M50B25

The M50B25 is an inline-six cylinder internal combustion engine produced by BMW. It belongs to the M50 engine family and was manufactured from 1989 to 1995. This engine is widely recognized for its smooth operation and strong performance characteristics, making it a popular choice in various BMW models during its production run.

The M50B25 features a displacement of 2.5 liters (2494 cc) and utilizes a dual overhead camshaft (DOHC) design with four valves per cylinder. It was available in both 2.5i and a more powerful 2.5i variants, often distinguished by their internal specifications or tuning. The engine block is typically constructed from cast iron, while the cylinder head is made of aluminum. Key technologies employed include a Bosch Motronic engine management system and often Vanos, BMW's variable valve timing system, which was introduced in later versions of the M50 series.

This engine powered several BMW models, including the E34 5 Series (525i) and the E36 3 Series (325i, 325is, 325ix). Its robust construction and responsive power delivery contributed to BMW's reputation for producing engaging driving experiences. The M50B25 is still held in high regard by enthusiasts and tuners for its reliability and potential for modification, often serving as a base for performance upgrades.