BMW M50

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BMW M50 engine
1993 bmw 325is engine.jpg
Post-September 1992 version (M50TU)
Overview
Manufacturer BMW
Production 1990–1996
Layout
Configuration DOHC straight-6
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 M50TU ("technical update"), which added variable valve timing to the intake camshaft (called single VANOS by BMW).[2]

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[edit]

Initial version of the M50 engine (up until "Technical Update")

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.[3] Both engines use an iron block with an aluminum alloy head.[4] 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),[5] whereas it is in the rear on the E36 3 Series.[6]

Models[edit]

Engine Displacement Power Torque Years
M50B20 1,991 cc (121 cu in) 110 kW (148 bhp)
@ 6000 rpm
190 N⋅m (140 lb⋅ft)
@ 4700 rpm
1990-1992
M50B20TU 110 kW (148 bhp)
@ 5900 rpm
190 N⋅m (140 lb⋅ft)
@ 4200 rpm
1992-1996
M50B24 2,394 cc (146 cu in) 115 kW (154 bhp)
@ 5900 rpm
235 N⋅m (173 lb⋅ft)
@ 4700 rpm
1991-1992
M50B25 2,494 cc (152 cu in) 141 kW (189 bhp)
@ 5900 rpm
245 N⋅m (181 lb⋅ft)
@ 4700 rpm
1990-1992
M50B25TU 141 kW (189 bhp)
@ 5900 rpm
245 N⋅m (181 lb⋅ft)
@ 4200 rpm
1992-1996
S50B30
(Euro-spec)
2,990 cc (182 cu in) 213 kW (286 bhp)
@ 7400 rpm
350 N⋅m (258 lb⋅ft)
@ 3250 rpm
1992-1996
S50B30US
(US-spec)
179 kW (240 bhp)
@ 6000 rpm
305 N⋅m (225 lb⋅ft)
@ 4250 rpm
1993-1995
S50B32 3,201 cc (195 cu in) 236 kW (316 bhp)
@ 7400 rpm
350 N⋅m (258 lb⋅ft)
@ 3250 rpm
1995-1996

M50B20[edit]

M50 engine in BMW Museum

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.[7]

Applications:

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

M50B20TU[edit]

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.[7]

Applications:

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

M50B24[edit]

This is a 2.4 L engine used in the Thailand and Oceania markets.[8] It is based on the 2.5 L M50B25 with the stroke reduced to 72 mm (2.8 in).

M50B25[edit]

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.[7] The compression ratio is 10.0:1.

Applications:

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

M50B25TU[edit]

The M50B25 was updated with single VANOS in 1992, resulting in peak torque becoming available at 4200 rpm.[7] The compression ratio was increased to 10.5:1.

Applications:

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

S50[edit]

BMW S50 engine
BMW M3 Evo Coupe E36 - Flickr - The Car Spy (5).jpg
Overview
Manufacturer BMW
Production 1992–1999
Layout
Configuration DOHC straight-6
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.

S50B30[edit]

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.[9][10]

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.[11][12] 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.[9]

The limited edition "M3 GT" model from 1995 produced 220 kW (295 hp).[9] It had different camshafts and a redesigned sump and oil pump.

Applications:

  • 1992-1995 E36 M3 (except for US)

S50B30US[edit]

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).[9][13] This engine was based on the M50B25TU and uses the same compression ratio,[9] 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.[14]

In 1996, the S50B30US was replaced by the 3.2 L S52 (in the United States and Canada only).[15]

Applications:

S50B32[edit]

In 1996, the S50B32 replaced the S50B30 (except in Canada and the United States, where the S52 engine was used instead).[16] Power output increased to 321 PS (316.6 bhp; 236.1 kW) at 7400 rpm and 350 N⋅m (258.1 lb⋅ft) at 3250 rpm of torque.[17] [18] and the displacement increased to 3,201 cc (3.2 L; 195.3 cu in), due to an increased stroke of 91 mm (3.58 in) and a slight increase in bore to 86.4 mm (3.40 in).[19]

Variable valve timing is fitted to both camshafts and a secondary oil pick-up was added (from the "M3 GT" version of the S50B30).[20] The compression ratio is 11.3:1 and the redline is 7,400 rpm.[21] 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[edit]

References[edit]

  1. ^ "BMW 5 Series E34 History and Characteristics". www.bmwguide.net. Retrieved 27 October 2017. 
  2. ^ "BMW M50 engine". www.usautoparts.net. Archived from the original on 2012-05-12. 
  3. ^ "BMW M50 M52 M54 Engines". www.unixnerd.demon.co.uk. 
  4. ^ "The BMW Six Cylinder Guide". www.autospeed.com. 
  5. ^ "5' E34 525i Short Engine". www.realoem.com. Retrieved 28 September 2017. 
  6. ^ "3' E36 325i Short Engine". www.realoem.com. Retrieved 28 September 2017. 
  7. ^ a b c d "Engine specifications- M50". www.bmwheaven.com. 
  8. ^ Hudock, Greg. BMW E - Series Restoration Bible. Brooklands Books. p. 8-6. ISBN 9781855209701. 
  9. ^ a b c d e "BMW M Registry - FAQ E36 M3 3.0". www.bmwmregistry.com. 
  10. ^ "1 of 45: 1994 BMW M3 Canadian Edition". www.germancarsforsaleblog.com. Retrieved 29 September 2017. 
  11. ^ "BMW E36 3 Series Coupe M3 Specs". www.ultimatespecs.com. Retrieved 1 October 2017. 
  12. ^ "1993 BMW M3 E36". www.carfolio.com. 
  13. ^ "Engine specifications- S50 B30 US". www.bmwheaven.com. 
  14. ^ "1994 BMW E36 3 Series Coupe M3 Automatic (US spec)". www.ultimatespecs.com. 
  15. ^ "E36 M3 coupe model selection- March 1996 in US spec". www.realoem.com. 
  16. ^ "1995-1999 BMW M3". www.motortrend.com. 
  17. ^ "1997 BMW M3 Coupé specifications". www.automobile-catalog.com. Retrieved June 18, 2018. 
  18. ^ "BMW E36 3-series Coupé specs". www.specs4bmw.com. Archived from the original on 2015-12-24. 
  19. ^ "Engine specifications- S50B32 Euro". www.bmwheaven.com. 
  20. ^ "FAQ E36 M3 3.2". www.bmwmregistry.com. Retrieved 1 October 2017. 
  21. ^ "BMW M Registry - FAQ E36/8 M coupe". www.bmwmregistry.com.