Turbocharged Engine

Mechanical Engineers, always make something better, cheaper, more efficient, in other words more environment friendly. 

It is always possible to build an engine that can go faster and travel further using less fuel. One way to improve an engine performance is to use a Turbocharger, a pair of fans that harness waste exhaust power from the back of engine to cram more air into the front, delivering more “oomph” than you’d otherwise get. When people talk about racing cars or high performance sports car, the topic of turbochargers usually comes up. A turbo can significantly boost an engine’s horsepower without significantly increasing its weight, which turns into a huge benefit that makes turbos so popular.

Turbocharger, also known as turbo, is a turbine driven force induction device that increases an internal combustion (IC) engine’s efficiency and net power output by forcing extra compressed air into the combustion chamber. Turbochargers are most often used with Otto cycle and Diesel cycle internal combustion engines. Originally known as Turbosuperchargers, when all forced induction devices were classified as superchargers. The major difference between a turbocharger and a conventional supercharger is that a supercharger is mechanically driven by the engine, often through a belt connected to the crankshaft, whereas a turbocharger is powered by a turbine driven by engine’s exhaust gas. An engine with both a supercharger and a turbocharger is known as Twincharged engine. 

Working of Turbocharger:

A turbocharger consists of two little air fans (also called as impellers or gas pumps) placed on same metal shaft so that both spin around together. One of these fans, called as the turbine, is placed in the exhaust stream from the cylinders. As the cylinders blow hot gases past the fan blades, they rotate and the shaft they are connected to (technically called the center hub rotating assembly or CHRA) rotates as well. The second fan is called the compressor, is mounted inside the car’s air intake so, as it spins, it draws air into the car and forces into the cylinders.  These are covered by a snail shaped housing featuring an inlet port, which the wasted exhaust gases enter at a high pressure and outlet port through which gases is passed out.

The basic idea is that the exhaust gases drive the turbine which is directly connected to the compressor, which rams air into the engine.

·        Fresh air enters the engine’s air intake and moves towards the compressor,

·        The compressor fan suck air in and squeezes and heats up the incoming air and blows it out again,

·        Hot, compressed air from the compressor passes through the heat exchanger, which cools it down,

·        Cooled, compressed air enters the cylinder’s intake. The extra oxygen helps to burn fuel in the cylinder at a faster rate,

·        As per requirement, cylinder burns more fuel producing energy more quickly and transfers more power to the wheels via the piston, shafts and transmission,

·        The hot exhaust gases blowing past the turbine fan make it rotate at high speed,

·        The spinning turbine is mounted on the same shaft as the compressor. So, as the turbine rotates the compressor rotates too,

·        The exhaust gas leaves the car, wasting less energy than it would otherwise.

In order to achieve such boost, the turbocharger uses the exhaust gas flow from the engine to spin a turbine, which in turn spins an air pump. The turbine in the turbocharger spins at speeds of up to 250,000 rotations per minute (rpm), which is about 30 times faster than most car engines can go. Since, turbocharger is connected up to the exhaust, the temperature in the turbine is extremely high. So, they typically have an oil cooling system to make sure that they don’t run too hot.

Turbocharged engines produce more power in the same sized engine. This is because every stroke of the piston generates more power than in naturally aspirated engines. A good example of such engine is Ford’s decision to replace its standard 1.6L petrol engine with a 1L turbocharged unit, which it calls as EcoBoost. Today, all modern diesel cars are fitted with a turbocharger, improving fuel economy and reducing emissions.

Even on the smallest engines, turbocharger produce more torque, particularly lower down the rev range. It means car can get benefit from strong, nippy performance, which is great around worn and helps the engine to feel more refined at higher speeds on motorways.

As the air in a turbocharged engine is filtered through more pipes and components, the intake and exhaust noise is reduced and refined, making for a quieter and smoother engine noise. This was one of the most unexpected benefits of a turbocharged engine.

Pros:

·        A turbocharged engine is typically more fuel efficient than a regular engine at a given horsepower: pleasant punch for passing and merging.

Cons:

·        It can be thirstier than a regular engine if you have a heavy foot,

·        Turbochargers themselves can fail and be costly to replace,

·        Turbo lag is a brief delay in response after pressing the throttle, which can occur when the engine isn’t producing enough exhaust gas to spin the turbo’s intake turbine quick enough.