Rising demand for compact, high output medium speed diesel
propulsion installations—particularly from cruise and ferry sectors—
stimulated Sulzer to introduce in 1995 a larger bore derivative to
complement the successful ZA40S engine. This 500 mm bore/
660 mm stroke ZA50S design extended the power range of the
programme to 21 600 kW at 450 rev/min from six, eight and nine inline
and V12-, 14-, 16- and 18-cylinder models (Figures 26.16 and
26.17). The ZA50S engine is no longer in the Wärtsilä programme, its
output range covered by the Wärtsilä 46 design.