The Cummins B Series is a family of American straight-four and straight-6 diesel truck and industrial piston engines that are manufactured by Cummins. The B Series is known for the popular 3.9 liters (238.0 cu in) straight-four and 5.9 liters (360.0 cu in) straight-six motors. Straight-fours displacing 3.3 liters (201.4 cu in) and 4.5 liters (274.6 cu in) are also available. The B Series is widely used in many segments, including pickup trucks (the Dodge Ram), buses, military vehicles, construction equipment, and marine vehicles. Some of the construction and marine applications use a dual installation, of two B Series Cummins engines. The engine was originally designed by Cummins and Case Corporation for commercial truck applications, and gained much of its popularity after appearing in th