phil, the "grates"
that channel airflow to the radiator or a/c cooler
are for the birds. in all the vehicles i worked on, import or domestic there was always a huge gap between them and the radiators, lots of possibility for air to go errand and irrevocably attempting to hit the fins at an angle instead of just flowing through. when u put the gardening tools away think of fashioning
some tighter airflow straigteners and be amazed how lil cooling air your engine acutally needs.
out of pure experimentation i removed the only, thermostatically controlled electric fan on my 82 IDI Jetta wondering if it was possible to go without.
that was 4 years ago. the only time it gets hot is in traffic when i use the heater and simlpy open the windows :=) the aperture is about 2/3 the size of yours, and i left the air snorkle to fend for itself.
b.t.w. i live near the desert in central california.
Bondo:
there is no perceptible gap in the picture of your cab/aerolid, how wide is it actually? the airflow does seem to be seperating but at least it is not going turbulent. the dip generated by the fitup of the aerolid to the cab, and the channel on the top of the aerolid is causing a very interesting swell which is forced to flow over the prevailing airflow going over the top.
very interesting. wonder what would have happened if and exact fitup (more difficult to suit all truck shapes) had been done?
regardless great work!