Mercedes-Benz M18 engine
The Mercedes-Benz M18 engine is a naturally-aspirated, 2.9-liter, straight-6, internal combustion piston engine, designed, developed and produced by Mercedes-Benz; between 1933 and 1937. M18 Engine
The six-cylinder 2,867 cc side-valve engine produced a maximum output of  at 3,200 rpm. In 1935 the compression ratio was increased along with maximum power which was now given as . Power was delivered to the rear wheels via a four-speed manual transmission with synchromesh on the top two ratios. Applications
Mercedes-Benz W18

References

Mercedes-Benz engines
Straight-six engines
Engines by model
Gasoline engines by model