BMW M43B18

BMW M43B18The BMW M43B18 is a 1.8 liters (1,796 cc, 109.6 cu·in) straight-four, four-stroke cycle, natural aspirated gasoline engine from the BMW M43-family. The engine was manufactured from 1993 to 1999 at the Steyr engine plant.

The M43B18 engine features a cast-iron cylinder block, a crankshaft with four counterweights and aluminum head with a chain-driven single overhead camshaft (SOHC) and two valves per cylinder (8 in total) with hydraulic tappets. It has an 84.0 mm (3.31 in) cylinder bore and 81.0 mm (3.19 in) piston stroke. Compression ratio rating is 9.7:1.

This engine used a Multi Point Fuel Injection system (MPFI), the Bosch Motronic M 1.7 engine management system and a dual length intake manifold (BMW “DISA”). Redline is 6,200 rpm.

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. There was also a natural gas-powered (Compressed natural gas, CNG) version for the BMW 518g Touring (E34). This engien version produced 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.

The breakdown of the engine code is as follows:

  • M43 – Engine Family
  • B – Gasoline
  • 18 – 1.8 Liter displacement

General information

Engine Specifications
Engine codeM43B18
LayoutFour stroke, Inline-4 (Straight-4)
Fuel typeGasoline
Displacement1.8 L, 1,796 cc (109.6 cu in)
Fuel systemMulti Point Fuel Injection (MPFI)
Power adderNone
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
Firing order1-3-4-2
Dimensions (L x H x W):

Cylinder block

Cylinder block
Cylinder block alloyCast-iron
Compression ratio:9.7:1
Cylinder bore:84.0 mm (3.31 in)
Piston stroke:81.0 mm (3.19 in)
Number of piston rings (compression / oil):2 / 1
Number of main bearings:5
Cylinder inner diameter (standard):84.000-84.014 mm (3.3071-3.3076 in)
Piston skirt diameter (standard):83.985 mm (3.3065 in)
Piston ring side clearance:Top0.020-0.200 mm (0.0008-0.0079 in)
Second0.020-0.100 mm (0.0008-0.0039 in)
Piston ring end gap:Top0.200-1.000 mm (0.0079-0.0394 in)
Second0.200-1.000 mm (0.0079-0.0394 in)
Oil0.400-1.400 mm (0.0157-0.0551 in)
Crankshaft journal diameter:60.000 mm (2.3622 in)
Crankpin journal diameter:45.000 mm (1.7717 in)

Cylinder head

Cylinder head
Valve Arrangement:SOHC, chain-driven
Valves:8 (2 valves per cylinder)
Intake/Exhaust duration:
Valve head diameter:INTAKE42.000 mm (1.6535 in)
EXHAUST36.000 mm (1.4173 in)
Valve steam diameter:INTAKE6.975-7.000 mm (0.2746-0.2756 in)
EXHAUST6.960-7.000 mm (0.274-0.2756 in)

Maintenance data

Oil system
Recommended engine oilSAE 0W-40, 5W-30, 5W-40
Oil typeAPI SG or SF and better
Engine oil capacity (Refill capacity)4.0 L (4.23 US. qt, 3.52 Imp. qt.)
Ignition system
Spark plugBosch FGR7DQP, NGK BKR6EQUP
Spark plug gap:0.5 mm (0.0197 in)

Vehicle applications

ModelYears Produced
BMW 318i (E36)1993–1999
BMW 518i (E34)1994-1996
BMW 518g Touring (E34)1995-1996
BMW Z3 1.81996–1998
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 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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