M20B20

The M20B20 is an inline-six cylinder gasoline engine produced by BMW. It is part of the M20 engine family, which was widely used in BMW models during the 1980s and early 1990s. The "20" in M20B20 refers to its approximate displacement of 2.0 liters.

This engine features a cast-iron block and an aluminum cylinder head. It utilizes a single overhead camshaft (SOHC) to operate its two valves per cylinder. Early versions of the M20B20 were equipped with carburetors, but later models transitioned to Bosch L-Jetronic fuel injection systems. The engine's bore and stroke are designed to achieve its 1990 cc displacement.

The M20B20 was commonly found in entry-level and mid-range BMW models of its era, such as the E21 3 Series, E30 3 Series, and E28 5 Series. It was known for its smooth operation and reliability, characteristic of BMW's inline-six designs. While not the most powerful engine in the M20 family, it offered a good balance of performance and fuel efficiency for its intended applications. It was eventually succeeded by newer engine families as BMW evolved its lineup.