TLDR: The BMW N20 engine is a turbocharged four-cylinder engine that was produced by BMW from 2011 to 2017. It replaced the N53 engine and was known for its power and efficiency.

The BMW N20 engine is a type of internal combustion engine that is used in BMW vehicles. It is a four-cylinder engine, which means it has four cylinders where the fuel is burned to create power. The N20 engine is special because it is turbocharged, which means it has a device called a turbocharger that helps to increase the power output of the engine. This makes the N20 engine more powerful and efficient than non-turbocharged engines.

The N20 engine comes in two different sizes: 1.6 liters and 2.0 liters. The size of the engine is measured in cubic centimeters (cc) or cubic inches (cu in). The larger the size, the more power the engine can produce. The N20 engine also has a variable valve lift and variable valve timing, which helps to optimize the engine's performance at different speeds and loads.

One of the key features of the N20 engine is its twin-scroll turbocharger. This type of turbocharger helps to improve the engine's responsiveness and efficiency by separating the exhaust gases from different cylinders. The N20 engine also has other advanced technologies, such as direct injection, automatic stop-start, and an electric water pump, which further enhance its performance and fuel efficiency.

While the N20 engine was praised for its power and efficiency, it did have some issues. Early production models of the N20 engine were found to have faulty internal plastic timing chain guides, which could cause catastrophic engine damage. As a result, a class action lawsuit was filed against BMW by owners seeking compensation for the faulty engines. BMW attempted to dismiss the lawsuit, but the court ruled that the lawsuit could proceed.

Overall, the BMW N20 engine was a powerful and efficient turbocharged four-cylinder engine that was used in BMW vehicles from 2011 to 2017. It offered a balance of performance and fuel efficiency, but it also had some issues with faulty timing chain guides.