Turbo-Charger

A turbocharger is actually a type of supercharger. Originally, the turbocharger was called a “turbo super charger.” Obviously, the name was shortened out of convenience.

A turbocharger’s purpose is to compress the oxygen entering a car’s engine, increasing the amount of oxygen that enters and thereby increasing the power output. Unlike the belt-driven supercharger that is normally thought of when one hears the word “supercharger,” the turbocharger is powered by the car’s own exhaust gases. In other words, a turbocharger takes a by-product of the engine that would otherwise be useless, and uses it to increase the car’s horsepower.

Cars without a turbocharger or supercharger are called normally aspirated. Normally aspirated cars draw air into the engine through an air filter; the air then passes through a meter, which monitors and regulates the amount of air that enters the system. The air is then delivered to the engine’s combustion chambers, along with a controlled amount of fuel from the carburetor or fuel injectors.

In a turbocharged engine, however, the air is compressed so that more oxygen will fit in the combustion chamber, dramatically increasing the burning power of the engine. The turbocharger is composed of two main parts: the compressor, which compresses the air in the intake; and the turbine, which draws the exhaust gases and uses them to power the compressor. Another commonly used term in relation to turbochargers is boost, which refers to the amount of pressure the air in the intake is subjected to; in other words, the more compressed the air is, the higher the boost.

Although the increase in power is advantageous to the car — and likely a source of enjoyment for the driver — a turbocharger has its drawbacks. First and foremost, a turbocharged engine must have a lower compression ratio than a normally aspirated engine. For this reason, one cannot simply put a turbocharger on an engine that was intended for normal aspiration without seriously undermining the life and performance of the engine. Also, a lower compression ratio means the engine will run less efficiently at low power.

Another major drawback of a turbocharger is the phenomenon known as turbo lag. Because the turbocharger runs on exhaust gases, the turbine requires a build-up of exhaust before it can power the compressor; this means that the engine must pick up speed before the turbocharger can kick in. Additionally, the inlet air grows hotter as it is compressed, reducing its density, and thereby its efficiency in the combustion chamber; a radiator-like device called an intercooler is often used to counter this effect in turbocharged engines.

AUTOMOBILE ENGINES

The working of an automobile engine follows the same principle as an internal combustion engine. Air, from outside, enters the engine through the air cleaner and reaches the throttle plate.
The pedal in your car is the control for the amount of air that you would want to be taken in, and you control it by pressing on this gas pedal.
The air is then distributed through the intake manifold of the cylinders.

At some point fuel is injected into the air stream, and the mixture vaporizes and is drawn into the cylinders as they start their intake stroke.

This way, when the cylinder has reached its bottom, it has drawn in sufficient mixture. As it moves up, compressing the mixture, the spark plug ignites the mixture, and as the powerful gas formed expands, it pushes the cylinder to the bottom with the cylinder once again drawing in the mixture.

In designing automobile engines, you need to be a specialist in automobile engineering.
The consideration that is taken while designing such an engine is whether it should be a carburetor or a diesel one. carburetor engines are most commonly found in passenger cars and low capacity trucks, while trucks with a capacity over two tons are fitted with diesel engines, including dump trucks, trailer tractors and bus.

Increasingly the medium and low-capacity vehicles are being fitted with diesel engines, since the fuel consumption of these engines are 30% to 50% lower than the carburetor engines.
Diesel engines not only cost more, but maintenance is much more expensive than the other type of engine. Diesels require more metal parts per kilowatt.
The critical parts of diesel engines are made of alloy steel, and the fuel injection system is much more expensive than carburetor engines.

However, the cost of manufacturing carburetor engines has increased with the use of higher mechanical grade components, considering the thermal loads of the material used. At the same time the use of high alloys and increase in production costs have contributed to the higher price of such engines.

There is a sharp rise in using aluminum alloys in design of carburetor engines in passenger cars, and with the use of high octane petrol, the cost of operation of these cars have come down extensively. Using alloy steel in constructing the engine body and other parts of the engine, makes the car lighter and hence fuel consumption goes down substantially.

The main parts that are made of high steel alloy are the main casting of the engine, the cylinder head, water and oil pumps, oil filter housing, end covers of the generator and starter, and the intake pipes. It has been observed that by using high steel alloys, the weight of the car is reduced by 35%.

The power per liter, per unit of piston area, and the brake effective pressure are 6% to 8% lower in air-cooled engines, compared to engines having liquid cooling mechanism. This is due to the fact that in engines with liquid cooling there are great losses in cylinder charging caused by the high temperature in pipes, ducts in the head, cylinder walls and head, etc.

The size of air cooled engines are much bigger than the engines with liquid cooling having the same capacity, and this is because the cylinder axes difference is larger in air-cooled engines. Taking account of the radiator dimensions, if both engines are compared, the air-cooled engine will vary slightly with its height a little longer than or approximately the same length as the water-cooled engine. As far as the width and the height is concerned both engines are about the same.

The auxiliary units of the feed and ignition, and generator and starter systems are a bit difficult to fit on the body of the air-cooled engines, because of the presence of hoods and having a danger of over-heating.