Turbochargers

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What Does A Turbocharger Do?

A turbocharger increases the performance figures including the horsepower and torque of a car by forcing more air into the engine allowing more fuel to be used.

The purpose of a turbocharger is to take advantage of the exhaust gases produced by the engine to rotate an assembly that pulls in and compresses the intake charge.

How Does It Work?

A turbocharger increases the flow of air to the engine, especially during low air pressure situations typical with a naturally aspirated engine.

A turbocharger has a shaft that is connected to a turbine wheel and compressor wheel located at the opposite ends.

Both these wheels are located in a housing and the exhaust gases produced by the vehicle’s engine are forced into this housing through an inlet from where it goes to the turbine wheel.

The turbine wheel housing is made in a way that the incoming exhaust gases rotate the turbine at a high speed.

Because the turbine wheel is connected to the compressor wheel through the shaft, it also starts rotating quickly drawing in more air into the housing and then compressing it.

This compressed air then exits the housing through an outlet pipe and supplies fresh air to the engine.

As this air is enriched with more oxygen due to compression, this helps in making a more saturated air and fuel mixture which therefore results in more power and torque.

What To Look For When Buying A Turbocharger?

Here are some of the factors that need to be taken into account when buying a turbocharger:

Watch our video on choosing Turbochargers on our YouTube channel.

Choosing The Waste Gate

The waste gate is an important part of the turbo that controls the boost and thus it deserves attention while making the purchase.

Turbo Trim

Another significant consideration during the process is turbo trim which is the inducer-to-exducer ratio.

This means that a turbo with a higher trim lets more air pass through its wheels.

AR Value

AR, which stands for area over radius, is another important feature of a turbo that should be taken into account while purchasing.

Size Of Turbo Housing

The size of the turbine housing also plays an important role in the performance of a turbo, and the power you want for your vehicle varies greatly depending on the size of the turbine housing.

Why Does The Size Matter?

As the size of the turbine housing increases, so does its ability to gulp in air as well as the compression in the compression chamber, resulting in a higher saturation of the fuel and air mixture which leads to higher combustion rates, thereby generating more power.

Lags & Spools

The higher the value of AR, the higher is the flow rate, but it is also worth noting that a larger turbine housing creates more lags and thus takes longer to spool.

A smaller turbine housing has lower lag values and thus spools up quickly thus such turbos are more responsive.

The Choice of Turbochargers Seems Complicated

In the end, it all comes down to choosing between:

  • Getting high horsepower but with a lag;
  • Relatively lower horsepower but a more responsive turbo.

This trade-off usually makes the choice a rather difficult one but if done correctly, the results are impressive and with modern turbo components the trade off has been minimized.

Which Are The Best Turbocharger Brands?

The following are some of the world-famous turbo manufacturers:

  1. IHI;
  2. Honeywell;
  3. Cummins;
  4. Bosch Mahler;
  5. BorgWarner;
  6. Garrett;
  7. Mitsubishi.

A turbocharger is an extremely expensive part and thus you need to get one from a trusted source and that too at a reasonable price.

Click here to see some of the turbocharger options available for your vehicle, regardless of its country of origin.

How Hard Is It To Install Turbocharger?

Installing a turbocharger is not a difficult process but as the trend of taking complex ventures as DIY projects has seen a rise, many people have successfully done so on their own.

Several videos of such individuals are available on the internet. However, it is worth keeping in mind that this process can go wrong really quickly and due to a large number of parts in a turbo kit, you must only start it if you have a basic understanding of how this stuff works.

I rate the process as 7 out of 10 in terms of difficulty (10 being the hardest).

What Are The Benefits Of Fitting Better Quality Turbocharger?

A higher-quality turbo has more information provided by the manufacturer. For example, the size of the inducer and the exducer is specifically stated so in case any racing enthusiast is interested in that kind of stuff, he can do whatever he wants.

We have images below that show the difference between a conventional turbo and a twin scroll turbocharger.

Using the standard four-cylinder firing sequence of 1-3-4-2, you'd draw 2 and 3 into one side of the scroll and 1 and 4 into the other. When further cylinders are added, the procedure is repeated with each additional odd firing cylinder.

Thus, when the first cylinder completes its expansion stroke, the exhaust valves on the second cylinder open as they overlap and the second cylinder reaches the end of its exhaust flow, and this gas pressure interferes with the engine's exhaust flow rates due to two distinct speeds/pulses meeting.

A dual scroll engine entirely eliminates this and provides the engine's maximum flow rates.

What is the difference between a dual scroll turbo and a twin turbo?

Interestingly, BMW dropped the double turbo configuration on the 335i in favour of a twin scroll single turbo, although power output stays relatively comparable.

While the two turbo system provides higher top end power and gains when adjusted, both turbos operate quite well, with the twin scroll turbo providing a lot quicker spool up and improved low end power.

The Benefits of Twin Scroll Turbochargers

  1. The boost reaction is far quicker, kicking in considerably sooner.
  2. The fuel economy is improved ( up to 5 percent )
  3. They seem to be more dependable based on anecdotal evidence.
  4. Space-saving compared to a similar twin turbo setup
  5. Increased bottom-end torque and a smoother spool-up
  6. Increased power over the rpm range
  7. More efficient across the whole rpm range ( up to 8 percent more efficient)
  8. They compensate for the different exhaust lengths produced by a single turbo configuration.

What To Do After Installing The Turbo?

As the process of installing a turbocharger is pretty daunting, many individuals often forget to go through even the basic stuff.

So, here are some of the steps that you must undertake once you have finished installing the turbo on your vehicle:

Experts suggest that for getting oil to the turbo, it is a good idea to turn the key to the on position without cranking it. Let it stay there for a minute or so and then turn it off.

After this, repeat the process but this time for around half a minute and then crank the engine.

Allow the vehicle to idle for at least 5 to 10 minutes. This is vital because if any sort of oil or gas leakage is occurring, this is the time to fix the issue.

In the case of a VNT turbo, the actuator must work properly. It is also worth noting that hearing a high pitch noise is not unusual in the case of an electric actuator, so you should not be much concerned about it.

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