Mr_Goodbar

First, Let me tell you about my car. I have a 97 Civic Coupe. I have for sound a Blaupunkt head unit, Khoiler 4x100 amp w/ variable crossover, Blaupunkt 6'' 2ways getting the mid to hi range in the front, Sony 3 way Xplod 6x9 getting mid to lows in the back, Explore(p.o.s.) 400 wattx2 for 2 Rockford Fosgate sealed subs in the trunk. I replaced the "floor" of my trunk with 1/2" MDF and bolted the Sub right to it with some brackets. I screwed some old carpeting to the bottom of the MDF to keep it from rattling around. I have dynamat Extreme lining the underside of where the 6x9 are and its also on part of the trunk lid.
The interior of my car is absent. I have taken out my entire rear seat and quarter panels to do some modifications to the wiring and to retrieve pieces of my side moulding clips from when I broke them off. I did put the rear dash back in. It rattles a bit without the quarter panels to hold it down securely, but it doesn't really when all the interior panels are in place.
I have a stock everything except suspension components. Stock tires, exhaust, motor etc.
My car is pretty loud when I drive and I cant remember what the interior sounded like with the rear panels in. I can really hear the wind blowing past the holes for the side moulding clips. I also get all kinds of tire noise b/c there is nothing between me and the rear fenderwell pieces.
My plans are to put in a JDM H22 and build and turbo the shit outta it cuz I like going really fast just like everyone else here. I want to keep the car for about 5-6 years, especially if Im gonna put this much $$$$$$ into building it.
My question is, should I put Dynamat in to help deaden the road noise while driving? I see alot of people put it over the entire floor, doors, and rear quarter panels, as well as the trunk. Im sure this virtually eliminates road noise and really helps the sound quality of their stereo system....but it adds a lot of weight. Would it be worthwhile to do the entire interior of the car, excluding the trunk, or should I put it in certain places i.e. the big holes in the rear interior quarter panels, and the doors and floor in an effort to keep weight to a minimum? Anyone with any advice would be appreciated.

b00gers

Adding Dynamat to your whole car will add some weight, maybe around 30-50 lbs. This will NOT get rid of road noise. This will help deaden the panels which will help with the midbass and bass, and help with some of the rattles...but it will not get rid of all the road noise.

Mr_Goodbar

So the car will not actually be quieter from outside noise? I know it helps the bass frequencies b/c I did notice a difference when I put that little bit in the trunk but I figured it would also deaden noise fromt he outside as well. If it doesnt deaden road noise then I sure as hell am not gonna put 30-50 pounds of useless weight in.

jacktdurden

If you're as concerned about adding every possible HP, the extra weight of any dynamat won't be worth it. If you seal up all of the holes you uncovered, it should silence the car at least back to OEM standards. A last resort is Expanding Foam, but experiment with it first, that stuff grows exponentially! Good Luck.

99IntegraGS

I know a guy who really messed up his trunk lid on his Sentra using that stuff. Be very careful... use the stuff that fills, but doesn't expand.... if you're going to go that route.

jacktdurden

Exactly, it is virtually impossible to remove, but very effective if you are familiar with it.

blueextc

Dynamat and the like are used to change the RESONANT FREQUENCIES of panels which vibrate at their individual resonant frequencies. You will notice that a different panel vibrates on your car with each change of frequency. The most effective way to combat "road noise" is the OEM standard felt carpet backing. (looks like lint rolled out flat). This dense and lightweight material is researched in depth by the auto manufacturers. Try to overlap the pieces if you are unable to find a whole piece for your particular vehicle. Some higher end vehicles have rubber topped felt which helps add weight to the panels as well, further dampening the panels and helping blanket the road noise out.
This only covers the floorboards, however. Doors, roof, and glass are also ways ambient road noise can enter the vehicle. doors are hollow and amplify the road noise. My suggestion is to concentrate on a good door seal, and floor felt, and less on the more expensive Dynamat if you are looking primarily to cancel road noise.

starsixtynin

what about using fiber glass insulation? That should lessen road noise. It would be mighty heavy though but maybe you can use it in the big hole spaces or at least just the floor.

Ludemandan

I'm also battling road noise, so let me add what I know:

I tore out my interior and put butyl mat on the floor, back seats and doors, it was a big project, and it didn't really reduce noise. Maybe the doors did a little. I still wear earplugs on long freeway drives.

Then I started reading write-ups on www.DIYmobileaudio.com, and I learned a lot. Foam is what blocks or absorbs noise, not mat. Mat reduces panel vibration. Open-cell foam absorbs noise, closed-cell foam blocks it. The thicker the foam, the lower frequency sound it is capable of stopping.

Raam Audio (www.raamaudio.com) makes a product called Ensolite specifically for noise reduction. I'm finally ordering mine tonight. Raamaudio (Rick) is a member of diymobileaudio.com and is building up a project Scion tC for autox and sound quality competition, and it's coming out lighter than stock with a system in it. You can read about how to efficiently reduce noise on that site. It also involves egg carton-shaped foam where there is more room, like inside your doors. Apparently this can also make your door speakers sound smoother by softening the surface behind them.

-Dan

P.S. If you put all this work into your car and turbo it, I hope you will keep it for more than 5-6 years!