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24-457: The block features an aluminium crankcase and cylinder heads . It uses aluminium sand casting in bedplate construction (divided at the height of the crankshaft ) with wet cylinder liners made of cast iron. The main bearings are reinforced, cast in GGG ductile cast iron . Rather than the usual 90° " vee " angle between the cylinder banks, a 75° angle was chosen due to the space available to install

48-615: A variable geometry turbocharger . The compressed air from these is cooled by an air to water heat exchanger with an additional cold water circuit. Compared to the OM628, the OM629 engine has an improved common-rail system, and higher boost from the turbochargers. It displaces 4.0 L (3,996 cc) and produces between 225 to 235 kW (306 to 320 PS; 302 to 315 hp) at 3600 rpm, and 700 to 730 N⋅m (516 to 538 lb⋅ft) of torque between 2000–2600 rpm. Crankcase A crankcase

72-863: A conventional wet-sump system, which uses only the main sump (U.S.: oil pan) below the engine and a single pump. A dry-sump engine requires a pressure relief valve to regulate negative pressure inside the engine, so internal seals are not inverted. Dry-sumps are common on larger diesel engines such as those used in ships, as well as gasoline engines used in racing cars , aerobatic aircraft , high-performance personal watercraft and motorcycles. Dry sump lubrication may be chosen for these applications due to increased reliability, oil capacity, reduction of oil starvation under high g -loads and/or other technical or performance reasons. Dry sump systems may not be suitable for all applications due to increased cost, complexity, and/or bulk, among other factors. Engines are both lubricated and cooled by oil that circulates throughout

96-523: A dry sump engine which requires initial oil change after 500 miles. The dry-sump lubrication is particularly applicable to motorcycles, which tend to be operated more vigorously than other road vehicles. Although motorcycles such as the Honda CB750 (1969) feature a dry-sump engine, modern motorcycles tend to use a wet-sump design. This is understandable with across-the-frame inline four-cylinder engines , since these wide engines must be mounted fairly high in

120-411: A messy environment, because oil spray from the moving parts was not contained. Another disadvantage was that dirt and dust could get into moving engine parts, causing excessive wear and possible malfunction of the engine. Frequent cleaning of the engine was required to keep it in normal working order. Some two-stroke diesel engines, such as the large slow-speed engines used in ships, have the crankcase as

144-414: A pressure pump in the pump stack . Dry sump systems may optionally be designed to keep the engine's crankcase at lower than atmospheric pressure (vacuum), by sealing the crankcase and allowing the scavenge pumps to draw out both oil and gases. An equilibrium pressure will be reached when the rate of gases entering the crankcase (blow-by gases past the piston rings, but also air leaks and oil vapor) equals

168-438: A separate space from the cylinders, or as an open crank. The spaces between the crosshead piston and the crankshaft, may be largely open for maintenance access. Dry sump A dry-sump system is a method to manage the lubricating motor oil in four-stroke and large two-stroke piston driven internal combustion engines . The dry-sump system uses two or more oil pumps and a separate oil reservoir, as opposed to

192-399: A single pulley at the front of the system can run as many pumps as the engine design requires. It is common practice to have one scavenge pump per crankcase section; however, in the case of inverted engines (typically aircraft engines ) it is necessary to employ separate scavenge pumps for each cylinder bank . Therefore, an inverted V engine would have a minimum of two scavenge pumps and

216-431: Is not used for the fuel/air mixture. Engine oil is recirculated around a four-stroke engine (rather than burning it as happens in a two-stroke engine) and much of this occurs within the crankcase. Oil is stored either at the bottom of the crankcase (in a wet sump engine) or in a separate reservoir (in a dry sump system). From here the oil is pressurized by an oil pump (and usually passes through an oil filter ) before it

240-423: Is squirted into the crankshaft and connecting rod bearings and onto the cylinder walls, and eventually drips off into the bottom of the crankcase. Even in a wet sump system, the crankshaft has minimal contact with the sump oil. Otherwise, the high-speed rotation of the crankshaft would cause the oil to froth, making it difficult for the oil pump to move the oil, which can starve the engine of lubrication. Oil from

264-441: Is the housing in a piston engine that surrounds the crankshaft . In most modern engines, the crankcase is integrated into the engine block . Two-stroke engines typically use a crankcase-compression design, resulting in the fuel/air mixture passing through the crankcase before entering the cylinder(s) . This design of the engine does not include an oil sump in the crankcase. Four-stroke engines typically have an oil sump at

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288-443: Is the power piston, the lower side acts as a pump. Therefore an inlet valve is not required. Unlike other types of engines, there is no supply of oil to the crankcase, because it handles the fuel/air mixture. Instead, two-stroke oil is mixed with the fuel used by the engine and burned in the combustion chamber. Large two-stroke engines do not use crankcase compression, but instead a separate scavenge blower or supercharger to draw

312-404: Is uncovered and the compressed fuel/air mixture is pushed from the crankcase into the combustion chamber. Crankcase-compression designs are often used in small petrol (gasoline) engines for motorcycles, generator sets and garden equipment. This design has also been used in some small diesel engines, however it is less common. Both sides of the piston are used as working surfaces: the upper side

336-436: The bottom of the crankcase and the majority of the engine's oil is held within the crankcase. The fuel/air mixture does not pass through the crankcase, though a small amount of exhaust gasses often enter as "blow-by" from the combustion chamber , particularly in engines with worn rings. The crankcase often forms the upper half of the main bearing journals (with the bearing caps forming the other half), although in some engines

360-411: The crankcase completely surrounds the main bearing journals. An open-crank engine has no crankcase. This design was used in early engines and remains in use in some large marine diesel engines. Many two-stroke engines use a crankcase-compression design, where a partial vacuum draws the fuel/air mixture into the engine as the piston moves upwards. Then as the piston travels downward, the inlet port

384-425: The crankcase, contamination of the oil and rust from condensation. To prevent this, modern engines use a crankcase ventilation system to expel the combustion gases from the crankcase. In most cases, the gases are passed through to the intake manifold. Early engines were of the "open-crank" style, that is, there was no enclosed crankcase. The crankshaft and associated parts were open to the environment. That made for

408-415: The engine, feeding various bearings and other moving parts and then draining, via gravity, into the sump at the base of the engine. In the wet-sump system of nearly all production automobile engines, the oil that's not actively circulating is stored in the sump, which is large enough for this purpose. A pump collects oil from the sump and directly circulates it back through the engine. In a dry-sump system,

432-469: The engine. The consequence of this specific angle is free inertial forces of the first order. To compensate for this, the OM628 and OM629 use a balancer shaft located in the vee of the engine. To ensure even firing intervals the crankshaft uses split crank pins . The engine uses 97.0 mm cylinder spacing. The engine uses dual overhead camshafts on each bank (‘quad-cam’) with four valves per cylinder, operated by hydraulic tappets . Each cylinder bank uses

456-426: The filter and into the engine itself. An adjustable pressure regulator ensures that the oil pressure is kept stable at different engine speeds. The dry-sump system requires at least two pumps - one pressure and one scavenge - and sometimes as many as four or five scavenge pumps are used to minimize the amount of oil in the engine. The pressure pump and scavenge pumps are frequently mounted on a common crankshaft, so that

480-413: The fuel/air mixture into the compression chamber. Therefore the crankcases are similar to a four-stroke engine in that they are solely used for lubrication purposes. Most four-stroke engines use a crankcase that contains the engine's lubricating oil, as either a wet sump system or the less common dry sump system. Unlike a two-stroke (crankcase-compression) engine, the crankcase in a four-stroke engine

504-500: The oil still falls to the base of the engine, but into a much shallower sump, where one or more scavenge pumps draw it away and transfer it to a (usually external) reservoir, where it is both cooled and de-aerated before being recirculated through the engine by a pressure pump. The sump in a dry-sump system is not actually dry; it is still wet from oil draining from the engine. The reservoir is usually tall and narrow and specially designed with internal baffles, and an oil outlet (supply) at

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528-800: The rate of gas removal from the scavenge pump capacity beyond what's required to remove just the oil. Alternatively, the crankcase may be kept near atmospheric pressure by venting it to the oil reservoir, which in turn is vented into the engine's air intake, or to outside air. A dry-sump system offers many advantages over a wet-sump. The primary advantages include: Dry-sump engines have several disadvantages compared to wet-sump engines, including; Dry-sumps are common on larger diesel engines such as those used for ship propulsion, largely due to increased reliability and serviceability. They are also commonly used in racing cars and aerobatic aircraft, due to problems with g-forces , reliable oil supply, power output and vehicle handling. The Chevrolet Corvette Z06 has

552-430: The sump may splash onto the crankshaft due to g-forces or bumpy roads, which is referred to as windage . Although the piston rings are intended to seal the combustion chamber from the crankcase, it is normal for some combustion gases to escape around the piston rings and enter the crankcase. This phenomenon is known as blow-by . If these gases accumulated within the crankcase, it would cause unwanted pressurisation of

576-400: The very bottom for uninhibited oil supply even during sloshing. The dry pump operation consists of a pressure stage and a scavenging stage. Although the term "stages" is commonly used to describe the work of the multiple pumps, they typically run in parallel rather than in series as might be implied by the term. The pressure stage draws oil from the bottom of the reservoir and passes it through

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