Engine block

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Engine block, 4- cylinder in - line engine

An engine block is part of an internal combustion engine . In addition to the cylinders, it also combines the crankshaft bearings and, in the case of water-cooled engines, the water jacket. In technical terms, however, the combination of the above-mentioned components is called the crankcase . On the engine block there is usually the option of attaching the ancillary units necessary for the operation of the engine .

Main tasks

The main functions of the engine block are

  • Transmission of dynamic forces (mass and gas forces) of an engine,
  • Bearing of the crankshaft ,
  • and often the camshaft (except when it is in the cylinder head ),
  • to form the end of the engine room together with the oil pan ,
  • To provide a connection for mounting the engine in the vehicle,
  • Inclusion of auxiliary units and
  • of the cylinder head
  • as well as the inclusion of any existing cylinder liners .

Due to the large number of tasks, the crankcase is also subject to many stresses, such as torsional moments or forces from the transmission of gas forces from the cylinder head to the crankshaft bearings.

Construction and materials used

The majority of all small and medium-sized engine blocks produced consist of a cast part, with cast iron , nodular cast iron (for higher loads) and light metal (mainly aluminum) being used as the material. In some medium-sized and almost all large engines, the engine block is separated into two or more cast parts because of the casting problems. Most often, in this case, the cylinders are manufactured separately from the crankcase and attached with expansion bolts . In order to circumvent the difficulties that arise with increasing casting sizes, welded constructions made of steel or cast steel are preferred for the largest engines (thermal power plants and large ship propulsion systems) .

Other distinguishing features

Another distinguishing feature is the design of the top of the engine block, the so-called cover plate. A distinction is made between closed-deck and open-deck designs. In the closed-deck version, the water jacket surrounding the cylinder is closed at the top, so when looking at the engine block, only the cylinder bores and the engine oil and cooling water duct bores can be seen. In the case of an open deck block, the cylinders are free-standing and the water jacket is open at the top; it is then closed by means of a special head gasket through the cylinder head during assembly; Another task of the cylinder head is to fix the free-standing and thus easily movable cylinders. The advantage of the closed-deck construction is the slightly higher rigidity of the engine block and the need for a cylinder head gasket; however, this comes at the price of a more complicated casting process .

Colloquially, the internal combustion engine of a motor vehicle is also referred to as a whole as an “engine block”. This means the entire engine as a unit, i.e. the actual engine block, supplemented by the crankshaft drive - namely the crankshaft , pistons and connecting rods with all bearings, as well as the cylinder head and fittings. In technical terms, however, the engine block (without cylinder head and ancillary units, but including all internals) is called a short engine .

The connection between crankshaft bearings and cylinders is characteristic of an engine block. The engine block is very often the largest and most expensive cast part in a motor vehicle. Often only the oil pan is mounted under the engine block. The lower bearing of the crankshaft with individual bearing caps (cast or forged parts) and their bearing shells are counted as part of the engine block: An engine block is only complete when it can accommodate the crankshaft and contains the cylinders.

Big Block and Small Block

Big block and small block are names from the USA to differentiate between V8 motor vehicle engines. The difference is not primarily in the displacement , but in the dimensions of the engine block and the space available for the cylinders: Small block engines generally have a bore of less than 4 inches or 10 cm , while big block engines usually have more than this value.

Big block engines were produced almost exclusively by Ford , General Motors, and Chrysler in the United States and were used in large American vehicles and in muscle cars . Big blocks are rare today, especially in pick-ups , American sports cars, and trucks .

The small block has a typical 5.7 liters, since 1957 in the Corvette series. However, there are also engines with a displacement of 7.0 liters, such as the Chevrolet Corvette Z06 , as well as big-block engines with a displacement of 5.9 liters.

GM celebrated the 50th anniversary of its small block in 2006 and produced the one hundred millionth small block on November 29, 2011.


  • Richard van Basshuysen, Fred Schäfer: Handbook Internal Combustion Engine Basics, Components, Systems, Perspectives. 3rd edition, Friedrich Vieweg & Sohn Verlag / GWV Fachverlage GmbH, Wiesbaden, 2005, ISBN 3-528-23933-6

Individual evidence

  1. 50 Years of the Small Block: The Birth Of A Notion , motortrend.com.
  2. heise: GM produces the 100,000,000th Small Block V8 .

Web links

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