At the center of every internal combustion engine is a major component upon which the rest of the powerplant is built.
The engine cylinder block is one of the most important and heaviest components of automobile designs, a structural member that makes possible the efficient operation of everything from passenger cars to heavy-duty engines.
Knowing the engine cylinder block is essential for all who work with engines, whether a professional mechanic, an engineering student, or a hobbyist. In this guide, we cover the whole gamut of cylinder blocks from manufacture to use.
What is Cylinder Block?
An engine block is a housing to accommodate the cylinders and the various parts of an internal combustion engine. In older engines, the engine block consists only of the cylinder block to which a separate crankcase was bolted.
In modern engines, the engine block consists of the crankcase combined with the cylinder block as one rigid unit. Engine blocks also frequently contain passages for cooling medium and oil galleries.
The cylinder block, cylinder head, and crankcase are the three portions from which is constructed the foundation or main stationary body of an automobile engine; they form an enclosure for the parts that move in their interior, where these parts of necessity occupy the same relative position to each other.
The cylinder block may contain in itself a separate crankcase for the crankshaft; this construction is limited to the larger engines, marine, and stationary. A separate crankcase located lower down in a motor car would mean less weight and also a cheaper and quicker means of replacement.
Parts of Cylinder Block
The following are the parts of the cylinder block:
- Cylinders
- Oil passages and galleries
- Deck
- Crankcase
- Head studs
- Core plugs
- Water pump mounting
- Oil filter
#1. Cylinders.
These are the parts in which the movement of the piston takes place. These are usually of large size and have holes whereby they form a seal with the piston. The more numerous they are, the greater the power, and also the size of the engine.
#2. Oil Passages and Galleries.
These provide oil to reach the cylinder head and crankshaft, and all are of the greatest importance in the cylinder block for lubrication purposes.
#3. Deck.
Simply the flat top of the block where the end of the cylinder comes.
#4. Crankcase.
A house for the crankshaft situated under the modern block.
#5. Head Studs.
Usually made from a round rod of alloy steel; both ends are threaded, the idea being to obtain a closer fit in the block so that the stud does not pull out when the stud nut is removed.
#6. Core Plugs.
This is a cap for the end of a coolant passage in the block, and so shuts off the flow of water or coolant from the engine.
#7. Water Pump Mounting.
A water pump is provided at the side of a cylinder block in a housing coupled with the coolant casing.
#8. Oil Filter.
Usually situated on the flank or below the engine block, there is an oil filter, which keeps as much dirt and other substances out of the lubricant that passes through the engine.
Material Used in Cylinder Block
The cylinder block is generally of gray cast iron, sometimes nickel and chromium steel; some blocks are constructed of aluminum, and cast iron or steel sleeves are used therein.
For most engines, the use of cast iron as a cylinder wall material is found sufficient, as it has better wearing qualities, but in some small engines, the cylinder walls are lined with chromium to reduce wall wear and to increase their service life.
Tests are being made at the present time with high silicon-aluminum alloys to test their possibilities as a material for cylinder block and crankcases. These alloys have a low coefficient of thermal expansion and high wear resistance.
Functions of Cylinder Block
The blinds of the L-head engine contain openings for the valves and valve ports. The bottom of the block supports the crankshaft and oil pan. In most of these engines, the camshaft is supported in the cylinder block by a bushing that fits in machined holes in the block.
In the L-head inline engine, the intake and exhaust manifolds are attached to the side of the cylinder block. In the I-head, the manifolds are attached to the cylinder head.
Other parts attached to the block are the water pump (at the front), timing gear or timing chain cover (at the front), flywheel and clutch housing (at rear), ignition distribution, and fuel pump.
The cylinder head is mounted on top of the block. Some parts are attached to the cylinder block and sealed by means of sealing gaskets, which make a good seal to prevent the escape of water, oil, or gas. Some parts are secured by bolts and some by studs and nuts.
In some instances, lock washers are used underneath the nuts or bolt heads. Water-cooled engines have passages around each cylinder, valve, and also the spark plug.
The circulating water keeps the engine at its exact working temperature and prevents excessive expansion and therefore deformation and the consequent breakdown of relative moving parts.
Types of Cylinder Block
Engine blocks are classified according to the size of the engine cylinders.
The following are the types of cylinder blocks:
- V-engine cylinder
- Inline cylinder
- Opposed engine or Boxer engine cylinder
#1. V-engine Cylinder.
This is the modern engine cylinder and is a widely used engine nowadays. In this case, there are engines provided in 2 rows. These 2 rows are at an angle to each other. The angle V is kept between 15° to 20°, as a larger angle makes balancing the engine difficult.
These are not balanced properly with the counterweight on the crankshaft. There are different types of v engines, V16s, V8s, for heavy vehicles, and V4s for small motorcycles, which are used as cylinder blocks.
#2. Inline Cylinder.
An inline engine is a type of cylinder block, wherein a series of cylinders is arranged so that they run in a line.
Vehicles with this type of cylinder block run very smoothly. They are mostly employed where high rpm is needed. It is often used in passenger cars.
#3. Opposed Engine or Boxer Engine Cylinder.
The Boxer engine is a flat pressed V engine. In this engine cylinder, the blocks coming in 2 rows of 2 cylinders are fitted as opposed to each other. They are also known as pancake engines. They require very little headroom, as the engine compartment can be such a small space.
These are often seen on 4-cylinder Volkswagen engines. Besides, these are also used on Porsche and Subaru, and some other high-speed engines.
Problems of Cylinder Block
When cylinder blocks are in active service, they sometimes crack or wear out detrimentally. A look at things that make them worse.
- Leakage of external engine coolant
- Worn or cracked cylinder
- Porous engine block
#1. Leakage of External Engine Coolant.
This leak could be from the water pump, radiator, heater core, or a loose hose. Sometimes it can also be due to engine block because of cracks.
#2. Worn or Cracked Cylinder.
Upon the cylinder being in use for quite a long time, generally, the case is worn in the cylinder. In time, this damage affects the smooth machined wall, and also affects the sealing by piston rings. This can be avoided by increasing the bore size.
#3. Porous Engine Block.
This is usually because of contaminants entering the metal. This often happens while the manufacturing process is going on. You cannot avoid that, because that’s where the cylinder block originated.
FAQs.
Q: What is the function of a Cylinder Block?
Cylinder blocks keep pressure at various temperatures and loads while lubricating the engine as well. They help transfer oil to the various parts of the engine through the formation of several oil galleries, lubricating all vital parts.
Q: Where is the Cylinder Block found?
The cylinder block is a structural element that runs from the centerline of the main support for the crankshaft to the junction with the cylinder head, working its way upwards.
Wrapping It Up
As you are well aware now, the cylinder block is the portion of an internal combustion engine that encloses the cylinders and other parts of an engine. So, I hope that I’ve still managed to touch upon everything about the cylinder block parts, and their function.