What is a Turbocharger in Car Engine?

source:silodrome

Turbochargers are popular among most automobile manufacturers nowadays as it improves a vehicle's overall performance. For instance, you will find turbochargers in the new Chevrolet Equinox and Trax. 

With time, the number of vehicles with turbocharged engines will surpass that of traditional gasoline engines. 

A turbocharger is a forced induction device powered by a flow of exhaust gases. It uses this energy to compress intake air, forcing more air into the engine to produce more power for a given displacement. Turbocharger is placed between the engine and the exhaust. 

Turbochargers are commonly used in diesel engines but are also becoming increasingly popular in gasoline engines. 

A turbocharger works by utilising energy from exhaust gases of an internal combustion engine to increase the amount of air entering an engine's cylinders, thereby increasing power output. 

The following step-by-step guide explains a turbocharger working process in detail:

Step 1: Exhaust gas flow

As the engine's exhaust gases exit the combustion chamber, they pass through the exhaust manifold and into the turbine housing of the turbocharger.

Step 2: Turbine wheel

Exhaust gases flow over a turbine wheel connected to a shaft. The high-velocity flow of exhaust gases causes the turbine wheel to spin rapidly.

Step 3: Compressor wheel

The shaft connected to the turbine wheel also drives a compressor wheel located on the other side of the turbocharger. The spinning turbine wheel rotates the compressor wheel.

Step 4: Compressed air intake

The compressor draws ambient air from the surroundings and compresses it. Compressed air is then forced into the intake manifold or directly into the cylinders, depending on the engine's design.

Step 5: Increased air density

Compressed air from the turbocharger has a higher density and oxygen concentration than the ambient air. This allows more air to enter the engine's cylinders during each intake stroke.

Step 6: More fuel combustion

The increased air available in the combustion chamber allows more fuel to be burned. This results in a more efficient combustion process, generating more power and torque from the engine.

Step 7: Wastegate 

Some turbocharged engines feature a wastegate, which helps control the boost pressure produced by a turbocharger. Wastegate bypasses some exhaust gases around the turbine wheel, limiting its speed and preventing over-boost conditions.

By forcing more air into the engine, a turbocharger allows an engine to generate more power without increasing its displacement. This technology is commonly used in high-performance vehicles, diesel engines, and even smaller engines to improve efficiency and performance.

The turbo in the car engine is attached to the engine's exhaust manifold and operates similarly to a gas turbine engine. Go through below pointers to learn its design in detail: 

• As exhaust gases from cylinders flow through turbine blades, the turbine begins to rotate. 

• The turbine is connected to the compressor by a shaft, and the compressor is positioned between the air filter and intake manifold. Its purpose is to pressurise air entering the engine's pistons.

• The rotation of the turbine is driven by exhaust gases passing through its blades. The faster the exhaust flow, the quicker the turbine blades spin.

• The compressor pumps air into the cylinders on the opposite end of the shaft that connects to the turbine. It functions as a centrifugal pump, drawing air at the centre of its blades and expelling it outward as it rotates.

Some manufacturers place an intercooler into the turbo system between the turbocharger and cylinder. This intercooler actively cools the air before it enters the combustion chamber, effectively decreasing any likelihood of knock.

There are four parts or components of a turbocharger that work in conjunction to make the whole process happen:

Turbocharger/ Turbine

Turbocharger has a snail-like appearance and consists of various components, including an air intake, an exhaust intake, two distinct impellers (a turbine located at the rear and a compressor positioned towards the front), and a charged air exhaust that connects to the intercooler. Additionally, there is a designated hose line for oil.

Intercooler

To decrease the temperature of pressurised air expelled by a turbocharger, an intercooler, acting as a secondary radiator, is positioned to intercept the air before it reaches the engine. The intercooler utilises coolant as a cooling agent to lower the air temperature.

Wastegate

A wastegate controls the boost pressure by actively bypassing the turbine through a valve between the exhaust intake and the turbocharger.

ECU Tune

To ensure proper functionality, if an engine, not originally designed for a turbocharger, is modified to include one, the engine's electronic control unit or ECU requires reprogramming. This recalibration is necessary because a turbocharged engine necessitates distinct adjustments in fuel-to-air mixtures and ignition timing, differing from a naturally aspirated engine.

In addition to these main parts, several other smaller parts make up a turbocharger. These include the turbine blades, the compressor blades, the shaft seals, and the bearing housing.

You can find great varieties of turbochargers. Here are some of the most common ones: 

Single Turbocharger

A single turbocharger is a forced induction system that uses a single turbine to compress the air before it enters the engine. This type of turbocharger is the most common in the automotive industry, and it is often available in cars that do not need a lot of horsepower or torque. 

One example of a car that uses a single turbocharger is the Honda Civic. The Civic is a popular car for tuners because it is relatively affordable and easy to modify.

Twin Turbocharger

Adding a second turbocharger to an engine can increase the air forced into the engine, creating more robust power and torque. The setup of a twin-turbo system is similar to that of a single turbocharger system but with two turbochargers instead of one.

Sports cars and supercars such as the McLaren 570S use this system.

Quad Turbocharger

The only production car using a quad-turbocharged setup is the Bugatti Chiron. It combines two large turbochargers and two small turbochargers to an 8-litre W16 engine, producing 1,500 horsepower. The man who took it to 304 mph said it was a rush.

E-Turbocharger

Taking inspiration from the current crop of Formula 1 cars, an e-turbocharger adds electricity to the mix to eliminate turbo lag. A small electric motor between the turbine housing and the compressor runs off a 48V electrical system. The electric motor can spin the compressor quicker than the exhaust gases. It thus removes the time lag to boost.

Compound Charger

A compound-charged system pairs a turbocharger with a supercharger to generate more immediate torque and extend the top-end horsepower. Volvo uses this system in its T6-grade cars and SUVs, where the supercharger generates immediate torque for responsive acceleration, and the turbocharger provides additional power at higher speeds.

Hot-V Turbocharger

A "Hot-V" setup places the turbocharger or turbochargers inside the "V" of an engine, reducing the space needed for the engine and the distance the charged air needs to travel between the compressor and the engine. This allows the turbocharger or turbochargers to spool quicker and reduce lag.

The first automaker to put the "Hot-V" setup into production was Mercedes-Benz.

The various advantages of turbochargers are as follows: 

• A turbocharger increases airflow into an engine, which adds more power and torque to the engine performance. 

• Turbochargers can produce a lot of power, so manufacturers can reduce engine displacement and still achieve good efficiency and emissions.

Although there are benefits to using a turbocharger, there are also some disadvantages. 

• One disadvantage is that turbochargers are more complex than naturally aspirated engines, making them more expensive to repair. 

• Another disadvantage is that turbochargers can experience turbo lag, a delay between when the driver presses the accelerator pedal and when the turbocharger starts to provide a boost.

This piece discusses in detail what a turbocharger is, its working procedure, types, benefits, and drawbacks. They are becoming increasingly popular as manufacturers look for ways to reduce emissions and improve fuel economy.