Less than a dozen: in-line descendants of the V-2 tank diesel engine
V-4 or “half” V-2
Ages 12 and younger
Family of fast-moving tank The emergence of diesel engines with fewer than a dozen cylinders was no accident. Its origins lay in the philosophy that emerged at the Kharkiv Locomotive Plant (KhPZ) named after the Comintern in the early 1930s. The plant's "400" department was headed by Konstantin Fedorovich Chelpan, a prominent organizer of diesel engineering. Working alongside him were leading designers Yakov Yefremovich Vikhman, Ivan Yakovlevich Trashutin, and N. P. Bogdanov, head of the experimental workshop. They devised a modular system. It was based on a single base cylinder. Its diameter was 150 mm, and its piston stroke was 180 mm.
Initially, this cylinder underwent bench testing in a single-cylinder section. Then, it was tested in a two-cylinder section. Only after experiments confirmed the design's effectiveness did the designers begin assembling real multi-cylinder engines. Chelpan and his colleagues' vision proved prescient. With a proven cylinder and piston, a single cylinder head with four valves per cylinder, identical connecting rods with floating piston pins, a common valve train, and identical auxiliary units, it would be possible to build an entire line of engines. Inline and V-shaped, six-, eight-, ten-, and twelve-cylinder—all of them would meet the needs of a wide variety of vehicles: tanks, artillery tractors, and engineering vehicles.
The first living embodiment of this idea was the experimental V-3 diesel engine. It was created at the turn of 1935–1936. It was an inline six-cylinder engine producing 300 hp. It differed from its later production counterparts in its six-plunger fuel pump and shortened crankshaft. However, the piston group and cylinder liners were completely identical to those of the V-2. The engine was installed in the experimental BT-5 tank with a diesel engine (BT-5M) and in artillery tractor "Voroshilovets".
Voroshilovets was originally designed for a six-cylinder V-3.
Field testing in 1935–1936 revealed a host of teething problems—a common occurrence for pioneering designs. The cast-iron block proved insufficiently rigid. Uneven heating of the rear and front cylinders caused it to deform. This was due to poor coolant circulation. Cavitation erosion appeared on the outer surface of the cylinder liners, concentrated in the connecting rod's swing plane. Engineer Kugel's fuel injection system, with its plunger pairs, operated intermittently, delivering uneven fuel. When using heavy fuel, the injector nozzles coked up. Head gaskets were prone to blowouts. This occurred because the load-bearing studs were loosely and unevenly tightened and deformed due to temperature fluctuations. A commission from the Main Armored Directorate of the Red Army concluded that the V-3 was essentially viable, but required radical revision. First of all, this concerned the crankcase and cooling system.
Meanwhile, in Kharkov, work was in full swing on an improved version—the V-4 diesel engine. It was designed specifically for the T-50 light tank. By 1940–1941, the engine had been fully developed. In correspondence, it was sometimes referred to as the six-cylinder "half of the V-2." It was a four-stroke, naturally aspirated diesel engine producing 300 hp and a displacement of 19,1 liters. It differed from its predecessor in that it had a significantly reinforced crankcase. The side walls of the upper half were given a box-shaped cross-section. The longitudinal ribs of the lower half were thicker in cross-section. The nose with the eighth support was removed, shortening the crankcase by 77 mm. The intake manifold was designed so that air was evenly distributed across all six cylinders. The Kimaf air filter was mounted with its cover facing the flywheel, making it easier to service in the tank's engine compartment.
The engine was started in two ways: by an electric starter and a backup compressed air system via an air distributor. The six-cylinder engine gave the T-50 the same power-to-weight ratio as medium tanks and allowed it to reach speeds of up to 60 km/h. Accumulated design experience helped increase the engine's warranty to approximately 200–250 hours—an impressive figure for pre-war times. But then the Great Patriotic War began, and the manufacturing plant was evacuated. T-50 production ceased, with only 75 vehicles produced. Therefore, the V-4 remained a limited-production series.
The eight- and ten-cylinder variants—the V-8 and the hypothetical V-shaped V-10—never made it beyond the draft stage. In the pre-war plans of the People's Commissariat of Medium Machine Building, they were listed as promising power plants for light artillery tractors, high-speed wheeled and tracked supply transporters, and aerosled tugs. The war forced all efforts to focus on producing the V-2 for the T-34, KV, and IS tanks. But the idea of a modular design didn't die. The design headquarters was evacuated to Chelyabinsk and then Barnaul along with the equipment. Specialists preserved both the drawings and the concept of a universal six-cylinder diesel engine. This engine was destined to become a true "workhorse" of Soviet light armored vehicles for half a century to come.
B6 family
The concept's revival began in 1949–1951 at the Barnaul Transport Machine-Building Plant (Barnaultransmash, BZTM). Under the leadership of chief designer Evgeny Artemyev, they developed the V-6 diesel engine (factory designation 8D6). This was the first post-war mass-produced six-cylinder tank engine. Essentially, it was an in-line "half" of the V-2. Unification with the V-2 family was almost complete. Cylinder liners, aluminum alloy pistons, floating piston pins, valves with springs, lead-bronze connecting rod bearings, closed-type injectors (with a four-hole nozzle and hydraulic needle lift), as well as water and oil pumps remained interchangeable. The only differences were in the layout. The engine featured a unique, unheated, seven-bearing crankcase.
In-line diesel engine B-4
The crankshaft was made shorter, with a flange for the flywheel. A ring gear was pressed onto the flywheel for electric starting. The main connecting rods dispensed with the connecting rod lugs—the V-shaped B-2 required them. The fuel pump was a six-plunger type.
From the very beginning, the basic V-6 became the heart of the PT-76 light amphibious tank. It was accepted into service with the Soviet Army in 1951. A modification of the V-6V (8D6-V) with a power take-off (PTO) was developed for the BTR-50P armored personnel carrier, driving a winch. This variant was not interchangeable with the tank variant. Oil was supplied to the crankshaft through the PTO housing, which was attached to the end of the crankcase in place of the central inlet cover. In June 1954, the Kimaf oil filter was replaced with a Kimaf-STZ. The new filter had a check valve. Before starting the tank after a long period of inactivity, it ensured oil flow—a small detail, but critical for service life.
Since June 1957, the engines were equipped with a thermal smoke suppression system (TDA). This allowed the tank to create a concealing smoke screen by injecting fuel directly into the exhaust tract. In 1960, the V-6PG and V-6PV variants appeared. Their crankcases were first heated: electric heating elements were embedded in the walls. Powered by an external source, they heated the oil to a fluid state in temperatures as low as -40 degrees Celsius. Between 1962 and 1964, the BZTM design bureau and the engine bureau of the Stalingrad Tractor Plant (STZ, headed by Algin) completed a radical modernization. The V-6B diesel engine, among other things, received the piston group from the V-55 tank engine, with steel thermostatic inserts in the piston heads. The V-55, however, is a heavily modernized V-2 for the T-55 tank.
Diesel V-6
At the same time, Barnaul engineers were developing high-performance versions. They pushed the limits of the inline "half" engine. The V-6R diesel engine was developed for the ZSU-23-4 Shilka self-propelled anti-aircraft gun. It featured an NK-6 fuel pump with plunger assemblies of increased diameter—up to twelve millimeters. The engine lacked a generator: it was mounted separately, driven by the transmission transfer case. The engine produced 280 hp at 2000 rpm—40 hp more than the standard version. It provided a stable power supply to the radar and instrumentation system of the quadruple anti-aircraft gun. In 1969, a late modification, the V-6R-1, went into production. It received improved injectors and a modernized cooling system. This solved the chronic problem of overheating of the fifth and sixth cylinders. An even more powerful version, the V-6M (factory designation 8D6-280), was developed in 1959–1960. It produced 300 hp.
This engine was installed on the chassis of the anti-aircraft gunrocket The 2K12 Kub system and the Object 910 experimental launcher of the Luna-M system were developed simultaneously. Prototypes with turbocharging and intercooling were produced simultaneously. They demonstrated a power output of over 350 hp without reducing the warranty period. However, the decision to mass-produce turbocharging on the V-6 was never made. The conservatism of military acceptance prevented this: they feared that operation would be too complex.
In the early 1960s, Soviet designers wondered: what if a tank diesel could run not only on diesel fuel, but also on gasoline or aviation Kerosene? In May 1964, the Volgograd Tractor Plant produced a trial batch of nine PT-76BM tanks and one BTR-50P with an experimental V-6M engine. It could burn diesel fuel, A-66 and A-72 motor gasolines, TS-1 aviation kerosene, and T-2 aviation gasoline. To achieve this, the design underwent significant modifications.
The driver-mechanic was given a stop switch that adjusted the fuel pump to a specific fuel grade. Anything leaking through the pump and injectors was carefully diverted back into the fuel channels rather than lost. The pump tappets and shaft were now lubricated with engine oil instead of fuel. The pump pressure was increased to 3–3,5 kgf/cm². Continuous circulation was established through the system—approximately 90 liters of fuel per hour—with return to the tank to prevent vapor lock. Special breather tubes equalized the pressure in all tanks, preventing them from bulging with vapor.
Military trials were conducted in the Belarusian, Turkestan, and Far Eastern military districts. They confirmed that the diesel engine could operate on light fuels for 200–250 hours without catastrophic failure. However, some annoying issues emerged. Gasoline vapors penetrated the fighting compartment and engine compartment. And starting a warm gasoline engine required excessive cranking.
Drawing on this experience, the designers created an improved V-6D engine. It was tested in 1965–1966 in Samarkand and near Yavorov in the Altai Territory. The fuel injection angle was increased to 34°±0,5°. The intake manifold was redesigned—air was now supplied centrally to ensure uniform cylinder filling. The piston oil scraper rings were chrome-plated. The connecting rod bushings and bearings were lead-coated to facilitate rapid break-in when changing fuel. The injector nozzles were cold-treated to relieve residual stress. A new 896-4 fuel pump from an aircraft design bureau was installed. As a result, the specific fuel consumption was 180 grams per horsepower per hour—virtually the same for any fuel type. The warranty service life was increased first to 350, then to 500 engine hours. There is now the prospect of increasing it to 1000 engine hours when running on regular diesel fuel.
In the late 1950s, Barnaultransmash, together with the Ural Turbomotor Plant, developed a whole range of commercial diesel engines based on the same six-cylinder block. The naturally aspirated 1D6, producing 150 hp, became the heart of thousands of 100 kW diesel generator sets—they powered remote weather stations, geological survey teams, oil fields, pipeline pumping stations, nodes of the Sever tropospheric line, and reserve command posts of the Strategic Missile Forces. Moreover, these highly automated engines started and shut down automatically, without human intervention.
The 2D6S2 modification with a friction clutch was used in EKG quarry excavators, auger-rotor snow blowers, and sleeper tamping machines, while the turbocharged 2D6N-250S2 was used in drilling rigs and emergency pumps. But the true legend was the marine 3D6—the ubiquitous engine for river and coastal waters. fleet, which, with a reverse gear transmission and right-hand and left-hand rotation options, was used on the Kostromich tugboats, the Yaroslavets cutters of all imaginable types, the Moskvich and Moskva passenger ships, ferries, fireboats, and landing craft. Its turbocharged counterpart, the 3D6N-235S2, propelled border patrol boats and high-speed motor vessels. And that's far from the full range of capabilities of the legendary V-2's descendants.
The B-2, like no other diesel engine, left a significant mark on the technical stories The Soviet Union and modern Russia. The design from the 30s was so ahead of its time that both the tank diesel engine itself and its modular variants will continue to be found under the hoods of military and civilian vehicles for a long time to come.
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