BMW M500, the first aluminium V8s born 70 years ago

The BMW M501-507 engines are a family of aluminium V8 engines built for large saloon and sports cars.

By: Filippo Einaudi

Oct 21, 2023 at 1:00am ET

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Whilst for Mercedes-Benz the tradition of V8 engines began in the 1960s, more precisely in 1963, with the powerful 6.3-litre of the 600, for rivals such as BMW the first approach to eight-cylinder engines was even earlier.

In fact, the Munich-based company developed its first V8 family no less than 10 years earlier, to set a higher tone for saloons and sports cars, as the six-cylinder engines available after the war, good as they were, still dated from the golden pre-war years.

The 'OHV' series

BMW's V8 blocks were referred to by the abbreviation OHV, indicating the presence of a single central camshaft. Production of these engines began in 1954, although the project started a few years earlier.

The aim was to raise the power level of the new representative cars, i.e. the flagship 501 and 502, but also the later sports cars, by overcoming the physical limits of the six-cylinder which would have required excessive increases in displacement. At the same time, however, the aim was not to exceed the weight, which is why the new V8s were produced for the first time in history (and not only those of BMW) with crankcases and cylinder heads made of aluminium.

BMW M502-1 1955

The engine, which had a 90° V-architecture and two valves per cylinder driven by connecting rods and rocker arms, was developed in two displacement variants, a 2.6-litre and a 3.2-litre, with a bore of 74 mm and 82 mm, respectively. The stroke was the same at 75 mm, making the former almost 'square'. Both came in different power variants with different codes depending on the model for which they were intended.

BMW 502 2.6L from 1954

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From flagships to coupés

The 2.6-litre engine debuted in an initial 100 bhp version called the M502/100, which found its way under the bonnet of the 502, the more luxurious and refined version of the 501, in 1954. Soon after, it was 'decaffeinated' to 95 bhp (M502/1) and was also offered in the simpler 501, while the 502 received its first 120 bhp 3.2 (M506/1).

BMW M502-1 1955

In 1958, the 2.6 became the only option available for the 501, which then changed its name to the BMW 2.6, and similarly the 502 was renamed BMW 3.2 and fitted with the most powerful unit, featuring the supercharged variant with 140 bhp.

In 1961, when the models were renamed BMW 2600 and BMW 3200, the 100 bhp 2.6 was offered with a second version called 'L', delivering 110 bhp.

At the same time, the 140 bhp 3.2 V8 was also fitted in the 503 and 507 sports cars. The 503 Coupé and Cabriolet started in 1956 directly with the 140 bhp version of the 3.2, which in fact carried the 503/1 badge. For the special 507 Roadster, however, an even more powerful 150 bhp version arrived, also in 1956, with the 507/1 badge.

M506 en el BMW 3200 CS Coupé de 1961

BMW M534 en el 3200 CS 1963

The last act in the history of BMW's 'OHV' family came at the end of 1962, when the 3.2 engine (M506) took its place under the bonnet of the new 3200 S/CS coupé. From 1963, this unit was revised in structure and fitted together with the gearbox (M534). In the mid-1960s, BMW returned to six-cylinder development, so the V8 blocks were temporarily shelved. They did not reappear until the early 1990s with the 3.0-litre and 4.0-litre M60 range in the 5 and 7 Series.