OM427

The 90° V-engines that launched this family in 1969 were developed jointly with MAN, and part of the bargain was that Daimler-Benz would not use the shared inline six in trucks in Europe. So the sixes went into buses instead — upright, and in a version laid flat for rear-engined underfloor installation. The OM 427 was the 1980 revision of that engine: bore taken out to 128 mm, stroke settled at 155 mm for the inline units, offered naturally aspirated and as the turbocharged OM 427 A, with roughly 240 to 300 PS depending on version.

Its career was brief. The horizontal OM 427h appears in the Mercedes-Benz O 405 — the second-generation VÖV standard city bus — for barely more than a year from late 1985, rated at 220 kW. By then the next revision was already in production, and the OM 447 took over with the same 128 × 155 mm cylinder and a far longer run ahead of it. MTU, which acquired industrial sales rights to these engines in 1988, kept both generations going under the single designation Series 183.