Thermal insulation on underside of tunnel on a Cobra

[xb-60]

Got a question about thermal insulation....

I've seen it commented several times over the years that thermal insulation is really only required in the area of the footboxes. Any comments to the contrary?
More specifically - do the sides and the top of the tunnel really need thermal insulation on the underside?

Cheers!
Glen

[deano59]

i would imagine in our cars glen with all the alloy construction the big flat alloy floor and trans tunnel the more we insulate the cooler our cars would be inside . i think with nothing or little there the cabin would become one great big heat sink.

i used all of what pace supplied and then bought a box of more insulation to cover as much as i can .
cheers dean

[RockBit]

I covered the underside of the aluminum tunnel (sides and top) with foil backed insulation called EZ Cool, attaching it with contact cement.

Even with that, the tunnel surface stays warm. A lot of the engine heat is moving through the tunnel.

[letsboogie351]

I used a ceramic coating inside the cockpit and covered the floor, foot boxes and, tranny tunnel. I then used a thermal barrier (cool Tech - similar to Ezi cool) over the ceramic coating. It reduced the heat considerably. Prior to this in summer in stop start traffic there was a lot of heat soak into the metal foot boxes and trans tunnel.
I agree with Deano's comment "the more we insulate the cooler our cars would be inside "

Doug

[kyleb]

You won’t regret spending the time to insulate those areas Glen.

[xb-60]

Thanks for the comments.

I eventually found the thread regarding insulation of the footboxes....
Where to insulate?

Cheers,
Glen

[Modena]

Be aware that this is very car dependent, including such factors of type of fibreglass, thickness of fibreglass, where the exhaust routes, and a myriad of other factors. Personally I have cats under-bonnet, side pipes, and aluminium heat shields which are 10mm spaced off the foot boxes. the CR body is a polyester quad-mat fibreglass, and no other insulation, and I have no heat problems.

[xb-60]

Thanks Ben. Yes, I agree with your comments; it’s very much according to the mechanical characteristics of the individual car. It is, however, an advantage to establish how big the ballpark is if you’ve not done this (build a Cobra replica) before.

Mistakes can be expensive in terms of $ and time taken backtracking and correcting “issues”. I’m always aware that what appears to be a straightforward task can easily blow out (again, in $ and time), so if there are things that I can do “easily enough” later if I find that they actually are necessary, I’ll leave it to later.

My motive power is an SBF with a Toploader behind it, so even though in basic terms, that amounts to quite a significant amount of hot cast iron, it is quite a lot smaller in terms of physical size and power (and therefore potential energy in the form of heat) than a 7 litre engine.

Hopefully, I'll beat the heat !

Cheers,
Glen

[Jaydee]

I have used the 20mm black flexible foam they use to make fridge insulation from Acroll Inns. On top of the tunnel under the carpet. And not a bit of heat gets through that. JD

[Rob. Smith]

I used Lizard Skin along the tunnel and across the foot boxes. ( it's a spray on coating) It keeps the heat to a "warm" temp. The front of the foot boxes have a spaced aluminium heat shield with that woven heat cloth stuff (looks like fibreglass cloth but is thicker) as they are close to the headers. I can drive barefoot in summer without any discomfort .