Motoren-Werke Mannheim AG has designed a new series of in-line 4 stroke cycle Diesel engines with 2, 3, 4 and 6 cylinders in naturally aspirated and, except the 2-cylinder engine, turbocharged version. Although the new design would have allowed to increase the displacement, the 105 mm bore and the 120 mm stroke as well as the external dimensions of the previous series were maintained.
The explanation of the reasons for this decision is followed by a description how the increase of the performance range was achieved without enlarging the displacement. This involves mainly the load capacity of the engine components required by higher degrees of turbocharging and improved cooling. As installation in agricultural tractors is a main application the capability of the engine structure to be loaded by increased external torsional and bending moments was also an important requirement.