MB852

The 850 series was a construction kit. Every engine in it used the same 115 mm bore and 140 mm stroke, turned at the same 2,000 rpm and gave roughly 20 PS per cylinder, so the range stepped cleanly from the single-cylinder MB 851 through this two-cylinder unit and the three-cylinder MB 853 into vee configurations of four, six and eight cylinders at 80, 120 and 160 PS. Water cooling, direct injection and a mean piston speed of 9.33 m/s ran through the whole family. A buyer specified power by choosing how many cylinders to pay for.

Here that meant 40 PS from 2.9 liters in a unit weighing a little over 400 kg dry — weight being beside the point, since these were installation engines destined for machinery expected to hold a steady load for hours rather than accelerate. Daimler-Benz had served that trade since the 1920s with slow-running horizontal singles like the OE and the later MB 821 A, sold to drive irrigation pumps, generating sets and stationary plant in places where no technically trained staff were on hand. The 850s were the faster-turning modern replacement, shadowed throughout by an air-cooled parallel family, the 860s, built from the same cylinder.