The 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 code | M43B18 |
| Layout | Four stroke, Inline-4 (Straight-4) |
| Fuel type | Gasoline |
| Production | 1993-1999 |
| Displacement | 1.8 L, 1,796 cc (109.6 cu in) |
| Fuel system | Multi Point Fuel Injection (MPFI) |
| Power adder | None |
| 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 order | 1-3-4-2 |
| Dimensions (L x H x W): | – |
| Weight | – |
Cylinder block
| 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) | |
| 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: | Top | 0.020-0.200 mm (0.0008-0.0079 in) |
| Second | 0.020-0.100 mm (0.0008-0.0039 in) | |
| Piston ring end gap: | Top | 0.200-1.000 mm (0.0079-0.0394 in) |
| Second | 0.200-1.000 mm (0.0079-0.0394 in) | |
| Oil | 0.400-1.400 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: | INTAKE | 42.000 mm (1.6535 in) |
| EXHAUST | 36.000 mm (1.4173 in) | |
| Valve steam diameter: | INTAKE | 6.975-7.000 mm (0.2746-0.2756 in) |
| EXHAUST | 6.960-7.000 mm (0.274-0.2756 in) | |
Maintenance data
| Oil system | |
| Recommended engine oil | SAE 0W-40, 5W-30, 5W-40 |
| Oil type | API SG or SF and better |
| Engine oil capacity (Refill capacity) | 4.0 L (4.23 US. qt, 3.52 Imp. qt.) |
| Ignition system | |
| Spark plug | Bosch FGR7DQP, NGK BKR6EQUP |
| Spark plug gap: | 0.5 mm (0.0197 in) |
Vehicle 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 |
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