• Tue. Feb 27th, 2024

Engine bloc

In a sense, a piston engine’s frame is made up of the cylinder block or engine block. Its exterior is constructed in such a way as to form the cylinders or the sites for the additional liners in a motorization.  The crankcase may now freely circulate cooling water.

The cylinder block’supper portion serves as the engine cylinder head’s mating surface. The later component seals the combustion chamber and the cylinders.

What function does an engine block serve?

The engine block has many purposes. It must, first and foremost, be impervious to combustion and gas pressure, which could cause it to expand and push on the cylinder head. Additionally, it aids in piston guidance and ought to reduce friction while enhancing wear resistance.

The coolant is also present in the cylinder block. Therefore, this element must have exceptional corrosion resistance.The different types of engine block This part is divided into two main categories: the engine block without liners and the engine block with liners (dry liners or wet liners).

block without shirts

With this type of engine block, the cylinders must be cast directly in a single piece of cast iron. In this case, the block and the cylinders are combined into one piece. It is also called a direct bore block. When the cylinders wear, you have to rebore them to a higher dimension to then adapt pistons with a larger diameter.

Block with shirts

In order to minimize the wear of the cylinder walls, certain manufacturers equip their vehicles with engine blocks with sleeves. Indeed, the latter benefit from a great resistance. They are arranged in the cylinder bores.

The shirt in question consists of a tube that is detachable from the cylinder. It is shaped before assembly in a material (cast iron or steel) more resistant than that of the cylinder block.

To guarantee optimal robustness, this element is cast by centrifugation in suitable factories. This type of block can be provided with dry liners or wet liners.

Blocks with dry shirts

Blocks fitted with dry liners are made of aluminum or cast iron. If it is an aluminum block, the dry liners are installed when the block is manufactured. Therefore, sometimes they are not replaceable, but can be rebored.

On some models, you can change the liners, because the latter are only fretted. With a cast iron block, it is quite possible to change the liners when they are heavily worn.

But whether the block is made of cast iron or aluminum, fins or water chambers intended for engine cooling must be present.

Blocks with wet shirts

With this type of block, the liners are placed in a hollow casing. Their upper part is held by the cylinder head, while the lower part is supported by the crankcase.

Here the shirts are easier to replace. On the liquid-cooled engines of the 1920s which had wet steel liners screwed into an aluminum block, the extraction of the liners can be particularly tricky. This greatly complicates the change of shirts.

With this type of block, the liners are placed in a hollow casing. Their upper part is held by the cylinder head, while the lower part is supported by the crankcase.

Here the shirts are easier to replace. On the liquid-cooled engines of the 1920s which had wet steel liners screwed into an aluminum block, the extraction of the liners can be particularly tricky. This greatly complicates the change of shirts.
The materials of manufacture of an engine block

The engine block can be made with various materials. There is, for example, the aluminum alloy which is mainly used for models made in die casting. It is offered at a discounted price in the international market. It has excellent thermal conductivity.

This material is perfect for producing precision parts that benefit from complex shapes with supports for auxiliary components, oil pipes and water passages.

Then come the engine blocks made of lamellar graphite cast iron (FGL) or even vermicular graphite cast iron. This material is heavier. It also guarantees excellent mechanical temperature resistance compared to aluminium. As a rule, this engine block is used on diesel cars.

You can also find engine blocks made of magnesium, a material lighter than cast iron. There are also bi-material blocks with an internal aluminum part and an external magnesium part.

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