A simple word about the BMW diesel engine

The term diesel engine refers to an internal combustion engine that uses heat of compression to initiate cylinder ignition to burn the fuel injected into the combustion chamber. This is different from spark ignition engines, such as gasoline engines, which rely on spark plugs to ignite the air-fuel mixture. The engine has the highest thermal efficiency of any other external or internal combustion engine due to the very high compression ratio required to ignite the fuel. All diesel engines are modeled after the thermodynamic diesel cycle developed by Rudolf Diesel in 1897.

Explaining how an engine works is a complex process. Initially only air can enter the combustion chamber, then this air is compressed to a ratio of about 15: 1 to 22: 1 and the temperature of the air in the cylinder rises to about 550c or 1022f. At the top of the compression stroke, fuel is injected into the compressed air in the combustion chamber. The heat from compression evaporates the fuel and causes combustion. The rapid expansion of the combustion gas drives the piston downwards to power the crankshaft. The crankshaft drives the pistons of another cylinder upwards to repeat the process and keep the engine running continuously.

BMW introduced the 2.4-liter M21 in-line 6-cylinder engine in 1983 and began using the engine in vehicles. This first version was not available in the United Kingdom and was primarily sold at Lincoln Continental in North America.

In 1994, a new engine from BMW was announced. This engine was an M41 1.7 liter in-line 4-cylinder engine. This engine was available on the 1994-2000 E36 318tds BMW.

In 1998, BMW added three different engines. The 2.0 liter M47 was a straight 4, followed by a straight 6 M57 in the 2.5 to 3.0 liter range, and finally a 3.9 liter M67. v8 configuration. M67 has won two International Engine of the Year awards.

In 2006, the 2.0-liter in-line 4-cylinder N47 was launched. This latest version, known as the Common Rail Engine, has significantly improved emissions and fuel efficiency.

In 2008 BMW introduced the N57 engine. It was a 2.5- to 3.0-liter in-line 6-cylinder engine. These engines were common rail engines with turbochargers.

Some of the engines listed are still in production, such as the N57, M57 and N47. BMW has tuned its diesel engine line to be as environmentally friendly as or even better than gasoline products from other manufacturers.