Airflow problems, need opinions...

[Rob]

Just found this post, dunno why I missed it before.

I am also thinking about using the underside of the bug (in my case) to pull the air. Somebody told me that there is a high pressure area right in front of the torsion beams. If that is the case, then I won't even need a big scoop, the air would be forded in there automatically.

If I were you I would start with that as well, just hack a hole in the floor (nicely) and see how much air is coming through when driving.
Use the string/tape method mentioned before to see if there is air coming in.

Are you sure those louvres are big enough to vent the bus ? Maybe try running without the backhatch for a bit to see if it makes a difference.
I was also wondering if there is a low pressure area somewhere near or at the back of the bus that you could use. If you would place a vent there, it would pull the air out of the back of the bus (and suck it in before the rad).

Just my 2 cts....

Rob.