BMW N43B20

BMW N43B20The BMW N43B20 is a 2.0 liters (1,995 cc, 121.7 cu·in) straight-four, four-stroke cycle natural aspirated gasoline engine from the BMW N43-family. The engine was manufactured from 2007 to 2011 on the BMW Plant Hams Hall (Coleshill, Birmingham, United Kingdom).

The N43B20 engine features an aluminum cylinder block and aluminum head with a dual overhead camshaft (DOHC) and four valves per cylinder (16 in total). The cylinder bore is 84.0 mm (3.31 in) and the piston stroke is 90.0 mm (3.54 in). This engine used a direct injection fuel system and the Siemens MSD 81.2 engine management system. Redline is 5,000 rpm.

The N43B20 had three variants:

  • N43B20K0 – 122 PS (90 KW; 121 HP) at 6,000 rpm of horsepower and 185 Nm (18.9 kg·m; 136.5 ft·lb) at 3,000 rpm of torque. This engine was used on the BMW 116i (E81/E87).
  • N43B20U0 – 143 PS (105 KW; 141 HP) at 6,000 rpm of horsepower and 190 Nm (19.4 kg·m; 140.2 ft·lb) at 4,250 rpm of torque. This version was used on the BMW 118i (E81/E87/E88) and BMW 318i (E90/E91/E92/E93).
  • N43B20O0 – 170 PS (125 KW; 168 HP) at 6,700 rpm of horsepower and 210 Nm (21.4 kg·m; 155.0 ft·lb) at 4,250 rpm of torque. This version was used on the BMW 120i (E81/E82/E87/E88), BMW 320i (E90/E91/E92/E93) and BMW 520i (E60/E61).

The breakdown of the engine code is as follows:

  • M20 – Engine Family
  • B – Gasoline
  • 20 – 2.0 Liter Displacement

General information

Engine Specifications
Engine codeN43B20
LayoutFour stroke, Inline-4 (Straight-4)
Fuel typeGasoline
Production2007-2011
Displacement2.0 L, 1,995 cc (121.7 cu in)
Fuel systemDirect injection
Power adderNone
Max. horsepower N43B20K0: 122 PS (90 KW; 121 HP) at 6,000 rpm
N43B20U0: 143 PS (105 KW; 141 HP) at 6,000 rpm
N43B20O0: 170 PS (125 KW; 168 HP) at 6,700 rpm
Max. torque N43B20K0: 185 Nm (18.9 kg·m; 136.5 ft·lb) at 3,000 rpm
N43B20U0: 190 Nm (19.4 kg·m; 140.2 ft·lb) at 4,250 rpm
N43B20O0: 210 Nm (21.4 kg·m; 155.0 ft·lb) at 4,250 rpm
Firing order1-3-4-2
Dimensions (L x H x W):
Weight

Cylinder block

Cylinder block
Cylinder block alloyAluminum
Compression ratio:
Cylinder bore:84.0 mm (3.31 in)
Piston stroke:90.0 mm (3.54 in)
Number of piston rings (compression / oil):2 / 1
Number of main bearings:5
Cylinder inner diameter (standard):84.000 mm (3.3071 in)
Piston skirt diameter (standard):83.996 mm (3.3069 in)
Piston ring side clearance:Top0.020-0.060 mm (0.0008-0.0024 in)
Second0.015-0.060 mm (0.0006-0.0024 in)
Piston ring end gap:Top0.150-0.300 mm (0.0059-0.0118 in)
Second0.200-0.400 mm (0.0079-0.0157 in
Crankshaft journal diameter: 1-4: 56.000 mm (2.2047 in)
5: 65.000 mm (2.5590 in)

Cylinder head

Cylinder head
Valve Arrangement:DOHC
Valves:12 (2 valves per cylinder)
Intake/Exhaust duration:
Valve head diameter:INTAKE
EXHAUST
Valve steam diameter:INTAKE6.000 mm (0.2362 in)
EXHAUST6.000 mm (0.2362 in)

Maintenance data

Compression pressure
Standard15.0 bar (217 psi)
Oil system
Recommended engine oilSAE 5W-30, 5W-40
Oil typeBMW Lognlife-04
Engine oil capacity (Refill capacity)4.25 L (4.49 US. qt, 3.74 Imp. qt.)
Ignition system
Spark plugNGK ZKBR7A-HTU

Vehicle applications

ModelYears Produced
BMW 116i (E81/E87)2007–2011
BMW 118i (E81/E87/E88)2008-2011
BMW 318i (E90/E91/E92/E93)2007-2011
BMW 120i (E81/E82/E87/E88)2007-2011
BMW 320i (E90/E91/E92/E93)2007-2011
BMW 520i (E60/E61)2007-2009
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We try to use verified sources and official documentation, however, differences between sources or errors in entering information may occur. We do not provide advice on technical issues related to the engines operation or repair. We do not recommend using provided information for engines repairing engines or spare parts ordering, use only official service manuals and spare-parts catalogs.

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