M196

The 1954 Grand Prix formula halved capacity to 2.5 liters unsupercharged, and Fritz Nallinger and Rudolf Uhlenhaut chose a straight-eight — but not a conventional one. It was split into two four-cylinder blocks with the drive taken off in the middle, which shortened the loaded length of a crankshaft made long by its roller bearings and calmed the torsional vibration that would otherwise have wrecked it. The heads were welded to the blocks and the bores chromed. In place of valve springs there was a desmodromic mechanism that pulled each valve shut with a second cam, permitting lift and engine speeds no spring of the day could survive.

Hans Scherenberg had worked on the DB 601 aero engine before the war and, at Gutbrod, on the first production petrol direct injection after it; back at Daimler-Benz from 1952, he and Karl-Heinz Göschel gave the M 196 the same technology. It ran on RD1, an Esso mixture of benzole, methanol and nitrobenzene so aggressive that tanks and lines were flushed with ordinary petrol after every race. Juan Manuel Fangio took the championship with it in 1954 and again in 1955 — nine wins and eight poles from twelve starts. Enlarged to 2,983 cc for the 300 SLR, and tractable enough at last to run on pump fuel, it carried Stirling Moss through the Mille Miglia and won the sports car title at the Targa Florio before Mercedes-Benz left racing altogether.