Has anyone added insulation under the carpets?

Chris,
I just finished putting Dynamat underneath the entire interior of my 328 as well as Dynaliner in areas where it would fit. I've used this on a '59 Vette, '63 230 SL, '69 Fairlady Z, and have been very happy with it. Dynamat makes kits for some cars (like the '59 Vette) but not our 308/320. Still, you can do a great job with the standard items, perhaps even better as you can cut exactly for your car. I'm putting the console in right now so can't give you a for sure, but the carpet fit well and I think it will be a great addition. Got mine through Crutchfield's and they are the same price as Amazon, but are happy to help in any way. Mike

 

Also check to see if you have the foam seals on the hood. They'll help some of the warm air from coming right into the cabin. I didn't put anything on my floors when I redid my interior.

 

Since this is about heat/thermal control and not sound insulation (Dynamat, etc.)

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Paul installed both Dynamat and Dynaliner in my Boxer when replacing the carpet. Good sound deadener, not the best for heat though. I remember a thread where someone took Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login temperature readings in the cabin trying to determine the source of the heat. I seem to recall somewhere in the footwell or under the dash as the leading contributor.

 

TBH, I have never noticed much heat coming into the cockpit from the floor area/coolant pipes but am thinking...wouldn't it be more effective to insulate the pipes rather than the floor? I have no idea of the actual physics/heat transfer involved - just wondering.

 

Its fairly easy to survey the interior using an inexpensive digital infrared thermometer. You might use one to see if you have a problem somewhere.

Most of us find that the predominance of engine heat is radiated through the front bulkhead. The dashboard gets remarkably hot. The central tunnel contributes but does not dominate.

In the sun, huge amounts of solar heat enter through the uninsulated roof and through the glass.

I put Dynamat on my floor and tunnel. I don’t think it insulates against heat very much; just sound, which it is what it was designed for.

There is that “space shuttle heat shield” insulation that is now available in thin sheets. That might be the best insulation for the tunnel (and rear firewall).

 

Thanks! Good info. By the way, Dynaliner is for heat shielding. You are correct about Dynamat being mainly for sound, hence, why we use both. Happy 4th!

 

I used double sided insulation from aircraftspruce on the tunnel. Looked at insulating pipes themselves but not enough clearance and too many jagged edges.

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I installed Dynamat in my interior to deaden the sound. I also put Reflectix double bubble insulation (bubble wrap with silver foil on both sides) over the metal tunnel of the floor. I then put the Reflectix on the inside of the console tunnel.

That gives 3 layers of material to prevent the heat from transferring from pipes to interior. This worked extremely well.

Also insulating the front bulkhead where the pedals are is important as is proper foam insulation around all 4 sides of the radiator and on the hood.



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Right. I put neoprene rubber insulation on the trunk side of the dashboard firewall to stop warm air leaking in. And reflective insulation behind radiator cavity.


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I wrapped my coolant pipes with exhaust wrap, replaced the foam around the radiator, ceramic coated my headers, replaced the AC compressor, and have no cats. The center tunnel definitely feels cooler than before, but the new compressor is the most notable difference. And the car is actually comfortable into the 90’s. It’s been said before here, the front windshield is the most notable source of heat. I’m thinking about a clear tint on the front windshield to block UV rays.


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I’ve added NVX to my 85 308. it’s a decent solution for vibration and temperature.
add a light tint or IR shield to the windscreen inside and you have a nice reduction in cabin temperature so you can run AC on level 2 not 4.

All done without removing the seats.
When I get the carpets done I’ll insulate behind the seats also.

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NVX? An applied black topcoat that deflects heat? Can you give us any more information on this? Thanks!

 

It looks like sound deadening?

I put dynamat for sound and whatever they call their foam for heat....neither the temp of volume of the cabin changed in a noticeable way so both will be removed the next time the carpet is replaced. I hunted the heat issue for years and just recently found holes/splits in the heater air hose....hopefully that's it but for sure dynamat was not the solution.

 

Good to know, thanks! I currently have the interior out of my QV And thought now would be a good time as any if I was going to do this. Think I’ll let it slide . Was Curious about the black coating (Black absorbs heat where light colors reflect heat) Haven’t ever heard of a paintable topcoat that would have any noticeable improvement in heat deflection in a cabin.. but what do I know.

 

It’s not just for heat insulation but it also act as sound deadening.

 

If I was going to do this, i would look at removing the bottom belly pan and installing appropriate material on the underside of the floor, and as much firewall/bulkhead as i could reach.

Doug

 

its like dynamat and dropped the temp in the car enough that on a sunny summer day I can run the AC on 2. Also have the windshield tinted with 5% to reduce IR heat transfer.

 

Is this heat issue more in the 308 than in the 328 ? Or it’s also an issue in the 328?


I just bought a 328 but won’t receive it until 3-4 weeks more

 

I got my 308qv cold with a/c by blocking all the vents at the firewall from the front blower motors as all they do is pump in hot air from the radiator. Also I made sure the foam around the centre 3 vents on dash was sealed so no cold a/c was wasted going under the dash . The a/c is like its always on recirculate. I have insultaion similar to dynamat but it made little difference in my case

 

Don't forget the cooling tubes running under the console! Also, as I did on my GTB, you might try 3M Crystalline window tint. I tinted ALL my windows including the windshield and it make a big difference.
It's not a dark tint but almost clear with a slight blue hue. It blocks almost 90% of UV and that's where the heat comes from. Really a good investment.

PS, I'm in FL and it's hot down here...