June 5, 2023

Perfection comes in a small block

BMW 4-cylinder

No one can doubt that, in terms of quality and performance, the German automotive industry is one of the best and most efficient in the world. An example of this is the story that we will tell today and whose main character is a four-cylinder BMW engine that was the basis of enormous successes for the Bavarian brand.

Introduced in 1961, the BMW M10 block served to drive the 1500, 1600, 2000 and 2002 series. Its simplicity, reliability and power soon made it one of the favorites for brand users. Also in 1973, the 2002 Turbo was presented at the Frankfurt Motor Show and was the first European production car to mount a turbocharged engine. These characteristics were decisive for the factory to develop a version for competition: the M12.

With an aspirated 2000 cc configuration and approximately 300 hp, this engine won six European Formula 2 championships between 1973 and 1982. It was also successful at the Deutsche Rennsport Meisterchaft -DRM- where BMW, Ford and Porsche competed under FIA Group 5 rules. In this case, the M12 had reduced its displacement to 1400 cc but thanks to the thrust of a KKK turbocharger it developed 400 hp at 9400 rpm. In 1978 BMW won the championship with its 3 Series driven by Harald Ertl.

With the impetus of the F2 championships, BMW decided to compete in Formula 1, where turbo technology had been present since the late 1970s thanks to developments carried out by Renault. The 1500 cc 4-cylinder M12 engine had an iron block, aluminum cylinder head and weighed 170 kilos adding turbo and intercoolers. With a pressure of 3.0 bars it delivered 740 hp, although in qualifying 800 hp was obtained thanks to a higher pressure.

The association with Team Brabham in 1982 proved promising and even as the team alternated between Cosworth and BMW engines, the German factory took its first F1 victory at the Canadian GP thanks to the brilliant driving of Nelson Piquet. The following year, the brazilian won 3 races and became the first driver in Formula One history to win the Championship with a car powered by a turbocharged engine: the Brabham-BMW BT52. Let’s remember that the motor base had been the 4 cylinders M10 with 123 hp from the sixties…

Around the same time, BMW began work on the development of a sports car that would not only be iconic but also a huge success in competition: the E30 M3. Introduced at the 1985 Frankfurt Motor Show, the M3 is the version developed by BMW Motorsport whose four-cylinder, four-valve per cylinder 2302 ci S14 double overhead cam engine was also based on the M10. It delivered 200 hp at 6750 rpm and achieved numerous titles in the various World Touring championships.

The M12 and M13 – its immediate evolution – continued in Formula 1 until 1986. With a pressure of 3.6 bars for the race, it delivered 850 hp. In qualifying, however, with a pressure of 5.5 bars, the power climbed up to 1300 hp, although many claim that they reached 1500 hp. BMW technicians never confirmed or denied this rumor: “we do not know for sure what the power is since our dynamometer supports up to 1200 hp…”.



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