BMW M20 is the internal name for a series of internal combustion engines ( gasoline engines ) from BMW.
The M20 is a six-cylinder in-line engine with 2 to 2.7 liters of displacement. It was developed in the mid 1970s as a "small " six-cylinder, as the built starting in 1968 "big" six-cylinder M30 was not suitable because of its dimensions for the BMW 3 Series. The M20 was first used under the designation M60 ( according to the old version number system ) from 1977 320 ( E21) and 520 ( E12). The M20 replaced the BMW 3 Series and 5 Series built since 1961 four-cylinder engines M10 with two liters of displacement, which were until 1987 for the smaller displacements continue in the program.
The M20 was produced up to the attitude of the E30 convertible 1993. Successor was built in 1990 and significantly more modern BMW M50 six-cylinder engine with four-valve technology.
For the first time in the BMW overhead camshaft was driven by toothed belt instead of chain. The cam shaft in the cross-flow cylinder head from an aluminum alloy is operated via rocker arms each two V- shaped overhead valves per cylinder. The engine block is made of cast iron.
For mixture preparation to start serving depending on the age, size and series a carburetor ( 320/6 and 520 /6) and later a mechanical (K- Jetronic) or electronic ( L-Jetronic/Motronic ) fuel injection in the models 320i/323i / 325i/520i/525i. It gave him in a variety of size variants, ranging from 2.0 l to 2.3 l and 2.5 l to 2.7 l ( 325eta/525eta ) and outputs of 90 kW (122 hp) to 125 kW ( 171 hp). Alpina, Schnitzer and Hartge offered the engine with enhanced performance with up to 210 hp.
Hallmark of this unit with fuel injection is the cast intake manifold and the realized resonance air intake system, in which the natural vibration of the air column acts in a narrow speed range as a slight charge. This intake manifold differs only minimally in the engine capacity variants. Larger, although not at first glance visible changes she experienced at the eta versions. Characteristic of the motor series is also the drive of the overhead camshaft by means of toothed belt instead of the chain drive normally used.
Made famous are the engines of the M20 series by its silky smooth, turbine-like, absolutely vibration-free operation. The M20 is valid, regular maintenance and slow warm-up provided as a durable motor. However, he was also known for his two weak points in the negative sense: On the one hand, the toothed belt camshaft drive, which quickly tears at neglected maintenance, on the other hand tends to the cylinder head of the line six cylinder under non-uniform heating through cracks in the camshaft bearing between the 5th and 6th cylinder and continuing to the inlet valve of the fifth cylinder into the water channel.
Is interesting to compare the same time offered in the E30 or E28 injection versions between the displacement weakest with 2.0 liter and the cubic capacity, but not the most powerful version with 2693 cc, since both have the same about performance, but an entirely different engine characteristics. Initially 520i and the 525e 92 kW/125 hp were offered only the high -compression engines without factory the intended catalyst in 320i. These versions can be identified by the single-flow exhaust system just like the later introduced, provided for the use of catalyst and the slightly compressed versions with 90 kW/122 hp in the 325e and 525e.
(Available only to large facelift 1987 325e ) in E30 Near the end of the insert and E28 low density versions with 95 kW (129 hp) in 320i/325e or 520i/525e were also prepared. They are recognizable by the double-flow exhaust system. Due to the large displacement, the eta version has a significantly higher torque at low speeds. The maximum value of 178 Nm of the 2.0-liter engine reaches the 2.7L offered already below 1000 revolutions per minute, the maximum value is 240 Nm at 3250/min and thus roughly at the height of his time in the 528i or 728i "big " M30 six-cylinder engine with 2.8 liter displacement, but which reached a significantly higher power ( 135 kW/184 hp at 5400/min ). By designing to more displacement, but lower speeds, the motor can be driven very sparingly. Since it does not correspond to the typical BMW character of variable speed motors joyful, the market success of the 325eta model was limited (number of items: 175 508 ).
Was derived from the M20 diesel engine BMW M21 2443 cc. These, there were in the normal Saugvariante with 63 kW/86 hp in the E30 324d and the E28 524d. The supercharged turbo version with 85 kW/115 hp was offered in the E30 324td Touring, E28/E34 524td.
Also 2.7 liters had the rare Alpina C2 and B3 installed M20 versions.
The M20 was from May 1990 at BMW E34 ( 520i/525i ) replaced by the M50 engine with hydraulic tappets and the camshaft chain drive, the main innovation was the four-valve technology and the increase in output associated with it.
The M20 was used in the E30 sedan and 1991 and in a convertible and touring until 1993.
The E30 - E36 successor received already from the start of production 11/1990 M50 engines with 2.0 and 2.5 liter displacement in the models 320i and 325i.
1984-1987 M20 Bosch Motronic M1.0 - M20 1987-1991 Bosch Motronic M1.1 - M20 1987-1991 Bosch Motronic M1.3
- BMW engine
- Motor model ( series motor)