# BMW M50

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 M50TÜ (Technische Überarbeitung, "technical revision"). This was BMW's first engine to use variable valve timing. Called single VANOS by BMW, the system adjusted the phasing of the intake camshaft.
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.

## Design

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. Both engines use an iron block with an aluminum alloy head. 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), whereas it is in the rear on the E36 3 Series.

## Models

| 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 | 1,991 cc (121.5 cu in) | 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 (180 lb⋅ft) at 4,200 rpm | 1992-1996 |
| 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 | 2,494 cc (152.2 cu in) | 141 kW (192 PS; 189 hp) at 5,900 rpm | 250 N⋅m (180 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 | 329 N⋅m (243 lb⋅ft) at 3,500 rpm | 1992-1995 |
| S50B30 (US) | 2,990 cc (182.5 cu in) | 240 hp (180 kW; 240 PS) at 6,000 rpm | 225 lb⋅ft (305 N⋅m) at 4,250 rpm | 1994-1995 |
| S50B30GT | 2,990 cc (182.5 cu in) | 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; 316 hp) at 7,400 rpm | 350 N⋅m (260 lb⋅ft) at 3,250 rpm | 1995-2000 |

### M50B20

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 (150 PS; 148 hp). The compression ratio is 10.5:1.
Applications:
* 1990-1992 E34 520i
* 1991-1995 E36 320i

### M50B20TÜ

The M50B20 was updated with single VANOS in 1992. Peak torque became available at 4,200 rpm. It produces 110 kW (150 PS; 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

### M50B24TÜ

This is a 2,394 cc (146.1 cu in) engine used in the Thailand and Oceanian markets. 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 (188 PS; 185 hp) at 5,900 rpm and 240 N⋅m (180 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

### M50B25

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 (192 PS; 189 hp) at 6,000 rpm and 245 N⋅m (181 lb⋅ft) at 4,700 rpm. The compression ratio is 10.0:1.
Applications:
* 1990-1992 E34 525i, 525ix
* 1991-1992 E36 325i, 325is

### M50B25TÜ

The M50B25 was updated with single VANOS in 1992, resulting in peak torque becoming available at 4,200 rpm. It produces 141 kW (192 PS; 189 hp) at 5,900 rpm and 250 N⋅m (180 lb⋅ft) at 4,200 rpm. The compression ratio was increased to 10.5:1.
Applications:
* 1993-1995 E36 325i, 325is
* 1992-1996 E34 525i, 525ix

### M50B30TÜ concept

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 (246 PS; 243 hp) and 316 N⋅m (233 lb⋅ft) respectively.

## S50

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.

### S50B30

The S50B30 was used in most countries, except for the United States. The S50B30 produces 210 kW (286 PS; 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. 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.
The limited edition "M3 GT" model from 1995 produced 220 kW (299 PS; 295 hp). It had different camshafts and a redesigned sump and oil pump.
Applications:
* 1992-1995 E36 M3 (except for U.S.)

### S50B30US

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 (243 PS; 240 hp). This engine is more closely related to the standard M50 engine and has the same compression ratio as the M50B25TÜ, 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.
In 1996, the S50B30US was replaced by the BMW S52 engine (in the United States and Canada only).
Applications:
* 1994-1995 E36 M3 (U.S. only)

### S50B32

In 1995, the S50B32 replaced the S50B30 in world markets. Power output increased to 236 kW (321 PS; 316 hp) 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).
The S50B32 has double-VANOS (variable valve timing on both camshafts) and a secondary oil pick-up was added. The compression ratio is 11.3:1 and the redline is 7,600 rpm. 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)