The 6BT belongs to the Cummins B Series family of American-made diesel engines produced since 1984 for multiple applications for on-road and off-road and light and medium-duty vehicles. It was first manufactured in North Carolina before getting made in plants around the world, including the UK, Brazil, Turkey, and Mexico.
The B-Series Cummins engine has seen three generations with various displacement capacities delivered in straight-four and straight-six formats. Perhaps, most gearheads associate Cummins engines the most with the Dodge Ram pickup trucks as well as the 23/44-seater British-made Dennis Dart and the 64/90-seater Alexander Dennis Enviro400 school buses.
The 6BT comes in the straight-six configuration with a turbocharged 5.9-liter displacement, with a cast-iron block and head and a 12-valve OHV valve mechanism. This is the reason the 6BT is often referred to as the 12-valve Cummins. One of the primary distinguishing features of the B-Series from earlier Cummins engines is the cylinder bores that are now machined directly into the block instead of the wet liners.
It also differs from other Cummins versions by using a shallow one-piece head. Furthermore, the B-Series Cummins used Bosch direct-injection engine technology, eliminating the need for glow plugs, unlike other diesel engines of that time. It didn't use belts and chains either, but had a timing kit at the front of the engine.
The successful Cummins 6BT seems to be an unstoppable engine, sitting in a range of vehicles, including the mighty Dodge Ram pickup truck.
Most gearheads will gladly present the Cummins 6BT (also known as a 12-valve Cummins) as second to none in the pantheons of reliability and, in fact, the best diesel engines ever made. The reason is simple. The Cummins 6BT uses the simplest design of mostly mechanical components, rather than a complicated electronic build. Besides the reliability afforded by such simplicity, the Cummins 6BT’s simple design creates ample potential for impressive power.