BMW M20

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BMW M20 engine
M20B25.jpg
Overview
Manufacturer BMW
Production 1977–1993
Combustion chamber
Configuration Straight-six engine
Displacement
  • 2.0 L (1991 cc; 121.5 cu in)
  • 2.3 L (2316 cc; 141.3 cu in)
  • 2.5 L (2494 cc; 152.2 cu in)
  • 2.7 L (2693 cc; 164.3 cu in)
Cylinder bore
  • 80 mm (3.1 in) (2.0, 2.3)
  • 84 mm (3.3 in) (2.5, 2.7)
Piston stroke
  • 66 mm (2.6 in) (2.0)
  • 75 mm (3.0 in) (2.5)
  • 76.8 mm (3.0 in) (2.3)
  • 81 mm (3.2 in) (2.7)
Chronology
Predecessor None
Successor BMW M50

The BMW M20 is a straight-six SOHC piston engine produced from 1977-1993. It was released in the 1977 in the E12 520/6 and E21 320/6 and began to be phased out following the introduction of the M50 engine in 1990.

Like the larger capacity M30 engine it is derived from, the M20 has a SOHC and 2 valves per cylinder. While the M30 camshaft is chain driven, the M20 camshaft and auxiliary shaft are driven by a timing belt. Initially released with a carburetor, later models used Bosch fuel injection.

History[edit]

With displacements ranging from 1991 cc to 2693 cc, it was the "little brother" to the larger BMW M30. It has 91 mm (3.6 in) bore-spacing[1] instead of the 100 mm (3.9 in) of the M30 six-cylinder and the M10 four-cylinder engines.

Powering the E21 and E30 3-Series, as well as E12, E28 and E34 5 Series cars, it was produced for nearly two decades, with the last examples powering the E30 325i touring built until April 1993.[2]

Early versions of the M20 were sometimes referred to as the "M60",[3][4] although the M60 code has since been used by BMW for a V8 engine produced from 1992-1996.

The M20 was the basis for the M21 diesel engine and the M70 V12 engine.[5]

Models[edit]

Models
Engine Displacement Power Torque Redline Comp Years Cars Market/Cat Fuel feed
M20B20 2.0 L (1,990 cc/121 in³) 90 kW (122 PS; 121 hp) at 6,000 16.3 kg·m (160 N·m; 118 lb·ft) at 4,000 6,400 9.2:1 1977.09-1981 320, 520 EU - 1x4-bbl Solex[6]
92 kW (125 PS; 123 hp) at 5,800 17.3 kg·m (170 N·m; 125 lb·ft) at 4,000 6,400 9.8:1 1982-1985 320i EU - L-Jetronic[7]
92.5 kW (126 PS; 124 hp) at 5,800 17.3 kg·m (170 N·m; 125 lb·ft) at 4,000 9.9:1 1981.06-1985 520i EU - K-Jetronic[8]
95 kW (129 PS; 127 hp) at 6,000 17.7 kg·m (174 N·m; 128 lb·ft) at 4,000 6,200 9.8:1 1985-1990 320i, 520i EU - LE-Jetronic[9]
95 kW (129 PS; 127 hp) at 6,000 16.7 kg·m (164 N·m; 121 lb·ft) at 4,300 6,200 8.8:1 1986-1992 320i, 520i EU X ME-Motronic[9]
M20B23 2.3 L (2,316 cc/141 in³) 105 kW (143 PS; 141 hp) at 5,300 19.4 kg·m (190 N·m; 140 lb·ft) at 4,500 6,400 9.5:1 1978-1982 323i EU - K-Jetronic[6]
102 kW (139 PS; 137 hp) at 5,300 20.9 kg·m (205 N·m; 151 lb·ft) at 4,000 9.8:1 1982.11-1985 323i EU - L-Jetronic[7]
110 kW (150 PS; 148 hp) at 6,000 20.9 kg·m (205 N·m; 151 lb·ft) at 4,000 6,500 9.8:1 1983.09-1985 323i EU - L-Jetronic[10]
M20B25 2.5 L (2,494 cc/152 in³) 126 kW (171 PS; 169 hp) at 5,800 23.0 kg·m (226 N·m; 166 lb·ft) at 4,000 6,500 9.7:1 1985.06-1990 325i EU - ME-Motronic[9]
125 kW (170 PS; 168 hp) at 5,800 22.6 kg·m (222 N·m; 163 lb·ft) at 4,300 6,500 8.8:1 1986-1993 325i EU, US X ME-Motronic[9]
M20B27 2.7 L (2,693 cc/164 in³) 90.5 kW (123 PS; 121 hp) at 4,250 23.5 kg·m (230 N·m; 170 lb·ft) at 3,250 4,800 9.0:1 1982-1987 325/e/es, 528e US X L-Jetronic/Motronic[11]
92 kW (125 PS; 123 hp) at 4,250 24.5 kg·m (240 N·m; 177 lb·ft) at 3,250 5,000 11.0:1 1983-1984 525e EU - L-Jetronic[12]
95 kW (129 PS; 127 hp) at 4,250 24.5 kg·m (240 N·m; 177 lb·ft) at 3,250 10.2:1 1984-1988 325e,[13] 525e EU - ME-Motronic[14]
90 kW (122 PS; 121 hp) at 4,250 23.5 kg·m (230 N·m; 170 lb·ft) at 3,250 4,800 9.0:1 1984-1988 325e, 525e EU X ME-Motronic[9]
95 kW (129 PS; 127 hp) at 4,800 23.5 kg·m (230 N·m; 170 lb·ft) at 3,200 5,200 8.5:1 1987.09-1988.09 325, 528e US X ME-Motronic[15]

M20B20[edit]

The first models to use the M20 were the E12 520/6 and the E21 320/6, which used the 1991 cc M20B20.[16][17] This engine uses a bore of 80 mm (3.1 in) and a stroke of 66 mm (2.6 in).[16] Fuel was supplied by a Solex four-barrel carburetor.

The M20B20 first became fuel-injected in the 1982 520i,[18] with Bosch L-Jetronic used. In 1987, the M20B20 was again revised with the addition of Bosch Motronic engine management[19] and a catalytic converter.

Applications:

  • 1977–1981 E12 520/6
  • 1979–1983 E21 320/6
  • 1982–1984 E28 520
  • 1982–1988 E28 520i
  • 1983–1992 E30 320i
  • 1988–1990 E34 520i

M20B23[edit]

The 2.3 litre M20B23 used the same head and block as the carbureted 2.0 liter but used a longer 76.8 mm (3.0 in) stroke crank. The engine was first used in E21 323i[20] and was replaced by the M20B25 in 1985.[19]

The E30 version used L-Jetronic.[21] and initially produced 102 kW (137 hp), which was increased to 110 kW (150 hp) in 1984.[22] The 102 kW version continued to be available in certain markets with strict emissions regulations, such as Switzerland, until replaced by the 325i.[10]

The M20B23 was not sold in North America.

Applications:

  • 1977–1982 E21 323i
  • 1982–1985 E30 323i

M20B25[edit]

The M20B25 has a capacity of 2494 cc and produced 126 kilowatts (169 hp) (without a catalytic converter).[22] The M20B25 head is known as "885" (since the casting number ends in 885), it has a bore of 84 mm (3.3 in), a stroke of 75 mm (3.0 in), a compression ratio of 8.5:1 and used the Bosch Motronic 1.1/1.3 engine management system.[23][dead link]

Applications:

  • 1986–1993 E30 325i, 325iS, 325iC, 325iX
  • 1989–1990 E34 525i
  • 1988–1991 Z1

M20B27[edit]

The 2693 cc M20B27 was designed for efficiency (thus the e for the Greek letter eta in 325e) and low-rev torque.[24] Compared with the M20B25, the stroke is increased from 75 mm (3.0 in) to 81 mm (3.2 in).[23]

Power output is 121 hp (90 kW) at 4,250 rpm for M20B27 engines produced up until 1987 and 127 hp (95 kW) at 4,800 rpm for the "325es" model produced in 1988.[23] Peak torque is 170 lb·ft (230 N·m) at 3,250 rpm for M20B27 engines. In 1987, the fuel injection was upgraded from Motronic 1.0 to Motronic 1.1/1.3.[23] In the early 1990's BMW South Africa used components from the Alpina C3 2.7 to produce a E30 specifically for Stannic Group N production car racing. The first iteration of this engine used in the E30 325iS produced 145kw and the second revision, often referred to as "Evo2" or on the VIN plate as "HP2" produced 155kw.

Applications:

  • 1982–1988 E30 325e, 325es
  • 1982–1988 E28 525e (called 528e in the North America)
  • 1989–1992 E30 325iS (Only available in South Africa)

References[edit]

  1. ^ http://www.usautoparts.net/bmw/engines/m50.htm
  2. ^ http://www.autoevolution.com/cars/bmw-3-series-touring-e30-1986.html
  3. ^ http://www.bmwccbc.org/resources/index.html
  4. ^ http://www.unixnerd.demon.co.uk/m20.html
  5. ^ http://www.usautoparts.net/bmw/engines/m21.htm
  6. ^ a b Lösch, Annamaria, ed. (1981). World Cars 1981. Pelham, NY: The Automobile Club of Italy/Herald Books. p. 107. ISBN 0-910714-13-4. 
  7. ^ a b Büschi, Hans-Ulrich, ed. (March 10, 1983). "Automobil Revue '83" (in German and French) 78. Berne, Switzerland: Hallwag, AG: 204. ISBN 3-444-06065-3. 
  8. ^ Automobil Revue '83, p. 205
  9. ^ a b c d e Büschi, Hans-Ulrich, ed. (March 5, 1987). Automobil Revue 1987 (in German and French) 82. Berne, Switzerland: Hallwag AG. pp. 184–186. ISBN 3-444-00458-3. 
  10. ^ a b Büschi, Hans-Ulrich, ed. (March 1, 1984). "Automobil Revue '84" (in German and French) 79. Berne, Switzerland: Hallwag, AG: 179. ISBN 3-444-06070-X. 
  11. ^ Automobil Revue '83, p. 206
  12. ^ Automobil Revue '84, p. 183
  13. ^ Automobil Revue '87, p. 105
  14. ^ Heitz, Rudolf, ed. (1985-08-01). Auto Katalog 1986 (in German) 29. Stuttgart: Vereinigte Motor-Verlage GmbH & Co. KG. p. 210. 81530/85001. 
  15. ^ James M. Flammang (1994). Standard Catalog of Imported Cars, 1946-1990. Iola, WI: Krause Publications, Inc. pp. 125–126. ISBN 0-87341-158-7. 
  16. ^ a b http://www.carfolio.com/specifications/models/car/?car=119361
  17. ^ http://www.specs4bmw.com/e21/3-series/sedan
  18. ^ http://www.automobile-catalog.com/car/1982/262835/bmw_520i_4-speed.html
  19. ^ a b http://www.e30club.com/bmw-e30
  20. ^ http://www.bmwheaven.com/database/show.php?id=133
  21. ^ http://www.automobile-catalog.com/car/1985/265070/bmw_323i_sport_gearbox.html
  22. ^ a b http://www.bmwheaven.com/database/engine.php?type=M20
  23. ^ a b c d http://e30world.com/specifications/BMW-E30-specs-table
  24. ^ http://www.e30info.com/pages/diff.htm