What are the differences between the S50 and S54 engines?
The S54 powerplant of the later M roadsters is technically an evolution of the iron-block S50 B32 unit that is found in later Eruopean-spec E36 M3s, as well as all European-spec M roadsters and M coupes built through June of 2000. The two motors develop similar peak power ratings: 321 hp (DIN) at 7,400 rpm and 258 lb/ft of torque at 3,250 rpm for the S50 versus 325 hp (DIN) at 7,400 rpm and 261 lb/ft of torque at 4,900 rpm for the S54. However, they share few major components and differ in the following areas: -Increased cylinder bore to 87mm (from 86.4mm) for a new total displacement of 3,246cc (from 3,201cc) -Modified camshafts -High pressure Double VANOS continuously variable valve timing system with faster operation at high rpm -Increased compression to 11.5:1 (from 11.3:1) -More advanced BMW/Siemens MSS 54 engine management control -Finger-type rocker arms for reduced reciprocating mass and friction -One-piece aluminum head casting for lighter weight -Scavenging oil pump to mainta
