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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 combus ...
, the engine block is the structure which contains the cylinders and other components. In an early automotive engine, the engine block consisted of just the cylinder block, to which a separate
crankcase In a piston engine, the crankcase is the housing 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/a ...
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 A coolant is a substance, typically liquid, that is used to reduce or regulate the temperature of a system. An ideal coolant has high thermal capacity, low viscosity, is low-cost, non-toxic, chemically inert and neither causes nor promotes corrosio ...
passages and
oil An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) & lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturated ...
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
cylinder 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 infin ...
s, 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 pr ...
and
machining Machining is a process in which a material (often metal) is cut to a desired final shape and size by a controlled material-removal process. The processes that have this common theme are collectively called subtractive manufacturing, which utilizes ...
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 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 infin ...
, 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 A flat-six engine, also known as a horizontally opposed-six, is a six-cylinder Internal combustion engine#Reciprocating engines, piston engine with three cylinders on each side of a central crankshaft. The most common type of flat-six engine is th ...
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 A crankshaft is a mechanical component used in a piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating shaft containing one or more crankpins, that are driven by the pistons via the connecting ...
. 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 impuriti ...
or an
aluminium alloy An aluminium alloy (or aluminum alloy; see spelling differences) is an alloy in which aluminium (Al) is the predominant metal. The typical alloying elements are copper, magnesium, manganese, silicon, tin, nickel and zinc. There are two principal ...
. 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 A ''monobloc'' or ''en bloc'' engine is an internal-combustion piston engine some of whose major components (such as cylinder head, cylinder block, or crankcase) are formed, usually by casting, as a single integral unit, rather than being assembled ...
. 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 Casting is a manufacturing process in which a liquid material is usually poured into a mold, which contains a hollow cavity of the desired shape, and then allowed to solidify. The solidified part is also known as a ''casting'', which is ejected ...
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 The straight or inline engine is an internal combustion engine with all cylinders aligned in one row and having no offset. Usually found in four, six and eight cylinder configurations, they have been used in automobiles, locomotives and aircraft ...
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 relati ...
, 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 bala ...
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 Lancia () is an Italian car manufacturer and a subsidiary of FCA Italy S.p.A., which is currently a Stellantis division. The present legal entity of Lancia was formed in January 2007 when its corporate parent reorganised its businesses, but it ...
22½° narrow-angle
V12 V12 or V-12 may refer to: Aircraft * Mil V-12, a Soviet heavy lift helicopter * Pilatus OV-12, a planned American military utility aircraft * Rockwell XFV-12, an American experimental aircraft project * Škoda-Kauba V12, a Czechoslovak experim ...
of 1919, which used a single block casting combining both banks. The
Ford flathead V8 Ford commonly refers to: * Ford Motor Company, an automobile manufacturer founded by Henry Ford * Ford (crossing), a shallow crossing on a river Ford may also refer to: Ford Motor Company * Henry Ford, founder of the Ford Motor Company * Ford F ...
introduced 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 Stiffness is the extent to which an object resists deformation in response to an applied force. The complementary concept is flexibility or pliability: the more flexible an object is, the less stiff it is. Calculations The stiffness, k, of a b ...
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 Plasma transferred wire arc (PTWA) thermal spraying is a thermal spraying process that deposits a coating on the internal surface of a cylindrical surface, or external surface of any geometry. It is predominantly known for its use in coating the cy ...
, instead of cylinder sleeves, to further reduce weight. These types of engines can also be made of
compacted graphite iron Compacted graphite iron (CGI), also known as vermicular graphite iron (GJV, VG, JV or GGV from the german: "Gusseisen mit Vermiculargraphit") especially in non-English speaking countries, is a metal which is gaining popularity in applications that ...
, such as in some diesel engines.


Integrated cylinder block and head

Some modern consumer-grade
small engine A small engine is the general term for a wide range of small-displacement, low-powered internal combustion engines used to power lawn mowers, generators, concrete mixers and many other machines that require independent power sources. These eng ...
s 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 engine A transverse engine is an engine mounted in a vehicle so that the engine's crankshaft axis is perpendicular to the direction of travel. Many modern front-wheel drive vehicles use this engine mounting configuration. Most rear-wheel drive vehicles ...
s, have used an engine block consisting of an integrated
transmission Transmission may refer to: Medicine, science and technology * Power transmission ** Electric power transmission ** Propulsion transmission, technology allowing controlled application of power *** Automatic transmission *** Manual transmission *** ...
and crankcase. Cars that have used this arrangement include the 1966-1973
Lamborghini Miura The Lamborghini Miura is a sports car produced by Italian automaker Lamborghini between 1966 and 1973. The car was the first supercar with a rear mid-engined two-seat layout, although the concept was first seen in a production road car with Ren ...
and cars using the BMC A-series and E-series engines. This design often results in the engine and transmission sharing the same oil. Motorcycles such as the Honda CB750 use a similar layout, with the cylinder block and crankcase integrated with part of the transmission. Many farm
tractor A tractor is an engineering vehicle specifically designed to deliver a high tractive effort (or torque) at slow speeds, for the purposes of hauling a trailer or machinery such as that used in agriculture, mining or construction. Most common ...
designs have the cylinder block, crankcase, transmission, and rear axle integrated into a single unit. An early example is the
Fordson Fordson was a brand name of tractors and trucks. It was used on a range of mass-produced general-purpose tractors manufactured by Henry Ford & Son Inc from 1917 to 1920, by Ford Motor Company (U.S.) and Ford Motor Company Ltd (U.K.) from 1920 to ...
tractor.


See also

*
Core plug Core plugs, also called freeze plugs or Welch plugs, are used to fill the sand casting core holes found on water-cooled internal combustion engines. Purpose Sand cores are used to form the internal cavities when the engine block or cylinder he ...
*
Cylinder head In an internal combustion engine, the cylinder head (often abbreviated to simply "head") sits above the cylinders and forms the roof of the combustion chamber. In sidevalve engines, the head is a simple sheet of metal; whereas in more modern ov ...
*
Head gasket In an internal combustion engine, a head gasket provides the seal between the engine block and cylinder head(s). Its purpose is to seal the combustion gases within the cylinders and to avoid coolant or engine oil leaking into the cylinders. Leak ...
* Automobile engine replacement § Short block * Automobile engine replacement § Long block


References

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