The BMW M40B18 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 1987 to 1994 .
A 84.0 mm (3.31 in) cylinder bore and 81.0 mm (3.19 in) piston stroke give the M40B18 engine a total of 1796 cc of displacement. The compression ratio rating is 8.8:1.
The BMW M40B18 engine produced 113.0 PS (83.0 kW; 111.0 HP) at 5,500 rpm of maximum output power and 162 N·m (16.5 kg·m, 119.4 ft·lb) at 4,250 rpm of peak torque for E30 model, or 115.6 PS (85.0 kW; 114.0 HP) at 5,500 rpm of horsepower and 165 N·m (16.8 kg·m, 121.6 ft·lb) at 4,250 rpm of torque for E36 model.
The BMW M40B18 features:
- Belt-driven single overhead camshaft (SOHC)
- 8 valves with hydraulic tappets
- Cast-iron cylinder block
- Crankshaft with eight counterweights
- Multi Point Fuel Injection (MPFI)
- Bosch Motronic M 1.3 or Bosch Motronic M 1.7 engine management system
- Pressurized lubrication system
- Liquid-cooled cooling system
General information
| Engine Specifications | |
| Engine model | M40B18 |
| Engine type | 4-stroke, SOHC, inline-4 |
| Displacement | 1.8 L, 1,796 cm3, (109.6 cu·in) |
| Max. horsepower | E30: 113.0 PS (83.0 kW; 111.0 HP) at 5,500 rpm E36: 115.6 PS (85.0 kW; 114.0 HP) at 5,500 rpm |
| Max. torque | E30: 162 N·m (16.5 kg·m, 119.4 ft·lb) at 4,250 rpm E36: 165 N·m (16.8 kg·m, 121.6 ft·lb) at 4,250 rpm |
| Cooling system | Liquid-cooled |
| Lubricating system | Pressurized lubrication |
| Fuel system | Multi Point Fuel Injection (MPFI) |
| Engine management system | E30: Bosch Motronic M 1.3 E36: 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: | 8.8:1 |
| 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 small end diameter (standard): | 22.005-22.012 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) |
| 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) |
| Number of main bearings: | 5 |
| Crankshaft main journal diameter: | 60.000 mm (2.3622 in) |
| Crankpin journal diameter: | 45.000 mm (1.7717 in) |
| Cylinder head | |
| Cylinder head alloy: | Aluminium |
| Valve arrangement: | SOHC, belt driven |
| Valves: | 2,(8 valves in total) |
| Head height: | 141.000 mm (5.5512 in) |
| Intake valve duration: | 244° |
| Exhaust valve duration: | 244° |
| Valve head diameter (INTAKE): | 42.000 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) |
| Valve lift (INTAKE): | 10.6 mm (0.4173 in) |
| Valve lift (EXHAUST): | 10.6 mm (0.4173 in) |
Service Data
| 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.) |
| Ignition system | |
| Spark plug: | Bosch F8LCR, Champion C9YCC, NGK ZFR5F-11 |
| Spark plug gap: | 0.7-0.9 mm (0.0276-0.0354 in) |
Applications
| Model | Years Produced |
| BMW 318i (E30) | 1987–1994 |
| BMW 318i (E36) | 1992–1993 |
| BMW 518i (E34) | 1989–1994 |
References
1. BMW TIS (Technical Information System)
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