This common rail system provides the highest injection pressure of any other common rail system. The 1998 ISB was rated at 235 horsepower (175 kW; 238 PS) and 460 pound-feet (624 N·m) when equipped with the manual transmission. The ISB uses electronically controlled Robert Bosch GmbH fuel systems, unlike the 6BT systems which were mechanical. Early ISB engines utilize Bosch injectors and a Bosch VP44 high pressure pump.
The engine’s widespread applications include light and medium duty trucks, agricultural equipment, and construction machinery. A long stroke and undersquare bore-to-stroke ratio yield favorable low end performance, producing peak torque at a meager 1,600 rpm. Although the 6BT tips the scales at a hefty 1,100 lbs, its burly cast iron block and cylinder head contributes to the engine’s superior reputation with regard to reliability and longevity. Multiple manufacturers produce a KDP eliminator kit and although the installation is labor intensive, it’s inexpensive insurance against engine failure. The 6BT used Robert Bosch GmbH fuel systems, injector, and VE rotary pump and P7100 inline injection pumps.
The compression ratio in these engines was 17.2:1. The 1998–2000 ISB was rated at 215 horsepower (160 kW; 218 PS) and 420 pound-feet (569 N·m) when equipped with the 47RE automatic transmission. The 3.9L/4B is an inline four-cylinder turbodiesel that was popular for many step van applications, including bread vans and other commercial vehicles. It has also gained popularity as an engine swap into smaller trucks. The high output ISB was rated at 245 horsepower (183 kW; 248 PS) and 505 pound-feet (685 N·m), with only a NV5600 six-speed manual transmission available.