Insulation Overkill?

I am working to make my SPF a little more livable in the summer by cutting down on the heat and a bit of the noise. Yes, I recognize this will add weight, I am okay with that. That said, I am now concerned I may have gone overboard... I have now:
- Koolmat
- Second Skin Damplifier Pro
- Second Skin Luxury Liner Pro
- New Carpet

I already torn out the old carpet torn and striped the interior so I am about ready for install. My worry is, will I overdo it for no good reason. The car is obviously warm in the summer and while it is not painful, at freeway speeds there is some drone. Koolmat claims 28db reduction in noise, if I put koolmat on the firewall overlaid with damplifier pro and finally the LLP with carpet on top, might that be overkill? I was going to do damplifier pro and LLP on the floors under the seats as well.

For those that only race, I know the answer is yes, it is overkill. Other thoughts?


Jim Craik

Lifetime Supporter

I'm assuming that Koolmat is similar to Dynamat, as a sound reducer. That said, what you are doing sounds like will be just fine.

But remember most of the sound and a lot of the heat comes from the firewall window and the tunnel between the seats.

By far the best addition I made was the 3/4' lexan window kit, that made a huge differance.

Also when it was up on a lift, I used that spray, foam insulation and filled as much of the center tunnel as possable. Before I did that, hot air was comming out of the hand break area, after, the foam...nothing!
Thanks Jim,

I should have mentioned that I have the upgraded window and have filled the tunnel with closed cell foam. I have also closed up all the other holes in the firewall with closed cell foam which should also cut down on the heat transfer.

Regarding Koolmat, it is more of a heat shield but apparently has some sound deadening qualities to it. I purchased it primarily to reduce the heat coming through and around the engine cover and at the base of the seats, right now I have permanent seat heater.


Jim Craik

Lifetime Supporter

It sounds like you have a good handel on it.

Dynamat is something of a two edged cure. It works very well as a sound reducer, but it is heavy.

As I understand, it is a very thin sheet of lead, with one side a shiny reflective cover and a stickey backing on the other.

Lead works well for sound deadening as it is very dense, but then it is heavy, as it is very dense.

Weigh was not at the top of my list of concerns as I only use mine as a street car.

Perhaps, others may know of a solution that does not require adding lead to a race car:)

Jim Craik

Lifetime Supporter

You learn something every day, as I recall the person I bought from said it was lead.

So what do you think it is. Its certainly heavy, and bends like lead. But lead is toxic, so that makes sense too.
My Pantera is, by far, the most comfortable Pantera I've ever been in. I took great pains to insulate the cabin for both noise and heat. Every metal surface (except for the underside of the roof) got a single layer of Dynamat--floors, sills, center tunnel, firewall, the inside of the door frames, and the inside of the front fenderwells. I also used some simple JC Whitney jute-like insulation blanket (which has a layer of mylar on one side) against the firewall and the center tunnel.

The difference was like night and day. Expensive, but worth it IMHO. You might get similar results with a product that costs much less--or you might not. Dynamat is a known quantity.

It's sold on Amazon for less than half what Summit gets for it, by the way. It makes it almost reasonable.
Not sure if its been mentioned yet but ALOT of heat radiates through the windshield/side windows. If you can get away with it tinting would probably help a bit.

Robert S.

GT40s Supporter

By far the best addition I made was the 3/4" lexan window kit, that made a huge difference.
Jim, is the 3/4" thermo plastic window kit one solid sheet 3/4" thick, or is it insulated glazing, AKA double glazing, i.e., two 1/4" thick sheets with 1/4" space between them? This method, I have come to understand, results in a higher R-value because dead air space is more effective for noise abatement too, since the air space disrupts the transfer of sound (conductance) through a solid object.
Additional thoughts: For maximum sound mitigation, a large air space improves the noise insulation quality or sound transmission class. Asymmetric double glazing, using different thicknesses of sheets rather than the conventional symmetrical system (equal glass thicknesses used for both sheets) will improve the acoustic attenuation properties of the IGU (Insulated glass unit). Conclusion: double glazing is exponentially more effective for both insulation and noise reduction than a single solid sheet even when it's the same overall thickness. Triple glazing with two air spaces is exponentially more effective than double glazing. Granted, such multi-sheet units must be sealed on the edge side using either polysulphide, silicone sealant or similar material, and contain desiccant to remove moisture between sheets.
Also, if you could post or PM me with contact info for such kit, I would appreciate it. Thanks, Robert

Ian Anderson

Lifetime Supporter
I remember whe going through this with my car and a lot of the manufacturers of the products say to fit the material on the engine side of the firewall. Most of these had a shiny surface to reflect the hear back away from the firewall. Fitting it on the cabin side will work but to a much lesser extent.



Lifetime Supporter
For any of you SPF owners I have new firewall panel that Olthoff made for me when he built my car. It is insulated and mounts over the oem unit addind additional insulation to keep engine heat and noise out of the cabin. It is made of aluminum to be light and is covered in leather and is quite nice. I never installed it and after driving mine a little last fall before putting it up for winter decided I didn't mind the noise and heat levels in the cabin. If anyone is interested in it, shoot me a PM.

Chet Schwer

Lifetime Supporter
I installed a glass rear bulkhead window and filled the rear of the center tunnel with removable closed cell foam to help the noise and heat. Other than taking out the side windows, I don't see much else that can be done except maybe a A/C upgrade/overhall. I don't think the cabin noise is bad at all and most of my trouble with the heat is only when the sun is coming thru the windows. I'm still trying to figure out a way to keep water out of the cabin. You know it is a race car when you ass gets wet and water drains out of the car for a day after a rain!
I find this an interesting read. It really does come down to different strokes for different folks. My CAV is IMO well insulated and has the glass bulkhead window but I find the noise intrusion part of the, dare I say, "charm" of the car. As for heat intrusion...not so charming especially here in Florida.