Reduce interior sound
 

Per my previous post I explained all the mods I got on my car and how much I enjoyed them except for the interior noise it brings. From the outside the car sounds amazing with intake, header, exhaust air flow but the the inside is difficult to bare on road trips with a rev past 3k rpm.

My question in this post is does DynaMats, or any other product similar, work well? I have been recommended from several people to check it out and they say I will notice a huge difference. Can someone please give me there thoughts? I want to know how it works on the FRS. A few people told me that the FRS has no insulation so it should make a night/day difference. Is this true?

Before I was told about this option I was going to start pulling my parts and putting the stock ones back on which I really didn't want to do.

Thank you for your input!

Dynamat is a brand name for vibration damper. Any product that will stick directly to the surface of a panel will help reduce vibration. This is good for making your speakers sound better (your door panels won't flex with the speakers), not necessarily to reduce road/engine noise.

What you really want to do is line the firewall, floor, doors, and trunk in mass loaded vinyl. That will help reduce road/engine noise considerably more than if you were to stick Dynamat everywhere.

Read up on all this stuff at http://www.sounddeadenershowdown.com/

Sounds like you have an exhaust that drones? In my past experiences, no amount of sound insulation would get rid of it. The only thing that would get rid of it was a properly tuned exhaust. YMMV

Or try getting a few resonators put in the exhaust system.

I checked your other thread. Nice selection of parts; hope you got a great deal on them. But having said that...personally, I don't see the point in spending money to make the car louder then spending more money to try to quiet it down.

What's the actual model of the catback, and which header is it? A UEL header paired with the Invidia N1 exhaust is a VERY loud combination, so if that's what you're using it's no surprise you're getting that much noise even at lower RPMs. And from what you're describing it sounds like drone coming from the exhaust. I'd hesitate to blame the intake as usually those only get significantly louder when you get on the throttle rather than at cruising speed.

You will definitely want a tune at some point with all those mods on the car but I doubt it'll do much to reduce drone coming from the exhaust. Like m.wood says, you could try getting some resonators installed to reduce the drone but it's anyone's guess at how much that will help. I doubt dynamat will help in this case.

If this really is too much noise and the resonators don't do enough to help, you may want to save up a bit and get a different catback. Keep the headers, as that's where your best performance increase comes from, but something like the Perrin catback will tame the noise a lot more than what you have now (assuming it's the N1).

Yep. Some math can be used to fix it as well (Helmholtz resonance) but it still usually requires a bit of fiddling to get it right on a car.

I meant tuning in the way you tune a musical instrument :) It is a resonance, so it applies. I've seen people make their own Helmholtz resonance tube (on other cars) that slipped so it could be "tuned" much like a wind instrument and then locked into place.



To the OP: Trust me, I've been where you are. I loved my car loud until I drove 5 hours straight in it. After that trip I immediately dumped a lot of money (more than I should have) into shutting it up. Best part was, the quality exhaust I bought gave me more power as well.

I think I'm getting old, but I'd really like to see an exhaust that sounds close to say a G35 in tone for this car. Until that time I'll probably stay stock on my own car when I get it.

Depending on how much you're looking to spend, aircraft sound deadening material would probably be the best.

Any gain you have from your mods is going to be lost making your car quiet.

Get an exhaust that is not so loud and put your cats back on.

how is making his car quiet inside going to hurt performance?

Adding weight slows down

I've done a lot of research about this... the people that have done CLD+CCF+MLV on their '86's have added betwen 17 - 32 lbs of sound deadening materials (total) mostly spread across the floor of the car and in the doors. That's not enough weight to affect performance much at all. If a person wants to balance the added weight, simply remove the spare and tools, change the battery or a myriad of other minor mods (driver diet anyone?). We're not talking about 100 or even 50lbs here.

First Layer:
**CLD = Constrained Layer Damer (Dynamat, RAAMat, FATmat, etc).
Dampens vibrations on metal and plastic. Use 3x3 tiles, don't coat whole panels.

Second Layer:
**CCF = Closed Cell Foam (RAAMaudio Ensolite, 3M Thinsulate Acoustic, etc.)
Fills in gaps where air would otherwise vibrate and transfer sound. Lay behind panels, under carpet, in gaps.

Third Layer:
**MLV = Mass Loaded Vinyl (any brand, search for it).
THE BARRIER - Dense enough that it doesn't easily vibrate and thus transfer sound. Lay on top of CCF and CLDs.

Helmholtz resonator is a simple sound tube in the exhaust and won't add much weight at all.

Also, like I said, no amount of dynamat is going to solve a droning exhaust. It's still going to get in the car through windows, etc.

Dynamat or equivialent vibration dampener combined with sound barrier such as mlv will help block some exhaust noise and make the ride all around quieter. These cars have very little sound insulation from the factory. Dont go overboard and u wont have to worry about weight becoming a factor. Although i hear making it quieter will slow you down...
Infinite012's post has a great link.

Good MLV is right around 1 lb/sq ft. I really don't see how someone would do a halfway decent job using that little material. I'd budget ~75 lbs to do it properly (doors , quarters, floor, transmission tunnel, etc). I guess if you just did the doors and the footwells you could do it with that little material, but I used something like 60-70 sq ft in my build (started off with 90, have about 15 left on the roll, plus a box of scraps that weighs about 10 lbs), plus another ~15 lbs of CLD, CCF, and that stuff. Just the passenger compartment is about 6-6.5 feet wide (when you include the inside rocker panels and transmission tunnel curves), and maybe 5 feet long, so you're at the upper end of your proposed weight if you just do that, and skip the doors, trunk, rear wheel wells, etc.