FWIW - my tips on installing engine sound mat

[markmalin]

Hi all,

This weekend I installed an engine sound mat on my '85 Carrera. It went quite well and wasn't all that difficult, so I wanted to share a brief narrative and add a couple tips. I did this with the engine in place (no drop or partial drop).

On my car the AC compressor is not present and the previous owner had removed the heater fan and plumbing, so that made it all the easier. What I did was remove the air box and Air Flow Meter to get better access. I stuffed a rag in the intake hose leading to the throttle to keep gunk out of there. The previous owner had completely removed the old mat, though all the glue was still there. I decided that because I was using a spray-on adhesive, it was pointless to remove all the old glue and then just spray the stuff back on, so I left the old stuff in place.

After removing the air box I removed the deck lid "shock" and propped up the lid with a piece of wood. Next I did a "dry fit" to see how this thing was going to line up. Seemed pretty straight forward so I decided to go for it.

Tip one: Wurth's Trim Adhesive. Seems like a lot of people use a tube of trim adhesive, but I bought a can of Wurth and it made it quite easy. This stuff sprays out in a "flat" pattern which produces a line about 3" long. This makes it very easy to not over spray. I covered the engine with an old sheet and sprayed the Wurth adhesive on the fire wall. Again, very controlled so it was very easy to spray it where I wanted it, and not get it where I didn't want it! After spraying the engine bay, I laid the mat out (spungy side up) on a piece of plastic and sprayed it with adhesive.

Tip two: Get the top lined up first. The Wurth is tacky right away and I was worried about the mat sticking in there wrong while I was sliding it in behind the engine and then not being able to get it out to re-adjust it. Turns out I was able to slide it into place and get the upper part stuck down, then any lower parts of the mat that stuck to the fire wall or bunched up (i.e. mat stuck together) I was able to pull apart and re-align. After it was all lined up the way I wanted it was just a matter of pressing it firmly into place. This was the most stressful part, but if you are down on your hands and knees you can get both arms in there. The good thing about the Wurth adhesive is that you can still pull parts of the matt off and stick it back down.

That's it! I just made sure every part of the mat was pressed firmly into place and it was done. There was one part where I didn't get any glue, but I was able to peel back the mat and spray the adhesive in there, press it back into place and it stuck just fine. The fact that the nozzle of the Wurth adhesive is so directional and accurate helps out a lot!

In the end I think the most difficult part is getting the mat lined up down behind the engine because when the mat contacts the firewall, it really wants to stay put! So you have to be careful and think it through and need to pull it back off in places to re-align.

Edit: Just FYI I drove the car 2 days later and peeked in the engine compartment. There were a couple spots where the mat had sagged. I pressed it back into place and it stuck nicely. If it were to sag anywhere it would have been because I didn't get enough adhesive there. What I would do in that case is squirt a little of that 3M Trim Adhesive back there (the stuff that comes in the tube).

Here are some pic's of the mat all in place:

[Swoboda]

What mat did you get/use?

Thanks for a great write-up and pictures.

[markmalin]

I bought this one from Auto Atlanta:

Porsche R91155689101 Genuine Engine Compartment Insulation - 1 required per car.

It was $69.28 and the Wurth Spray Adhesive was $16.84.

Mark.

[Canada Kev]

So, the most important thing: Results!! How does it work? Big difference, no difference, super duper quieter...

[markmalin]

Originally Posted by syzygy

So, the most important thing: Results!! How does it work? Big difference, no difference, super duper quieter...

Because of the blasted, miserable, rainy spring weather in Wisconsin (have I mentioned the that I'm frustrated with the rain this spring?) I haven't been able to drive it Tomorrow, though, they're predicting sun so I'm going to take it to work. I'll post the results. To be honest, I don't know whether I'll be able to tell much difference, but we'll see. I did drive it across town (at 55mph) after the install and was able to hear the radio, which seemed better than before but don't have any hard evidence.

[Canada Kev]

I hear ya, though no pun intended. It's raining rather steadily here, too, but we need it. It was so dry and with some very high winds last week, a grass/forest fire destroyed over half of a small town a couple hours drive away. They had to evacuate almost ten thousand people - some with just the clothes on their backs. Kinda makes the rain a bit more bearable, eh?

[markmalin]

I know. I shouldn't complain. The "driving season" here is so short, though. I get my cars out mid April and drive them until mid November if I can. But if it's rainy and cold it's no fun. But yes, a little rain is much better than having my town burnt to the ground!

Seriously - after 50 winters in Wisconsin I am ready for a change. We're trying to find a job down in Arizona...but that's another story I keep looking on my iPhone at the forecast in Tucson and Flagstaff and comparing it to WI. All that sun...it's hard to fathom. And they can actually drive their "summer cars" all year round! But I digress...

[jorijori]

Subscribed and thank you. One question, how heavy is the matt? Mine is crumbling too.

[RoninLB]

an addition is removing the cabin back seat bulkhead panel and installing some Dynamat


[Everyone should give Pelican 1st shot for parts]

[tobluforu]

Originally Posted by jorijori

Subscribed and thank you. One question, how heavy is the matt? Mine is crumbling too.

Just installed one on my 72 and I think there are two versions, but the one I bought is super light, non-aluminum version.

[markmalin]

Originally Posted by jorijori

Subscribed and thank you. One question, how heavy is the matt? Mine is crumbling too.

The mat is super light weight. Like lighter than a piece of cardboard that size. No metal, just a shiny black "outer skin" on the foam on the side toward the engine.

[markmalin]

Originally Posted by RoninLB

an addition is removing the cabin back seat bulkhead panel and installing some Dynamat

[Everyone should give Pelican 1st shot for parts]

How did that work out with the Dynamat? I'm considering getting some, maybe for the floor and then possibly adding some on the back like you did.

Also, do you have a good source for it? It seems really expensive IMHO.

Mark.

[markmalin]

Drove the car in this morning (about 30 miles). Yes, it is quieter. I think what I notice the most is that at 60 MPH at 2500 RPM's you hear this pleasant "humm" from the engine, road noise and wind noise. It's not dominated by engine noise. I can actually turn on my radio and hear it at highway speeds. It's totally perception, but the car feels more solid to me now (I know, I know, very subjective...but I get that impression now). When you stomp on the gas it still sounds like a 911, though! Up around 4000 - 6000 RPM's you still hear all that great engine noise. But at 2500 rolling down the country highways it's pleasantly quiet.

Your mileage may vary. This is certainly not scientific!

Mark.

[911FASCINATION]

Hi Mark-Thanks for posting this-not to get off subject, but without any mat at all, was it just ridiculously loud to drive? My 84 has the original mat, sagging a bit of course, and I'd like to just remove it and clean up/paint the firewall. I love the motor sound as is, I never use the stereo anyway, and I thought it may help my baby to run even cooler.

[markmalin]

Originally Posted by 911FASCINATION

...Hi Mark-Thanks for posting this-not to get off subject, but without any mat at all, was it just ridiculously loud to drive?....

Oh, absolutely not! Honestly, I think going from having a mat to removing it you aren't going to notice a whole lot of difference. It will be louder, but not substantially.

In my case I started with headers, dual inlet/outlet exhaust, no cats and no sound mat. I swapped the OEM exhaust back on and THAT was a substantial change! Adding the sound mat just quieted it down a little more.

If you imagine "Mark's Loudness Scale" from 1 - 100, where 1 is where I started out (no mat and headers) and 100 is stock, putting the OEM exhaust on but no mat brought me about 90% of the way. Adding the mat was the final 10%. (I hope that made sense to someone else besides me...)

[RoninLB]

Originally Posted by markmalin

How did that work out with the Dynamat? I'm considering getting some, maybe for the floor and then possibly adding some on the back like you did.

Also, do you have a good source for it? It seems really expensive IMHO.

Mark.

I was after getting rid of the high frequency tin can sound from road noise and engine

I also did floor and doors

I still hear a loud exhaust but it's a cleaner sound. There is also a mat called "Brown Bread" that should be cheaper and tests similar to the high model of the Dynamat line but without the foil

there is plenty of other recomendations for this in the archives. Search Dynamat