| BMW M50 engine | |
| Production: | 1990 - 1996 |
| Configuration: | Straight-6 |
| Valvetrain: | DOHC, VVT ("TU" versions only) |
| Head: | Aluminium |
| Block: | Cast iron |
| Predecessor: | BMW M20 |
| Successor: | BMW M52 |
| Fueltype: | Petrol |
| Displacement: | 1991cc 2394cc 2494cc |
| Bore: | 80mm 84mm |
| Stroke: | 66mm 72mm 75mm |
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 M50TU ("technical update"), which 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 | 1991abbr=onNaNabbr=on | 1100NaN0 at 6,000 rpm | 1900NaN0 at 4,700 rpm | 1990-1992 | |
| M50B20TU | 1100NaN0 at 5,900 rpm | 1900NaN0 at 4,200 rpm | 1992-1996 | ||
| M50B24TU | 2394abbr=onNaNabbr=on | 1380NaN0 at 5,900 rpm | 2400NaN0 at 4,200 rpm | ||
| M50B25 | 2494abbr=onNaNabbr=on | 1410NaN0 at 6,000 rpm | 2450NaN0 at 4,700 rpm | 1990-1992 | |
| M50B25TU | 1410NaN0 at 5,900 rpm | 2500NaN0 at 4,200 rpm | 1992-1996 | ||
| S50B30 | 2990abbr=onNaNabbr=on | 2100NaN0 at 7,000 rpm | 3190NaN0 at 3,500 rpm | 1992-1995 | |
| S50B32 | 3201abbr=onNaNabbr=on | 2390NaN0 at 7,400 rpm | 3500NaN0 at 3,250 rpm | 1995-2000 |
The 1991abbr=onNaNabbr=on M50B20 was introduced with the 1990 520i. It has a bore of 802NaN2, a stroke of 662NaN2 and produces 1100NaN0. The compression ratio is 10.5:1.[8]
Applications:
The M50B20 was updated with single VANOS in 1992. Peak torque became available at 4,200 rpm. It produces 1100NaN0 at 5,900 rpm and 1900NaN0 at 4,200 rpm. The compression ratio was raised to 11.0:1.
Applications:
This is a 2394abbr=onNaNabbr=on engine used in the Thailand and Oceania markets.[9] It is based on the 2494abbr=onNaNabbr=on M50B25TU with the stroke reduced to 722NaN2 and produces 1380NaN0 at 5,900 rpm and 2400NaN0 at 4,200 rpm. The compression ratio is 10.5:1.
Applications:
The 2494abbr=onNaNabbr=on M50B25 was introduced with the 1990 525i and 525ix. It has a bore of 842NaN2, a stroke of 752NaN2 and produces 1410NaN0 at 6,000 rpm and 2450NaN0 at 4,700 rpm. The compression ratio is 10.0:1.
Applications:
The M50B25 was updated with single VANOS in 1992, resulting in peak torque becoming available at 4,200 rpm. It produces 1410NaN0 at 5,900 rpm and 2500NaN0 at 4,200 rpm. The compression ratio was increased to 10.5:1.
Applications:
In 1993, BMW Individual created an concept of BMW E34 530iX called Enduro Touring. Only one car was produced, having an up-sized variant of M50B25TU engine. Bore and stroke was increased and the total displacement of 3.0 was achieved. The power and torque both increased to 1810NaN0 and 3160NaN0 respectively.
| BMW S50 engine | |
| Production: | 1992 - 2000[10] |
| Configuration: | Straight-6 |
| Valvetrain: | DOHC, with VVT |
| Head: | Aluminium |
| Block: | Cast iron |
| Predecessor: | None |
| Successor: | BMW S54 |
| Fueltype: | Petrol |
| Displacement: | 2990cc 3201cc |
| Bore: | 86mm 86.4mm |
| Stroke: | 85.8mm 91mm |
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] The S50B30 produces 210kW, has a bore of 86abbr=onNaNabbr=on, a stroke of 85.8abbr=onNaNabbr=on and a compression ratio of 10.8:1.[12] [13] 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.[14]
The limited edition "M3 GT" model from 1995 produced 2200NaN0.[15] It had different camshafts and a redesigned sump and oil pump.
Applications:
In the United States, the 1994-1995 model years of the E36 M3 are powered by the S50B30US, a 29901NaN1 engine which produces 1790NaN0.[16] This engine is more closely related to the standard M50 engine and has the same compression ratio as the M50B25TU, but uses a different camshafts, crankshaft, connecting rods, and pistons. The bore is 86abbr=onNaNabbr=on, the stroke is 85.8abbr=onNaNabbr=on 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:
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 [20] and the displacement increased to 3201cc, due to an increased stroke of 912NaN2 and a slight increase in bore to 86.4mm.[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: