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In an
internal combustion engine An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal co ...
, the engine block is the structure which contains the
cylinders A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an infini ...
and other components. In an early automotive engine, the engine block consisted of just the cylinder block, to which a separate crankcase was attached. Modern engine blocks typically have the crankcase integrated with the cylinder block as a single component. Engine blocks often also include elements such as coolant passages and oil galleries. The term "cylinder block" is often used interchangeably with "engine block", although technically, the block of a modern engine (i.e. multiple cylinders integrated with another component) would be classified as a monobloc. __TOC__


Construction

The main structure of an engine typically consists of the cylinders, coolant passages, oil galleries, crankcase, and cylinder head(s). The first production engines of the 1880s to 1920s usually used separate components for each of these elements, which were bolted together during engine assembly. Modern engines, however, often combine many of these elements into a single component in order to reduce production costs. The evolution from separate components to monobloc engine blocks has been a gradual progression since the early 20th century. The integration of elements has relied on the development of
foundry A foundry is a factory that produces metal castings. Metals are cast into shapes by melting them into a liquid, pouring the metal into a mold, and removing the mold material after the metal has solidified as it cools. The most common metals ...
and machining techniques. For example, a practical low-cost V8 engine was not feasible until Ford developed the techniques used to build its flathead V8 engine. Those techniques were then applied by other manufacturers to their engines.


Cylinder block

A cylinder block is the structure which contains the cylinder, plus any cylinder sleeves and coolant passages. In the earliest decades of internal combustion engine development, cylinders were usually cast individually, so cylinder blocks were usually produced individually for each cylinder. Following that, engines began to combine two or three cylinders into a single cylinder block, with an engine combining several of these cylinder blocks combined. In early engines with multiple cylinder bankssuch as V6, V8, or flat-6 engineseach bank was typically made of one or multiple separate cylinder blocks. Since the 1930s, mass production methods have developed to allow both banks of cylinders to be integrated into the same cylinder block.


Cylinder liners

Wet liner cylinder blocks use cylinder walls that are entirely removable, which fit into the block by means of special gaskets. They are referred to as "wet liners" because their outer sides come in direct contact with the engine's coolant. In other words, the liner serves as the entire cylinder wall, rather than being merely a sleeve. Advantages of wet liners are a lower mass, reduced space requirements, and coolant being heated faster from a cold start, which reduces start-up fuel consumption and provides heating for the car cabin sooner. Dry liner cylinder blocks use either the block's material or a discrete liner inserted into the block to form the backbone of the cylinder wall. Additional sleeves are inserted within, which remain "dry" on their outside, surrounded by the block's material. For either wet or dry liner designs, the liners (or sleeves) can be replaced, potentially allowing an engine overhaul or rebuild without replacing the block itself, although this is often not a practical repair option.


Coolant and oil passages


Crankcase

The crankcase is the structure that houses the crankshaft. As with cylinder blocks, this is primarily an integrated component in modern engines.


Materials

Engine blocks are normally cast from either
cast iron Cast iron is a class of iron– carbon alloys with a carbon content more than 2%. Its usefulness derives from its relatively low melting temperature. The alloy constituents affect its color when fractured: white cast iron has carbide impu ...
or an aluminium alloy. Aluminium blocks are much lighter in weight and transfer heat more effectively to coolant, but iron blocks retain some advantages, such as durability and reduced
thermal expansion Thermal expansion is the tendency of matter to change its shape, area, volume, and density in response to a change in temperature, usually not including phase transitions. Temperature is a monotonic function of the average molecular kinetic ...
.


Monoblocs

An engine where all the cylinders share a common block is called a monobloc engine. Most modern engines use a monobloc design of some type, and few modern engines have a separate block for each cylinder. This has led to the term "engine block" usually implying a monobloc design, with "monobloc" itself rarely being used. In the early years of the internal combustion engine, casting technology couldn't produce large castings with complex internal cores (for water jackets etc). Most early engines, particularly those with more than four cylinders, had their cylinders cast as pairs or triplets of cylinders, then bolted to a separate crankcase. As casting techniques improved, an entire cylinder block of 4, 6, or 8 cylinders could be produced in one piece. This monobloc construction was simpler and more cost-effective to produce. For straight engine cylinder layouts, this meant that all the cylinders, plus the crankcase, could be produced in a single component. One of the early engines produced using this method is the 4-cylinder engine in the
Ford Model T The Ford Model T is an automobile that was produced by Ford Motor Company from October 1, 1908, to May 26, 1927. It is generally regarded as the first affordable automobile, which made car travel available to middle-class Americans. The relat ...
, introduced in 1908. The method spread to
straight-six engine The straight-six engine (also referred to as an inline-six engine; abbreviated I6 or L6) is a piston engine with six cylinders arranged in a straight line along the crankshaft. A straight-six engine has perfect primary and secondary engine bal ...
s and was commonly used by the mid-1920s. Up until the 1930s, most
V engine A V engine, sometimes called a Vee engine, is a common configuration for internal combustion engines. It consists of two cylinder banks—usually with the same number of cylinders in each bank—connected to a common crankshaft. These cylinder ...
s retained a separate block casting for each cylinder bank, with both bolted onto a common crankcase (itself a separate casting). For economy, some engines were designed to use identical castings for each bank, left and right. A rare exception was the Lancia 22½° narrow-angle V12 of 1919, which used a single block casting combining both banks. The Ford flathead V8introduced in 1932represented a significant development in the production of affordable V engines. It was the first V8 engine with a single engine block casting, putting a V8 into an affordable car for the first time. The communal water jacket of monobloc designs permitted closer spacing between cylinders. The monobloc design approach also improved the torsional rigidity of engines, as cylinder numbers, engine lengths, and power ratings increased.


Integrated cylinder block and crankcase

Most engine blocks today, except some unusual V or radial engines and large marine engines, use a monobloc design with one block for all cylinders, plus an integrated crankcase. In such cases, the skirts of the cylinder banks form a crankcase area of sorts, which is still often called a crankcase despite no longer being a discrete part. Use of steel cylinder liners and bearing shells minimizes the effect of the relative softness of aluminium. Some engine designs use plasma transferred wire arc thermal spraying, instead of cylinder sleeves, to further reduce weight. These types of engines can also be made of compacted graphite iron, such as in some diesel engines.


Integrated cylinder block and head

Some modern consumer-grade small engines use a monobloc design where the cylinder head, block, and half of the crankcase share the same casting. One reason for this, apart from cost, is to produce an overall lower engine height. The primary disadvantage can be that repairs become more time-consuming and perhaps impractical. An example of engines with integrated cylinder heads are the Honda GC-series and GXV-series engines, which are sometimes called "Uniblock" by Honda. Includes sectioned drawings


Integrated crankcase and transmission

Several cars with transverse engines, have used an engine block consisting of an integrated transmission and crankcase. Cars that have used this arrangement include the 1966-1973 Lamborghini Miura and cars using the BMC A-series and
E-series E series may refer to: * BMC E-series engine, a series of automobile engines * Electronic E series of preferred numbers, a series of preferred values for electronic components such as resistors, capacitors, inductors, zener diodes * Entwicklung seri ...
engines. This design often results in the engine and transmission sharing the same oil. Motorcycles such as the
Honda CB750 The Honda CB750 is an air-cooled, transverse, in-line four-cylinder engine motorcycle made by Honda over several generations for year models 1969–2003 as well as 2007 with an upright or standard riding posture. It is often called the origi ...
use a similar layout, with the cylinder block and crankcase integrated with part of the transmission. Many farm tractor designs have the cylinder block, crankcase, transmission, and rear axle integrated into a single unit. An early example is the Fordson tractor.


See also

* Core plug *
Cylinder head In an internal combustion engine, the cylinder head (often abbreviated to simply "head") sits above the cylinder (engine), cylinders and forms the roof of the combustion chamber. In sidevalve engines, the head is a simple sheet of metal; whereas ...
* Head gasket * Automobile engine replacement § Short block * Automobile engine replacement § Long block


References

{{DEFAULTSORT:Engine Block Automobile engines Engine technology Piston engine configurations