Here's a novel thought. S2s are inherently noisy.

"OK, so what are you going to do about that. Bob?"

This all started when I swapped out the stock boiler looking and quite heavy mufflers for a pair of Magnaflows. Suddenly the car began to sound like a proper sports car. After a while, it began sounding like a Jamaican steel drum.

I trolled the S2KI site and found all sorts of threads on sound deadening. Some were even more volatile than certain threads that appear in these hallowed halls from time to time. If there was agreement on any point, it was that the car is basically pretty raucous stock and that exhaust mods introduced a 3.5K drone that is bearable with the top down, but a real drag with the lid up.

First step was to separate the wheat from the chaff. Not that I wanted to use wheat or chaff to quiet down the S2, but I did want to understand more about the acoustical dynamics of the car. After a couple of months of academic as well as applied research, I came the the conclusion that:

1. Much of the noise that is offensive comes not from the drivetrain (including modified exhaust), but from sympathetic resonance that develops secondary to the drivetrain and/or road noise.

2. The best approach was not to try to "silence" the offending machinery, but to keep the "head of the steel drum" from picking up and amplifying the normal sounds of the car.

Armed with my newfound information, I ordered 50 sq ft of matting (Be-Quiet) that was non asphaltic (bad deadening properties and very smelly).

Upon receipt of the matting, I took out all the trunk trim and applied the matting everywhere I could and particularly where the surface sounded like it could have been used in a Bob Marley recording. Above all, the area immediately under the spare tire is a serious resonator. After I buttoned it all up, I went for a drive with top up and down. Under both scenarios, the exhaust note, which had been placed about at my ears (without the deadening material) was now appearing to come from about a foot or so behind my head. Not bad for a start.

Next up was the passenger side. This is another of the "bang for the buck" spots, mainly because of the routing of the exhaust system. After removing all the trim, carpets and seat, I applied at least one layer of matting over the entire floor area as well as up along side the right side of the transmission tunnel. Once again out to the test track (I have unbelievable roads up here), and the difference was amazing. Where the exhaust note had moved from ears to a foot or so behind my ears with the trunk work, the exhaust was now sounding ike it was coming from just behind the car.

Since I was on a roll, I went back home and stripped out the driver's side and did the same thing as was done of the passenger side. At this point, my wife had come home and I asked her if she wanted to take a short ride down Canyon Way. She agreed and we had gone no more than 50 feet before she asked, "what did you do to quiet this thing down?"

Not one to rest on laurels, I ordered a couple of gallons of a product called Quiet Coat. It works on the same principle as the matting and would be a bit easier to apply in some of the remaining areas I wanted to take on, you simply paint it on. My thought was to do the wheel wells and maybe to cover some of the matting with another coat of deadener.

All the while, I had wondered about the tray that sits between the folded top and the opening of the trunk. Since Honda had seen fit to glue some carpet batting to the bottom of it, that made me think that they had identified it as a source of noise. Boy, were they ever right. Three coats of Quiet car later and I drove down the road with the exhaust note another foot or so behind the car and virtually no 3.5K resonance in the cockpit with the top up. It is my humble opinion that the top tray is the source of much of the offensive noise being generated by the S2. It is like a tympany head and it goes crazy with resonance if left to its own devices.

While I was at it, I applied three coats of QC to the area beneath the spare and it now sounds acoustically "dead". Wheel wells are next on the list.

If you like noise, this thread ain't for you, but if you value your hearing, this stuff works. I have now helped two friends do their cars and they are both delighted with the results. No, I'm not doing this for $$, I already have too many demands on my retirement time, but I would be happy to answer any questions and offer tidbits of very valuable information about how not to screw up the inside of your car as you attempt to reveal its inner workings.

 

I used Dynamat on my STi in a similar (but not such a thorough) fashion, and it sure made a difference. These lightweight cars are just not designed to be quiet, like fancy sedans are.

Is this stuff you used lightweight? Dynamat (which, I think, is the asphalt stuff you referred to) weighs a ton. HPH

 

That's an excellent write-up and would be a nice addition to the "Under The Hood" section of DIYs. I can see where the noise could get to you after a while, but I still get such a kick out of the car that I accept and even enjoy the racket. I opted for "noise balance" by sticking on a K&N fipk and redistributed the noise partially to the engine bay. A bit like 5.1 surround.

 

A solution to the noise problem is earplugs. Works great although you can't hear the radio worth a damn.

BUTT seriously, I use my Etymotic ER4 earphones with an iPod. Cuts out the external noise and the music is concert hall quality. Works good on my motorcycles too.

 

Ed,

All joking aside, I'm looking for a pair of earphones/headphones that I can use as ear protectors (in addition to listening to music) while I ride my lawn tractor, push my mower or use my leaf blower. are the Etymotics up to the task? I've never tried noise cancelling headphones, but I'm told that they are not powerful enough for the kind of noise that I'm talking about.

Thanks.

 

The Etymotics are excellent for mowing the lawn, etc. There are other less expensive solutions though. The ER4P earphones work great with the iPod. Small enough to fit in the ear without interference with a helmet on too so I can listen to music while touring on my FJR1300.

 

Thanks. I'm going to look into them.

 

Back on topic. Has Honda added any sound deadening material on the later MY S? I saw a picture of a MY00 or 01 with a bare metal trunk interior and was wondering. My MY05 sounds pretty quiet all things considered. The entire trunk interior is covered with stiff carpeting.

 

^No, they all came with carpeting.

Very nice write up. Thanks bb. I think it would be helpful to know how much the mats your used weigh. I would never "paint" my car, but I suppose that is not an issue for some.

This thread points up what a good job Honda did with this car right out of the box. The stock exhaust manages to cancel all the resonance that is experienced with any aftermarket system and still delivers virtually all of the available power the engine can produce. Mugen may be an exception from what I have heard. After dealing with the resonance for a while, I simply went back to my stock system. It weighs about 25 pounds more than the single I had on, but that weight is at least positioned low and is part of the 50/50 weight distribution of the car. I didn't put on the single to gain noise. I did it to loose weight. For me, there is no real benefit to adding the weight of mats and paint to my car to cancel noise that I don't want.

 

^ Yeah, I was wondering about that Bill... So, it was because of the noise that you went back to stock?

The stock system is pretty dang heavy though (as you said).

I wonder if an aftermarket exhaust combined with some of the sound deadening Bob mentioned would work. I just love the sound of the Spugen duals, but I know they're loud for everyday...