The BMW M42B18 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 1989 to 1996.
A 84.0 mm (3.31 in) cylinder bore and 81.0 mm (3.19 in) piston stroke give the M42B18 engine a total of 1,796 cc of displacement. The compression ratio rating is 10.0:1.
The BMW M42B18 engine produced 136.0 PS (100.0 kW; 134.0 HP) at 6,000 rpm of maximum output power and 172.0 N·m (17.5 kg·m, 126.8 ft·lb) at 4,600 rpm of peak torque for E30 model, or 140.0 PS (103.0 kW; 138.0 HP) at 6,000 rpm of horsepower and 175.0 N·m (17.8 kg·m, 129.0 ft·lb) at 4,500 rpm of torque for E36 model.
The BMW M40B18 features:
- Cast-iron cylinder block
- Crankshaft with eight counterweights
- Aluminum cylinder head
- Chain-driven double overhead camshafts (DOHC)
- Low-maintenance timing chain with a self-adjusting hydraulic chain tensioner
- 16 valves (4 per cylinder) with hydraulic tappets
- Multi Point Fuel Injection (MPFI)
- Bosch Motronic M 1.7 engine management system
- “Coil-on-plug” ignition system with fully electronic controlled ignition timing
- Dual length intake manifold (BMW “DISA” system) for later versions
- Pressurized lubrication system
- Liquid-cooled cooling system
General information
| Engine Specifications | |
| Engine model | M42B18 |
| Production | 1989-1996 |
| Engine type | 4-stroke, DOHC, inline-4 |
| Displacement | 1.8 L, 1,796 cm3, (109.6 cu·in) |
| Max. horsepower | E30: 136.0 PS (100.0 kW; 134.0 HP) at 6,000 rpm E36: 140.0 PS (103.0 kW; 138.0 HP) at 6,000 rpm |
| Max. torque | E30: 172.0 N·m (17.5 kg·m, 126.8 ft·lb) at 4,600 rpm E36: 175.0 N·m (17.8 kg·m, 129.0 ft·lb) at 4,500 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: | 10.0:1 |
| 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): | 28.000 mm (1.1024 in) |
| Connecting rod small end diameter (standard): | 22.0050-22.0120 mm (0.8663-0.8666 in) |
| Piston pin diameter: | 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) |
| Side clearance (Oil): | 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): | 0.200-1.000 mm (0.0079-0.0394 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: | 40.5 mm (1.595 in) |
| Cylinder head | |
| Cylinder head alloy: | Aluminium |
| Valve arrangement: | DOHC, chain driven |
| Valves: | 4 ,(16 valves in total) |
| Head height: | 139.550-140.000 mm (5.4941-5.5118 in) |
| Valve head diameter (INTAKE): | 33.0 mm (1.2992 in) |
| Valve head diameter (EXHAUST): | 30.5 mm (1.2008 in) |
| Valve steam diameter (INTAKE): | 5.975-6.000 mm (0.2352-0.2362 in) |
| Valve steam diameter (EXHAUST): | 5.960-6.000 mm (0.2346-0.2362 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: | 4.8 L (5.07 US. qt, 4.22 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 | |
| Type: | Electronic “Coil-on-plug” ignition system |
| Spark plug: | Bosch F7LDCR, Champion RC8DMC, NGK BKR6EK |
| Spark plug gap: | 0.9 mm (0.0354 in) |
| Spark plug torque: | 27 N·m (2.8 kg·m, 19.9 ft·lb) |
Applications
| Model | Years Produced |
| BMW 318is (E30) | 1989–1991 |
| BMW 318i (E30) | 1990–1992 |
| BMW 318i (E36) | 1992–1995 |
| BMW 318is (E36) | 1991–1995 |
| BMW 318ti (E36) | 1994–1995 |
References
1. BMW TIS (Technical Information System)
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