The BMW M337 is a

straight-6 The straight-six engine (also referred to as an inline-six engine; abbreviated I6 or L6) is a piston engine with six cylinders arranged in a straight line along the crankshaft. A straight-six engine has perfect primary and secondary engine bal ...

OHV An overhead valve (OHV) engine, sometimes called a ''pushrod engine'', is a piston engine whose valves are located in the cylinder head above the combustion chamber. This contrasts with earlier flathead engines, where the valves were located bel ...

petrol engine installed at a slanted angle which was produced in three variants (M337/1, M337/2 and M337/3) from 1952-1958. Built to power BMW's first new car after World War II, the M337 engine was a replacement for the

BMW M78 The BMW M78 is an overhead valve straight-six petrol engine which was produced from 1933 to 1950. It is the first straight-6 automobile engine produced by BMW, an engine layout which has been a key feature of the brand for many years since. The M ...

Design

Compared with its M78 predecessor, the M337 features a revised

cylinder head In an internal combustion engine, the cylinder head (often abbreviated to simply "head") sits above the cylinders and forms the roof of the combustion chamber. In sidevalve engines, the head is a simple sheet of metal; whereas in more modern ov ...

, a new

inlet manifold In automotive engineering, an inlet manifold or intake manifold (in American English) is the part of an engine that supplies the fuel/air mixture to the cylinders. The word '' manifold'' comes from the Old English word ''manigfeald'' (from th ...

and a reinforced

crankshaft A crankshaft is a mechanical component used in a piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating shaft containing one or more crankpins, that are driven by the pistons via the connecting ...

with bigger, more modern bearings. As per the M78, the M337 has an iron

engine block In an internal combustion engine, the engine block is the structure which contains the cylinders and other components. In an early automotive engine, the engine block consisted of just the cylinder block, to which a separate crankcase was atta ...

, an iron

and

overhead valves An overhead valve (OHV) engine, sometimes called a ''pushrod engine'', is a piston engine whose valves are located in the cylinder head above the combustion chamber. This contrasts with earlier flathead engines, where the valves were located bel ...

with two valves per cylinder.

Versions

M337/1

The first version of the M337 engine has a displacement of . It produces at 4,400 rpm and at 2,000 rpm. Applications: * 1952-1954

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M337/2

In 1954, a revised engine was released which produced at 4,400 rpm and at 2,500 rpm. The compression ratio for this engine is 6.8:1. Applications: * 1954-1955 501A * 1954-1955 501B

M337/3

The final version of the M337 had an increase in

bore Bore or Bores often refer to: *Boredom * Drill Relating to holes * Boring (manufacturing), a machining process that enlarges a hole ** Bore (engine), the diameter of a cylinder in a piston engine or a steam locomotive ** Bore (wind instruments), ...

of , which increased displacement to . The

compression ratio The compression ratio is the ratio between the volume of the cylinder and combustion chamber in an internal combustion engine at their maximum and minimum values. A fundamental specification for such engines, it is measured two ways: the stati ...

was also increased to 7.0:1. Despite these changesm the M337/3 produced no more power than the previous version. However torque increased to at 2,500 rpm. Applications: * 1955-1958 501/3

References

{{BMW automotive petrol engines: 1940s to 1960s BMW engines Straight-six engines Slant engines Gasoline engines by model