[Jonny042]

Hello all,

I have been chasing interior noise reduction in my car for the last two driving seasons - really my car has been quite painful to drive, requiring earplugs for trips of any duration on the highway.

I have posted a few "is this normal?" kind of threads, and really, I have wondered, over and over, how on earth Porsche could ever have sold a car that was this noisy. Most of the problem comes from the rear,engine noise. So I've really been working away on it lately, stripped the interior down to nothing in the rear, and performed the following:

- stripped off all the original yellow glue (using lacquer thinner mostly)
- added 3 heavy coats of "quietcar" sound deadener
- dynamat (approx 30-40% coverage, more on back shelf)
- closed cell foam lining side and rear panels
- mlv (mass loaded vinyl) sound blocker, 2 layers, to replace old sound blanket
- retained old sound pad on rear seat area (seems like a good design and should be effective, hard to do better!)
- re-installed everything else including carpet, and rear seats (which I have found do help with noise a bit when they are up).

I've been careful to weigh all of my materials and I have added less than 10 pounds to the car overall.

I was pleased with the results, and as I was driving on surface streets to get to the highway I was thinking it made a big difference, and it did, but once back on the highway, same old story, a funny whiny resonance from 2800-3000rpm coupled with an overly boomy sound from the intake/exhaust, still bad enough to give you a dull headache after an hour or so, and loud enough to make conversation difficult and make my Mcintosh stereo completely useless. Still all this sound reduction stuff does work and my car feels great, the door close with a wonderful solid sound, and I can barely hear the G50 whine anymore.

So I was pretty frustrated with all this hard work getting me small improvements but still not meeting my objective - to be able to take a nice relaxing road trip with my Gal, sans ear protection. I maintain that it should be possible to do that in a "high-end" sprts car, even if it's from 1987. It's one of the reasons I bought the car!!

A few weeks ago as I was scouring the board for ideas and found someone stating that new engine mounts had quietened a noise from their engine, so I ordered brand new, genuine porsche engine mounts to replace the URO parts mounts that I replaced my originals with last spring (this part of a "while I'm in there" engine out blitz while replacing the clutch).

So, tonight, as a last ditch attempt I had two things planned, first, replace the mounts, and if that didn't work, put the stock cat back on in place of my M&K Euro pre-muff. Changing the mounts is a 15 minute job at most, and I could hardly believe my ears when I went out to test it.... like a NEW CAR. Really. That big of a difference.

When I compared the new mount to the old one, the old one had sagged and deformed to the point that the protrusion of the rubber at the top was less than half that of the new one. It is possible that I had over-torqued the old mounts when I installed them and that caused the engine support bar to wind up and tighten the mount but I think, plain and simple, the genuine mounts are that much more supple and soft. No ill effects, either, it's not like the motor is bouncing around to much or anything.

I'm really VERY happy. I was actually checking prices on 993's thinking I might have to upgrade/downgrade to one just to get a car that I could actually USE!!