09/25/2023
Hello everybody! Yes, it has certainly been a while. But I am back and providing you all with install photo goodies, as well as sound treatment before & after data!
That said, I have recently rented a small shop with the intentions of hosting training classes, and doing installs, but that has also had to be put on pause until an unknown date due to having to get everything back and set up in the new shop. We have a good amount of crazy installs lined up, and those will start as soon as I can, but this vehicle in particular wanted to have something done first that I could do without anything but my hand tools, and something we are the experts of the subject in our industry: Sound Treatment.
My client took delivery of this 2023 Porsche GT3 Touring recently, and immediately noticed how unnecessarily loud it was, but not in the ways you'd expect a naturally aspirated daily-drivable race car from a luxury brand such as Porsche would be. The panel resonance, rattles, and body drone was absolutely through the roof, and was to the point where his wife didn't even want to drive in the car with him. The problems were relayed to me as accurately as possible, and we came up with a game plan to reduce the rattles, drone, and tire/gravel noises that my client described to me. That said, when on the phone, I was almost in disbelief at the level of noise he was claiming, especially considering it is the Touring model. I have driven many Porsche's, including GT3's, but never a 992 GT3, or a GT3 Touring. It just didn't make sense that the car would be THAT loud. Upon drop off and my initial test drive with it, I immediately understood where he was coming from. It was bad. Lets get into the "before" details of what I personally heard.
Doors: The doors were the first thing that stood out to me because as soon a I started the car, the doors started rattling at idle. Very weird, and definitely not something I would expect out of a car like this. The rest showed up while driving. The wind noise through the doors and resonance from the door was drastic. It sounded like a hollow drum, just while driving. The drone and wind noise from it at speeds over 50mph were really bad.
Rear Parcel Shelf/Quarter Panel Area: The rear portion of the vehicle was the worst offender. It seemed as if every bit of the body under the plastic trim panels were having a party. The drone from resonance was insane. You could tell that this wasn't just a loud exhaust causing this noise, but was in fact being caused by resonating panels generating a noise of their own. Once again, this entire area sounded like a hollow drum, but did so at all speeds, even at idle and low RPM's it was obvious. You also heard a ton of tire noise coming from the quarter panel areas, which brings us to our next and final problem area..
Wheel Wells: The wheel wells are usually the largest source of noise in any given vehicle that doesn't have a loud engine/exhaust. While they weren't the loudest source of noise to my ears, they certainly were more offensive in this car than most others. That can be attributed to three things. First, the tires themselves. The tires on a sports car such as this are very hard, and the sound they make slapping on the pavement is much less forgiving than most other tires. Second, is the suspension of the vehicle. A stiffer and sportier suspension will mean the tires are mechanically coupled to the body of the vehicle more so than a vehicle with a "looser" suspension. This means that more energy can be transmitted from the tire into the body of the vehicle, which can then radiate from the body as sound energy. Third, is the overall construction of the wheel wells. The thinner the metal, the weaker the panel, the less sound absorbers and noise barriers they use, etc. all affect how much sound can be transmitted through it, as well as how resonant this part of the vehicle is as a whole. In this car, the rear wheel wells sounded like a damn wind tunnel, which was surprising upon disassembly of this area, as Porsche utilized a healthy dose of sound absorbing material as well as a molded and decoupled noise barrier over the interior wheel well. Apparently, it wasn't nearly enough. The front wheels were also not very forgiving. I would say about 30% of the wheel well is "open" and allowed rocks to be slung into the body of the car, creating very loud "ping" sounds. Rocks also got sent onto the very flimsy wheel liners, and created a very loud "pop" noise. So from the wheel wells, we dealt with wind noise, overwhelming tire noise, resonance, and pings/pops from rocks being thrown up by the aggressive tires.
After discussing the situation with the owner of the vehicle, a plan was formed. I originally proposed a solution that treated the doors, wheel wells, rear interior, as well as the front floor boards and center console area. We decided to skip the front floorboards and center console area since that area would have utilized ResoNix Barrier, and the owner didn't want to add too much weight.
We ended up with the following. Doors received ResoNix CLD Squares, ResoNix Fiber Mat 25, and ResoNix Guardian. The rear interior received ResoNix CLD Squares and ResoNix Fiber Mat 45. The wheel wells and fender liners received ResoNix CLD Squares and ResoNix Fiber Mat 25/45.
For those that are unaware, the ResoNix CLD Squares are the highest performing CLD (Constrained Layer Damper, also known as "sound deadener") product on the market. The function of a Constrained Layer Damper is to reduce resonance in the panel it is adhered to. Constrained Layer Dampers do NOT block or absorb noise, regardless of what other companies say in their marketing material about their constrained layer damper products. How much the end result is contributed by a CLD is very dependent on the vehicle and the panels you are working with. If the car you have has thin sheet metal with no real structure to it and is overall very resonant, then doing just a Constrained Layer Damper will have a very meaningful end result. That said, most noise in a vehicle is not generated from panel resonance. Most of what you hear while driving a car is going to be tire and wind noise. This is where ResoNix Fiber Mat comes in and does the heavy lifting. ResoNix Fiber Mat is the very best automotive sound absorber on the market, and also acts as a panel decoupler to prevent panel-on-panel vibration. ResoNix Fiber Mat is to be used anywhere we can get it in our offending areas in order to absorb sound that passes through to reduce sound transmission from noise that originates outside of the car, as well as generated by the resonating panels that reside behind the Fiber Mat.
Note about Constrained Layer Dampers. They perform best in larger singular pieces. Not a bunch of smaller pieces. They also aren't very useful on panels that aren't resonant. Areas that are structural do not really benefit much from the application of a CLD. Sure, it never hurts, but in an application where we are trying to save weight, such as doing sound treatment in a GT3, we can skip this structural areas without second thought. If you can knock on it with your knuckle and there is no ringing, CLD application to that area won't be as useful compared to an area that does ring.
Note about sound absorbers, such as Fiber Mat. Sound absorbers work by imparting an acoustic impedance to the sound energy that is trying to travel through it, and by the cells or fibers (depending on what the absorber is made of, Fibers are vastly superior for our application) vibrating and moving as sound energy passes over them. This reduces the overall amount of sound energy due to a large portion of it being converted into mechanical and thermal energy. In order for this product to work correctly, those fibers need to be able to move. What I am getting at here, packing in and compressing as much ResoNix Fiber Mat into an area wont work nearly as well as filling an area without compressing it. More is always better when it comes to sound absorbers, but that rule goes out the window the second you start compressing it. Compressing Fiber Mat does have other benefits, such as providing stability to the panel it is pushing against, but for general automotive sound reduction, we want to stay away from this.
Now that we are done with that essay, let's move on to the install!
