OM421

In 1980 Daimler-Benz reworked the whole V-range into the OM 42x generation. The bore went from 125 to 128 mm, the stroke across every V-engine was standardized at 142 mm — the figure the V12 had used from the start — and rated speed came down from about 2,500 to 2,300 rpm. More consequential than any of that, this was the generation with which the firm began moving its trucks away from atmospheric engines towards turbocharging. The V6 grew to 11 liters and 216 PS, with turbocharged and intercooled versions following for export and industrial buyers.

In the New Generation range it drove the 1622 and the nineteen-tonne 1922, a step below the V8s and a step above the surviving inline sixes. What it did not gain was refinement: the uneven firing of a 90° V6 was inherent in the shared crankshaft layout, and was only engineered away in 1985, when the OM 441 arrived with offset crankpins. From 1988 Mercedes-Benz handed distribution of these engines outside its own vehicles to MTU, which sold the V6 alongside its larger relations as part of Series 183.