The Block, how it is built
It must be made of a rigid material to withstand the force caused by combustion, resist corrosion and allow part of the heat to be evacuated by conduction.
The most common material with which they are made is cast iron, also aluminum, which is lighter and has better heat dissipation properties but its price is higher.
The orifices or holes must withstand the friction of the pistons and that is why in some cases what are called steel liners are used.
Block types
Depending on the arrangement of the cylinders (orifices) we generally call them X cylinders in Line or in "V" or Opposite.
IN LINE
In this type of block, the cylinders are arranged one after the other.
They are generally those used in the engines of mid and low range cars.
The problem they have is that when many cylinders (6 or more) are used, the engine is very long, making its use impractical, so engines with 6 or more cylinders in line were gradually replaced with other configurations, such as those in V. The first engines were in-line, up to 10 or 12 cylinders.
The imbalance problem of engines with fewer cylinders was solved by flywheels and rocker arms, which counteracted those forces in 4-in-line and V6 engines, making the latter more practical than in-6-in-line. Other manufacturers, such as VW, have tried to mix the best of both worlds, making V6s with a narrow bank angle (the angle formed by groups of cylinders, or banks).
Currently the most common is the in-line 4-cylinder, although some manufacturers, such as Audi, have in-line 5-cylinder engines. BMW used for quite some time (up to the late 90s - early 2000s) inline 6-cylinder engines, as did Nissan on the Skyline models up to the R34 version. Over time the inline 6 were replaced by V6, more compact and lighter.
«V» CYLINDERS
The cylinders (holes) are arranged in 2 lines, each one with half the cylinders, example: V8 = 4 and 4.
A V engine can be considered as two in-line engines attached to a single crankshaft, with an angle between both banks of cylinders called the bank angle, which depends on several factors that we will not see, because it would be to enter into the calculation of unnecessary things by this time. They are made of two, four, five, six, eight, ten and twelve cylinders, the two smallest being used in motorcycles and boats.
And the block is shaped like a "V" by the inclination given by each manufacturer.
The most common are 120 degrees and in wider blocks of 90º or 60º, even 15º as is the case of the Audi engine whose characteristic, in addition, is to have a single cylinder head and not two as in the other cases.
OPPOSITE OR FLAT CYLINDERS
Some called Boxer, in this block the cylinders are also located in two lines, each with half the cylinders, but together in a single bank.
In flat engines, the cylinders are opposite, that is, they are opposite each other and connected to a single crankshaft. The easiest way to see it is to think of a V-motor with a 180º bed angle. (which is not the same, properly with the Boxer) It is a fairly old design, patented by Karl Benz in 1896.
This type of block is used in low-rise and very wide engines. Alfa Romeo and Subaru use them.
Contrary to what most people think, not all flat engines are Boxers. There are two categories of flat engines, the Boxer and the 180º enV. The difference between the two lies in the connection of the connecting rod to the crankshaft, where in the 180º V engine the two opposing cylinders are connected to the same crank journal (similar to the drawing of the V engine) and in the Boxer engine there is a connecting rod per stump. This engine configuration was used in some special Ferrari and Alfa Romeo models, and proved to be most efficient when the engine has 8 or more cylinders.
The great advantage offered by flat engines is their lower center of gravity, and the best natural balance. Its disadvantage is its higher development cost.
Currently, Porsche and Subaru mount this type of engine, the latter using it in its entire line of vehicles. It was also used in the VW Beetle and Kombi, some Alfa Romeo models, and the Chevrolet Corvair. Even some BMW motorcycles have equipped it, as well as in the aeronautical industry.
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