BMW M50

BMW M50 engine
Overview
Production	1990–1996
Layout
Configuration	Straight-6
Displacement	1,991 cc (121 cu in) 2,394 cc (146 cu in) 2,494 cc (152 cu in)
Cylinder bore	80 mm (3.1 in) 84 mm (3.3 in)
Piston stroke	66 mm (2.6 in) 72 mm (2.8 in) 75 mm (3.0 in)
Cylinder block material	Cast iron
Cylinder head material	Aluminium
Valvetrain	DOHC, VVT ("TÜ" versions only)
Combustion
Fuel type	Petrol
Chronology
Predecessor	BMW M20
Successor	BMW M52

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.^[1]

In September 1992, the M50 was upgraded to the M50TÜ (Technische Überarbeitung, "technical revision"). This was BMW's first engine to use variable valve timing.^[2] Called single VANOS by BMW, the system adjusted the phasing of the intake camshaft.^[3]

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.

A significant advance over its M20 predecessor, the M50 features dual overhead camshaft (DOHC) with four 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.^[4] Both engines use an iron block with an aluminum alloy head.^[5] The redline is 6,500 rpm for the M50B25 and 6,750 rpm for the M50B20 (7,000 rpm 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),^[6] whereas it is in the rear on the E36 3 Series.^[7]

Engine	Displacement	Power	Torque	Years
M50B20	1,991 cc (121.5 cu in)	110 kW (150 PS; 148 hp) at 6,000 rpm	190 N⋅m (140 lb⋅ft) at 4,700 rpm	1990-1992
M50B20TÜ		110 kW (150 PS; 148 hp) at 5,900 rpm	190 N⋅m (140 lb⋅ft) at 4,200 rpm	1992-1996
M50B24TÜ	2,394 cc (146.1 cu in)	138 kW (188 PS; 185 hp) at 5,900 rpm	240 N⋅m (177 lb⋅ft) at 4,200 rpm
M50B25	2,494 cc (152.2 cu in)	141 kW (192 PS; 189 hp) at 6,000 rpm	245 N⋅m (181 lb⋅ft) at 4,700 rpm	1990-1992
M50B25TÜ		141 kW (192 PS; 189 hp) at 5,900 rpm	250 N⋅m (184 lb⋅ft) at 4,200 rpm	1992-1996
S50B30 (EU)	2,990 cc (182.5 cu in)	210 kW (286 PS; 282 hp) at 7,000 rpm[a]	329 N⋅m (243 lb⋅ft) at 3,500 rpm	1992-1995
S50B30 (US)		179 kW (243 PS; 240 hp) at 6,000 rpm	305 N⋅m (225 lb⋅ft) at 4,250 rpm	1994-1995
S50B30GT		217 kW (295 PS; 291 hp) at 7,100 rpm	323 N⋅m (238 lb⋅ft) at 3,900 rpm	1994-1995
S50B32	3,201 cc (195.3 cu in)	236 kW (321 PS; 317 hp) at 7,400 rpm	350 N⋅m (258 lb⋅ft) at 3,250 rpm	1995-2000

The 1,991 cc (121.5 cu in) M50B20 was introduced with the 1990 520i. It has a bore of 80 mm (3.15 in), a stroke of 66 mm (2.60 in) and produces 110 kW (148 hp). The compression ratio is 10.5:1.^[8]

Applications:

• 1990-1992 E34 520i
• 1991-1995 E36 320i

The M50B20 was updated with single VANOS in 1992. Peak torque became available at 4,200 rpm.^[8] It produces 110 kW (148 hp) at 5,900 rpm and 190 N⋅m (140 lb⋅ft) at 4,200 rpm. The compression ratio was raised to 11.0:1.

Applications:

• 1992-1994 E36 320i
• 1992-1996 E34 520i

This is a 2,394 cc (146.1 cu in) engine used in the Thailand and Oceanian markets.^[9] It is based on the 2,494 cc (2.5 L) M50B25TÜ with the stroke reduced to 72 mm (2.83 in) and produces 138 kW (185 hp) at 5,900 rpm and 240 N⋅m (177 lb⋅ft) at 4,200 rpm. The compression ratio is 10.5:1.

Applications:

• 1993-1995 E36 325iA/2.4
• 1992-1996 E34 525iA/2.4

The 2,494 cc (152.2 cu in) M50B25 was introduced with the 1990 525i and 525ix. It has a bore of 84 mm (3.31 in), a stroke of 75 mm (2.95 in) and produces 141 kW (189 hp) at 6,000 rpm and 245 N⋅m (181 lb⋅ft) at 4,700 rpm.^[8] The compression ratio is 10.0:1.

Applications:

• 1990-1992 E34 525i, 525ix
• 1991-1992 E36 325i, 325is

The M50B25 was updated with single VANOS in 1992, resulting in peak torque becoming available at 4,200 rpm. It produces 141 kW (189 hp) at 5,900 rpm and 250 N⋅m (184 lb⋅ft) at 4,200 rpm.^[8] The compression ratio was increased to 10.5:1.

Applications:

• 1993-1995 E36 325i, 325is
• 1992-1996 E34 525i, 525ix

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In 1993, BMW Individual created a concept of BMW E34 530iX called Enduro Touring. Only one car was produced, having an up-sized variant of M50B25TÜ engine. Bore and stroke was increased and the total displacement of 3.0 was achieved. The power and torque both increased to 181 kW (243 hp) and 316 N⋅m (233 lb⋅ft) respectively.

BMW S50 engine
Overview
Production	1992–2000[10]
Layout
Configuration	Straight-6
Displacement	2,990 cc (182 cu in) 3,201 cc (195 cu in)
Cylinder bore	86 mm (3.4 in) 86.4 mm (3.40 in)
Piston stroke	85.8 mm (3.38 in) 91 mm (3.6 in)
Cylinder block material	Cast iron
Cylinder head material	Aluminium
Valvetrain	DOHC, with VVT
Combustion
Fuel type	Petrol
Chronology
Predecessor	None
Successor	BMW S54

The S50 is the high performance version of the M50 which was used in the E36 M3, replacing the four-cylinder BMW S14 engine used in the E30 M3. Like the M50, the S50 has an iron block and aluminum head with four valves per cylinder.

In the United States, a less powerful engine called the "S50B30US" was used, which shares more in common with the regular M50 engine than the other S50 versions.

The S50B30 was used in most countries, except for the United States (in 1993, BMW Canada officially imported 45 M3's with the S50B30 engine).^[11][12] The S50B30 produces 210 kW (282 hp), has a bore of 86 mm (3.39 in), a stroke of 85.8 mm (3.38 in) and a compression ratio of 10.8:1.^[13][14] The redline is 7,200 rpm. The S50 has an individual throttle body for each cylinder, single-VANOS (variable valve timing on the intake camshaft), Bosch Motronic M3.3 engine management and redesigned intake and exhaust systems.^[11][15]

The limited edition "M3 GT" model from 1995 produced 220 kW (295 bhp).^[11] It had different camshafts and a redesigned sump and oil pump.

Applications:

• 1992-1995 E36 M3 (except for U.S.)

In the United States, the 1994-1995 model years of the E36 M3 are powered by the S50B30US, a 2,990 cc (182.5 cu in) engine which produces 179 kW (240 bhp).^[11][16] This engine is more closely related to the standard M50 engine and has the same compression ratio as the M50B25TÜ,^[11] but uses a different camshafts, crankshaft, connecting rods, and pistons. The bore is 86 mm (3.39 in), the stroke is 85.8 mm (3.38 in) and the redline is 7,000 rpm.^[17]

In 1996, the S50B30US was replaced by the BMW S52 engine (in the United States and Canada only).^[18]

Applications:

• 1994-1995 E36 M3 (U.S. only)

In 1995, the S50B32 replaced the S50B30 (except in Canada and the United States, where the BMW S52 engine was used instead).^[19] Power output increased to 236 kW (321 hp)^[20] and the displacement increased to 3.2 L; 195.3 cu in (3,201 cc), due to an increased stroke of 91 mm (3.58 in) and a slight increase in bore to 86.4 mm (3.40 in).^[21]

The S50B32 has double-VANOS (variable valve timing on both camshafts) and a secondary oil pick-up was added.^[22] The compression ratio is 11.3:1 and the redline is 7,600 rpm.^[23] Engine management is the Siemens MSS50, with 3 knock sensors.

Applications:

• 1995-1999 BMW M3 (E36) (except Canada and the United States)
• 1996-2000 BMW M Coupé and M Roadster (except Canada and the United States)

• BMW engines