Cummins B Series engine

The 3.9L/4BT Cummins is an engine in the same family as the 5,883 cc (5.9 L; 359.0 cu in) Cummins turbo-diesels. 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. Additionally it has seen broad usage in agricultural equipment. It has also gained popularity as an engine swap into smaller trucks. The lowest powered 4B produces 53 hp (40 kW).[1]

The 5,883 cc (5.9 L; 359.0 cu in) 6BT, also known as the Cummins "12-valve" (since it has 2 valves per cylinder) was the first member of the "B" engine family to be used in a light truck vehicle. The 6BT used Bosch fuel systems, injector, and VE rotary pump and P7100 inline injection pumps. Some early 6BTs were supplied with CAV rotary pumps instead, before the Bosch system became the sole standard. This engine started life in 1984 designed as an agricultural engine, for use in Case agricultural equipment.[3] After 1989, the 6BT engine was used in light duty, medium duty and select heavy duty trucks and buses. The 6BT engine has recently become very popular for use in repowering various vehicles, in the UK they have proven very popular in the Land Rover community, commonly known as the ‘good’ conversion.

Appearing in the 1989–1998 Dodge Ram pickup truck, it became a popular alternative to the large gasoline V8 engines normally used in full-size pickup trucks, since it produced the torque at low engine speeds, and significantly better fuel mileage. During that time, the Dodge Ram was the only diesel pickup that did not rely on glowplugs for cold weather starting.[3]

The 5.9 L; 359.0 cu in (5,883 cc) QSB (Quantum System B) is the off-road, heavy duty version of the ISB. Typically used in marine, agricultural, and construction applications, these engines share many of the same parts as the ISB and utilize the same Bosch fuel system.

Midway through model year 1998, the Dodge Ram switched from the 6BT to the ISB to meet updated emissions requirements. Like other ISB's, these engines started out using the Bosch VP44 rotary injection pump. The VP44 setup meant that timing and fuel could be precisely controlled, which led to cleaner emissions. However, VP44 failure rates were higher than the older P7100 injection pump. The compression ratio in these engines was 17.2:1. The 1998–2000 ISB was rated at 215 hp (160 kW; 218 PS) and 420 lb⋅ft (569 N⋅m) when equipped with the 47RE automatic transmission. The 1998–2000 ISB was rated at 235 hp (175 kW; 238 PS) and 460 lb⋅ft (624 N⋅m) when equipped with a manual transmission. For the 2001–2002 model years, a standard output and a high output ISB Cummins engine were offered. The standard output, which was the same as the previous engines was rated to 235 hp (175 kW; 238 PS) and 460 lb⋅ft (624 N⋅m) when equipped with either a manual transmission or automatic. The high output ISB was rated at 245 hp (183 kW; 248 PS) and 505 lb⋅ft (685 N⋅m), with only a NV5600 six-speed manual transmission available. The high output engine was different in a few ways from the standard output engine; it had higher compression (17.3:1), powdered metal valve seat inserts, a larger flywheel, the Bosch fuel system was reworked to allow higher fuel flows, and fuel-injection timing was altered.

For the 2003 model year, the Cummins was introduced with Bosch high pressure common rail fuel injection, again increasing power output. On automatic equipped vehicles, the 47RE was upgraded internally to increase durability and torque capacity, now known as the 48RE. The 2003 rating for the Dodge truck was released at 305 hp (227 kW; 309 PS) and 555 lb⋅ft (752 N⋅m). Midway through the 2004 model year, the Cummins 600 was introduced, producing 325 hp (242 kW; 330 PS) at 2,900 rpm and 600 lb⋅ft (813 N⋅m) at 1,600 rpm. This engine was noticeably quieter than the previous engines.[4]

There are many changes over the previous B5.9 for the Dodge truck, the most obvious being the larger displacement. The B6.7 had an increase of cylinder bore and piston stroke to 107 mm × 124 mm (4.21 in × 4.88 in), respectively, thereby giving a displacement of 6.7 L; 408.2 cu in (6,690 cc).[6]

With the 6.7 L Cummins Engine came the introduction of the Variable Geometry Turbocharger (VGT). The VGT Turbocharger was introduced to reduce turbo lag by adjusting the vanes by sliding a steel ring in the exhaust housing dependent on engine RPM creating more or less pressure inside the exhaust housing and controlling the speed of the turbocharger. It also works as an integrated exhaust brake system and is all controlled by an electronic actuator on the turbocharger. This VGT system has been an extremely common issue with the 6.7L Cummins platform and is typically diagnosed by the loss of the trucks exhaust brake.[7]

The two-thirds version of the ISB is the 4-cylinder 4.5-liter at 185 hp (138 kW), used in the New Routemaster, a series hybrid diesel-electric doubledecker bus in London.[8][9][10]

In the earlier models of the Cummins B Series Engine, it was almost entirely mechanical including its fuel system. The fuel pump used in these engines was the P7100 injection pump, this pump is driven off the camshaft gear and drives it own internal camshaft to inject fuel to the individual injectors.[11] This pump itself was one of the most popular options for fueling for the B Series Engines because of this simplistic design and how reliable it was. The P7100 injection pump also allows for large amounts of fuel to be delivered into the system with simple tweaking to the system to allow for larger injection events.

In the later models of B Series Engine, the fuel system was switched from mechanical injection and timing to mechanical injection with electronic timing. This was all thanks to Bosch’s new VP44 injection pump. The VP44 injection pump is driven at half the camshaft speed and produces fuel pressure at about 4,500 psi to pop the vertically centered injectors in the engine.[12]  These injection pumps need to have constant fuel pressure behind them of at least 10psi at all times to maintain the priming of the system.[12] If you run these pumps dry it can cause your pump to fail quickly. The VP44 injection pumps were the first pumps placed in the Cummins engine to have an FPCM. FPCM stands for the fuel pressure control module, and this is responsible for maintaining and controlling the fuel pressure of the system. However, even though this new technology to control fuel pressure was convenient, it had a major downfall. The problem was them was that they were unable to be serviced without replacing the entire fuel pump. Another important piece of the puzzle that is responsible for the longevity and functionality of the VP44 was the fuel transfer pump mounted on the side of the block next to the ECM. This electronically driven vane pump is what supplies that minimum of 10psi to the injection pump so it maintains constant fuel pressure as well, as cools itself, and lubricates itself. [12]

The most recent method of fuel injection that is still in use today is called common rail injection. Common rail injection is a completely revolutionary design to fuel injection since a fuel pump is now used to pressurize a rail and then from there sends the fuel to each injector. A major benefit of switching over to this fueling system was how it allowed for much less leakage into the cylinders pre and post ignition. This is all possible since this fuel system operated upwards of 2600 bar so they are able to set spring tension higher in each injector to allow for more precise fuel injection and timing.[13] Another benefit of using common rial injection and having one rail pressurized compared to pressurizing each individual injector is that it is more reliable since it allows for more consistent fuel delivery to each injector.[14]