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post #81 of 314 (permalink) Old 12-20-2010, 05:21 AM Thread Starter
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Well, after reading all that...

Yes it should be a whole lot quieter, but not quiet...You'll understand what I mean when you experience it. Just don't glue anything down, after you try it if you don't like it you can easily remove it...I highly doublt you will, then you can go back and glue things down if you want. I have not glued down anything to date, but will glue down the bulkhead area when I do it.

2009 Saffron Yellow Elise Purist Edition - Unpurified (oem cupholder, leather tunnel cover, and black door panels), Difflow 5 element railer JR, Janspeed Stage II Exhaust, ongoing sound proofing project, kahtec blinking 3rd brake light.
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post #82 of 314 (permalink) Old 12-20-2010, 05:28 AM
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With doing the whole firewall and the floor, a whole lot quieter. Yes, as psoup said, still noisy compared to BMW, MB, etc, but you can hear yourself think at 80 on the freeway.

BTW, Ali, how loud is that Scuderia compared to the Exige?

Still didn't get to do the doors since I seem to have caught some sort of bug...

However, on Saturday we did the undertray and diffusor of my boss'es Exige and that positively fixed the "oh my God the car is falling apart" noise when driving over a bump. We will keep an eye on those damplifier pieces when doing an oil change to make sure there's no corrosion going on underneath. If anything starts to show, I'll just pull it off, paint underneath and put a new sheet back on.
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post #83 of 314 (permalink) Old 12-20-2010, 05:35 AM Thread Starter
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Zuspeil, thanks...I'm just hesitant to make too bold of claims about stuff, cuz I don't want people to come back and say "I spent $xxx.xx on doing this and it doesn't do what you said"...But a confirmatory opinion is hugely helpful.

Oh, and I have been thinking a lot about the floor corrosion issue, and kinda came up with the same thought, some clear coat or something to protect the aluminum if needed.

2009 Saffron Yellow Elise Purist Edition - Unpurified (oem cupholder, leather tunnel cover, and black door panels), Difflow 5 element railer JR, Janspeed Stage II Exhaust, ongoing sound proofing project, kahtec blinking 3rd brake light.
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post #84 of 314 (permalink) Old 12-20-2010, 07:19 PM
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Finally getting around to posting some pics.

As per my previous post (#38), you have to be careful with this stuff. It's fun to see how quiet you can make the car, but then you've added about a half tank of fuel in terms of weight to the car before you know it. I'd highly recommend keeping track of how much you've used so you can keep an eye on weight.

Furthermore, I thought I wanted the car as quiet as possible, and I got that, but it was not satisfying. The wind noise just gets really loud and it's a little eery to be driving such a visceral car without hearing any of the *good* sounds.

I did use an SPL meter for my testing, but I wasn't diligent enough to make it super scientific (I wasn't willing to keep tearing the car apart to try different scenarios--I'd just change a few things and then measure). Furthermore, if you're measuring exhaust noise SPL is pretty interesting, but many of the higher-frequency, lower energy sounds are more about sound quality than just volume.

So I'll show you my results and you can use them how you want. My goals wound up being:
- not have to wear ear plugs in the car
- to be able to crank some music and enjoy it
- make the sounds of the car sound GOOD from inside the car

In summary, this is what worked, and I'll show pics of each one:

- damping sheet beneath seats (if not already there)
- no touring pack firewall foam (doesn't make much difference if you have damping sheet, and since touring foam weighs 5 lbs, it's better just to put some damping sheet there and get away with less weight)
- damping sheet on firewall itself
- just a couple squares of damping sheet on the plastic firewall cover (I originally covered all of it and removed most and it made little difference)
- small damping sheet and tiny bit of sound barrier in door skins
- a couple pieces of sound barrier inside body near intake if you have the cup box

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post #85 of 314 (permalink) Old 12-20-2010, 07:23 PM
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First the materials. Cascade Audio Engineering products:

Vmax - elastomeric damping sheet for panel resonance
VB4 - sound barrier sheet to block sound transmission, especially low frequency

And from Electronics Express:

Open-cell foam with damper layer - a minimal-weight way to absorb high-frequency and some low frequency sound

BTW, Cascade Audio Engineering (up in Bend, OR) was great for understanding real-world sound transmission paths and how to identify where to get the most bang for your buck.
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post #86 of 314 (permalink) Old 12-20-2010, 07:33 PM
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On the firewall, I found there to be a lot of tinny engine noise coming through (not the good kind of engine noise).

I found I got the same attenuation or better with damping sheet on the firewall instead of the touring pack foam, with half the weight. I used 8 10"x10" sheets of Vmax for the firewall, including some inside of the side body panels (2.35 lbs), along with some open-cell foam (0.26 lbs) to absorb the high frequency side body panel resonance noise. There was no point in using the 5 lb touring pack foam after this--I could not notice a difference.
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post #87 of 314 (permalink) Old 12-20-2010, 07:35 PM
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I originally plastered the inside of the firewall trim piece with Vmax damping sheet. This was way overkill. I wound up removing a bunch of it, and I suspect taking even more off would be the thing to do, with just one small sheet in the middle of the panel, if anything. What's shown adds 1.17 lbs.

Note: remember to not cover the upper inside where the trim piece touches the roll bar. It make things not fit right.
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post #88 of 314 (permalink) Old 12-20-2010, 07:37 PM
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post #89 of 314 (permalink) Old 12-20-2010, 07:41 PM
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In general, I was trying to get rid of the "tinny" sounds to be able to hear crisp intake and exhaust notes (and music). The doors seemed to be contributing to this. I put a couple narrow strips of Vmax damping sheet (0.52 lbs) inside the middle of the door panels, and put a small amount of open cell foam (0.66 lbs) over the top to actually absorb the high frequency panel resonance noise.

A by-product is that the doors close with a bit more of a "thud" than before, too.
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post #90 of 314 (permalink) Old 12-20-2010, 07:44 PM
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The best bang-for-the-buck to reduce tinny road noise was to put Vmax damping sheet beneath the driver and passenger seat (if you don't already have it). This added a total of 1.16 lbs.
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post #91 of 314 (permalink) Old 12-20-2010, 07:49 PM
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I put a cup air intake box on the car, and although the louder intake sound was nice, the quality wasn't so good. It was OK at lower RPM, but then would suddenly go WAAHHHH in an unsettling way at high RPM (it sounded like an on-off switch). It was also vibrating something annoyingly in the cockpit.

After trying some things to no avail in the passenger compartment, some open-cell foam (0.49 lbs) around in the inside body panel next to the intake worked GREAT! I played with several configurations to get just the right volume and tone, and be totally linear with throttle. You can make it sound great with this if you get the right configuration.
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post #92 of 314 (permalink) Old 12-20-2010, 07:51 PM
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I found the factory carpet to be a lightweight way to absorb some high frequency noise in the cockpit (0.61 lbs). It makes a difference to have one less hard surface in there.
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post #93 of 314 (permalink) Old 12-20-2010, 07:59 PM
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How much weight did all that add?

8.52 lbs, if you include the 0.13 lb for 2 4x6" sheets of Vmax on the inside of the shift console (though I'm not sure that does much).

What would I change? Eventually, I think I'll remove some damping sheet from the firewall trim panel, and also some from the inside of the doors. I think I still overdid that. So you could probably get away with 6-7 lbs and with a huge difference in sound level and sound quality.

Another thing to add, though somewhat obvious--tire condition makes a HUGE difference on cockpit noise. I actually went to a street tire from my A048s (Bridgestone RE-01R), and WOW, they were so much quieter! Well, then I went back to A048s, and they were significantly quieter than my worn RE-01Rs!

The results? It's not as quiet as it could be in the cockpit, but I don't need earplugs, can listen to music and not be annoyed, hear really nice intake and exhaust notes, and still hear some communication between the tires and road surface. For my goals I'm totally happy with it, and well worth the 8 lbs even though I'm a weight weenie.
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post #94 of 314 (permalink) Old 12-20-2010, 08:05 PM
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Now what did I find NOT worth it?

The biggest thing was VB4 sound barrier I cut for all four floor wells and the "gas tank cover" panels behind the seats. Yes--it cut down road noise to basically nothing. But it was weird. Really weird. I discovered I like *some* tire noise to hear the communication of the car with the road.

Since this was easy to remove, even while driving, I played with it a lot. For my purposes, definitely NOT worth the weight!

It took 11.5 pounds of VB4 for the coverage shown here.
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post #95 of 314 (permalink) Old 12-20-2010, 08:09 PM
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Another fail... as mentioned above, I got the same or better attenuation and saved 2.5 lbs but using Vmax damping sheet on the firewall instead of the touring pack foam (which weighs 5 lbs). (I had cut a couple blocks out to be able to use it with the harness bar, which could be installed after installing the harness bar.)
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post #96 of 314 (permalink) Old 12-20-2010, 08:11 PM
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I originally overdid the firewall trim piece with Vmax sound damping sheet. It was way overkill, heavy, and made no noticeable difference (see above, though I'd still remove more).
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post #97 of 314 (permalink) Old 12-20-2010, 08:19 PM
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In order to run a louder-than-stock side-exit exhaust (BOE Silent Touch), and still not have to wear ear plugs for drone (I know, some are much worse!), I tried making an aluminum sound deflector/absorber, to try attenuating the noise at the source.

I created a reasonably well-sealed structure around the exhaust to deflect all the noise rearward, minus about a fingers-width around the exhaust itself. I lined it with VB4.

It was quite an effort with the crazy angles involved (check out that pattern), and made almost no difference. It weighed 4.6 lbs, canceling some of the savings of the exhaust, and this is when I finally realized it's a lot lighter to just cut exhaust noise at the source with the right exhaust, rather than add 25 lbs of insulation everywhere else (and still not be effective).

I didn't mention that I also tried lining the whole firewall with VB4 sound barrier, and it made no noticeable difference.

Can someone please make an exhaust lighter than stock that's just as quiet?
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post #98 of 314 (permalink) Old 12-20-2010, 08:26 PM
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FWIW, if listening to music is part of the noise equation for you, I highly recommend adding a subwoofer. I wasn't willing to add the weight, so made a self-powered removable one, described here:
https://www.lotustalk.com/forums/f133...d-sound-91960/

In fact I found that works so well that I'm going to just remove the rear speakers since they really don't add anything sound quality-wise. I tried to add sound insulation, as per above, to try to make them sound better, but I think it's pretty impossible without any sort of semi-sealed enclosure. So then when you want your car to be light, it's actually lighter than stock.

Now don't get me started on mods to improve shift quality!

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post #99 of 314 (permalink) Old 12-21-2010, 03:42 AM Thread Starter
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Mtribe, thanks for sharing. Nice to hear your experiences and see your great pics of your project in progression.

I have heard good things about cascade audio products, but have not personally used them, but they are another good source for materials. I just looked over their product catalog, and they really do have a great variety of products that all look to be high quality. There are several companies out there that produce products that are nearly identical with slight variations on thickness or material design.

VB4 is nearly identical in design to Luxury Liner Pro in that it is a mass loaded vinyl with foam decoupler. It seems to me that you bought this and didn't really use much of it though, especially with the whole project coming in at the weight it did.

V-Max is nearly identical to Damplifier, basically a butyl rubber product with a constraining foil layer.

The product you describe from audio express seems to me to be two layers of foam sandwiched around a thin MLV layer, just eyeballing it it looks like probably 0.25-0.5 lb/sqft MLV. Do you know the weight per square foot of this product?

Your experience about adding dampening material to the bulkhead plastic piece not making much of a difference is about spot on with what I have been reading from other sources, and it's nice to see this confirmed by you. Essentially plastic and fiberglass are "supposedly" relatively self attenuating for vibration and do not develop the high frequency vibrations that metal does, and so benefit little from adding dampening. They do however have low frequency rattles, and do not act as much of a barrier at all to sounds; adding a foam product however should help significantly with decreasing the low frequency rattles and filtering out the higher frequency ambient sounds like road noise - even something thin like 1/8 or 1/4 inch product to the plastic bulk head piece (I have not done this yet, but this is the approach I plan to take). Additionally, flat surfaces are much more prone to developing resonance than more complex shapes, even curves and bends diminish resonance substantially. I think this is why adding dampener under the seats as you describe makes such a substantial difference.

One place that you might address that seems to make a good deal of difference in ride quality is the under tray, a little dampening there seems to cut some of the unpleasant road noise, especially that rattle trap sound when hitting bumps in the road. Zuspiel has added some to the diffuser, which probably is a good idea, I have just been hesitant to do it because of the heat generated there, but plan to if followup from him or others find no problems because of the heat.

I am curious, based on the description of what you have done with the amount and types of materials used...It would seem to me that the quality of the sound would be substantially improved - I would expect you would have a lot less drone and high frequency noises such as tire and pavement noise which should be filtered well by the lighter weight foams and dampening. But, without some sort of mass barrier (although it does appear you have some mass barrier, just a small one, in that product from audio express) I would assume that the volume level largely generated by the engine and exhaust is still about where it was before, maybe a small reduction ????

So the quality of the sound should be great, but the volume I would expect to be near to what it was before? I believe this is what you were alluding to in some of your previous posts, and using mainly a dampener and foam is roughly about what I would expect.

OH, and, thanks again for your thorough write up and pics.

2009 Saffron Yellow Elise Purist Edition - Unpurified (oem cupholder, leather tunnel cover, and black door panels), Difflow 5 element railer JR, Janspeed Stage II Exhaust, ongoing sound proofing project, kahtec blinking 3rd brake light.
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post #100 of 314 (permalink) Old 12-21-2010, 05:16 AM
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MTribe, thanks a lot for the nice writeup and the excellent pics. I like the tuning of the cup box. As for the foam+MLV on the floor, I like the much lower road noise. I seem to be able to hear the tires fine through the wheel wells. But this is like talking about what music we enjoy

psoup, I *think* the damplifier on the diffusor will be fine but we'll know for sure at the next oil change... I'll keep you posted.
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