put a snorkel on top of it to direct air onto the the IC in the ‘blue’ position. You could integrate a fan under the IC to provide airflow when stopped to minimize heat soak that is pulling air from well outside the engine compartment.
Last night I did a quick mock-up of my intended IC location. Basically mounted flat (horizontal) in the 'blue area' I described previously. The bottom of it was flush with the level of the engine cover's lower edge, so it extends up above the 4" thickness of the IC. I already intended to make a new cover with increased air flow anyway and I like the overall orientation of the IC sitting there (short/straight plumbing runs, away from major heat sources, available air flow to both sides, no interference with other components). It has an electric fan mounted to it as well. So that is where I will mount it.
However a question to be answered is which direction to direct the air flow, top-to-bottom or bottom-to-top (the rotation of the fan and added ducting can push or pull the air either way). I posted this question previously in another thread, and I've consulted a couple of outside sources. There are pros and cons to both possibilities.
The air outside the engine bay is cooler than the air within. So moving the air from top to bottom means cooler outside air coming across it (as Special K describes). But that might also be opposite to the natural direction of flow; hot air rises, and there is a low pressure area above the engine bay. So the fan will be less effective as it fights the natural flow path. Also the heated air coming off the IC will be blowing into the already hot engine bay (although this might help push air through the bay and actually be cooler overall?).
Moving the air from bottom to top means warmer air will cross the IC, and therefore less thermal efficiency. But it follows the natural direction of flow so perhaps greater air volume crossing the IC. If the air can be brought up from under the floor pan, directed to the IC, and then exit the top of the bay it should be cooler and overall more efficient (at the IC). The ducting needed to do that will reduce the movement of air through the rest of the engine bay (the air that otherwise would be flowing through it from bottom to top), making the rest of the bay hotter. With a turbo generating a LOT of heat in the confined bay this is significant.
Due to the amount of added equipment required for the turbo system, and for the sake of overall layout and heat management, I plan to convert the trunk into an extension of the engine bay. This is done by opening up the panel between the bay and the trunk and adding a grill to the rear panel (between the tail-lights). Hopefully this will extract hot air from the turbo and reduce bay temps.
How might this influence the answer to the above question of direction of flow? Looking at the 'bottom to top' option, ducting dedicated air from below the car up through the IC and out the top of the bay would not have as much effect on bay temps, as additional air movement can now pass through the rear. On the other hand with the 'top to bottom' option, the heated air coming off the IC can also be extracted out the rear reducing its impact on bay temps. No clear advantage either way?
Looking at some 'factory' turbo models with the IC located over the engine I found both solutions used. So there wasn't a clear answer there either. Going 'top to bottom' seems slightly more common on front engine vehicles with a large amount of air directed toward the hood. Not sure how much the mid mounted location of the X's engine effects this.