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Turbocharger: What is it and How it Works?

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These are the signature sound of a turbocharger, desired by many! Have a listen to AdamC3064’s turbo sound compilation.

“Vroom vroom vroom – stutututuutuuu” says the Turbocharger.

If you’ve seen or heard a car passing by you with blazing speed, loud buzzing noise and fumes coming out of their exhaust, you’ve just witness turbocharger (or a supercharger) at work.

Some symbolizes it as the epitome of manliness, and success.

So, what is this majestic device and how does it work?

Let’s vroom vroom right into the content!

What is a Turbocharger?

Turbocharger gives you wings!
Turbocharger gives you wings!

Turbocharger makes your car go significantly faster in a very short time.

It works by channeling exhaust fumes through a turbine before exiting your car. When the turbine turns, it sucks in more air into your car engine.

That’s all it does.

So, how does more air gets you more power? To answer that, we have to take a step back and see how car engine works.

Our engine combusts fuel to generate power. The more fuel burned, the more power. That’s pretty easy, because adding more fuel into the engine is just as easy as adjusting the throttle to your car engine.

Simple, right? But there’s more to it.

Air-fuel ratio needs to be in certain ratio otherwise it will either cause engine damage or perform inefficiently. We call this a stoichiometric mixture. Generally, we need 14.7 parts of air to 1 part of fuel.

So if we increase the fuel intake, it will upset the ratio. It may become 13 : 1 or 12 : 1 because we have lesser air to fuel ratio now. Whatever it is, we need to increase the air intake to get that 14.7 : 1 back so that the mixture becomes stoichiometric again.

Now, this is where turbocharger comes in handy. It gives extra air intake to the car engine.

By burning more fuel and more air at the same time, your car produces more power to send you skyrocketing forward.

What makes up a Turbocharger?

Turbocharger can be divided into three parts.

  • Turbine
  • Compressor
  • Centre Hub Rotating Assembly
The hot side of a turbocharger is appropriately coloured red, while the cold side of a turbocharger is coloured blue.
The hot side of a turbocharger is appropriately coloured red, while the cold side of a turbocharger is coloured blue.

The picture above did a fantastic job illustrating it. The turbine is the red color portion; the compressor is the blue color portion; and the centre hub rotating assembly is the yellow and green side.

Part #1 : Turbine

Turbine is equipped directly to the exhaust manifold of our car engine. This side of the turbocharger is hot. They can be heated up to 200 degree Celsius and hence, it is also appropriately called the “hot side”.

The heat and pressure of the exhaust fumes are forced onto the turbine wheels (the blades) so that it turns. It’s the same working principle as a wind turbine.

Turbine are typically made from cast-iron. It also has a filter that screens tiny particles and impurities out of the system.

Part #2 : Compressor

Compressor is known as the cold side.

It’s purpose is to draw air into the compressor, compresses them and then send them into the engine intake manifold. Typically made from aluminum alloys.

Part #3 : Centre Hub Rotating Assembly

The centre hub rotating assembly houses bearings and shaft that connects the turbine wheels onto the compressor wheels. It’s basically the middle man.

It has proper sealings to avoid exhaust fumes from the turbine side mixing with the air from the compressor side.

How turbocharger works?

You can clearly see the where and how the hot air (red) and cold air (blue) moves in and out of the car engine and turbocharger. What a great overview!
You can clearly see the where and how the hot air (red) and cold air (blue) moves in and out of the car engine and turbocharger. What a great overview!

Source

Animation by PatriciaWrites under CC BY-SA 4.0.

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It starts from the exhaust manifold of our car engine.

As engine combusts the air-fuel mixture, it produces by-product that we call exhaust fumes. Despite being called a “by-product”, these exhaust fumes actually have a lot of heat energy and pressure which we can use.

If you’ve ever accidentally stood near an exhaust pipe, you know what I mean.

So, instead of wasting them, we connect our turbocharger to the exhaust stream. This way, the exhaust fumes are channelled onto the turbine blades of our turbocharger, which turns the turbine blades.


Turbine blades are connected directly to the compressor blades through a shaft, found inside the centre hub rotating assembly. When turbine blade turns, the compressor blade turns as well.

As soon as the compressor rotates, air inside the compressor are displaced. This creates a partial vacuum effect with low pressure on the compressor side. This way, it draws in more air from the surrounding to equalize the pressure.

Finally, the compressor compresses the air, and then sends the compressed air directly to the engine intake manifold.

With more compressed air, our car engine can combusts more fuel, and that provides the extra power boost to our car.

[Bonus] How blowoff valve works?

“But what is making the beautiful stututuutuuu sound that is exclusive to a turbocharged car?”

This deserves a mention on its own. It’s a supplementary component to our turbocharger, designed specifically to prevent compressor surge. In layman’s term, you can think of them as air pressure-regulator.

Compressor surge happens when you suddenly lift your feet off the gas pedal which causes the throttle to abruptly closes. Because the turbine blades are still spinning from inertia, the last remaining compressed air tries to enter the engine intake manifold. But, only to be stopped by a closed throttle.

WIth nowhere else to go, the compressed air flows back into the compressor, which messes with the turbo response and ruins drivability.

This is where blowoff valve comes in.

The valve is actuated by pressure. When the difference in pressure is high, it opens up to release air into the atmosphere instead of reversing back into the compressor. As the compressed air exits the valve, it create a very distinctive hissing sounds that people go absolutely crazy for.

Here's a comparison WITHOUT blowoff valve working (left) and WITH blowoff valve working (right). It helps to relief the pressure.
Here’s a comparison WITHOUT blowoff valve working (left) and WITH blowoff valve working (right). It helps to relief the pressure.

People love it so much that some turbocharged car owners would purchase and install the blow off valve purely to get that auditory effect. Some would even go to the extent of modifying the valve exit design to a get louder, and perhaps different sound.

Here’s how blowoff valve sounds like for your pleasure.

Advantages and disadvantages of having turbocharger

We all know that turbochargers are there to satisfy your need for speed. But, what are some of the other factors that you should consider before getting your engine turbocharged?

Here are some pros and cons of having a turbocharger.

Fuel Economy: Savings or Sabotaging?

The first advantage of having a turbocharger is you get more power while having the same size of engine. But, producing more power equals more energy output which means your engine will burn more fuel. Therefore, an engine with a turbocharger is not fuel efficient in that way.

But, in practice, having an engine with a turbocharger are much smaller and lighter than engines without a turbocharger, so a turbocharger gives a better fuel economy in that aspect. Car manufacturers can fit a much smaller engine to the same car. Instead of a big V8 engine, they can fit a much smaller turbocharged V6, or instead of having a V6, they can fit a much smaller and lighter turbocharged four-cylinder engine. These lighter turbocharged engines could well save up to 10% of your fuel.

As you can see, this is a controversial debate.

Some drivers claim that not only their power is boosted, but so did their fuel economy. While on the other end of the spectrum, some claims that the fuel economy benefits promised by the turbochargers manufacturer did not turn out as they are supposed to. There was a study done in 2013 by Consumer Reports which found out that small turbocharged engines actually give worse fuel economy than their regular size engines.

Whose side are you on? Let us know in the comment section below!

Higher maintenance cost

Many car models don’t come with turbocharged engine. If you want to turbocharge your engine, be ready to fork out a good couple thousand Ringgit Malaysia, with good reasons. The car workshop would have to lift your car engine, install the turbocharger, additional wiring and tubings.

It’s a lot of work!

Then, there is the maintenance cost as well. Having a turbocharger on your engine means that you have another layer of mechanical complexity to your engine. Although, turbochargers are usually very robust and can last up to 10 years. At one point or another, you will have to change it and that means $$$.

And guess what?

It’s not just the turbocharger itself, engine components will have a shorter lifespan too. A turbocharged engine will sustain greater pressure and temperature than usual, which damages the parts. As a result, you may find yourself more often at a local car workshop.

Difference between turbocharger and supercharger

Turbocharger and supercharger are very similar, but different. Here’s a great video by Engineering Explained explaining and comparing turbochargers and superchargers.

During your hunt for more engine power, you may come across a thing called supercharger.

It’s very similar to a turbocharger!

When speaking about turbocharging and supercharging, people mention them in the same breath. Both of them are able to provide that extra power to your engine. They both create a considerable amount of boost that can reach up to 50% more power to the engine.

But, there are definitely enough differences between them that you may have to consider before picking a side!

Here’s a quick summary of their differences.

Enjoy!

TurbochargerSupercharger
Powered by exhaust streamPowered by engine
Improves efficiency by utilizing energy that would otherwise be wasted. Does NOT improve efficiency because it is a parasitic load on the engine.
Increase up to 50% engine power Increase up to 50% engine power
Smog filteringNo smog filtering
Turbine spins up to 150,000 RPMTurbine spins up to 50,000 RPM
Better boost at higher engine RPMBetter boost at lower engine RPM
Signature turbo flutter soundMore reliable
Harder to maintainEasier to maintain

The Bottom Line

Well, that sums up the introduction to a turbocharger.

What do you think?

If you own a fancy turbocharged engine, leave a comment down below.

Do you love your turbocharger? Or do you regret it? Let us know.

Until then, drive safe and drive smart!

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