| Mercedes-Benz M100 engine | |
|---|---|
 | |
| Overview | |
| Manufacturer | Daimler-Benz |
| Production | 1963-1981 |
| Layout | |
| Configuration | Naturally aspiratedV8 |
| Displacement |
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| Cylinder bore |
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| Piston stroke | 95 mm (3.74 in) |
| Cylinder block material | Cast iron |
| Cylinder head material | Aluminum |
| Valvetrain | SOHC |
| Compression ratio |
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| Combustion | |
| Fuel system | Mechanical fuel injection |
| Management |
|
| Fuel type | Gasoline |
| Oil system | Dry sump |
| Cooling system | Water-cooled |
| Output | |
| Power output |
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| Torque output |
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TheMercedes-Benz M 100 engine was a 6,333 cc (386.5 cu in) or 6,834 cc (417.0 cu in)[1]single overhead camV8 produced byMercedes-Benz between 1963 and 1981. The successor to theM 189 version of the company's venerated 2,996 cc (182.8 cu in)straight-6M 186, it was introduced in the flagshipMercedes-Benz 600 in 1963. From 1968 to 1972, it was fitted also into the S-class body for a specialhigh-performance300 SEL 6.3 sports sedan that was replaced by the450 SEL 6 9 in 1975.
The original displacement of 6,333 cc (386.5 cu in) exceeded that of the firstRolls-Royce V8 engine with 6,231 cc (380.2 cu in) by approximately 0.1 L. In the 1970s, AMG enlarged M 100 engines to 6,8 L, for racing and road use. In the US, catalytic converters and unleaded fuel caused loss of power. Rolls-Royce had now 6,750 cc (6.8 L; 411.9 cu in), and for the450 SEL 6.9 (1975-1981) the M 100 engine was enlarged to 6,834 cc (417.0 cu in). Actually a 6.8 L engine, it was designated 6.9 to emphasize that its displacement still exceeded that of the enlargedRolls-Royce V8 engine.[citation needed]
The M 100 featured a cast iron block, aluminum alloy heads, and aircraft-stylesodium-filledvalves operating against hardened valve seats. As in all Mercedes-Benz automobile engines, thecrankshaft,connecting rods and pistons wereforged instead ofcast.
Each hand-built unit was bench-tested for 265 minutes, 40 of which were under full load. When introduced, it utilized a complicated 8-pistonmechanical fuel injection system designed and built in-house by Daimler-Benz. The 6,834 cc (417.0 cu in) version used a simplerBoschK-JetronicContinuous Injection System.
The 6.3 L engine was conservatively rated at 250 PS (184 kW; 247 hp), with 51 kp⋅m (500 N⋅m; 369 lb⋅ft) oftorque helping to compensate for the 2.85 to 1[2] finaldrive ratio necessary for sustained high-speed cruising.
In non-US trim, the larger engine produced 286 PS (210 kW; 282 hp) with 550 N⋅m (406 lb⋅ft) of torque. The North American version, introduced in 1977, was significantly less powerful at 250 hp (186 kW; 253 PS) and 360 lb⋅ft (488 N⋅m) of torque due to more stringentemissions control requirements.
As adry sump enginelubrication system reduces overall engine height, the 6.8 L M 100 used it in order to fit into the much flatter motor house of theW 116. As a side effect it enhanced longevity. Originally developed for racing as a way to prevent oil starvation during aggressive cornering, which in turn would create a serious drop in oil pressure, it allowed sustained high speeds at full engine power. The M 100 system circulated a massive twelve litres of oil through the engine and a storage tank mounted inside the right front fender, as opposed to the usual five or six litres found in V8s with a standard oil pan and oil pump configuration. The dry sump system also had the benefit of extending the oil change interval to 12,500 miles (20,100 km). This, along with hydraulic valve lifters which required no adjusting and special cylinder head gaskets which eliminated the need for periodic retorquing of the head bolts, made the 6.9 nearly maintenance-free for its first 50,000 miles (80,000 km).