maxcooper

New camera. I could still use a lot of help with my composition, but the camera pretty much keeps me from messing up the shot too badly. :}

Hey, I just noticed that I got the camera strap in the second shot.

Perhaps it is mostly a placebo effect, but the car really does seem quieter now.

-Max

DamonB

Sound meters measure dB directly but our brains work otherwise. It's not just loudness of the noise that we notice, it's the quality of the sound itself. Any of the mats will not only lower noise, they will remove much of the ringing and harshness from the steel panel itself. These may not show as huge differences on the meter but your brain will find the improvement in noise reduction to be much greater.

You have to be very careful with sound meter measurements as well. The direction and placement of the mic must be exactly the same every time. How you hold the meter, where your body is in relation to the mic etc can all make errors in the order of a couple dB quite easily.

I have yet to line my roof, spare tire well and shock towers but I'm expecting to be quite happy with the results. One place to line to get rid of much of the noise is going to be around the rear shock towers and fenders. If you've ever driven without the rear strut tower trim caps in place or perhaps with the bins removed you realize how much noise comes through there. The area under the trunk latch is also a large resonant cavity quite close to the exhaust tip. I'm going to try stuffing that area with something.

Big kudos to Max for making this a real test!

maxcooper

Having a roll bar connected to the shock towers seems to transmit a whole lot of noise to the cabin. I'm sure sure yet how much I can do about this, but perhaps some damper material around the bar where it connects to the shock tower will help reduce the noise.

-Max

teeter

maybe fill the tubes with that "expando foam" stuff? then they won't have air in them so they won't resonate/transmit the noise so much?

maxcooper

Excellent idea! It might be a bit difficult for me to get one of the ends open so I can squirt the foam in now, but I will consider that if the car is still to noisy after all the "low hanging fruit" stuff has been done.

-Max

teeter

wouldn't have to be a big hole. just "fix" a LONG lenght of that clear vinyl tubing to the nozzle on the can...stuff it in till it goes from one side of the bar to the other...start squirting...and slowly pull it out...leaving a "full" tube behind.

john

maxcooper

Okay, I had a flat tire and that put a damper on my sound deadening work for a while. I got some Falken Azenis RT-615 tires mounted now (replacing my worn S-03s), and thankfully they seem quieter than the Azenis ST-215s I run on my daily driver. I'll start with a dB test to baseline with the new tires, probably tomorrow night.

I received my B-Quiet Ultimate, Vliner, and Hliner materials today. I also have the parts for my wastegate dumptube-back-into-downpipe mod (which shouldn't make any difference in noise unless I am boosting enough to open the wastegate) and my combination metallic cat / Magnaflow muffler midpipe, too, so I can get those things fabbed up soon.

-Max

maxcooper

Measured the 80 MPH cruise tonight:
81 dBA
100 dBC

About the same as before, which is good. +1dBA, but that isn't too bad. I've replaced a lot of suspension bushings, gotten an alignment, and some new tires (and balancing) as part of my recent efforts and the car feels so much better overall. It still has some rattles and is generally too loud, but I am very happy with the progress, including the sound level/quality changes, even though they haven't shown up much on the dB tests. The car really is more comfortable from a sound perspective. I am hopeful that some significant and measureable results are coming soon with the door insulation, etc.

I think I need to switch spark plugs to get a warm idle test that is comparable to my first test. I have some BR10EIX plugs in there now and it doesn't idle all that smoothly. Some other folks have mentioned similar results with those plugs on their cars, so I'm going to switch back to some B10EGV plugs or BUR9EQPs.

I'm going to try and get started with my new sound materials over the long weekend, too.

-Max

potatochobit

iTrader: (1)

what exhaust set up are you running again maxcooper?

maxcooper

Last night was:
- R85 downpipe (from single turbo kit)
- SR resonated midpipe (thin bullet style muffler, probably doesn't muffle all that much)
- RS*R dual tip cat-back (the one Racing Beat used to sell)

Today I swapped my N-Tech high flow cat back in. But I am having a metallic cat and Magnaflow 5x8" x 14" muffler midpipe made up for it soon.

My boost controller solenoid "starting" duty cycle was set to 49% with the midpipe, and I upped it to 69% after I reinstalled the cat and I could probably go even high without risking spikes. The car still feels fast as hell, but I was surprised how big the difference in solenoid duty cycle was needed. Anything over 50% would spike with the midpipe.

-Max

maxcooper

I put some McMaster-Carr mastic on the licence plate, and a little on the license plate frame to keep it from rattling against the plate. I also found that one of my licence plate lights was smashed and rattling around, so I used some safety wire to "repair" that as best I could. The repair wasn't great, but it doesn't rattle anymore and the light pattern is not all that noticably different from the other one. Good enough. I don't think it changed the sound level in the car at cruising speeds, but I think it eliminated some rattling sounds that were very noticable when revving the engine and standing behind the car. I guess I'll feel better about revving someone on the street now. Hmmm... maybe that was a bad idea.

I also switched the spark plugs from the BR10EIX to B10EGV in the leading positions only, and the idle is much more stable now. I didn't measure the warm idle sound levels again yet, though.

I also removed my worn hoodliner, but I haven't installed the new hoodliner material from B-Quiet yet. I didn't notice any difference in sound level readings at my 80 MPH cruise speed with the hoodliner removed. Maybe +0.5 dB, but nothing major and it didn't seem much different subjectively, either.

I didn't post about it last night, but after resetting the boost controller settings during some 3rd gear 70-to-100 MPH boost runs on the highway, the idle was bouncing very severely. And the vacuum was very low on the down swings. I thought I had popped the engine after swapping the midpipe for the highflow cat and reducing my base fuel pressure from 40psi to 37psi. I figured those two changes would even out, and though the car does run a tad leaner under boost now, it still runs in the high 10's or low 11 AFRs. Rich enough to be safe, though I thought that perhaps the heat from the car or something had conspired to pop the engine. Fortunately, today I went out to see how the car was doing and found the plastic PCV disconnected from its hose. Thank goodness, that was it! I immediately ordered some new track tires and then went for a cruise in my still healthy fun car.

-Max

maxcooper

I added some stuff to the driver's side door last weekend. I put some B-Quiet Ultimate to the inside of the outer door panel, and added some B-Quiet vliner (foam with thick rubber backing) to the lower portion of the inside of the door. I also tightened up a bunch of stuff that it attached to the door skin. I squirted some black silicone sealant between the vertical bar and the outer door sheetmetal to fix the broken attachments points (that were just some kind of goo ijn the first place). Here's a pic:


The door makes a much better thud when you close it now, but the mirror still rattles on close. I am not sure what it rattling in the mirror but I should probably take a look at some point. The door pull feels a lot better since I tightened everything up.

My test procedure of 80MPH cruise on the same stretch of road at night with light traffic got me:
80 dBA
100 dBC

About the same, really, both in the tests and in my subjective road noise evaluation. I was kind of disappointed. Maybe I need to put more sound deadening material in there. I only did one layer and didn't do the reinforcement bar. I did just one patch on the door sheetmetal behind the skin. I guess the improved door close noise is reward enough.

-Max

maxcooper

I had my custom metallic cat and Magnaflow muffler midpipe made up finally. HUGE difference in noise subjectively. And it did great on the meter, too:

My test procedure of 80MPH cruise on the same stretch of road at night with light traffic:
75 dBA
95 dBC

The exhaust drone is gone! The car finally sounds like a normal car, albeit still a bit of a loud one. But it sounds SO much better now. I could take this on a trip.

Read more about the cat+muffler midpipe here:
https://www.rx7club.com/showpost.php...0&postcount=79
https://www.rx7club.com/showpost.php...1&postcount=80
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/working-custom-metallic-substrate-cat-fd-425779/

-Max

7racer

Hey Max,

I was wondering if you could tell if by adding the sound deadening material, that it might make it tight to place the Bose unit back in. *I know you don't have the Bose system

Just wondering if you could hazard a guess.

Thanks!

maxcooper

I don't think it would make any difference. If you mean behind the speaker pod, remember that the window comes down between the back of the pod and the outer sheet metal of the door. I see that other folks used a lot more sound deadening stuff than I did. You can put it (or not put it) anywhere you want.

-Max

r0t0r-rooter

Wassup Max!
If you need any help with all of this, let me or Mild7 know I honestly haven't been keeping up with all of this since I accepted the noise...... If you need a couple extra hands on any Saturday, just let me know.

7racer

thanks max...I meant in the back trunk. Sorry.