The 3-cylinder diesel D 2900: the first entirely Bulgarian engine

The decision to produce Bulgarian engines under license from the British company Perkins was not accepted unanimously. Already in the late 1960s, when the license agreement was signed, there were many critics who wondered why another, for example, a West German company, was not chosen, why technical documentation developed in a different metric system had to be mastered, the adaptation of which would inevitably lead to errors and complications, etc. However, the decision was made finally, and so, despite the expected difficulties, the technology was mastered, and not long after, the first original Bulgarian developments appeared on this basis.

The 3-cylinder diesel D 2900: the first entirely Bulgarian engine

In the 1970s, the specialized VAMO plant in Varna was already producing a wide range of high-speed diesel engines with an effective power of 30 to 110 kW (40 – 150 hp). The main models of 3-, 4- and 6-cylinder engines were designed to drive forklifts, cars, tractors, agricultural machinery, electric generators, etc. However, their production was associated with a number of difficulties due to the lack of unification. While the basic four-cylinder D 3900 had a cylinder diameter of 93.4 mm and a piston stroke of 127 mm, the three-cylinder D 2500 had a cylinder diameter of 91.47 mm while maintaining the same piston stroke. In addition, the three-cylinder engine had a vortex chamber mixture formation, while the basic one had direct injection.

There are also some differences between the six-cylinder D 5800 and the base engine. Although the cylinder sizes are the same, the combustion chambers located in the pistons have a completely different configuration. The fuel injection pump and other auxiliary units are also driven differently.

All this necessitates the development of new 3-cylinder and 6-cylinder engines that will be completely unified with the base 4-cylinder engine.

This complex task was successfully solved by the engineering team of the Internal Combustion Engines section of the Engine and Automobile Laboratory in Sofia. In the late 1970s, the completely new three-cylinder D 2900 engine was created there, which differs from the others only in the number of cylinders. It shows very good technical and operational qualities and reliability, which were also confirmed in the homologation tests conducted by the British company Perkins. Its high potential was also demonstrated in real conditions, after one such unit was installed on a Massey Ferguson tractor, which was subjected to a series of complex tests also conducted in England.

The three-cylinder engine VAMO D 2900 has direct fuel injection, a working volume of 2900 cubic cm (cylinder diameter 98.4 mm, piston stroke 127 mm) and an effective power of 40 kW (55 hp) at 2500 rpm. Its production is carried out on the same technological lines on which the four-cylinder engine D 3900 is manufactured. It is intended primarily for installation in forklifts, wheeled tractors and construction machinery.

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In the 1970s, the specialized VAMO plant in Varna was already producing a wide range of high-speed diesel engines with an effective power of 30 to 110 kW (40 – 150 hp)

There are also some differences between the six-cylinder D 5800 and the base engine