exhaust noise :(

[glw]

ok, i got the new cat-back system installed and it's louder inside the car than outside. don't get me wrong... it sounds great just a little to loud for my tastes.

i don't know that much about this sound stuff so i did a search and read all the threads about dynamat and the other sound deadening products as well as the mass loading and sound blocking techniques. i think i have a resonance problem and could benefit from sound deadening. my questions are...

do you think i could cut out a significant portion of the exhaust sound using sound deadening products? any other ideas?

how much dynamat extreme would it take to cover the bottom and sides of the hatch area? and how much more to do the back seat and back seat floor area as well?

how much should i expect someone to charge to put it in both areas? where would be a good place to get it installed (i'm in so cal)?

thanks for the help!

ps: i visited a local al & ed's and got quoted $250 for the bulk pack of dynamat extreme and another $200 to install it from behind the doors (including the sides). i found the bulk pack (10455) for $140-160 online so that's how i would probably buy it.

[glw]

come on, someone help me out here... :o

[BlackNRedSi]

what brand is it? did it come or not come with a RESINATOR?

will be able to help you after that

[glw]

Originally posted by BlackNRedSi
what brand is it? did it come or not come with a RESINATOR?

will be able to help you after that the new magnaflow cat-back.

all stainless, 2.25" mandrel bent pipe, 4" hollow resonator, 5"x8"x11" muffler with 3.5" diameter 4" long double wall dual tips...
http://sourcecodegeeks.com/public/civic/images/7_closeup_sm.jpg

there is a fairly long thread (http://ephatch.com/forum/showthread.php?s=&threadid=14965) where my car being the test car for magnaflow is discussed, if you care to read... i really like the magnaflow system, but it's just a little loud in the cabin... magnaflow said i could rubber coat the undercarraige (small effect) and/or try dynamat inside (larger effect). they said an offset muffler with a single tip would help some too, but i like the dual tips... :)

[glw]

ok, now i'm confused. went to 2 stero install shops and 1 says dynamat extreme would definately make a difference and the other says i'd be throwing away my money. which is it?

[Brettnyt]

Tough to say, i have wondered the same thing... Is the sound of your exhaust nice? cuz it sure looks nice... I want one which is sporty, lots of onlookers are gunna hear, but is not too obtrusive...

[glw]

Originally posted by Brettnyt
Tough to say, i have wondered the same thing... Is the sound of your exhaust nice? cuz it sure looks nice... I want one which is sporty, lots of onlookers are gunna hear, but is not too obtrusive... exhaust tone (deep growling purr) is great on the outside... not that loud even. it doesn't turn a lot of heads on the street (only other car buffs) and i had my daughter drive behind me in her car and she said it wasn't that loud, but louder than stock. it sounds quite similar to the rsx sound clips on the magnaflow web site.

in any case, i really like the system i just think there is some resonance problem within my cabin. i've been researching this resonance problem and apparently other cars have had the same thing, the new bmw-mini being one. apparently the new mini gets some relief when putting dynamat under the rear seats. they also say cracking the window or sunroof also deadens the sound as well ??

[BarracksSi]

Originally posted by glw
ok, now i'm confused. went to 2 stero install shops and 1 says dynamat extreme would definately make a difference and the other says i'd be throwing away my money. which is it?

I remember a test -- Car Stereo Review or some other mag -- where they finally tried to settle the question by using a Real Time Analyzer to quantify the difference.

They found that when it came to road noise, the Dynamat made very little difference, if at all. Acording to them, it's not that good at sound insulation.

People do say that Dynamat will dampen resonances in the metal, though. With Dynamat (or anything similar -- I've seen an article on an installation that used lead sheeting!), the car's panels wouldn't "ring" or thump in response to the speakers.

I'm still undecided. I'm not sure if it would make much difference, but I would also like to think that I did everything I could to make a good install.

[BlackNRedSi]

Originally posted by glw
the new magnaflow cat-back.

all stainless, 2.25" mandrel bent pipe, 4" hollow resonator, 5"x8"x11" muffler with 3.5" diameter 4" long double wall dual tips...
http://sourcecodegeeks.com/public/civic/images/7_closeup_sm.jpg

there is a fairly long thread (http://ephatch.com/forum/showthread.php?s=&threadid=14965) where my car being the test car for magnaflow is discussed, if you care to read... i really like the magnaflow system, but it's just a little loud in the cabin... magnaflow said i could rubber coat the undercarraige (small effect) and/or try dynamat inside (larger effect). they said an offset muffler with a single tip would help some too, but i like the dual tips... :)

well it looks real nice...only thing i can think of right now, is that you said it was 4' hollow resinator...are there any guts in that resinatior or is it just a tube with nothing in it? d-mtt wont do alot, it will do some...you should look up JayDub, he did alot of deading to his car...other than that i really dont kno what to say....the resinator should be the product that kills loud exhaust noise, and raspy noises....

[younggotti266]

I wouldn't spend $500 to have dynomate installed the people that say it will work probably just want your $..

Dynomate is to reduce the vibration from the speaker that cause rattling in your car........

It's not gonna turn down the loudness of your exhaust.....


Don't do it....

Save your money..

[glw]

hmmm... i appreciate all the help because i'm no expert and far from experienced in this area, but from what i've been able to determine so far is that the belief is that the air rushing/pulsing through the pipes is similar to a musical instrument (and a loud speaker). the output is sound waves that vibrate the various panels along the underside of the body. the dynamat when pressed to the panels would perform a function called "mass loading" which would lessen the vibrations in the panels. i understand that dynamat is not meant to block much of the sound waves but it is designed to stop the panels from becoming, in effect, speakers (or at least lessen the their vibrations).

rubberized undercoating and other carpet padding products (like volara foam), which i am also considering, would be wave barriers that may provide additional sound deadening as well.

my problem is that i don't know if the panels themselves are causing the noise or if it's the sound from outside the car sneaking in. i'm inclined to believe it is the panels because other people have told me that it is not that loud outside the car...

ps: honda also does some mass loading from the factory... look in your trunk, under the carpet just above the muffler area... you'll see a pad attached to the metal flooring. it's other places, too.

[ep3guy]

Wow, that looks pretty nice.

I feel the same way with my b-pipe. 2.25 crush bent without a resonator. Ever since I got it, I got kinda annoyed. It sounds good, but it gets annoying sometimes. I doubt dynamat will help, since I believe it is used to keep things from rattling inside the cabin.

I see that you're on Orange County. You should drop by the Sonic Burger meet today. :)

[siver-SI]

Two things I can think of. What about upgrading the rubber hangers on the pipes so that they would not send as much sound through the car? The other is not dynomate but when I work on higher end cars to take out sound they use insulation that is about 1/4 thick but very dence. All is it made for is just like in your house it is made for to help keep out sound between walls.

[BarracksSi]

Originally posted by glw
.... they also say cracking the window or sunroof also deadens the sound as well ??

Just reread this post --

If you open a window, and "un-seal" the cabin, then you're likely to reduce the booming resonance.

It's possible, one way or another, for an exhaust to produce a frequency that happens to be a harmonic of the interior. If the sound chamber -- the cabin -- isn't sealed shut, then the resonance will vent to the outside, and not be so obtrusive. It's similar to how the stereo seems to lose bass with the windows open.

Honda ain't no backyard exhaust bender. They spent the R&D to tune the exhaust so that it doesn't get boomy inside the EP's specific cabin size & shape. They're good -- that's why they're Honda.

[glw]

Originally posted by BarracksSi


Just reread this post --

If you open a window, and "un-seal" the cabin, then you're likely to reduce the booming resonance.

It's possible, one way or another, for an exhaust to produce a frequency that happens to be a harmonic of the interior. If the sound chamber -- the cabin -- isn't sealed shut, then the resonance will vent to the outside, and not be so obtrusive. It's similar to how the stereo seems to lose bass with the windows open.

Honda ain't no backyard exhaust bender. They spent the R&D to tune the exhaust so that it doesn't get boomy inside the EP's specific cabin size & shape. They're good -- that's why they're Honda. barracks, thanks for all the great input. cracking the windows seems to help a little but not a whole lot. would that indicate that it is not a resonance problem and just a loud exhaust?

[Jpax]

just do this and it will "help" with some of the noise, link (http://ephatch.com/forum/showthread.php?s=&threadid=10760) you will notice it will help lessen the sound at higher rpms when you are moving and above certen rpms because the exhaust makes low frequencies, it will absorb some but not all of the sound. but this will be a expensive road to go down not to mention the amount of material you will need.

[CIVICBOOST]

I'm just going to suggest going with a bigger resonator and preferably one that has some guts to it

[islnena]

Originally posted by glw
the new magnaflow cat-back.

all stainless, 2.25" mandrel bent pipe, 4" hollow resonator, 5"x8"x11" muffler with 3.5" diameter 4" long double wall dual tips...
http://sourcecodegeeks.com/public/civic/images/7_closeup_sm.jpg

there is a fairly long thread (http://ephatch.com/forum/showthread.php?s=&threadid=14965) where my car being the test car for magnaflow is discussed, if you care to read... i really like the magnaflow system, but it's just a little loud in the cabin... magnaflow said i could rubber coat the undercarraige (small effect) and/or try dynamat inside (larger effect). they said an offset muffler with a single tip would help some too, but i like the dual tips... :)

[islnena]

Get a piece of foam rubber carpet pad for 5 bucks and put it under your removable trunk floor.......1/2 inch thick

[CIVICBOOST]

I like the look of the magnaflow its the same design as the borla but I really hope it sounds better than the borla, my opinion the borla sounds nasty

[glw]

ok... here's what i've done...

1) i sprayed a coat of rubberized undercoating underneath the back end of the ep.

2) i dynamat xtremed the rear (behind the rear seats) bottom.

result - each provided a little improvement knocking down some of the sound.

3) i took off the rear bumper cover and sealed up the vent just above the muffler (but not the one on the left side of the car). i used some leftover dynamat xtreme. heres a pic from the manual...

http://sourcecodegeeks.com/public/civic/images/vent.gif

result - another small improvement. still a little loud from 3500-4000 rpm. i may close off the vent on the left side, but i want to be able to close my doors with the windows rolled up. :D

oh, while i was under the car spraying the undercoat i noticed that the area above the muffler could use a heat/sound shield... i thought about crafting one up and am still considering it.

islnena: i'll try the pad... thanks

[trabadoo22]

I pm'd you a while back. I think you should deffinitly look into the accustic foam. Dynamat is not really meant to reduce road noise, exhaust noise etc. It is meant to reduce noise from vibrations in metal + plastic materials. If you think about it all it is doing is adding mass these types of materials to prevent them from vibrating. It may be helping if the exhaust is vibrating the car any, but the exhaust tone and noise level I don't think it will help too much. Anyways the foam type material is what I think will work best, just like in a recording studio or car audio show room. But now that you have the dynamat done it deffinitly won't hurt. If you are still not satisfied with the noise levels of the exhaust and are willing to do this then I would add the foam to the floor + trunk. Then the doors if you can.

[CIVICBOOST]

I finally got around to installing the same magnaflow system on my car today and I noticed it is pretty loud on the inside I'm just hoping its not as loud on the outside, I dont know because nobody drives my car but me so i cant hear it from that persepective. I think I remember reading it complys with the 95 decibel rating right so thats good. I'm pretty stumped about this sound deading thing but I too am considering this now.

[trabadoo22]

I thought the same thing at first. When I got mine for the first couple days I thought the noise was obnoxious. I was almost ready to take it off and sell it. Then after to talking with someone who allready had this exhaust for a while and after talking to a muffler shop, I was told that it should quiet down conciderably. I honestly didn't believe it because my previous magnaflow exhaust for my old civic went from almost silent to medium loud. Anyways the exhaust did quiet down alot and I am very happy with it now. I think after 100-200 miles on it you should notice it quieting down.