I want to do something to cut out some of the engine and wheel noise that enters the interior of my car. I notice some car makers put a sort of insulation on the firewall that dampems the engine noise a little. I had a Chevy S-10 with less engine noise then my 98 Maxiam. Any help would be appreciated..Thanks

 

Engine noise? The VQ is a pretty quiet motor, what do you hear from the engine compartment, I can barely hear my engine.

Road noise from my Z rated tires is another story. If you have a lot of tire noise, get quieter tires.

 

Come on Tom, you forgot to promote your gasket isolator invention


http://forums.maxima.org/showthread.php?threadid=123172

 

Well yeah the VQ is a pretty quiet engine but a little insulation would go a long way in making it even quieter. As for the tires, I know, I'm as picky about the tire noise because I know I can buy different tires. But come now, you know there is plenty of engine noise when you step on the gas, not unless you have the system pumping...lol...

 

Good point Ben, I haven't had my 2nd cup of coffee yet, didn't even think of that.

 

dynamatt your interior

 

where does it go? In the doors? What about under the carpet?

 

It goes every where you want it. as long as you wanna take your car apart to insulate the whole thing.But I would do the doors first.

 

do the entire car. it will be silent. the doors under the floor take the whole thing apart there are pictures online and i have copys of them if you need that expliam how to disasemble the entire car. also throw some on the roof, trunk, firewall, and in the console and wrap all wires you can in it and your car will be sound proof almost. its extreme but amazing. also the you can add any sound system you want and it will be amazing...

ya...

 

Yes....while being quite,you will also add 1 to even 2 passengers to the car. Is quitness worth speed?? NOPE

 

u sure sound insulation is the problem. mayb you have a blown or about to get blown motor mount makeing excess noise..only sound i ever hear commign from the engine is the intake..

 

Personally, I enjoy the growl the engine makes at certain throttle positions. I used to turn over the air cleaner top on my old mans 73 Riviera w/455 to get the same kind of sound out of it.

But, I do think my Max is otherwise noisier inside than it could be. One reason is the huge wheel well gap. It amplifies the road and wind noise. I've been meaning to undercoat the wells and add some under the floorpans to see if it helps. Anyone done this yet? There is a little bit of room for insulation under the kick panels that might help too.

Also, noise from the trunk area comes through the vents in the deck lid. Some added insulation in the trunk, and under the rear seat should help some.

I have not seen measured noise levels on a 4th gen max, or comparisons to other 4 door sedans. Cabin noise is probably in the middle range compared to other cars in it's class.

Insulation adds weight, and takes up space. So car makers have cut back on it to keep the weight down, and increase cabin space, which has added to the noise problems. Thinner metal and, more plastic do not help keep noise down either. The Max also has a lot of window area, which makes it noiser than 2 door cars and trucks too.

I also have an S-10. The Tahoe model has added insulation under every panel and added undercoating to reduce noise level. It is still a lot louder inside than my car though, except when the Bose is cranked.

 

No blown motor mounts. The car doesn't have the quietist of interiors and a big reason is no insulation on the firewall. Even the best of engines are going to make noise. Now I wouldn't go so far as to take the car apart but I would like to put something in certain areas to dampen a little road and engine noise. Plus I'm not in it for speed or racing.

 

I just checked out that Dynamat and it sounds like something I might be interested in. Is it relitively light or heavy? I don't think I want to take apart the doors but the floor and trunk area wouldn't be difficult. Also I'd love to put at least some on the firewall.

 

Greetings!

I kindly offer my 2c. Initially this writeup was sent to Frank@motorvate.com.

Eugene


Below are some notes on soundproofing my ‘98SE.

Soundproofing part.

Maxima is a noisy car compared to similar automobiles.

The Goal:

Reduce noise level by 10 dB across the spectrum.

The task, therefore, was to determining:

- Sources of (excessive) noise
- spectral content of it and
- most effective method to reduce level of noise. The job should be done once and forever.

(My concern was not about listening the music – then I drive I drive, and for the music I have very sophisticated sound system in my house. (In fact, if I could buy a car without radio, I’d pay extra for that))

Money was not concern either – not to say that I have disposable income, but to say that cost-effectiveness was not in my mind. I needed the best result.

We have another Maxima, ’98 GLE we bought new for my wife - thus allowing for direct comparison.

Some time ago I paid to have ’94 Saturn “soundproofed” with good results. This time I decided to do it myself.

.

Tools:

- Spectra RTA spectrum analyzer (PC-based)
- Gold Line spectrum analyzer, hardware-based, for on-the-road measurements
- Sound generator – sine wave and pink noise
- Measurement microphone (ADK condenser)
- Loudspeaker with 12 inch woofer
- Power amplifier
- SPL meter

Methods:

- Measure the noise and noise’s spectrum on different speeds to create baseline
- Installing loudspeaker in the trunk, measure the SPL in the trunk and inside the cabin on different frequencies and using Pink noise. Record spectral content.

Findings (Needles to say, hardly any news):

In ’98 Maxima, the major contributes to the cabin’s noise are, listed by “contribution”:

- Road noise entering to cabin from the trunk
- Road noise entering to cabin from wheels wells
- Exhaust noise
- Engine noise from front
- The ceiling and doors are NOT major contributors
- The hood is NOT major contributor

The “trunk’ noise is the most difficult to suppress because of high low-frequency content – much of it in 40 to 200 Hz range. There’s not much energy above 250 Hz and nothing above 500 Hz from the trunk entering cabin.

Wheel wells are difficult as well because of limited access. If both cases – trunk and wells – the ear is most sensitive to information coming from front and rear. Much less so to the sound coming from the side, which lessens the impact from doors.

Exhaust noise could be muted – to a degree – by insulating the floor of the cabin and insulating pipes themselves. (upcoming project).

Sound- and vibro- absorbing materials have great impact; some more than others.
The carpeting has little and none on low F.

The sprays have no impact whatsoever and IMHO are waste of time and money.

The best source of materials, and the best prices, in my experience, is Canadian www.b-quiet.com. Best effect/price ratio is Brown Bread.

Dynamat is greatly overrated and even more so overpriced.


All available materials were tried and several were used. Several are marketed by different names.

Done:

- The opening to the trunk was completely sealed. The rear desk (w/speakers) was permanently attached and all openings sealed. Four to six layers of vinyl-based absorbing material was used. It does affect the temperature in the trunk.
- The trunk covered with two to six layers.
- The rear hood used two layers; the hinges filled with expanding foam
- The cabin’ floor has six layers under the carpet
- The ceiling has four layers
- The headliner has four cans of “soundproofing” spray applied
- All pillars have two layers
- All attachable parts in cabin (such as fuse cover, steering column cover, etc) covered with one or two
- Door panels – four layers. Door’s panels – two. Doors’ packets – two.
- Lights in the storage (front passenger’ side) were removed and material applied
- Hood’s headliner removed and replaced with thick hood’ insulator from JCWhitney. Later was replaced with Brown Bread.
- Wheels well sprayed with underbody spray, about 20 layers. Has no effect.
- The sunroof was completely removed/reinstalled. Major source was the thin aluminum inside cover. One layer of Brown Bread, the metal side toward the sun, is a tremendous help. As an added benefit, it reduces amount of heat (as aluminum reflect the light) in the cabin – very important here, in Baltimore, having black car!)
- Tires used are Bridgestone Turanza, as I find them most quiet/best performed on my stock 16 inch rims.

Conclusions:

- Doors/ceiling needs just one layer of decent material, such as Brown Bread.
Increasing number of layers does not improve attenuation.

First, the Nissan engineers did most of cost-effective work already. The further noise level reduction is time- and cost- consuming. It takes about 40 hours for decent job. Removing/re-installing headliner was difficult part.

Second, don’t omit any part that is removable: leave no pillar, cover, door packets and such un-covered!

Third, some functionality was affected: the trunk pass-through was gone; the added weight.

- Floor benefits from more than three or four layer. The overall thickness is paramount, as well as vibro-absourbing properties. Combining different materials is good idea.
- Trunk insulation inside and from the cabin is the easiest and most beneficial. The more material, the better.
- Wheels wells are major source of road noise. Difficult do attenuate.
- The hood’ liner should be replaced with appropriate material
- The better materials are those with metal (aluminum) constraining layer.
- If cost is a concern, omit ceiling and doors – the trunk has the most impact.
- Overall noise reduction can be up to 20 dB, depending on frequency, and 10 db, A-weighted, reduction, can be achieved across full spectrum.

Since read suspension is of dependent type, I expected to find considerably less noise coming from it on new Altima; I tested one as soon as they appeared. To my dismay, the ‘02 Altima is even noisier than ‘02 Maxima. Therefore, I don’t consider it as a factor. I think the major source of (additional, excessive as compared to say, Toyota Campy) noise is the exhaust.

After completing, I noticed that the Bass control on the Bose radio needed to be adjusted about minus 3-5 dB (equals to double-triple the amplifier’s output). This is attributed to the reduced flexing of the rear desk and low-F noise, as it was masking the bass. The overall improvement of sound quality is negligible, however.

About 500 squire feet were used, for the cost of over 1000 USD.

Spectral measurement proved to be crucial.

Overall, I am happy with the work I’ve done and don’t think I could have gotten better result if hired somebody to do it for me. The cost of materials and the labor involved suggest the price would be at least triple for comparable job.

Thanks for reading!

 

Why spend that much money to make the Maxima more quiet? The Maxma is one of the quietest cars I have ever owned..... lol.....Of course, the other automobiles I have owned were junk..... Plymouth Duster, Ford F100, Ford Escort, Chevy S-10....... All of those cars were loud, and they were crap too.... lol

 

Trush me, there are much quietier cars out there. I'm not saying I would spend a thousand bucks to sound proof my car, but there are some areas I would like to be a little quieter.....It's a personal preferance I guess...

 

I can understand that...... Compared to my other cars, my Max is so quiet.... I love being able to hear the stereo over the engine or exhaust...

 

Great writeup! What kind of expanding foam did you use?

 

Gee, I need to hear my engine more!

Search for dynamat at Parts Express for a cheaper alternative.