Mercedes-Benz M100 engine
|Mercedes-Benz M-100 engine|
|Configuration||Naturally aspirated V8|
|Piston stroke||95 mm (3.74 in)|
|Block material||Cast iron|
|Fuel system||Mechanical fuel injection|
|Oil system||Dry sump|
The Mercedes-Benz M100 engine was introduced in the 1963 Mercedes-Benz 600 with 6.3 litres (6,332 cc), and later also used in the Mercedes-Benz 300SEL 6.3 from 1968 onwards, and even larger, in the 1970s 600 and Mercedes-Benz 450SEL 6.9.
Each hand-built unit was bench-tested for 265 minutes, 40 of which were under full load. The 6.3 litres (6,332 cc) version utilized a mechanical fuel injection system designed and built in-house by Daimler-Benz, the Bosch K-Jetronic CIS fuel injection system was used from 1973 when displacement was increased to 6.9 litres. No version of the M100 engine ever utilized the electronic Bosch D-Jetronic system as was employed on early iterations of the smaller M116/117 V8s. As in all Mercedes-Benz automobile engines, the crankshaft, connecting rods and pistons were forged instead of cast.
In non-US trim, the 6,834 cc (6.8 L; 417.0 cu in) power plant was conservatively rated at 286 PS (210 kW) with 550 N⋅m (406 lb⋅ft) of torque helping to compensate for the 2.65 to 1 final drive ratio necessary for sustained high-speed cruising. The North American version, introduced in 1977, was significantly less powerful at 250 PS (184 kW) and 488 N⋅m (360 lb⋅ft) of torque due to more stringent emissions control requirements.
In the interest of both engine longevity as well as an effort to reduce overall engine height, a "dry sump" engine lubrication system was used. Originally developed for use in race cars as a way to prevent foaming of the engine oil by the crankshaft which in turn would create a serious drop in oil pressure, the system circulated twelve litres of oil between the storage tank mounted inside the right front fender and the engine as opposed to the usual four or five litres found in V8s with a standard oil pan and oil pump. As a result, the engine itself had no dipstick for checking the oil level. Rather, the dipstick was attached to the inside of the tank's filler cap (accessible from the engine compartment) and the oil level was checked with the engine running and at operating temperature. The dry sump system also had the benefit of extending the oil change interval to 12,500 mi (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 mi (80,000 km). The 6.9 required little basic service other than coolant, minor tune-ups, oil changes and replacement of the air, fuel, oil and power-steering-fluid filters.