The year 1935 provided an excellent grand prix season, the best that Mercedes-Benz enjoyed against strong and varied opposition in year two of the new 750kg GP formula. In its second season, the W25 was fully proven and raced as part of a group that was at last operating as a team, driven by two absolute aces in Rudy Caracciola and Luigi Fagioli.
Caught napping by the Germans, who had been quicker to see the potential of the new rules, Alfa Romeo and Maserati introduced new and faster cars in 1935 that threatened to be sterner rivals in 1936. And the meteoric Bernd Rosemeyer was displaying uncommon skill at the wheel of his Auto Union. Major changes in the Mercedes-Benz equipment for the formula’s third year were clearly needed.
For 1936, the plan was to build an SSK version of the W25, a car that would be lower and shorter, especially at the rear. The reduction in size would make the car inherently lighter, so it could be equipped with a new and more powerful engine without exceeding the weight limit.
DAB hand
Conceived for this purpose by the Albert Heess engine group was a 60-degree V12 using the same construction techniques as the M25 eight. Cylinder blocks were welded steel with integral four-valve-per-piston heads.
The first of these D-series engines was designated DAB because they had the same dimensions as the latest eight, the M25AB, 82 x 88 mm for 5577cc (340ci). The design office estimated it would deliver 516bhp on 2B fuel, the usual racing blend, and 598bhp on WW, or pure alcohol.
‘Although the new car was within the 750kg limit, [with the V12] it had too much weight at the front end. It was quite good for setting records on a straight road but quite unsuitable for the Nürburgring’
Rudolf Uhlenhaut, engineer at Mercedes-Benz
In late summer of 1935, the first DAB engine was found to be disappointing, not in its power but in its weight. It scaled 650lb (295kg), almost 250lb more than the various M25 eights. This
