I would assume that the inside air has been blocked off so it would work. Of course that does not mean it is so. I did some tests a long time ago on my 77 datsun pickup with ram air, and there is a very small gain from it. I remember it was not enough to register on a a gauge that reads in psi, but it will register on a manometer reading in inchs of water. So less then 1 psi of boost, and of course only at speed. This of course being a na , not turbo application. It should help a turbo the same amount, as the turbo raises the pressure based on what pressure it recieves the air at.

Is it worth doing? I haven't done it to mine, and not going to. Much better ways to add power, without the odd looks.

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1977 240D turbo