The BMW M50 is a straight-6 DOHC petrol engine which was produced from 1990 to 1996. It was released in the E34 520i and 525i, to replace the M20 engine.
In September 1992, the M50 was upgraded to the M50TU ("technical update"), which added variable valve timing to the intake camshaft (called single VANOS by BMW).
The M50 began to be phased out following the introduction of the M52 engine in 1994.
The E36 M3 is powered by the S50 engine series, which is a high output version of the M50.
Video BMW M50
Design
A significant advance over its M20 predecessor, the M50 features dual overhead camshaft (DOHC) with 4 valves per cylinder (the M20 has a single overhead camshaft with 2 valves per cylinder), coil-on-plug ignition, a knock sensor and a lightweight plastic intake manifold. Both engines use an iron block with an aluminum alloy head. The redline is 6,500 rpm (except for S50 models), the same as the final version of the M20.
The location of the oil pan (sump) varies according to the model the M50 is installed in. It is in the front on the E34 5 Series (like the M20);, in the rear on the E36 3 Series.
Maps BMW M50
Models
M50B20
The 1,991 cc (121 cu in) M50B20 was introduced with the 1990 520i. It has an 80 mm (3.1 in) bore and 66 mm (2.6 in) stroke and produces 110 kW (150 hp). The compression ratio is 10.5:1.
Applications:
- 1990-1992 E34 520i
- 1991-1992 E36 320i
M50B20TU
The M50B20 was updated with single VANOS in 1992. The compression ratio was raised to 11.0:1. Peak torque became available at 4200 rpm.
Applications:
- 1992-1994 E36 320i
- 1992-1996 E34 520i
M50B24
This is a 2.4 L engine used in the Thailand and Oceania markets. It is based on the 2.5 L M50B25 with the stroke reduced to 72 mm (2.8 in).
M50B25
The 2,494 cc (152 cu in) M50B25 was introduced with the 1990 525i and 525ix. It has an 84 mm (3.3 in) bore and 75 mm (3.0 in) stroke and produces 141 kW (189 hp) at 6000 rpm and 245 N?m (181 lb?ft) at 4700 rpm. The compression ratio is 10.0:1.
Applications:
- 1990-1992 E34 525i, 525ix
- 1991-1992 E36 325i, 325is
M50B25TU
The M50B25 was updated with single VANOS in 1992, resulting in peak torque becoming available at 4200 rpm. The compression ratio was increased to 10.5:1.
Applications:
- 1993-1995 E36 325i, 325is
- 1992-1996 E34 525i, 525ix
S50
The S50 is the high performance version of the M50 which was used in the M3. Like the M50, it has an iron block and aluminum head with four valves per cylinder.
S50B30
The S50B30 is a 2,990 cc (182 cu in) higher output version of the M50 which powered the E36 M3, except in the United States. In Canada, BMW officially imported 45 M3s produced in late 1993 with the S50B30 engine.
The S50B30 produces 210 kW (282 hp), has a bore of 86 millimetres (3.4 in), a stroke of 86 millimetres (3.4 in) and a compression ratio of 10.8:1. The redline is 7,600 rpm. The S50 has an individual throttle body for each cylinder, variable valve timing (called "VANOS" by BMW) on the intake camshaft, Motronic M3.3 engine management and redesigned intake and exhaust systems.
The limited edition "M3 GT" model from 1995 produced 220 kW (295 hp). It had different camshafts and a redesigned sump and oil pump.
Applications:
- 1992-1995 E36 M3 (except for US)
S50B30US
In the United States, the 1994-1995 M3 is powered by a 3.0 L tuned version of the M50 which produces 179 kW (240 hp). This engine was based on the M50B25TU and uses the same compression ratio, but uses a different crankshaft, connecting rods, and pistons. The bore is 86 mm (3.4 in), stroke is 86 mm (3.4 in) and the redline is 6,500 rpm.
In 1996, the S50B30US was replaced by the 3.2 L S52 (in the United States and Canada only).
Applications:
- 1994-1995 E36 M3 (US only)
S50B32
In 1996, the S50B32 replaced the S50B30 (except in Canada and the United States, where the S52 engine was used instead). Power output increased to 239 kW (321 hp). and the displacement increased to 3,201 cc (195 cu in), due to an increased stroke of 91 mm (3.6 in) and a slight increase in bore to 86.4 mm (3 in).
Variable valve timing is fitted to both camshafts and a secondary oil pick-up was added (from the "M3 GT" version of the S50B30). The compression ratio is 11.3:1 and the redline is 7,400 rpm. Engine management is provided by a Siemens MSS50, with 3 knock sensors.
Applications:
- 1996-1999 E36 M3 (except Canada and the United States)
- 1996-1999 Z3 M Coupe and M Roadster (except Canada and the United States)
See also
- BMW engines
- BMW M20
- BMW M52
References
Source of the article : Wikipedia
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