Abstract: The invention relates to an engine housing (4) with a cylinder block (6) and a cylinder head unit (5) comprising a head portion (8) and at least one integrally cast cylinder portion (9) with an internally lying piston bearing surface (11). The cylinder portion (9) of the cylinder head unit (5) can be pushed at least partially in the axial direction of the cylinder portion (12) into the cylinder block (6). The cylinder head unit (5) can also be clamped in the axial direction of the cylinder portion (12) against the cylinder block (6) by means of at least one fixing element (23).