It's force cooled - 6" Comair Rotron @ 0-14 VDC w/ custom CNC'd shroud made of aluminum composite material (ACM).

I was talking about the heat gradient of water...If you put hot water into the bottom of the rad. and there is cooler water at the top does the water tend to rise and aid flow? :shrug:
edit: I was hoping you'd chime in...