Editing Engine block (section)

== Construction ==
The main structure of an engine typically consists of the [[cylinder (engine)|cylinder]]s, coolant passages, oil galleries, crankcase, and [[cylinder head|cylinder head(s)]]. The first production engines of the 1880s to 1920s usually used separate components for each element, which were bolted together during engine assembly. Modern engines, however, often combine many elements into a single component to reduce production costs.

The evolution from separate components to monobloc engine blocks has gradually progressed since the early 20th century. The integration of elements has relied on the development of [[foundry]] and [[machining]] techniques. For example, a practical, low-cost V8 engine was not feasible until Ford developed the methods used to build its [[Ford flathead V8 engine|flathead V8 engine]]. Other manufacturers then applied those techniques to their engines.
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=== Cylinder block ===
{{multiple image
| title             = Cylinder blocks for a [[straight-six engine|straight-6]] engine
| width             = 200
| align             = right
| direction         = vertical
| image1            = Wolseley 6-cylinder marine oil engine (Rankin Kennedy, Modern Engines, Vol V).jpg
| caption1          = Marine engine with cylinders cast in three pairs
| image2            = Six cylinder engine with three cylinder blocks (Autocar Handbook, Ninth edition).jpg
| caption2          = Cylinders cast in two blocks of three
| image3            = CarterBMW1.JPG
| caption3          = Cylinders cast in a single block of six, with an integrated crankcase (turbocharger in background)
| alt1              = Wolseley marine engine
| alt2              = Six-cylinder engine
| alt3              = BMW engine block
}}

A cylinder block is a structure that contains the [[cylinder (engine)|cylinder]], plus any [[cylinder (engine)#Cylinder sleeving|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 separately 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.

In early engines with multiple cylinder banks{{snd}}such as [[V6 engine|V6]], [[V8 engine|V8]], or [[Flat-six engine|flat-6]] engines{{snd}}each 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 and fit into the block using special gaskets. They are called "wet liners" because their outer sides come in direct contact with the engine's coolant. In other words, the liner is the entire cylinder wall, rather than merely a sleeve.

The advantages of wet liners are a lower mass, reduced space requirements, and coolant being heated faster from a cold start, reducing start-up fuel consumption and heating 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" 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. However, there are more practical repair options.

=== Coolant and oil passages ===
{{See also|Internal combustion engine cooling|Oil pump (internal combustion engine)}}

=== Crankcase ===
{{main|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 typically cast from either [[cast iron]] or an [[aluminium alloy]]. Aluminium blocks are much lighter and transfer heat more effectively to coolant, but iron blocks retain some advantages, such as durability and reduced [[thermal expansion]].

'''Weight reductions through material selection'''. Presently, most of the engine blocks in mass production are gray castings. Reducing weight has resulted in using aluminum-silicon alloys more frequently for the engine block in small-displacement engines. Engine blocks of comparable design, but using Al-Si alloys, are not lighter than cast iron engine blocks in the same ratio as that for the specific weights of the materials.

In engine blocks made of gray cast iron, weight can be reduced by optimizing the structure and thin-wall casting. With this casting technique, a wall thickness of as little as about 3 mm is generally possible. In comparison, the walls of cast iron engine blocks are usually from 4.0 to 5.5 mm thick.

Using vermicular graphite cast iron (GGV), a casting material with great strength, enables weight reductions by about 30% compared to conventional casting materials such as GG 25. Weight reduction, to this extent, requires engineering for the engine block, taking into account the particular needs of the material.<ref>{{cite web |title=Minimizing Engine Block Mass |url= https://studedu.org/s1396t1.html |access-date=2024-05-14 |website=studedu.org}}</ref>