Mercedes-Benz M103 engine
The Mercedes-Benz M103 was a straight-6 15 degrees, crossflow cylinder head with an inclination to the right, automobile engine produced from 1984 to 1997. It was a single overhead cam design with 2 valves per cylinder. The M103 was replaced by the M104 starting in 1989. The bore spacing on the M103 engine is 97 mm.
| Mercedes-Benz M103 engine | |
|---|---|
 | |
| Overview | |
| Manufacturer | Mercedes-Benz |
| Production | 1984 to 1997 |
| Layout | |
| Configuration | Naturally aspirated Straight-6 |
| Displacement | 2.6 L; 158.5 cu in (2,597 cc) 3.0 L; 180.6 cu in (2,960 cc) |
| Cylinder bore | 82.9 mm (3.26 in) 88.5 mm (3.48 in) |
| Piston stroke | 80.2 mm (3.16 in) |
| Valvetrain | SOHC 2 valves x cyl. |
| Compression ratio | 9.2:1 |
| RPM range | |
| Redline | 6200 |
| Combustion | |
| Fuel system | Continuous Injection System - Electronic |
| Fuel type | Gasoline |
| Oil system | Pressure circulation |
| Cooling system | Water cooled |
| Output | |
| Power output | 118–140 kW (160–190 PS; 158–188 hp) |
| Torque output | 220–260 N⋅m (162–192 lb⋅ft) |
| Chronology | |
| Predecessor | M110 |
| Successor | M104 |
3.0 L
The 103.980 engine of 3.0 L; 180.6 cu in (2,960 cc) uses the CIS-E (Continuous Injection System - Electronic).
- Specifications
- Engine power @ 5700 rpm: 132 kW (179 PS; 177 hp) with catalyst, 140 kW (190 PS; 188 hp) without catalyst
- Torque @ 4400 rpm: 255 N⋅m (188 lb⋅ft) (with catalyst), 260 N⋅m (192 lb⋅ft) without catalyst
- Bore and stroke: 88.5 mm × 80.2 mm (3.48 in × 3.16 in)
- Compression ratio: 9.2:1
- Redline: 6200 rpm
- Firing order: 1-5-3-6-2-4
- Lubrication system: pressure circulation
- Oil capacity: 6 litres (1.6 US gal; 1.3 imp gal)
- Coolant capacity: 8.5 litres (2.2 US gal; 1.9 imp gal)
- Number of valves: 1 intake, 1 exhaust with V-shaped overhead configuration
- Valve operation: 1 top camshaft.
- Camshaft drive: simple roller-type chain
- Starter motor: 1.5 kW electrical motor; since Jan 1988: 1.7 kW
- Ignition system: electronic ignition system.
- Recommended fuel octane: 91 RON/MON (96 RON) (86 MON).
This engine can be found in the W124 E-Class, W126 S-Class, Mercedes-Benz R129, W463 G-Class and the R107.
2.6 L
The smaller 103.940 engine of 2.6 L; 158.5 cu in (2,597 cc) also used the CIS-E engine management system.
- Specifications
- Engine power @ 5800 rpm: 118 kW (160 PS; 158 hp) with catalyst, 124 kW (169 PS; 166 hp) without catalyst
- Torque @ 4600 rpm: 220 N⋅m (162 lb⋅ft) with catalyst, 228 N⋅m (168 lb⋅ft) without catalyst.
- Bore and stroke: 82.9 mm × 80.2 mm (3.26 in × 3.16 in)
- Compression ratio: 9.2:1
- Redline: 6200 rpm
- Firing order: 1-5-3-6-2-4
- Lubrication system: pressure circulation
- Oil capacity: 6 litres (1.6 US gal; 1.3 imp gal)
- Coolant capacity: 8.5 litres (2.2 US gal; 1.9 imp gal)
- Camshaft drive: simple roller-type chain
- Number of valves: 1 intake, 1 exhaust with V-shaped overhead configuration
- Valve operation: 1 top camshaft
- Starter motor: 1.5 kW electrical motor; since Jan 1988: 1.7 kW
- Ignition system: electronic ignition system.
The only mechanical differences from the M103 3.0 L to the M103 2.6 L were the smaller bore and intake valves, with a slightly different airbox. The CIS-E components between 2.6 and 3.0 variants are all shared for any given model year with the exception of the ECU making engine swaps from 2.6 to 3.0 virtually bolt-in.
This engine can be found in the W201 (190), W124 E-Class and W126 S-Class.