In the second half of the 1990s, Mercedes-Benz carried out a small revolution, mechanically speaking, by introducing a family of V6 and V8 blocks with three valves per cylinder. The V6s, known by the designation M112, replaced the earlier M104 inline six-cylinder engines, in many cases also taking over their displacements and bore and stroke dimensions, but were lighter in weight.
They were the first V6 engines in the history of the company, which had never before used the V-architecture for six-cylinder engines. However, the first V6 to bear the star did not belong to this family. It was a racing engine that had already been built a few years earlier.
M106: for the heir to the 190 Evo II
The German marque's first V6 engine bore the M106 designation and was created in 1994 for racing use in an FIA Class 1 homologated saloon based on the C-Class W202, the car that replaced the legendary 190E on both the road and the racetrack.
The racing car is, in fact, the heir to the 190E Evo II which was powered by a 2.5-litre four-cylinder engine. For the new C-Class, Mercedes-Benz opted to develop a new V6, also a 2.5-litre, suitable for a very rearward-mounted position in a low, profiled car.
The 1994 M106 engine
This M106 engine was closely related to the 4.2-litre V8 M119 that Mercedes-Benz used in top models such as the E-Class 420. Like the latter, it featured a 90° angle between the cylinder banks and four valves per cylinder with twin overhead camshafts, unlike the later V8 M113 and the aforementioned V6 M112, which were distinguished by the adoption of only three valves per cylinder controlled by a single camshaft per bank.
With a bore and stroke of 90 x 68 mm, it was a short-stroke engine, another feature that facilitated higher revs. The compression ratio was 12:1, fuel injection was used and maximum output in the first 1994 version was around 365 bhp at 9,500 rpm, but in subsequent evolutions it increased to 493 bhp at 11,500 rpm in 1996.
Mercedes-Benz C AMG V6 DTM 1994-1996
With this engine, the C-Class V6 DTM won two DTM championships in 1994 and 1995 and the ITC in 1995, beating such prominent rivals as the Alfa Romeo 155 V6 TI and the Opel Calibra DTM.
The latter enjoyed all-wheel drive, while the Mercedes-Benz saloon, whose road-going variant did not have 4WD versions until the next generation, was rear-wheel drive with the gearbox mounted at the rear.