Engine Smoke

Black smoke:  when an engine smoke is black, it means there is too much fuel and less oxygen in the combustion space. Too much fuel in the combustion space also means flooding of the engine. Cars with fuel injectors don’t usually flood the engine.

car emitting black smoke

White smoke: when an engine emits white smoke, it means too much air in the engine and not enough fuel in the combustion space.

Blue smoke:  when an engine emits blue smoke, its means combustion of lubrication oil in the combustion space.

Life Support Systems of an Engine

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.

About Petrol and Diesel Engines

How can you differentiate a petrol or gasoline engines from a diesel engine, below are some basic facts about these engines.

Basic facts about Petrol and Diesel Engines

Engine that uses no spark plugs are diesel engines. Diesel engines do not require a spark for internal combustion to occur because they are compression ignition engines. Diesel can self-ignite under high compression, temperature and pressure within the combustion chamber of the engine.

Petrol engines are spark ignition engines. Petrol can’t self-ignite within the combustion chamber, it still needs a spark for internal combustion to occur.

Difference between Petrol and Diesel Engines.

Efficiency

The diesel engines have bigger cylinder volumes compared to petrol engines of the same size. Hence diesel engines have higher compression ratios making them more efficient than petrol engines. The compression ratio of a diesel engine is higher than that of a petrol by 2 to 1.

Noise

Diesel engines make louder noise than petrol engines.

Engine Size

In terms of engine size, diesel engines are bigger. Most big engines runs on diesel fuel. Note that most car engines run on petrol because the engine size are smaller while bigger vehicles such as trailers, lorries, bulldozers etc. runs on diesel.

Spark plugs

Petrol engine have spark plugs fitted, will sparks plugs are absent in a diesel. This is one way you can easily identify a petrol engine from a diesel engine.

Internal Combustion Engine

4 Stroke Engine courtesy Wikipedia

The internal combustion engine is an engine in which air and fuel mixture in a combustion chamber is ignited under high pressure and temperature, the power of the explosive energy created is transferred to the piston which in turn is converted to mechanical energy.

The 3 major substance needed for internal combustion to occur in an engine is Oxygen, heat and fuel.

Bottom Dead Center. (BDC):  when the piston is at the lowest possible level in the cylinder, its position is at the Bottom Dead Center.

Top Dead Center (TDC): when the piston’s position is at the highest possible level within the cylinder, it is at the Top Dead Center.

Stroke: when the piston moves from top dead center to bottom dead center, it is called a stroke. For internal combustion to occur, the piston moves from TDC to BDC and from BDC to TDC, that is, it takes 2 strokes for combustion to occur. This is where the name 2 stroke engine is derived.

Basic Process of the Internal Combustion in a 4 Stroke Engine.

Basically it involves 4 processes namely;

  1. Suction
  2. Compression
  3. Ignition
  4. Exhaust

Suction

The piston starts by taking a downward stroke and in the process, sucks in Air and fuel mixture into the cylinder until it reaches BDC.

Compression

 At the BDC, air/fuel intake supply is cut off and the piston now takes an upward stroke. In the process, the piston compresses the air/fuel mixture until it reaches TDC.

Ignition

At TDC, the spark plug ignites the mixture causing an explosion within the cylinder. The force of the explosion forces the piston back down.

Exhaust

As the piston moves back up after the impact of the explosive energy, the exhaust valve is opened to expel burnt air fuel mixture.

When the piston reaches TDC, the exhaust valve is closed and air/fuel intake valve is opened and the whole process repeats.

The up and down piston is converted to circular motion which is used for instance to rotate the wheels of cars, generate electrical energy and so on.

 The 2 Stroke Engine

 An engine is called 2 stroke engine if its takes just the piston to move 2 strokes for internal combustion to occur. In a 2 stroke engine, the piston moves from TDC to BDC sucking in air and fuel mixture into the combustion chamber. It then moves from BDC to TDC and in the process, compressing the fuel mixture, followed by ignition then exhaust of burnt mixture as the piston moves down to BDC.

The 2 stroke engine is not as efficient as a 4 stroke engine for this reason it is used for small engines. In the compression stroke of a 2 stroke engine, some air and fuel mixture escapes through the exhaust pipe. For this reason, power produced is smaller compared to a 4 stroke engine.