Mercedes-Benz M103 engine

The Mercedes-Benz M103 was a straight-6 15 degrees, 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 1992.

The 103.980 engine (181 in³ or 2960 cm³) produces 177 hp or 132 kW at 5700 rpm (with catalyst), 188 hp or 140 kW at 5700 rpm (without catalyst), and has a torque of 188 ft·lbf or 255 N·m at 4400 rpm (with catalyst), 191 ft·lbf or 260 N·m at 4400 rpm (without catalyst). It uses the CIS-E (Continuous Injection System - Electronic) and has a bore of 88.5 mm (3.48 in) and a stroke of 80.2 mm (3.16 in). The compression ratio is 9.2 : 1 with a redline of 6200 rpm. The firing order is 1-5-3-6-2-4. Lubrication system is pressure circulation lubrication system. Amount of oil in engine is 6.0 litres and amount of coolant is 8.5 litres. Number of valves is 1 intake, 1 exhaust with V-shaped overhead configuration. Valve operation was 1 top camshaft. Camshaft drive was simple roller-type chain. Starter motor is electrical with 1.5 kW; since 01.88 was 1.7 kW. Ignition system is electronic ignition system. Recommended fuel octane for the M103 is 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.

The smaller 103.940 engine (158 in³ or 2597 cm³) produces 158 hp or 118 kW at 5800 rpm (with catalyst), 166 hp or 124 kW at 5800 rpm (without catalyst), and generates torque at 162 ft·lbf or 220 N·m at 4600 rpm (with catalyst), 168 ft·lbf or 228 N·m at 4600 rpm (without catalyst). It also used the CIS-E engine management system and had a bore of 82.9 mm (3.26 in) and a stroke of 80.2 mm (3.16 in). The only mechanical differences from the M103 3.0 L to the M103 2.6 L were the decrease in bore, smaller intake valves and 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.

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