The 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) |
Applications
| 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 |
References
1. BMW TIS (Technical Information System)
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