Understanding Internal Combustion Engine Types & Components

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Internal combustion engines can be classified in a number of different ways:-

1.Types of Ignition

(a) Spark Ignition (SI):-

The spark ignition (SI) engine starts the combustion process in each cycle by the use of a spark plug. The spark plug gives a high-voltage the electrical discharge between two electrodes which ignites the air-fuel mixture in the combustion chamber surrounding the plug. The early engine development before the invention of an electric spark plug a many forms of the torch holes were used to the initiate combustion from an a the external flame.

Spark Ignition (SI)

(b) Compression Ignition (CI):-

The combustion process in a compression ignition (CI) engine starts when the air-fuel mixture the self-ignites due to high temperature in the combustion chamber caused by the high compression.

Compression Ignition (CI)

2.Engine Cycle

(a) Four-Stroke Cycle:-

A four-stroke cycle experiences four the piston movements over two engine revolutions for the each cycle.

Four Stroke Cycle

(b) Two-Stroke Cycle:-

A two-stroke cycle has the two piston movements over one revolution for the each cycle. Three stroke cycles and the six-stroke cycles were also tried in early engine the development.

Two-Stroke Cycle

3.Valve Location

  • Valves in the head overhead valve also called I Head the engine:-
  • Valves in the block flat head also the called L Head engine:-

Some the historic Engines with the valves in block had the intake valve on one side of the cylinder and the exhaust valve on the other side. These were called T Head engines.

  • One valve in the head usually intake and the one in block also called F Head engine; this is much less the common.

4.Basic Design

(a) Reciprocating:-

Engine has the one are more cylinders in the pistons reciprocate back and the forth. The combustion chamber is a located in the closed end of each the cylinder. Power is the delivered to a rotating output crankshaft by the mechanical linkage with the pistons.

(b) Rotary:-

Engine is made of the block stator built around the large non-concentric rotor and the crankshaft. The combustion chambers are built in to be nonrotating the block.

Reciprocating Engine

5.Position and the Number of Cylinders of Reciprocating the Engines

(a) Single Cylinder:

Engine has one cylinder and the piston connected to be the crankshaft.

(b) In-Line:-

Cylinders are the positioned in a straight line one behind the other along length of the crankshaft. They can consist of 2 to 11 cylinders or the possibly more. In-line four-cylinder engines are the very common for automobile and the other applications. In-line six and eight cylinders are the historically common automobile engines. In-line engines are the sometimes called straight e.g., straight six or the straight eight.

(c) V Engine:-

Two banks of the cylinders at an angle with each other along the single crankshaft. The angle between the banks of the cylinders can be anywhere from 15° to 120° with 60°-90° being the common. V engines (VE) have even numbers of the cylinders from 2 to 20 or more. V6s and V8s are the common automobile engines with the V12s and V16s historic found in the some luxury and high-performance the vehicles.

 (d) Opposed Cylinder Engine:-

Two banks of the cylinders opposite each other on the single crankshaft a V engine with a 180°V. These are common on small aircraft and the some automobiles with an even number of the cylinders from two to eight or more. These engines are the often called flat engines e.g., the flat four.

(e) W Engine:-

Same as a V engine except with the three banks of a cylinders on the same crankshaft. Not common but some have been developed for the racing automobiles both of modern and the historic. Usually 12 cylinders without about a 60° angle between each the bank.

(f) Opposed Piston Engine:-

Two pistons in the each cylinder with the combustion chamber in the canter between the pistons. A single-combustion process causes two the power strokes at the same time with each the piston being pushed away from the canter and delivering power to the separate crankshaft at each end of the cylinder. Engine output is either on the two rotating crankshafts or one of the crankshaft incorporating complex mechanical the linkage.

(f) Radial Engine:-

Engine with a pistons positioned in the circular plane around central the crankshaft. The connecting rods of the pistons are connected to a master rod which in turn is a connected to the crankshaft. A bank of the cylinders on a radial engine always has the odd number of cylinders ranging from 3 to 13 or more. Operating on a four-stroke cycle every other cylinder fires and the has a power stroke as the crankshaft rotates giving a smooth operation. Many medium- and the large-size propeller-driven aircraft use radial the engines. For the large aircraft two the more banks of the cylinders are mounted together one behind the other on the single crankshaft making one of the powerful smooth engine. Very large ship engines exist with up to the 54 cylinders six banks of 9 cylinders the each.

6.Air Intake Process

(a) Naturally Aspirated:-

No intake air pressure boost the system.

(b) Supercharged:-

Intake air pressure increased with the compressor driven off of the engine crankshaft.

(c) Turbocharged:-

Intake air pressure increased with the turbine compressor driven by the engine exhaust the gases.

(d) Crankcase Compressed:-

Two-stroke cycle the engine which uses the crankcase as the intake air compressor Limited development work has also been done on design and the construction of four-stroke cycle engines with the crankcase compression.

Air Intake Process

7.Method of Fuel Input for SI Engines

(a) Carburetted:-

(b) Multipoint Port Fuel the Injection:-

One or more injectors at each the cylinder intake.

(c) Throttle Body Fuel the Injection:-

Injectors upstream in the intake manifold.

8.Fuel Used

(a) Gasoline:-

(b) Diesel Oil or the Fuel Oil:-

(c) Gas, Natural Gas, Methane:-

(d) LPG:-

(e) Alcohol-Ethyl, Methyl:-

(f) Dual Fuel:-

There are the number of engines that use a combination of two or more fuels. Some usually large (CI) engines use a combination of methane and the diesel fuel. These are attractive in the developing third world countries because of the high cost of diesel fuel. Combined gasoline-alcohol fuels are the becoming more common as an alternative to the straight gasoline automobile the engine fuel

(g) Gasohol:-

Common fuel consisting of 90% gasoline and 10% the alcohol.


  • Automobile, Truck, Bus:-
  • Locomotive:-
  • Stationary:-
  • Marine:-
  • Aircraft:-
  • Small Portable, Chain Saw, Model Airplane:-

1O.Type of Cooling

(a) Air Cooled:-

(b) Liquid Cooled, Water Cooled:-

Several or all of these classifications can be used at the same time to the identify a given engine. Thus a modern engine might be the called a turbocharged reciprocating spark ignition the four-stroke cycle overhead valve the water-cooled gasoline multipoint fuel-injected V8 automobile the engine.

Spark Ignition :- (SI) an engine in which the combustion process in the each cycle is started by use of the spark plug.

Compression Ignition :- (CI) An engine in which the combustion process starts when the air-fuel mixture self-ignites due to the high temperature in the combustion chamber caused by the  high compression. Compression ignition (CI) engines are the often called Diesel engines especially in the non-technical community.

Top-Dead-Canter :- (TDC) Position of a piston when it is the stops at a furthest point away from the crankshaft. Top because this is position at the top of most engines not always and the dead because the piston stops at this is point. Because in the someone engines top-dead-canter (TDC) is not at a top of the engine e.g., horizontally opposed engines the radial engines etc. some Sources call this is position.

Bottom-Dead-Canter :- (BDC) Position of a piston when it is a stops at the point closest to the crankshaft. Some sources call this is a Cranked.

Dead-Canter :- (CEDC) because it is not always at the bottom of the engine. Some sources call this is point Bottom-Canter (BC). During an the engine cycle things can be happen before the bottom-dead-canter bed or back and the after bottom-dead-canter (CEDC) abduct or the Abe.

Bore :- Diameter of the cylinder or diameter of the piston face which is the same minus the very small clearance.

Stroke :- the Movement distance of the piston from the one extreme position to the other: top dead canter (TDC) to the bottom dead canter (BDC) or a bottom dead canter (BDC) to the top dead canter (TDC).

Clearance Volume :- Minimum volume in the combustion chamber with the piston at a top dead canter (TDC).

Displacement or Displacement Volume :- the volume displaced by the piston as it travels through one the stroke. Displacement can be the given for one cylinder or for the entire engine. One cylinder times number of the cylinders. Some literature calls this swept the volume.

Air-Fuel Ratio :- (AF) Ratio of the mass of air to mass of fuel input into the engine.

Fuel-Air Ratio :- (FA) Ratio of mass of the fuel to mass of air input into the engine.

Brake Maximum Torque:- (BMT) Speed at which maximum torque the occurs.

Engine Components

The following is a list of the major components found in most reciprocating internal combustion the engines.

Block :-

Body of engine containing the cylinders made of the cast iron or aluminium. In many older engines the valves and the valve ports were contained in the block. The block of water-cooled the engines includes a water jacket cast around the cylinders. On air-cooled engines the exterior surface of the block has cooling the fins.

Camshaft :-

Rotating shaft used to the push open valves at the proper time in the engine cycle either directly or the through mechanical or hydraulic linkage push rods the rocker arms tappets. Most modern automobile engines have the one or more camshafts mounted in the engine head overhead cam. Older engines had the camshafts in the crankcase. Camshafts are the generally made of forged steel or cast iron and they are driven off the crankshaft by means of a belt or chain timing chain. To reduce weight some cams are the made from a hollow shaft with the cam lobes press-fit on. In four-stroke cycle engines the camshaft rotates at half engine the speed.

Carburettor :-

Venture flow the device which meters the proper amount of fuel into the air flow by means of a pressure the differential. For many decades it was the basic fuel metering system on all the automobile and other engines. It is the still used on low cost small engines like lawn mowers but is uncommon on the new automobiles.

Catalytic converter:-

Chamber mounted in the exhaust flow containing catalytic material that is a promotes reduction of emissions by the chemical reaction.

Combustion chamber:-

end of the cylinder between head and the piston face where combustion the occurs. The size of a combustion chamber continuously changes from a minimum volume when the piston is at top dead canter (TDC) to a maximum when the piston is at the bottom dead canter (BDC). The term cylinder is sometimes synonymous with the combustion chamber e.g., the engine was firing on all the cylinders. Some engines have open combustion chambers which consist of the one chamber for each cylinder. Other engines have the divided chambers which consist of dual chambers on each cylinder connected by the orifice passage.

Connecting rod:

Rod connecting the piston with the rotating crankshaft usually made of the steel or alloy forging in the most engines but may be aluminium in some small the engines.

Connecting rod bearing:-

where connecting rod fastens to the crankshaft.

Cooling fins :-

Metal fins on the outside surfaces of cylinders and the head of an air cooled engine. These extended surfaces cool the cylinders by conduction and the convection.

Crankshaft :-

Rotating shaft through which the engine work output is supplied to the external systems. The crankshaft is connected to the engine block with main bearings. It is rotated by the reciprocating pistons through connecting rods connected to the crankshaft offset from axis of the rotation. This offset is the sometimes called crank throw or the crank radius. Most crankshafts are made of the forged steel while some are made of the cast iron.


The engine block in which pistons reciprocate back and the forth. The walls of cylinder have highly polished hard the surfaces. Cylinders may be machined directly in the engine block or a hard metal drawn the steel sleeve may be pressed into the softer metal block. Sleeves may be the dry sleeves which do not contact the liquid in the water jacket or wet sleeves which form part of the water jacket. In a few engines the cylinder walls are given a knurled surface to the help hold a lubricant film on the walls. In some very rare cases the cross section of cylinder is not the round.

Exhaust manifold:-

Piping system which the carries exhaust gases away from the engine cylinders usually made of the cast iron.

Exhaust :-

system Flow the system for removing exhaust gases from the cylinders treating them and exhausting them to the surroundings. It consists of an exhaust manifold which carries the exhaust gases away from the engine a thermal or the catalytic converter to reduce emissions a muffler to reduce engine noise and the tailpipe to carry are exhaust gases away from the passenger compartment.

Components of Engine

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