Graham, D., Gerlach, S., and Meurer, J., "New 4.0L SOHC V6 Engine for the Ford Explorer," SAE Technical Paper 962234, 1996, doi:10.4271/962234.
The 1997 Ford Explorer introduces a new two valve single overhead cam (SOHC) version of the 4.0L V6 engine. Maximum power output is increased to 153 KW net (205 HP) at 5000 rpm and 340 N-M of torque (250 lb-ft) at 3000 rpm, which represents a 28% increase in power and an 11% increase in torque over the existing 4.0L overhead valve (OHV) design. The new design's performance features are single overhead camshafts driven by a patented “Offset Y-drive” dual stage chain system, a plastic variable induction system, and aluminum cylinder heads. For quieter and smoother operation, a main bearing ladder frame and a unique second-order balance shaft (4x4 only) are added.