The BMW M10 is a SOHC inline-4 petrol engine which was produced by BMW from 1962-1988. It was the company's first four-cylinder engine since the BMW 309 ended production in 1936 and was introduced in the New Class sedans. The M10 was used in many BMW models, with over 3.5 million being produced during its 26 year production run. The turbocharged BMW M12 engine— used in the Formula One racing— was based on the M10 engine block and produced up to in qualifying trim. Following the introduction of the BMW M40 engine in 1987, the M10 began to be phased out. Development Baron Alex von Falkenhausen— an engineer and racing driver— designed the M10 . In the late 1950s, he was asked to design an engine with a displacement of , however he felt that this would be insufficient for the company's future needs. Therefore, he convinced BMW that the capacity should be instead and he designed a block that could be expanded to in the future. Design The M10 has a cast iron block and an aluminum alloy head with hemispherical combustion chambers and two valves per cylinder. It features a forged crankshaft, counterbalance weights, five main bearings and a chain-driven camshaft. The initial version of the M10 had a bore of and a stroke of , resulting in a displacement of . The peak power rating was . Naming conventions The engine was initially known as the "M115" (the last two digits representing the 1.5–litre capacity). Over the years, variants of the engine were given various codes (most of them starting with "M1" and the remaining digits relating to the capacity). In 1975, the engine became known as then "M10", then in 1980 it was given the standardised BMW engine code of M10B18 (where "M10" represents the series, B represents petrol (Benzin in German) and the "18" represented its then 1.8–litre capacity). The M115 and all related engines have become retroactively known as the "M10" family. Versions 1499 cc engines The M115 version has a displacement of and produces . It has a bore of and a stroke of . Lower power models have a compression ratio of 8.0:1, while higher power models have a compressions ratio of 8.8:1. Fuel is supplied via a Solex 38 PDSI carburettor. Applications: 1962-1964 BMW 1500 1975-1977 BMW 1502 1573 cc engines The M116 version has a displacement of and produces .