Ron:
Sorry for the delay in responding but life had kept me off the forums for a few days. When I got back on, I failed to check out the second page of this one... Until now... My bad.
Yes, I was referring to your Lola and I don't know if the same thing happens in an Europa, never having driven to the limits you have. I suppose. after I get mine back on the road, I could try and report back to you, but only if I can find a pair of brown trousers to wear before attempting it on the track... In public.
In regards to your duct question, I'd like to add that the openings on the rear deck are located in an area of low pressure. In my analysis of the design, at speed, with no snorkel, air is extracted from them, not the other way around as one would think they'd work. The underneath portion of the car is also a low pressure area and the engine itself is doing its part to further reduce the amount of air pressure and therefore, drag inside the rear of the car. As pressure drops, the air around the engine stops moving, thermal conduction slows, heat builds up and becomes problematic as Lotus Joe stated. The ducts start things moving again, bringing cool air in, mixing with the hot air, lowering the temperature and once more, making things right with the world.
This is only speculation, but I imagine a good part of the reason ducts aren't on all production Europas is because adding ducts (and side mounted fuel fillers) dramatically increases the complexity and cost of the manufacturing process.
I'm adding ducts to my S2, but discovered early on that if the inner skin is left un-modified, incoming air gets trapped inside the wings and between the body and engine compartment skins. With the exception of a couple of very small openings, it can't exit this space until it passes over the wheel wells. That's pretty much at the rear end of the car.
On the left side, I plan to cut an opening in the interior fiberglass skin directly behind the fuel tank so cool(er) and denser air is directed toward the DHOC carb's air intakes.
On the other side, I've glassed off the small openings between the skins, so all the air coming into the duct moves through the inside of the wing and empties into the large empty space at the rear corner (where the tail light and side marker are located). IMHO this is a perfect place to mount a future oil cooler. Having a forced air duct pre-installed will be a great bonus.
At the risk of becoming totally boring, I'm adding a couple of pictures, one of a Type 47 and one of mine. You can see how the 47's duct dumps directly into the engine bay. Mine continues through to the end of the wing section. It's also larger. It needs the additional area to help compensate for the increased friction of the trip to the rear. I also think it looks better:)
Again, sorry for the slow response. I'd like to add that I'm impressed with your creativity and, a bit disappointed that you couldn't scare anyone out of the unpublished pool. I've only been a member for a month or two and now they cant get me to shut up, so keep trying and keep thinking up more good stuff.
Bruce