According to Cummins, the 6BT was a 5.9-liter, inline-six, water-cooled, and turbocharged four-stroke diesel engine that produced between 160 and 215 horsepower and between 400 and 440 lb-ft of torque. The 6BT featured two overhead valves per cylinder, for a total of twelve, and was fed by a Bosch direct fuel injection system. Looking online, you’ll see folks putting the 6BT engine in just about anything that needs an engine, all in the name of reliability.
The Cummins 6BT is a simple engine with reasonable performance. According to the Chrysler press release on Allpar.com, the 6BT was chosen for the medium-duty truck because of its simplicity and torque — Not only was an inline-six engine easier to work on than the V-configurations it competed against, but it also had 40% fewer parts at the time. According to Dust Runners Automotive Journal, the BT6 featured a cast-iron cylinder head and engine block, which made it incredibly tough but sacrificed in the weight department. The all-mechanical direct fuel-injection system made it both easy to repair and work on, although some common problems with the 6BT are related to the fuel system, according to Diesel IQ.
Featuring a compression ratio of about 17:1 — low, considering some diesel motors run at up to 25:1, according to E-ZOIL – the 6BT is comparatively under-stressed, adding to its longevity. The combination of performance, ease of maintenance, and durability make the Cummins 6BT a fan favorite.