[Fluffy]

Hi,

On the internet you can see many things, sometimes opposite, when it comes to sound and heat insulation.

Anyway after some researching I decided to insulate my 2008 C6 for several reasons. The primary initial motivation was the heat insulation of the trunk that gets very hot due to the exhausts just under the trunk.

The secondary reason was noise reduction especially external noise reduction, the reason being that the in Europe noise regulations are more stringent than in the USA. The Corvette is, based on my understanding, at least 3dB above the legal limit.
Although it will be relatively easy to reprogram the engine so that it is a dog, tire noise and body resonance is an issue to deal with.

You can read more on the Euro regulations here

My initial stab consisted in only installing some foam surrounded by aluminium and the final result, whilst being satisfactory from a heat perspective, was not from a sound reduction stand point. Examples of such products are those sold by small vendors such as MadVette.

When it comes to noise reduction there are two aspects that need to be addressed: sound absorption and resonance attenuation (dampening).

Any object subject to vibration, such as an inner plastic panel, resonates and generates noise. The only way to reduce the noise generated by a plastic panel, or something else, is to increase the weight/density of the object. This is a sometimes referred to as a vibration damper.

Installing a sound dampener product is one of the components when it comes to reducing noise, but not sufficient by itself.

In my case, I decided to install DynaMat, rather expensive, after some internet searching. The main driver for the choice was the odour and the reported quality of the product. I purchased in bulk from Amazon sheets of Dynamat Xtreme for the sound dampening.

For sound absorption you need a sort of foam, I have tried several products and tested them individually. The only product that is satisfactory and worth the investment from my experience is Dynamat Hoodliner.

For the heat from the exhaust, I also purchased a

that you can stick outside above the exhaust.

An Important Note:

Please bear in mind that you are adding additional components to the car. This will increase the weight of the vehicle and the carpet will have difficulty fitting back in. It will fit but it will be different.

Note: it appears that people have been experiencing issues with MadVette. This doesn't impact the contents of this DIY because there are many vendors who provide such products.
In general do your due diligence before buying, the important part is how to do it, not what products :thumbsup:

 

[Fluffy]

Reducing noise in the trunk

Removing the inner trim is relatively easy and straight forward, just be patient and move slowly when in doubt so as to not break anything.

I started with the rear of the Corvette by removing the carpet, cleaning the carpet and then applying the dynamat product:

In order to apply correctly the dynamat product, I purchased the

. It is very important to ensure perfect adhesion, any bubble that appears during the application most be removed. Air bubbles render the sound dampening ineffective.

There is some sound dampening that is installed from the factory which I removed. It is not installed in quantity, in fact there is very little.

So I removed everything and covered the whole panel:

In every nook and cranny of the car:

Over the installation of the dynamat sound dampening, I installed the MadVette type product:

However, as the MadVette foam does not take form over the trunk I filled the cavities with the hoodliner product:

And taped closed with aluminium tape to ensure continued heat insulation and leave no gaps for the heat to go through.

 

[Fluffy]

Reducing outside noise generated by the tires

In order to reduce the amount noise generated by the tires of the Corvette, I also put sound damping and absorbers on the outside of the vette.

In order to this, it is necessary to jack the vette, remove the wheels and the inner wheel liner.

There is some existing sound dampening product that installed from the factory that I removed. I did not keep the existing sound damper for various reasons, the first and foremost is that is slapped on and not correctly applied against the support.

This can be seen in the photo hereafter because the glue that holds the damper to the wall is not everywhere:

The acual sound damper that was applied to this wall is in fact a rectangle, but looking at the mark left behind, it looks more like an arrow.

Anyway, I put dynamat here:

And also on the top side, and in general where ever panels can vibrate:

According to the various websites that I have browsed, and in particular the Dynamat website, in order to reduce vibration of a given panel, you need to cover at least 25% of the surface with a heavy product.
If you want to create a sound barrier, you need to apply Dynamat xtreme (or equivalent) to the entire surface and then cover it with a sound absorbent material.

In the trunk of the car I covered the entire section whereas on all the other various panels, I tried my best to cover a third of the panel.

I also glued a sound dampener and absorber on the outside panels. However, care should be taken to not put it everywhere, otherwise you will not be able to put the panel back in.

 

[Fluffy]

I also insulated the cabin area, first removing the seats and the carpet, as explained in the US to EURO conversion post

Before glueing or taping everything into place, I did a mock up to ensure that all parts would fit in comfortably:

In the cabin area, due to the tight fit, I only installed the sound dampener (Dynamat xtreme in my case) and the MadVette insulation. I did not put a sound absorber because it would move the carpet too much.

Great care must be taken around the bolts that hold the seats, leave some space so that the seat clamps down nicely to the chassis.

As you can see in the picture hereafter I did not put anything in the area where the seat is attached:

I did put some sound dampening and absorbing product in the panels around the door sill as shown hereafter:

 

[Fluffy]

I also put sound insulation in the cavities around the speakers, however care must taken to not isolate the speaker itself.

In order for the speaker to function correctly, air must be able to flow around freely:

Do not obstruct the seatbelt in any form or manner!

 

[Fluffy]

Front fender insulation

As the front fenders are quite hollow and the engine is rather noisy, I put insulation on the fenders themselves and on the structure beneath.

I also put some hoodliner under the actual Corvette hoodliner, care must be taken because in some the hoodliner actually touches the hood.

Fender first layer:

Fender second layer:

The inner structure has vibration dampeners

And it has sound absorbent material - I changed the material because I some foam with better acoustical qualities:

I also covered the removable inner wheel wells, except for the bottom part because water stagnates there:

It is important to take note of available spacing between parts so that you can mount the parts together after having installed the insulation.