ever. It's that much quieter. And, the sound system is so much better. I tested against a stock 2001, and while the vocals at 60 mph on the stock car were illegible, they are perfectly clear in mine. This is now the car it should have been all along. And, I've really worked to make it easy to do. Down to 2 components, and if the directions are followed, pretty much dummy proof. I now know all the shortcuts, having broken almost every type of fastener from the factory. Kits are ready to ship, but I am awaiting freight figures from one vendor. I will post in the group buys forum next week. No other single thing you can do to this car will improve the quality of ride so much. It is a GT now, with no performance loss. Long trips can actually be fun!
Thanks again for following the progress; you are a great bunch!

 

Can't wait for the full details & costs.

 

What did you soundproof with?

 

[QUOTE=jlucas,Jul 11 2004, 07:56 AM]Can't wait for the full details & costs.

 

Keep us posted. I'm definitely interested in this kit.

 

"Sounds" very interesting chipperman.
I've been considering upgrading my sound system but the current noise levels in the car really give you only one option while moving (overpower existing background sound by making your ears bleed). Sometimes you like to "feel" the music but really "listening" has its obvious pleasures also. This mod shows great promise in improving the driving experience on long trips and when you are simply crusin'. Hope to see some installation info before purchase. Hope it's not to involved.

 

A few little extra notes: At 60 mph or below, at least with a stock car, the engine noise is almost inaudible. This holds true for 3000 rpm and below, and is valid with the top up or down. With the top down, there is a very linear progression of wind noise from 60 up, but the mechanical is still muted. With the top up, the wind noise is less, but because of the way the rear window is installed, road and reflected noise comes through. In VTEC, forget it, but it still is way down (see first post). This has become a very nice cruiser at 60 and below and the music can be felt
AND heard.

The kits will have complete instructions, but just so you can think about what it involves, keep in mind that you should probably set aside a week, as the polymer has to go on in stages. You will also have to strip all of the interior, seats, carpet, roll bars, panels, console cover, etc., and remove most of the factory applied insulation and dampening material, with the exception of the hard mastics. This is a job made a lot more enjoyable (if you can call it that!) with a factory manual. Every time I thought I could figure it out without the book, I broke something. Doing this as a group would help. And, those of you with small hands, little kids, or tiny girlfriends, will find it helpful when trying to reach in those tight areas inside the door or behind the shock towers, for example.

The materials consist of a visco-elastic polymer and acoustic foam. How and where it is applied affects the outcome. As I said before, I've had this car apart a half dozen times, installing, measuring levels, ripping out and re-installing. I feel that I achieved the highest reduction with the least weight. As with all prototypes, some things don't work well, others do. You will like the results. It is measurable by instrumentation and butt-o-meter (or ear-o-meter). I think it has more of a luxury car feel, just from percieved quality. The inclusion of a multi-layer cloth top would really finish the job. For those of you with hardtops, I think the levels will be very close to a sedan. Like I said before, now I feel like I can take a long trip in comfort, at least leave the earplugs out below seventy. Let's face it, sometimes it can be nice to talk without shouting. If the car was this quiet from the factory, the sales numbers (providing they could build enough) would be way higher. If any of you are in or visiting Colorado, I'll be glad to demonstrate. And by next month, the car will be in Orange County, Cali, so many of you could hear it (or not hear it) there.

 

Oh, I almost forgot. That is what happens with sleep deprivation and old age.
I have 4.5" Kenwood rear speakers. No big deal, just for infill. Before the sound deadening project, I could sometimes hear vocals, but mostly part of the music. Now, at 60 with the top down, there is great clarity and it is easy to adjust front/rear fade for a "surround" effect. I used Bob Marley, Dion and the Belmonts, the Beach Boys, and Mario Lanza for testing. If your sound system is important, nothing will help it like this.

 

Chipperman, I've followed the original thread with great interest since last year. That's great that you've finished your research and have kit ready. I've taken some of the ideas you and others have discussed and have soundproofed my trunk (damper and barried) and my doors (acoustic foam).

For those of us that have started this process, will you be willing to provide a list of materials and instructions? I'd like to soundproof the cockpit area but would not necesarily need the entire kit.