BMW 525i FACTORY SERVICE REPAIR MANUAL FSM 1990 1991 1992 1993 1994 1995 1996 ONLINE DOWNLOAD
BMW 525i – 2.5 L M50B25 I6 192 PS (141 kW; 189 hp)
The 525i was built throughout the E34 production, and in 1992 was offered as a wagon (touring version) in the USA. In June 1990 (1991MY), the engine was switched from the single overhead cam M20 engine to the double overhead cam M50B25 engine, raising power from 170 to 192 horsepower (141 kW). Also, fuel economy by ten percent, and a change from a timing belt to a timing chain improved reliability. A further revision of the 525i engine took place in 1993, when VANOS was added to the M50 engine which was designated the M50TU. The TU represents a Technical Update, reflecting the variable valve timing technology (VANOS) added to the intake camshaft. VANOS brought no horsepower increase, but flattened the torque curve from about 3,000 rpm up to redline at approximately 6,300 rpm. M50 engine was the most popular variant sold in NA. Since models equipped with M50 engine lack power found in M30, M60b40 or S38 engines, many performance upgrades are available. For instance, for mere few hundred dollars, owners can install an aftermarket ECU chip to improve performance and even gain some fuel economy. Owners looking for a real upgrade in power have gone towards forced induction or an engine swap. Most popular engine swap is S50, and S52 found in E36 M3 and other M cars. They require very little modification to fit in 525i models.