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BMW M20 engines

Revision 3

by llandowtuninguk@gmail.com
Add variant-specific bore, stroke and compression figures

This is a historical revision. Read the current page or return to its history.

Page organisation in this revision
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Technical article
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Engines
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Section level
Applies to
No ECU-specific applicability
Tool groups
Not recorded in this older revision
Manufacturers
Not recorded in this older revision

BMW automotive engine families listed as M20. Specifications below retain the source's separate family and variant labels.

Family specifications

BMW M20 engine

FieldReported value
Production1977–1993
ConfigurationStraight-6
Displacement2.0 L (1,991 cc) 2.3 L (2,316 cc) 2.5 L (2,494 cc) 2.7 L (2,693 cc)
Cylinder bore80 mm (3.15 in) 84 mm (3.31 in)
Piston stroke66 mm (2.60 in) 75 mm (2.95 in) 76.8 mm (3.02 in) 81 mm (3.19 in)
Cylinder block materialCast iron
Cylinder head materialCast aluminum alloy
ValvetrainSOHC
Fuel typePetrol
PredecessorNone
SuccessorBMW M50

Variant specifications

Models

VersionDisplacementPowerTorqueBoreStrokeCompression RatioYearsNotes
M20B201,991 cc (121.5 cu in)90 kW (122 PS; 121 hp) at 6,000 rpm163 N⋅m (120 lb⋅ft) at 4,000 rpm80 mm (3.15 in)66 mm (2.60 in)9.2:11977-1982Solex 4A1 variant
M20B201,991 cc (121.5 cu in)92 kW (125 PS; 123 bhp) at 5,800 rpm170 N⋅m (125 lb⋅ft) at 4,000 rpm80 mm (3.15 in)66 mm (2.60 in)9.0:1 (catalyst) 9.8:1 (non-catalyst)1982-1984L-Jetronic fuel injection with "200" head
M20B201,991 cc (121.5 cu in)92 kW (125 PS; 123 bhp) at 5,800 rpm174 N⋅m (128 lb⋅ft) at 4,000 rpm80 mm (3.15 in)66 mm (2.60 in)9.0:1 (catalyst) 9.8:1 (non-catalyst)1984-1987LE-Jetronic fuel injection with "731" head
M20B201,991 cc (121.5 cu in)95 kW (129 PS; 127 bhp) at 6,000 rpm164 N⋅m (121 lb⋅ft) at 4,300 rpm80 mm (3.15 in)66 mm (2.60 in)8.8:11986-1992Motronic 1.1/1.3 engine management Compression ratio reduced to accommodate emissions controls and unleaded gasoline
M20B232,316 cc (141.3 cu in)105 kW (143 PS; 141 bhp) at 5,300 rpm190 N⋅m (140 lb⋅ft) at 4,500 rpm80 mm (3.15 in)76.8 mm (3.02 in)9.5:11977-1982K-Jetronic fuel injection
M20B232,316 cc (141.3 cu in)102 kW (139 PS; 137 bhp) at 5,300 rpm205 N⋅m (151 lb⋅ft) at 4,000 rpm80 mm (3.15 in)76.8 mm (3.02 in)9.0:1 (catalyst) 9.8:1 (non-catalyst)1982-1983L-Jetronic
M20B232,316 cc (141.3 cu in)110 kW (150 PS; 148 bhp) at 6,000 rpm205 N⋅m (151 lb⋅ft) at 4,000 rpm80 mm (3.15 in)76.8 mm (3.02 in)9.0:1 (catalyst) 9.8:1 (non-catalyst)1983-1987LE-Jetronic
M20B252,494 cc (152.2 cu in)126 kW (171 PS; 169 bhp) at 5,800 rpm226 N⋅m (167 lb⋅ft) at 4,000 rpm84 mm (3.31 in)75 mm (2.95 in)9.4:11985-1990For markets that did not require a catalytic converter
M20B252,494 cc (152.2 cu in)125 kW (170 PS; 168 hp) at 5,800 rpm226 N⋅m (167 lb⋅ft) at 4,300 rpm84 mm (3.31 in)75 mm (2.95 in)8.8:11987-1993For markets that required a catalytic converter
M20B272,693 cc (164.3 cu in)90 kW (122 PS; 121 hp) at 4,250 rpm230 N⋅m (170 lb⋅ft) at 3,250 rpm84 mm (3.31 in)81 mm (3.19 in)9.0:11982-1987For markets that required a catalytic converter
M20B272,693 cc (164.3 cu in)92 kW (125 PS; 123 hp) at 4,250 rpm240 N⋅m (177 lb⋅ft) at 3,250 rpm84 mm (3.31 in)81 mm (3.19 in)11.0:11982-1985For markets that did not require a catalytic converter Early high compression variant
M20B272,693 cc (164.3 cu in)95 kW (129 PS; 127 hp) at 4,250 rpm240 N⋅m (177 lb⋅ft) at 3,250 rpm84 mm (3.31 in)81 mm (3.19 in)10.2:11985-1987For markets that did not require a catalytic converter Compression ratio reduced to mitigate knocking
M20B272,693 cc (164.3 cu in)95 kW (129 PS; 127 hp) at 4,800 rpm240 N⋅m (177 lb⋅ft) at 3,200 rpm84 mm (3.31 in)81 mm (3.19 in)8.5:11988"Super" Eta engine Motronic 1.1

Recorded vehicle applications

M20B20

  • 1977–1981 E12 5 Series 520/6 (carburettor)
  • 1977–1982 E21 3 Series 320/6 (carburettor)

M20B20KE

  • 1981–1982 E28 5 Series 520i (K-Jetronic)

M20B20LE

  • 1982–1984 E28 5 Series 520i ( L-Jetronic )
  • 1982–1984 E30 3 Series 320i (L-Jetronic)
  • 1984–1987 E28 5 Series 520i (LE-Jetronic)
  • 1984–1987 E30 3 Series 320i (LE-Jetronic)

M20B20 (Motronic)

  • 1986–1987 E28 3 Series 520i (Motronic)
  • 1987–1992 E30 3 Series 320i (Motronic)
  • 1988–1990 E34 5 Series 520i (Motronic)
  • 1989–1992 Bertone Freeclimber (Freeclimber I)

M20B23

  • 1977–1982 E21 3 Series 323i (K-Jetronic)
  • 1982–1984 E30 3 Series 323i (L-Jetronic)
  • 1984–1987 E30 3 Series 323i (LE-Jetronic)

M20B25

  • 1985–1993 E30 3 Series 325i
  • 1989–1990 E34 5 Series 525i
  • 1988–1991 Z1

M20B27

  • 1982–1987 E30 3 Series 325e, 325e
  • 1982–1988 E28 5 Series 525e (called 528e in North America)
  • 1989–1992 E30 3 Series 325iS (only available in South Africa)
  • 1989–1992 Bertone Freeclimber (Freeclimber I)

BMW automotive engine directory

Design, development and variant notes

The 'little six' M20 has an iron block, aluminium cross-flow head and a belt-driven single overhead camshaft. Its smaller bore spacing and different mounting angle distinguish it from the larger M30.

Early 2.0-litre and 2.3-litre versions used different fuelling systems, including carburettor and Bosch K-Jetronic arrangements. The M21 diesel was developed from the M20 architecture.

Variant dimensions and compression

These values are associated with the named variant and source qualifier; equipment and market specifications can differ. A dash means the value is not listed here.

VariantBore (mm)Stroke (mm)Compression ratioSource qualifier
M20B20VE80669.2:1Early carburetted version
M20B23KE8076.89.5:1Initial K-Jetronic version
M20B2584759.4:1Initial 1985 version

Data adapted from the cited Wikipedia revision by Wikipedia contributors under CC BY-SA 4.0. Production dates and fitments reflect that revision; verify the exact engine code, market and vehicle before applying a specification.

Sources

Curated reference notes. Applicability follows the cited sources; hardware testing by this wiki is not implied.