A compressor (22) has: a case (32) defining: a first cylinder bank (70) having a plurality of cylinders (76, 77); a cylinder head (100); a suction port (26); a discharge port (28); and an economizer port (30); a plurality of pistons, each individually associated with a respective one of the cylinders; and a crankshaft (202) held by the case for rotation about a crankshaft axis and coupled to the pistons. The first cylinder bank cylinder head is divided into: a first suction chamber (130); a second suction chamber (132); and a single discharge chamber (128). The first cylinder bank first suction chamber is coupled to the suction port. The first cylinder bank second suction chamber is coupled to the economizer port. The first cylinder bank discharge chamber is coupled to the discharge port.