My BWL E8A will pull a dummy E8B and a 12 car BL up a straight 2% grade. (I don't have the 4 car add on set.) When I added a dummy E8A to the consist, it couldn't make the grade. I purchased another powered A unit (Trainworld sale) so I can run an ABA lashup pulling the BL.
The dummy B unit is a boat anchor, so I believe a single A unit could handle the 16 car BL. The unknown factor would be the drag caused by the curvature of the helix.
Bruce