The engine block: what it is, what it is made of, parts, types, manufacture

The engine block is the most important part of our car. Knowing it will help us to know what is hidden under the hood and to understand the operation of our vehicle. Its construction requires a great engineering job for its optimal performance.

What is an engine block

the engine block es the most important part of the engine. It is the structure on which the rest of the elements are placed, such as the stock at the top, the pistons on the inside and the base (if it has one) on the bottom.

As you can see in the main image, it is about a single piece with all the necessary cavities for mounting: cylinders, coolant and oil lines, holes for bolts and gaskets, etc. To make such a complex block in one piece, it is made from a sand mold.

How an engine block is made

To make this mold in the factory, zirconium sand, glue and a hardener are mixed. This sand is used because it has a very high melting point (close to 2.500ºC). The main steps for the manufacture of an engine block are:

• That mix of sand gets into the master molds to give it the desired shape and a gas is injected that solidifies the mixture. Then the different resulting molds are assembled, gluing the parts with a special glue that withstands extreme heat. In this way, a complete mold is achieved into which the molten metal is injected.

• This metal is obtained from ingots that are put into a smelting furnace. In the case of aluminum, it is heated up to 800ºC to liquefy it. Since it dilates in this state, we must use more metal to compensate for the shrinkage that occurs when it solidifies.
• Then is injected into the mold from below, to avoid contamination with aluminum oxide. A substance that is created when molten aluminum comes into contact with air. If it were done from above, the very action of the discharge would generate rust due to its greater contact with the air.
• The next step is to quit rest for six hours in a thermal recovery oven. This breaks down the glue so that the sand comes off. Also, this extra heat over several hours strengthens the metal.
• After this, the block is placed face down and shaken to loosen the sand. Thus, the aluminum block is exposed and only requires a few stories retouching:
  • The first is cut off the extra metal which was put into the mold to compensate for the 7% shrinkage that occurs with the solidification of the aluminum.
  • The second, polish surfaces with high precision, to give them the right finish for their use.
• Lastly, as with most parts of a car, it undergoes an inspection to check that everything is in perfect condition.

What is the engine block made of

Usually the engine block usually made of cast iron or aluminum. With the first, there is greater resistance in equal volume and with the second, weight is saved and cooling is improved.

This is not the case with all engines though. the general trend is to switch to aluminum, for many reasons. For example, better designs and higher build quality allow aluminum engine blocks to have very high strengths. Also, that the benefits of this material are very desirable for the reduction of emissions prevailing today (weight reduction).

Regarding its conductivity. Aluminum blocks have a lower thermal inertia. Which implies that take less time to heat up and less time to cool down. What added to a good design of the refrigeration system and block allows the entire engine to reach operating temperature sooner and dissipate heat more effectively when needed.

An example of just the opposite are some Ford EcoBoost engines. Keeping the cast iron blocks that take longer to heat up, they need secondary conduits for the coolant. In this way they can distribute the heat evenly throughout the block from the start and avoid harmful temperature differences.

To this, we must add that a lighter engine made of aluminum, makes it easier to achieve a better weight balance between the front and rear axle. What can suppose an improvement in the dynamic qualities of the vehicle.

engine block parts

Although this is indicated on some web pages, not part of the engine block pieces like the head gasket, pistons, rings, pins or Rods. These are all parts of the engine, but not the engine block itself. A correct way to divide important parts of the engine block are its different cavities:

Cylinders

Inside of engine block we meet the cylinders. It is where the pistons that generate the movement of the engine with the explosions are located.

These can go bare, that is, directly with the walls of the block in the air, or covered by shirts. That they are nothing more than some tubes that cover the cylinders to prevent their wear due to friction with the piston rings. Something that is not very common in conventional passenger car engines.

The size of the cylinders varies according to the stroke and size of the piston. On the other hand, the thickness of the walls that form the cylinders depends on the working pressure to which the engine is subjected. Taking this into account, we can say that diesel engines have thicker cylinder walls and/or resistant, since they work at a higher pressure than in gasoline engines

cooling channels

Around the cylinders are all the cooling channels where does the circulate antifreeze. Its design must be very precise in order to dissipate the heat by contact with the liquid, without losing too much resistance from the walls.

In addition, as we have said before, heat extraction must maintain sufficiently even temperatures between the different points of the engine. Otherwise, the dilation difference could cause problems.

oil galleries

are other channels where will the oil go required for each part of the engine. Without them, I don't know would lubricate moving parts and the motor would be unusable in a short time.

Its design is very important, for maintain correct oil pressure throughout the tour. Thus the flow will arrive in the right amount to each part.

Couplings

They are surfaces designed for attach other engine parts. For example: the coupling of the Water Pump, distributor coupling, gasoline pump coupling, oil filter support... and others, if required by the engine design.

As you can see, all of them are very important parts for the operation of the engine, which must be correctly anchored to the block. Go screwed and sealed by gaskets that withstand high temperatures. As is the case with the head gasket, which is the one that suffers the most if the car overheats.

crankshaft bearing

It's at the bottom and it's where is the crankshaft located. That is, the one in charge of converting the linear movement of the pistons into the rotary movement necessary to move the vehicle.

The bearing is the crescent that hugs the crankshaft from above and the bearing is the crescent that surrounds it from below and is screwed to the block. This part is only found on closed engine blocks. We will talk about it in the Block Types section (below).

other cavities

Depending on the design of the engine, the block must have some cavities or others. For example, valve lifter cavities.

Engine block types

Open or Closed

• Un open block is the one does not include any crankshaft support. So it is placed in the engine mount o directly in the crankcase, as designed.
• Un closed block is the one yes it includes a support for the crankshaft, so it has a half-moon part below to collect it (bearing) and then some screwed bearings to fix it to the block.

According to the arrangement of the cylinders

The shape of the block, as well as its structure, basically depends on the type of construction that the engine has, according to the engine types. Therefore, this categorization is the same as that applied to combustion engines:

• Online: The cylinders are placed one behind the other vertically.
• In V: the cylinders are placed diagonally and in pairs. In this way, two connecting rods are coupled to the same crankpin. A variant is the VR blocks, which have a V, but very closed.
• in W: which is like two V-engines together in the same block.
• Boxer: engine block with cylinders horizontal and facing each other.

Open Deck or Closed Deck

This differentiation refers to the arrangement of the cooling ducts. open deck it means that the cylinders are surrounded by cooling channels. So heat dissipation is easier.

In the case of blocks of the type closed-deck, these ducts do not surround the cylinders, so they are more resistant to pressure, but their cooling is more complicated. There are also Semi Open Deck or Semi Closed Deck, which are a combination of both types. Therefore, the cooling channels partially surround the cylinders.

Elements that are coupled to the engine block

Head

the butt, normally located on the engine block, It is the most complex component. when designing an engine. In addition, it is the piece that presents the greatest fragility since it has to withstand high stresses and very high temperatures in the combustion chamber. The valves and camshafts, among other elements, are located inside the cylinder head.

The material used to manufacture a cylinder head is very similar to engine block. For the design of the combustion chamber located in the cylinder head, the compression ratio at which the engine will work is taken into account, as well as the arrangement of the valves.

Between the cylinder head and the engine block is the head gasket. The mission of this board is to provide tightness and tightness. Thanks to the cylinder head gasket, antifreeze or oil leaks from the corresponding lubrication channels can also be prevented.

Bench or Carter

Depending on engine design, the block may have a bench coupled below, which is where the crankshaft (open block + bed) would rest. If NO, will be attached directly a crankcase, which is where the oil is located and where it is taken from to lubricate the rest of the engine.

Other engine parts

Again, depending on the engine design, the block will have different parts attached to it for proper operation. There can be many, but the most common are Water Pump, high pressure fuel pump, oil filter bracket, etc.

Images – nzhamstarS, Paul Schultz, OK Foundry Company, Inc., Colin, Ramsay Thomson, Eric Kilby, DieselDemon