OSHA says that noise over 85 dba requires a written hearing protection program.
Well I measured the sound level at 3000 RPM and I was at 87 dba.
Running a 3.2 with Bens headers.

Lots of free dba apps out there at no cost. Usually about +/- 1-2 error rate.
OSHAs hearing protection rules say anything over 90 dba 8 hour TWA requires hearing protection.

Of course these rules don’t apply to us but check out your sound measurements next time you take a drive........

Also know that 90 dba is twice as loud as 85dba.

What do you have on your firewall and is that with the top off or the windows and top up?

RR interior firewall pad with 911 carpet. Engine side pad removed, windows up and top on.
Click to view attachment

#TEAMBOSE

Is your 3.2L running a factory FI?

What exhaust are you running?

sorry I have to ask, who did the stitching on your seat inserts/ cushions and headrest pieces? looks awesome!( and center pieces)

- i'd say if the top is on and windows are up , if you have a sound pad in engine compartment, that's all you can do sort of putting additional padding behind carpet.

-that and your exhaust. is it carbs or injection? I know the muffler/header set up is going to make the biggest difference probably

Interior done by Patrick Motorsports, FI and Bens Headers.
Download a dba app. I think you will find that most of you will have readings in the mid 80s.

Only the wife complains about the noise so who cares.......

I downloaded an app... peaked at 100db at full accelleration
Cruising was mid 80s
Windows up and top on (it's 20*F here!)

No rear pad on interior or engine bay.
2056 with dual Webers
No radio

The factory engine bay sound deadening pad is heavy and can promote rust if the car is left to the elements, but it reduces noise big time. My 914/6 conversion I added a big firewall hatch and I cut and modified the OE pads in and out to fit tighter to the firewall.
I have webers, headers and a used old banana, but at cruise speeds you can carry on a normal conversation with a passenger.

I know many say leave the pad out because it can rust behind the pad, honestly my 914 is never left outside and is only driven on nice days, so that makes the rust argument moot.




My bug has a T4 914 based big bore with loud exhaust and nothing on the firewall just dynamat on the interior. It's so freaking loud in the car you have to shout at the passenger. Long trips I have to wear earplugs. The next time the engine comes out I'm going to add a firewall noise pad.

To confirm - no engine bay pad like Mark showed, correct?

Sorry for the confusion. Yes engine bay pad on interior only.

Is it engine noise or muffler or both? What muffler do you have? I installed bens quiet muffler and it made a big diference. No drone, I can here the stereo now and talk to a passenger. However I noticed the 3.2 with injection is louder than my 2.7 was with webers.

No engine pad here on my 1971 with stock D-Jet.

My biggest noise problem is the passenger screaming: " slow down in the corners!".

The engine firewall pad is a MUST, I just recently fixed mine as it was starting to fall in some places.

Engine noise and it sure sounds awesome.

After having my ears ring after some long drives, I resorted to ear plugs. No more ring and feel a bit less tired on long drives.

I put insulation on the solid part of the engine cover too.

PPE is the only solution

Bose
https://www.amazon.com/Mpow-Active-Noise-Ca...=dp_ob_title_ce


Domio Noise Cancelling Earplugs
https://domiosports.com/products/earplugs?v...BCABEgKNTvD_BwE


Howard Leight by Honeywell Impact Sport Sound Amplification Electronic Shooting Earmuff,
https://www.amazon.com/Howard-Leight-Honeyw...HHNH2334FEDMC7A

I know from experience that the type of air filter/cleaner setup impacts the interior sound a ton, particularly on a -6. On the extreme side there's the foam type filters like ITG, stock airbox and paper filter on the quieter side. Currently I've got Webers with flat-top K&Ns and zero sound insulation. My car is so loud even with the Dansk 1-out street muffler that I typically wear my custom earplugs when not in my helmet which has ear protection built-in.

If it's too loud, you're too old . . . as the saying goes.

I dunno about too loud too old.
I do know I'm only 44 and have lost a good bit of my hearing. I'd like to try and keep whats left.

My cabin got a LOT quieter after I replaced my GT lid with a stock engine lid and rain tray, and also installed the 914rubber engine side sound pad.

You can have a conversation in the car now without shouting. Unfortunately it means I also hear all the other squeaks and rattles in the cabin that I never was able to hear before.

Zach

What? I can't hear you!

Seriously I'm in the same boat w.r.t. hearing loss. Too many years around jet engines, guns, race cars, inside manufacturing plants, loud stereo's, etc.

However, I think we get lost in trying to compare these cars to modern cars. They will never be as quiet nor should they be. The sound of the car and an air cooled engine is part of what the experience is about.

IMHO if you want to have a quiet conversation, get a modern 911 or an even quieter a Buick!

On a more serious note if you want sound attenuation here is what can be done:

Switch from Leather / Vinyl seats to cloth. You want the accoustic absorption of the cloth.

Switch to thicker carpet pile.
Put shoddy under your floor carpets if you don't want thicker pile.

Put foam or shoddy on ther underside of the dash (on the bare sheetmetal)

Air leakage = sound leakage
Seal any stray holes in the dash and/or rear bulkhead
Make sure your window seals and Targa seals are in good shape and sealing

Put shoddy behind the rear back pad & make sure you have the engine side sound deadner in place too.

Put some sort of headliner (soft, fuzzy, acoustic material) on the underside of the targa.

You could also inset the door panels with cloth / Alcantera materials.

Question is - how much are you willing to do? Even if you did all the suggestions above, it still will never be as quiet as a Lexus for a multitude of reasons.

BWAHAHAHAHAHAhahahahahahahaha.......... You too?

Brand new build..needs a redo? What?
$20
https://www.earplugstore.com/boxes-of-dispo...m-earplugs.html
$400
https://www.bose.com/en_us/products/headpho...s_700_soapstone

I went from individual K&N filters back to stock plastic air cleaner,noticed a reduction in noise and the advantage of better filtration and ease of tuning the carbs.
I did spend some time fixing the backfire damage on one side of the aircleaner due to blocked pump nozzles and one broken (leaking) air bleed screw.
I'am still running the stock firewall insulation and have added some sound deadening behind the backpad...not too bad until you hit 3K + rpm then it gets a little loud.

Thought I would ring in on this. I am in the midst of cleaning the engine bay, have sandblasted and repainted.

I installed FatMat brand sound insulation, on the firewall, pretty simple.

Then I covered the engine side of the sound mat, with another layer of it. As an aside, when I scrubbed the sound mat, I was surprised to find that it was green, every 914 I have had, this is my third, the mat appeared to be black, probably do to it being filthy.

When I went to put the insulation on the sound mat, I could not get it to adhere, so I used contact cement on it.

Then screwed the mat to the firewall, which I was hesitant to do, but the original pins did not want to hold it in place.

Hopefully this will tone down some of the engine noise, but who cares, if you really don't want to hear it or want to listen to music, wear ear buds.

Also, when I get around to doing the interior, this summer, I am going to do the same thing to the cabin side of the firewall, in addition to doing the floor, before installing new carpet.

Have a nice day