| Mercedes-Benz M103 engine | |
| Manufacturer: | Mercedes-Benz |
| Production: | 1984–1997 |
| Predecessor: | M110 & M123 |
| Successor: | M104 |
| Configuration: | Naturally aspirated Straight-6 |
| Valvetrain: | SOHC / 2 valves x cyl. |
| Compression: | 9.2:1 |
| Redline: | 6200 |
| Displacement: | 2599cc 2962cc |
| Power: | NaN0NaN0 |
| Torque: | NaN0NaN0 |
| Bore: | 82.93NaN3 88.53NaN3 |
| Stroke: | 80.253NaN3 |
| Fueltype: | Gasoline |
| Fuelsystem: | Continuous Injection System - Electronic |
| Coolingsystem: | Water cooled |
| Oilsystem: | Wet sump |
The Mercedes-Benz M103 is a straight-6 15 degrees, crossflow cylinder head with an inclination to the right, automobile engine produced from 1984 to 1997. It is a single overhead cam design with 2 valves per cylinder. The M103 was replaced by the M104 starting in 1989. This engine received several updates over the years of production, one of the updates was a change from a spherical combustion chamber to a "heart shaped" combustion chamber.
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.
| Model | 260 | 300 | |
|---|---|---|---|
| Type | 103.940 | 103.980 | |
| Production period | 1984–1997 | ||
| Layout | |||
| Configuration | Straight-six | ||
| bore pitch | 973NaN3 | ||
| Cylinder bore | 82.93NaN3 | 88.53NaN3 | |
| Piston stroke | 80.253NaN3 | ||
| Displacement | NaN82.9^2*80.25*pi*6/4000 | NaN88.5^2*80.25*pi*6/4000 | |
| Max. engine speed | 6,200/min | ||
| Combustion | |||
| Principle | Internal combustion engine | ||
| Mode of operation | Four-stroke | ||
| Fuel type | gasoline | ||
| Fuel octane | 95 RON/85 MON · 91 RON/81MON via plug-in jumper located in the engine compartment | ||
| Fuel system | CIS-E (Continuous Injection System) | ||
| Ignition system | electronic engine control unit | ||
| Firing order | 1–5–3–6–2–4 | ||
| Valvetrain | SOHC | ||
| Valves per cylinder | 2 | ||
| Configuration | V-shaped overhead crossflow | ||
| Camshaft drive | simple roller-type chain | ||
| Aspiration | Naturally aspirated | ||
| Compression ratio | 9.2 : 1 | ||
| Management | |||
| Lubrication | pressure circulation with Wet sump | ||
| Oil capacity | 6L | ||
| Cooling | water cooled engine cooling | ||
| Coolant capacity | 8.5L | ||
| Starter motor | 1.5 kW electrical motor · since Jan 1988: 1.7 kW | ||
| Performance | |||
| Power w/ catalyst | 1600NaN0 | 1800NaN0 | |
| @ engine speed | 5,800/min | 5,700/min | |
| Torque w/ catalyst | 2200NaN0 | 2550NaN0 | |
| @ engine speed | 4,600/min | 4,400/min | |
| Power w/o catalyst | 1700NaN0 | 1900NaN0 | |
| @ engine speed | 5,800/min | 5,700/min | |
| Torque w/o catalyst | 2280NaN0 | 2600NaN0 | |
| @ engine speed | 4,600/min | 4,400/min | |
| Applications | |||
| W201 | 190 E 2.6 | ||
| W124 | 260 E · 300 E 2.6 | 300 E | |
| W126 | 260 SE | 300 SE · 300 SEL | |
| R107 SL | 300 SL | ||
| R129 SL | 300 SL | ||
| W463 | 300 GE | ||
| Isdera Spyder 036i | Isdera Spyder 036i | ||
The M 102 and M 103 engine family has a common piston stroke of 80.25 mm. As only one decimal place is usually given, a large number of publications are in circulation with the incomplete specification of 80.2 mm. This applies in particular to more recent publications after production was discontinued. As a result, the inaccurate figures of 2.597 cc instead of the actual 2.599 cc for the 2.6 l engine and 2.960 cc instead of 2.962 cc for the 3.0 l engine have become established.
| Model | 200 | 230 | 260 | 300 | |
|---|---|---|---|---|---|
| Engine | M 102 | M 103 | |||
| Type | 102.92X–96X | 102.98X | 103.940 | 103.980 | |
| Configuration | Straight-four | Straight-six | |||
| Cylinder bore | 893NaN3 | 95.53NaN3 | 82.93NaN3 | 88.53NaN3 | |