The life support system of an engine are;

Air and Exhaust

Lubrication oil

Fuel

Water

Electrical

Air and Exhaust System:

Oxygen is needed for internal combustion to occur. This is why engines are fitted with an air intake system. Air intake systems delivers filtered and cooled air into the combustion space.

Burnt air from the combustion chamber, is taken out through the exhaust system. Sound produced from internal combustion is very loud. The exhaust system also reduces this sound into acceptable levels.

Lubrication System;

Lubrication oil does two things for the engine; lubricate and cool the engine.

Lubrication system consists of mainly of, oil pump, oil filter, lubricating oil, and lubricating paths. Lubrication of engine parts is necessary to maintain optimum performance and prevent overheating.

Note that in smaller engines, a water radiator cooling system is not necessary. This is because the amount of heat generated  can be cool by the lubricating oil.

For two stroke engines or small engines, cooling and lubrication is achieved by mixing one part lubricating oil with 100 parts of fuel.

For bigger engines such as the 4 stroke engines, much heat is generated and so in addition to cooling and lubrication water is used to cool the engine.

Fuel System:

Fuel is needed to provide the energy needed for the engine to work. The 3 major fuel types are; petrol, diesel and gas. Modern day engines deliver fuel into the combustion space using fuel injectors. Fuel is delivered to the combustion space from the fuel tank with the aid of fuel pump through the fuel injectors. The injectors then delivers the fuel into the combustion space.

Cooling water system:

Water is used primarily to cool the engine. For smaller engines, it is optional. But bigger engines must be fitted with a water cooling system.

The main components of water cooling system consists of Radiator, fan, water pump, cooling water pipes and channels within the engine.

The main area of the engine that cooling water is required is the combustion chambers also known as cylinders. This is where combustion takes place, and consequently a lot of heat generated. Water is required to cool these areas so engine will not overheat and cause damage.

Cooling water passes through channels surrounding the combustion chambers to cool the engine.

The function of the radiator and fan is to cool down hot water generated when it initially passed around the hot combustion chambers before it recirculates.

Cooling water system thereby keeps the engine running at its optimum temperature.

Electrical System:

Engines are usually fitted with an electrical system to control the way the engine works. Among other functions, electricity is needed to control fuel injection into the combustion chambers. Modern day fuel injectors are electrically controlled.

The two main parts of and engine electrical system is a battery and an alternator. The major function of the battery is to start the engine. For smaller engines, a battery may not be required, a starter cord can be used to start the engine.

In a car engine for instance, battery supplies electricity to a starter motor for it to start. The starter motor drives a flywheel. The flywheel in turn rotates the crankshaft which make the piston move up and down for internal combustion to take place. The internal combustion produces the energy required to make the engine run on its own.  Once the engine starts to run on its own, the starter coil disengages to prevent itself from damage.

For a car, other battery loads include; interior and exterior lights, alarms, and very importantly, the engine control unit.

The engine control unit controls the timing and other operations of the engine. An example of a function of the engine control unit is the timing of the fuel injectors.

The alternator is powered by the engine. The function of the alternator is to charge the battery and supply electricity for other functions. For a car, the electricity supplied can be used to on headlamps,   interior lights, horns, radio, air conditioner etc., when the car engine is running.