Get Hotcars Premium. Start your free trial today

The 12-valve system Cummins has developed a cult status in the trucking community.

If there is one thing people are especially particular about in an automobile, it’s the type of engine the car has. A 12-valve Cummins diesel engine is the most famous diesel engine on the planet.

The 1,100 lbs iron monstrosity from Columbus, Indiana, is known for being practically unkillable, even after it's been tweaked to yield astounding power figures. It is arguably the most reliable diesel engine ever installed in a pickup truck, with the 7.3-liter Powerstroke providing the closest competition.

Without further ado, let's take a closer look at the 12-valve Cummins diesel engine.

Cummins, Inc. of Columbus, Indiana, built this engine. Cummins was founded in 1919 by diesel technician Clessie Cummins and has since grown to become one of the world's most respected diesel engine manufacturers. Cummins engines are found in a wide range of applications, including heavy machinery, buses, transport trucks, and even generators.

Cummins is one of the few businesses that truly understand diesel engines. It first appeared in the 1989–1998 Dodge Ram pickup truck, and it quickly became a popular alternative to the huge gasoline V8 engines commonly used in full-size pickup trucks because of its ability to create torque at low engine speeds while also providing much-improved fuel consumption. The Dodge Ram was the only diesel pickup at the time that didn't use glow plugs to start in the cold.

The Cummins 5.9-liter 6BT 12 valve has 230 HP, 440 lb-ft of torque, and a P7100 inline injection pump right out of the box. The 12-valve is also a popular engine swap choice, powering a slew of Jeep, rat rod, muscle car, and dragster projects.

RELATE:The Hidden Truth Behind The Cummins Diesel Engine

The 12 valve was manufactured between 1989 and 1993, and its common names include 6BT Cummins 12V, 12 Valve Cummins, and 1st Generation Cummins. The engine is an inline-6 cylinder with a cast-iron block and a cast-iron cylinder head with six head bolts per cylinder. It has a displacement of 5.9 liters or 359 cubic inches, a bore of 4.02 inches, a stroke of 4.72 inches, a compression ratio of 17.0:1, and a firing order of 1-5-3-6-2-4.

The Bosch VE44 mechanical injection pump, mechanical injectors, and direct-chamber fuel injection are used for fuel injection. The turbocharger is a Holset Fixed Geometry Turbocharger (VGT), the valvetrain is a 2 valve per cylinder Overhead Valve Engine (OHV), the pistons are cast aluminum, and the transmission is a Getrag 360, Torqueflite A727 5-Speed Manual A518, and 3-speed automatic (46RH) With overdrive, it's a 4-speed automatic transmission.

Early models used a single 1,025 CCA battery, but later models used dual 750 CCA batteries. Engine oil capacity with a filter is 12 Quarts or 11.4-liters, and the fuel, as mentioned, is diesel. Its governed speed is 2,500 RPM, it has160 HP at 2,500 RPM, and offers torque of 400 lb-ft at 1,700 RPM, with a dry weight of 1,100 lbs.

RELATED:This Swedish Diesel Engine Can Roll Coal Just As Well As Cummins

This engine is legendary and of a high priority for many people. Among its strong suits are;

While the 12-valve was built from 1989 to 1998, most people look for the 1994-98 model. The mechanical Bosch P7100 injection pump (commonly known as a "P-pump" or inline pump) was used in these engines, and it has six plunger and barrel assemblies, as well as cam and delivery valves. The six plunkers move when the camshaft rotates (the cam is in charge of the firing order).

Performance injectors for a 12-valve range from $450 to $1,000, compared to today's electronically controlled, common-rail diesel injectors, which can cost upwards of $3,000 per set (give or take). The injector for the 370 HP variant of the 12-valve utilized in maritime applications is one of the most frequent injectors. The maritime 370 injectors are made by Bosch and have a 5-hole nozzle with 0.012-inch holes.

From 1989 until 1998, the 5.9-liter Cummins had a 12-valve variant. A cast-iron block and head, forged steel crankshaft and connecting rods, an inline-six architecture, and mechanically regulated direct injection all contribute to a power unit designed for maximum reliability and lifespan. With a stroke of 4.72 inches and a diameter of 4.02, the engine produces 359 cubic inches of torque at low speeds.

RELATED:This Cummins-Swapped Ford Mustang Roars, Spits Flames, Leaves Sanity Completely Behind

The Holset HX35 turbocharger featured on 12-valve engines from 1994 to 1998 is one of the hardest factory turbochargers we've ever seen. Considering the fact that it was intended for 20 psi of boost in the 5.9-liter Cummins application, it doesn't appear to be out of its efficiency range, given that it produces twice the boost.

The HX35 produces higher power and lowers exhaust gas temperature while creating 35 to 40 psi (thanks to a deactivated wastegate). Exhaust flow improves, and drive pressure reduces. These engines have 160 to 215 HP at the crankshaft, depending on the model.

When it comes to making fueling modifications on the 12-valve Cummins, you don't have to rely on electronically communicating with the ECM because it's a mechanically injected engine.

This means that with a few simple hand tools and your own two hands, you can increase horsepower. The free mods start with the AFC (air-fuel control) housing, which is located at the back (top) of the P7100 injection pump.

Throughout the years, the Cummins 5.9 has seen a lot of minor changes. The engine received an intercooler a few years after its introduction in mid-1991. The motor was swapped from a rotary Bosch VE rotary pump to a P-Pump in 1994, and it was subsequently changed again.

When you consider the roughly 10,000 Cummins High Mileage Club members and the dozens of 5.9-liter owners who have surpassed one million miles, it's easy to see why this engine is considered by many to be the best diesel engine ever placed into a pickup. The 12-valve system Cummins has developed a cult status in the trucking community. The 12-valve is regarded as highly as the 2JZ or the K-series engines, and some argue that it is the best engine ever built.

NEXT:Cummins Aiming To Purchase Volkswagen’s Large Engines Division [Rumors]

OKUNLOLA Barnabas is an excellent content writer with a background in transportation and emerging technologies.