The Turbocharger

In the previous posts I had told you about the basic operating components of the engine. However, these alone can not give the car the boost it needs. For this purpose the"TURBOCHARGER" is attached to the engine. This name appears in almost all racing games. As I played one such game I realized that I knew the function of  all the upgrades
except the turbo(as it is called). All I cared was that it made my car go faster. Thus to find out more about the turbo I looked into it. Firstly this is how it looks.

  So, basically a turbo is based on the principle of injecting more air into the engine using turbine to suck in air. An engine can suck air only till a certain limit. However, the turbocharger takes in more air and forces into the chamber above the pistons. This helps in increased combustion of the air-fuel mixture thus producing more output and promoting increased efficiency.
The turbocharger can also be used to promote fuel efficiency. It manages this by  recovering waste energy in the exhaust and feeding it back to the main engine. Doing this ensures that most of  the energy-otherwise wasted- is utilized before the fuel is burned. Thus, by initiating this cycle the turbocharger is able to promote fuel efficiency.
Now the key components in the turbo are:
 1. the turbine  2. the compressor   3. the center housing rotating assembly(CHRA)
      The turbine: the turbine is responsible for forcing in extra air by spinning up to 
250,000 revolutions per minute(rpm).
      The compressor: This basically increases the amount of air inflow into the engine
      The CHRA: This connects the turbine to the compressor. It also has to maintain minimal friction to enable smooth running of high speed rotating shaft. For this it uses ball bearings coated with engine oil.

So this is what the turbocharger or the turbo is.

The Engine- part 3

So last time I explained how the spark plug operated. Today I am going to tell about the valves in the engine. The valves, though seem small and inconsequential, play quite an important role in the engine. A lot of times people ask what controls the inflow and outflow of air and fuel into the chamber above the pistons or how is a specific quantity of air fuel mixture administrated into this chamber? The answer is the valves.

The valves commonly called 'The Poppet Valves' are attached to long rod which pushes it down called the stem. First the stem pushes the inlet valve down which lets in the air fuel mixture. then the spring to which the inlet valve is attached retracts the stem and so the valve closes. The speed of this process is usually determined by the speed of the pistons.

The faster the pistons move the quicker the valves will open and close. Now the piston compresses the mixture. As the mixture is compressed the spark plug initiates a spark which ignites this mixture. Now the outlet valve opens and the heat generated escapes out.

The same cycle is repeated again.

Now the problem arises in racing or fast cars. The piston movement in those is extremely fast and thus the spring is not able to retract the stem and the valve quickly (This situation is called valve float). Thus, such cars are equipped with special type of valves called Desmodromic Valve, which being closed by a positive mechanical actions instead of a spring, are able to close quickly, thus facilitating fast and efficient closing and opening of the valve. This picture should you help you understand more clearly.

 

The Engine part 2- The Sparkplugs

Previously I talked about the air-fuel mixture getting compressed by the pistons which provided the force for the car to move. But what initiates this process? The answer is the Spark Plugs. It ignites the the air fuel mixture which leads to combustion of the mixture which leads to generation of heat which ultimately leads to the force which makes the car move.
The spark plugs are connected to high voltage source. When the circuit is completed the source supplies high amounts of electric power to the to the spark plug. Now you must be wondering that air is an insulator and doesn't conduct electricity then how is he air fuel mixture ignited? The answer lies in the fact that when huge amount of electricity (about 12,000-25,000 volts) is supplied then air gets ionized and is able to conduct electricity.
The spark plug does exactly this thing. Thus when the air fuel mixture is compressed by the pistons the spark plug ignites it and thus heat energy is generated.
Now the question arises that doesn't the spark plug conduct the electricity to other surrounding parts of the engine? The answer is no. This is ensured by the "insulator" present in the spark plug. It is made of a high resistance material which along with insulation provides mechanical support to the spark plug. The material used is sintered alumina which is not only provides insulation but also prevents the spark plug from glowing red hot. Further a corrugated part called "ribs" also provides insulation and prevents "leaking" of the electrical charge.
Now with the insulation on the outside the inside or the core of the spark plug is what conducts the electricity. The core of the spark plug has a negative electrode and a nickel plated positive electrode. The negative electrode helps in earthing while the nickel electrode provides the spark for ignition.
So this how a spark plug functions. Hopefully this picture will help you identify the parts I have mentioned in this post