BMW M43B18

BMW M43B18The BMW M43B18 is a 1.8 L (1,796 cc, 109.6 cu·in) straight-four natural aspirated four-stroke liquid-cooled internal combustion gasoline engine, manufactured by Bayerische Motoren Werke AG from 1993 to 1999.

A 84.0 mm (3.31 in) cylinder bore and 81.0 mm (3.19 in) piston stroke give the M43B18 engine a total of 1,796 cc of displacement. The compression ratio rating is 9.7:1.

The BMW M43B18 engine produced 115.6 PS (85.0 KW; 114.0 HP) at 5,500 rpm of maximum output power and 168.0 Nm (17.14 kg·m; 124.0 ft·lb) at 3,900 rpm of peak torque, or 100.6 PS (74.0 KW; 99.2 HP) at 5,500 rpm of horsepower and 142.0 Nm (14.5 kg·m; 104.8 ft·lb) at 3,900 rpm of torque for compressed natural gas (CNG) version.

The BMW M43B18 features:

  • Chain-driven single overhead camshaft (SOHC)
  • 8 valves with hydraulic tappets
  • Cast-iron cylinder block
  • Crankshaft with four counterweights
  • Multi Point Fuel Injection (MPFI)
  • Bosch Motronic M 1.7 engine management system
  • Dual length intake manifold (BMW “DISA”)
  • Camshaft position sensor and a knock sensor
  • Pressurized lubrication system
  • Liquid-cooled cooling system

General information

Engine Specifications
Engine model M43B18
Engine type 4-stroke, SOHC, inline-4
Displacement 1.8 L, 1,796 cm3, (109.6 cu·in)
Max. horsepower 115.6 PS (85.0 KW; 114.0 HP) at 5,500 rpm
CNG: 100.6 PS (74.0 KW; 99.2 HP) at 5,500 rpm
Max. torque 168.0 Nm (17.14 kg·m; 124.0 ft·lb) at 3,900 rpm
CNG: 142.0 Nm (14.5 kg·m; 104.8 ft·lb) at 3,900 rpm
Cooling system Liquid-cooled
Lubricating system Pressurized lubrication
Fuel system Multi Point Fuel Injection (MPFI)
Engine management system Bosch Motronic M 1.7
Starting system Electric starter 12V
Firing order: 1-3-4-2
Dimensions (L x W X H)
Dry weight

Cylinder Block and Head

Cylinder block
Cylinder block alloy: Cast-iron
Compression ratio: 9.7:1
Cylinder bore: 84.0 mm (3.31 in)
Piston stroke: 81.0 mm (3.19 in)
Cylinder internal diameter (standard): 84.000-84.014 mm (3.3071-3.3076 in)
Piston skirt outer diameter (standard): 83.985 mm (3.3065 in)
Number of piston rings (compression / oil): 2/1
Connecting rod big end diameter (standard): 48.000-48.016 mm (1.8898-1.8904 in)
Connecting rod small end diameter (standard): 22.005-22.012 mm (0.8663-0.8666 in)
Connecting rod center distance: 22.000 mm (0.8661 in)
Side clearance (Top): 0.020-0.200 mm (0.0008-0.0079 in)
Side clearance (Second): 0.020-0.100 mm (0.0008-0.0039 in)
Ring end gap (Top): 0.200-1.000 mm (0.0079-0.0394 in)
Ring end gap (Second): 0.200-1.000 mm (0.0079-0.0394 in)
Ring end gap (Oil): 0.400-1.400 mm (0.0157-0.0551 in)
Number of main bearings: 5
Crankshaft main journal diameter: 60.000 mm (2.3622 in)
Crankpin journal diameter: 45.000 mm (1.7717 in)
Crankshaft center distance: 36 mm (1.415 in)
Cylinder head
Cylinder head alloy: Aluminium
Valve arrangement: SOHC, chain-driven
Valves: 2,(8 valves in total)
Head height: 140.550-141.000 mm (5.5335-5.5512 in)
Valve head diameter (INTAKE): 42.00 mm (1.6535 in)
Valve head diameter (EXHAUST): 36.000 mm (1.4173 in)
Valve steam diameter (INTAKE): 6.975-7.000 mm (0.2746-0.2756 in)
Valve steam diameter (EXHAUST): 6.960-7.000 mm (0.274-0.2756 in)

Service Data

Compression pressure
Standard: 10-11 bar (10.1-11.2 kg/cm2; 145-160 psi)
Oil system
Lubrication system: Pressurized lubrication
Oil type: API SG or SF and better
Recommended oil: SAE 10W-40, 5W-30
Oil capacity: 4.0 L (4.23 US. qt, 3.52 Imp. qt.)
Oil pressure: 0.5 bar (0.51 kg/cm3; 7.25 psi) at Idle speed
4.3 bar (4.3 kg/cm3; 64.4 psi) at Rated speed
Ignition system
Spark plug Bosch FGR7DQP, NGK BKR6EQUP
Spark plug gap: 0.5 mm (0.0197 in)


Model Years Produced
BMW 318i (E36) 1993–1999
BMW 518i (E34) 1994-1996
BMW 518g Touring (E34) 1995-1996
BMW Z3 1.8 1996–1998


1. BMW TIS (Technical Information System)

Author: Sergei Wers
About: Co-founder and CEO of a multi-brand auto repair shop (engine repair, chassis repair, body repair and painting) for over 15 years. I have been developing internet sites with technical specifications for more than seven years.

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We try to use official documentation and verify the published data, but errors may occur. In addition, specifications of machinery and equipment may vary depending on markets and modifications. We do not recommend the use of this data for spare parts or repairs. Use official service manuals or parts catalogs for your product.

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