BMW OHV V8 engine

Development

The BMW 501, which began production in 1952, was the first car produced by BMW after World War II. It was powered by the 2.0 L BMW M337 straight-six engine (based on the pre-war BMW M78 engine), which produced only 65 PS and struggled with the 1285 kg mass of the 501. The competing Mercedes-Benz W187 was powered by a larger 2.2 L engine, which provided superior performance.

However, BMW had been developing a V8 engine since 1949, which was produced in 2.6 L and 3.2 L capacities. The design was finalized by Fritz Fiedler when he returned to BMW in 1952.

In 1954, the V8 engine was introduced (in 2.6 Litre form) in the BMW 502 - a higher specification version of the 501. In 1955, the 3.2 Litre version of the engine was introduced in the BMW 3.2, which was based on the 502.

Design

At the time, unique features of the BMW OHV V8 included the aluminium construction of the block and head, and a coolant passage design that increased the block stiffness over typical engines with wet cylinder liners. The layout of the engine is a 90° V8 with cast iron wet liners and stiffening webs between the cylinders. Apart from the materials, the engine was similar in overall design to the Cadillac OHV V8 and Oldsmobile V8 engine of the late 1940s, with a central camshaft using pushrods to operating overhead valves in crossflow cylinder heads with wedge-shaped combustion chambers.

The 2580 cc versions have a bore of 74 mm and a stroke of 75 mm. Initially, this engine used a two barrel Solex 30 PAAJ carburettor, a compression ratio of 7.0:1 and had a power output of 100 PS.

The extra capacity of the 3168 cc version was achieved by increasing the bore to 82 mm. The larger engine initially used a single 32 mm Zenith carburettor, a compression ratio of 7.2:1 and produced 120 PS. The highest power output version of the BMW OHV V8 produced 160 PS and was used in the 3200 S released in 1961.

Versions

The following is a summary of the engine's versions.

M502/1

The original 2580 cc version of the engine was developed for the BMW 502 and was introduced with it in 1954. The compression ratio is 7.0:1 and it uses a Solex 30 PAAJ carburettor.

In 1958, the 501 V8 and 502 were renamed the 2.6 and 2.6 Luxus respectively, with no changes in engine specification.

Applications:

• 1954-1958 BMW 502 — 100 PS
• 1955-1958 BMW 501 V8 — 95 PS.
• 1958-1961 BMW 2.6 — 95 PS
• 1958-1961 BMW 2.6 Luxus — 100 PS

M502/100, M502/110 and M533

In the summer of 1961, the 2580 cc engines were uprated with the Zenith 32 NDIX carburetor from the earlier 3168 cc engines and a 7.5:1 compression ratio. With this upgrade, the 2.6 became the 2600 and the 2.6 Luxus became the 2600 L. These cars continued in production until December 1963

In 1963, the 2600 L was produced with the gearbox directly mounted to the engine. This version of the engine is known as the M533.

Applications:

• 1961-1963 BMW 2600 — 100 PS
• 1961-1963 BMW 2600L — 110 PS

M506/1

The 3168 cc engine was developed in 1956, and was offered in the 502-based "BMW 3.2" sedan. The compression ratio is 7.2:1 and it uses a Zenith 32 NDIX carburettor.

Applications:

• 1955-1961 BMW 3.2

M503/1 and M507/1

BMW's V8 sports models, the 503 and 507, used M503/1 and M507/1 engines respectively, each with a pair of Zenith 32 NDIX two-barrel carburetors. With these, and a compression ratio of 7.5:1, the 503's engine produced 140 PS at 5000 rpm. The tuning of the 507's engine went further, with high-lift cams, a different spark advance curve, polished combustion chamber surfaces, and a compression ratio of 7.8:1, producing 150 PS at 5000 rpm. Both models were discontinued in March 1959.

The twin-carburetor engine from the 503 was used in the 502-based 3.2 Super from 1957 to 1961.

Applications:

• 1956-1960 BMW 503 — 140 PS
• 1956-1959 BMW 507 — 150 PS
• 1957-1961 BMW 3.2 Super — 140 PS

M506/140, M503/160, M532 and M534

In 1961, the "BMW 3.2" and "BMW 3.2 Super" sedans were replaced by the "BMW 3200 L" and "BMW 3200 S" sedans, with the engines upgraded to the M506/140 and M503/160 respectively. The increase in power came from larger Zenith 36 NDIX carburetors and a compression ratio of 9.0:1.

From 1963, the versions of the M503/160 and M506/140 with the gearbox directly mounted to the engine were called the M532 and M534 respectively.

Production of V8 sedans ended in 1963, but the engine from the 3200 S was used in the 3200 CS coupé from January 1962 to September 1965.

Applications:

• 1961-1963 BMW 3200 L — 140 PS
• 1961-1963 BMW 3200 S — 160 PS
• 1961-1965 BMW 3200 CS — 160 PS

Use by other manufacturers

Frazer-Nash Continental

Main article: Frazer-Nash

Frazer-Nash was an importer of BMW cars into the United Kingdom and had used the Bristol straight-six engine, which was based on the BMW M328. The BMW OHV V8 was fitted to the Frazer Nash Continental model. The Continental was intended to be available with either the 2.6 or 3.2-litre V8, but only a single prototype was ever made, with the 3.2 engine. It was the last car Frazer-Nash made.

Talbot-Lago America

Main article: Talbot-Lago

The 1955 Talbot-Lago Sport was originally powered by Talbot's own 2.5 Litre four-cylinder engine. In 1957, due to reliability problems, Talbot switched over to the BMW OHV V8 and renamed the car the Talbot-Lago America. Talbot reduced the bore to 72.5 mm to keep the engine displacement beneath 2.5 litres, a major tax threshold in France at the time.

References

References

1. "BMW 502 saloon model selection".
2. Noakes, Andrew. (2005). "The Ultimate History of BMW". Parragon Publishing.
3. "1952 BMW 501".
4. Norbye, Jan P.. (1984). "BMW - Bavaria's Driving Machines". Publications International.
5. Lange, Karlheinz. (2000). "BMW Dimensions: The History of Engines - Engines That Made History 1945-2000".
6. "BMW Classic- Recherche-Client".
7. "BMW 501 V8 / 502".
8. "BMW 502 Limousine".
9. "Betribsanleitung BMW 2600, 2600 L, 3200 L, 3200 S".
10. (21 October 2015). "Snapshot From 1960".
11. (2004). "Standard Guide to British Sports Cars". Krause Publications.
12. "Lost Marques: Talbot Lago".