The BMW M328 is an overhead valve straight-six petrol engine which was produced from 1936 to 1940. It was a high-performance development of the BMW M78 engine that was produced alongside the M78.
Compared with the M78, the M328 has an aluminium cross-flow cylinder head with hemispherical combustion chambers.
The M328 was used in the BMW 328 and BMW 327/28 coupes.
After World War II the engine was also licensed to Bristol Cars in the United Kingdom.
DesignThe M328 had an unusual valvetrain design; although the camshaft is located in the engine block, the exhaust valves are actuated by a transverse pushrod from the intake valves. This results in a valve layout similar to a DOHC engine.
With a bore of 66 mm and a stroke of 96 mm, the displacement was 1971 cc, the same as its M78 predecessor. Fuel supply was via three Solex "30 JF downdraft" carburetors.
The M328 engine has a compression ratio of 7.5:1 and produces 59 kW at 5000 rpm.