A 4BT Cummins is a turbocharged 3.9-liter four-cylinder engine with a cast iron block and cast iron cylinder heads. This direct-injected inline-four engine delivers 105 horsepower and 265 pounds of torque per foot. A crate 4BT weighs 475 pounds and fits applications with a 16,000-pound gross vehicle weight rating.
The 4BT Cummins engine measures 30.6 inches in length and 24.6 inches in width. The engine's height is 37.7 inches. With an overhead-valve design, the engine is cast with two valves per cylinder. The bore and stroke measurements of each cylinder are 4.02 inches and 4.72 inches, respectively. The 4BT's block is similar in size to the 5.9-liter 6BT Cummins six-cylinder engine and shares parts with the 5.9-liter 12V Cummins engine. The 4BT's pistons, fuel injectors, connecting rods and valve-train components match those on the 12V engine.
As a member of Cummins' B Series of engines, the 4BT and 6BT debuted in 1984 for use with commercial trucks, step vans and Case Corporation tractors. Manufactured until 1998, B Series engines had bores machined directly into the block and were fitted with shallow one-piece cylinder heads. The 4BT engine was coupled with a Holset H1C turbocharger for assisted aspiration. In 1989, Dodge equipped Ram trucks with the 4BT Cummins diesel engine.