| Cummins B-Series Engine | |
| Manufacturer: | Cummins |
| Aka: | 4B/4BT/4BTA 6B/6BT/6BTA ISB QSB |
| Production: | 1984–present |
| Configuration: | I4, I6 |
| Block: | Cast iron |
| Head: | Cast iron |
| Valvetrain: | Cam-in-block 2 (B-Series) or 4 (ISB, QSB) valves/cylinder |
| Turbocharger: | Holset Engineering (variable) |
| Fuelsystem: | Common rail high pressure direct injection, symmetrical combustion chamber with 7-hole injectors |
| Management: | Bosch mechanical with electronic advance |
| Fueltype: | Diesel |
| Oilsystem: | Wet sump |
| Coolingsystem: | Water cooled |
| Power: | NaNhp |
| Torque: | NaNabbr=on0abbr=on |
| Compression: | 17.2:1, 17.3:1, 17.5:1, 19:1 |
| Emissions Control: | Electronic fuel control, DPF and EGR |
The Cummins B Series is a family of diesel engines produced by American manufacturer Cummins. In production since 1984, the B series engine family is intended for multiple applications on and off-highway, light-duty, and medium-duty. In the automotive industry, it is best known for its use in school buses, public service buses (most commonly the Dennis Dart and the Alexander Dennis Enviro400) in the United Kingdom, and Dodge/Ram pickup trucks.
Since its introduction, three generations of the B series engine have been produced, offered in both inline-four and inline-six configurations in multiple displacements.
The B-series features engine bores machined directly into the block (rather than the wet liners used on earlier Cummins engines). It is also set apart by the use of a shallow one-piece head, requiring closer tolerances than in other Cummins products.[1] Unlike earlier diesel engines the B-series Cummins used direct injection and did not need glow plugs for cold starting.[2] The engine was first manufactured in Rocky Mount, North Carolina, and other plants were later added in Mexico, Brazil, Turkey, and Darlington, UK.[3]
Every Cummins powered Dodge Pickup (since initial production in 1989) has come equipped with a turbocharger. It uses a gear-drive camshaft for extra reliability. Also specified is a deep-skirt engine block and extra-strong connecting rods. A Holset turbocharger is used. The original B Series was updated with 24 valves and an electronic engine management system to become the ISB in 1998.
| 3.9 L | |||||
| 4B | 4 | Diesel | |||
| 4BT | 105 HP | 265 lb-ft | 1984? - 1998? | ||
| 4BTA | 170 HP | 440 lb-ft | 1998 - ? | ||
| 4.5 L | |||||
| ISB | 4 | Diesel | 185 HP | Euro 5 (2008–2014)Euro 6 (2015–present) | |
| QSB | |||||
| 5.9 L | |||||
| 6B | 6 | Diesel | |||
| 6BT | 160 HP | 400 lb-ft | 1989 - 1998 | ||
| 6BTA | |||||
| ISB | 1998 - 2007 | ||||
| 6.7 L | |||||
| ISB | 6 | Diesel | 2007–presentEuro 4 (2005–2008)Euro 5 (2008–2013)Euro 6 (2014–present) | ||
| B6.7N? | Natural Gas | ||||
The lowest powered, naturally aspirated 3.9-liter Cummins, the 4B, produces 530NaN0.[1] This variant is most commonly found in equipment such as generators and wood chippers.
The 4BT is one of two turbocharged variants of the 3.9L B-Series engine. It has two valves per cylinder for a total of eight. The most common output of this variant is 105 horsepower.
The 4BTA is the updated version of the 4BT, also turbocharged, with four valves per cylinder for a total of sixteen. The most common output of this variant is 170 horsepower.
The 6B is the naturally aspirated version of the 6BT with the power output of between 150 and 173 hp and with the compression ratio of 19:1. There were no OEM automotive applications for 6B engines.
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 torque at low engine RPM, and achieved significantly better fuel mileage. Due to the direct fuel injection, the 6BT has no glowplugs.[4]
The 4.5 L ISB is essentially a four-cylinder, two-thirds version of the 6.7 L ISB rated at 185hp, used in the New Routemaster, a series hybrid diesel-electric doubledecker bus in London.[5] [6] [7]
One unusual feature of the ISB is that it is a multi-valve pushrod engine design, with four valves per cylinder (popularly referred to as the "24-Valve" Cummins). The engine displaces 5883cc, with a NaN2NaN2 cylinder bore and piston stroke. A turbocharger is used to increase the output in the high-compression (17.2:1 in recent versions) diesel. It is an all-iron engine with forged steel connecting rods, an assembled camshaft, and a cast aluminum intake manifold. The engine is produced in Columbus, Indiana.
The ISB uses electronically controlled Bosch fuel systems, unlike the 6BT systems which were mechanical. Early ISB engines utilize Bosch injectors and a Bosch VP44 high pressure pump. Later ISB designs have common rail fuel injection, Bosch injectors, and a Bosch CP3 high pressure pump.[4]
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 2150NaN0 and 420lbft when equipped with the 47RE automatic transmission. The 1998–2000 ISB was rated at 2350NaN0 and 460lbft when equipped with a manual transmission. For the 2001–2002 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 2350NaN0 and 460lbft when equipped with either a manual transmission or automatic. The high output ISB was rated at 2450NaN0 and 505lbft, 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 3050NaN0 and 5550NaN0. Midway through the 2004 model year, the Cummins 600 was introduced, producing 3250NaN0 at 2,900 rpm and 600lbft at 1,600 rpm. This engine was noticeably quieter than the previous engines.[8]
The 6.7 L ISB is the latest version of the B Series. It is currently the largest straight-six engine produced for a light duty truck or school bus. It produces 3500NaN0 and 650lbft in the 2007.5 and newer Dodge 2500/3500 pickup trucks with the Chrysler-built six-speed 68RFE automatic transmission built at the Kokomo Transmission plant in Kokomo, Indiana. Engine torque is slightly reduced with the Mercedes G56 6-speed manual transmission at 3500NaN0 and 610lbft. The 2007 and newer 3500 Cab & Chassis trucks only get the 3050NaN0 and 610lbft version of the B6.7, whether it has the Aisin AS68RC or the Mercedes G56 6-speed manual transmission. As for the 2008 4500/5500 medium duty Chassis Cabs or the Sterling Bullet Trucks, they receive the 3500NaN0 and 610lbft version of the B6.7, whether it has the Aisin AS68RC or the Mercedes G56 6-speed manual transmission. Late model 2011 Ram trucks produce 3500NaN0 and 800lbft, with the exhaust brake rating boosted from 1500NaN0 to 2220NaN0.[9]
For 2019 this engine has been updated to produce 400 hp and 1000 ft-lb torque.
It is also used in the Blue Bird Vision, Thomas Saf-T-Liner C2, and IC CE school buses and BMC Procity city buses
There are many changes over the previous 5.9 L ISB for the Dodge truck, the most obvious being the larger displacement. The 6.7 ISB had an increase of cylinder bore and piston stroke to NaN2NaN2, respectively, thereby giving a displacement of 6690cc.[10]
With the 6.7 L ISB came the introduction of the Variable Geometry Turbocharger (VGT). The VG 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 6.7 L ISB and is typically diagnosed by the loss of the trucks exhaust brake.[11]
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 Bosch P7100 injection pump, this pump is driven off the camshaft gear and drives its own internal camshaft to inject fuel to the individual injectors.[12] 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 radial distributor injection pump.[13] The VP44 injection pump is driven at half the camshaft speed and produces an injection pressure of up to .[14]
The most recent method of fuel injection used in Cummins B Series engines is electronically controlled common-rail injection. It has been used in Cummins B Series engines and the B-Series based NEF engine since 2003.[15]