Engine identification

Engine number at the marked surface.

Replacement drives are already assigned a number containing the identification and engine number at the factory.

The old drive number must be imprinted for replacement crankcases.

Magnesium crank cases feature a label, the engine number does not need to be embossed.

N20: 

Fig 1: Engine Identification (N20/N26)

Courtesy of BMW OF NORTH AMERICA, INC.

N55: 

Fig 2: Engine Identification (N51/N52/N52K/N52T/N53/N54/N55)

Courtesy of BMW OF NORTH AMERICA, INC.