A turbocharger is a mechanical device that increases the amount of air entering an engine. In this article, we will learn about turbocharger maps and their applications.

What is a Turbocharger and How Does it Work?

Turbocharging was developed to produce smaller, lighter engines that are both more powerful and efficient. In this setup, a compressor and a turbine are mounted on the same shaft. The exhaust gases rotate the turbine, and this rotation provides the energy needed to drive the compressor, which in turn supplies air to the cylinders. The compressor and the turbine are connected by a shaft and housed in separate chambers within the turbocharger. As the exhaust gases enter the turbine chamber, they cause the turbine and compressor to spin rapidly.
The compressor is in the route of the air entering the engine, while the turbine is in the direction of the exhaust gases exiting the engine. The turbine impellers revolve due to the exhaust airflow to the engine, which causes the compressor to rotate. More air is forced into the engine due to the spinning of the compressor. Thus, increased engine efficiency is achieved by mixing more air with less fuel consumption.
Turbocharged engines also have an intercooler, which reduces the overall temperature of the engine and turbocharger to prevent system damage and premature fuel combustion in the cylinder.
Another important component in the turbo system is the wastegate. The wastegate is used to regulate turbo pressure and is commonly found in turbocharger systems. It is controlled by the ECU.

Advantages of Using a Turbocharger:

  1. Engine power increases significantly, and compact-volume engines can provide tremendous power.
  2. The amount of fuel used is reduced. As engine power has increased, it is no longer necessary to overdrive the throttle, which means driving at low RPM saves fuel.
  3. The turbocharger's efficiency is better than that of the supercharger because it obtains its necessary energy from the engine's exhaust gases rather than the engine itself, resulting in less energy loss.
  4. The use of a turbocharger reduces pollutants.

Disadvantages of Using a Turbocharger:

  1. The turbocharger turbine requires time to reach a position where it can create a boost that can be used for propulsion in turbochargers. This slows down the turbo and isn't present in superchargers (known as "turbo lag").
  2. Another downside is that the driver only gets this boost at certain engine speeds, and it is not available right away.
  3. Another disadvantage of turbochargers is that they generate a lot of heat. The source of energy comes from hot exhaust gases from the engine, which are cooled by the intercooler. Turbochargers function at higher temperatures than superchargers."

Main Turbo Tables in ECU:

Tables such as turbo pressure, turbo pressure limiter, and wastegate duty cycle are useful in understanding how the turbo control mechanism operates within the ECU. This is the simplest way to describe the Bosch ECU's turbo control mechanism.

Turbo Pressure:

Based on engine speed and input air pressure, this table shows the amount of turbo pressure in hpa or hectopascals.

Limiter of Turbo Pressure:

This table acts as a pressure limiter for turbochargers. It displays the maximum turbo pressure that can be achieved based on engine speed and turbo pressure. This table is used by the ECU to limit the boost pressure.

Wastegate Duty Cycle Table:

The vertical axis of the engine speed and the horizontal axis is relative desired boost pressure can be seen in the table. The percentage of the duty cycle of the wastegate solenoid is also included in the table. As previously said, the functioning of this table is based on the quantity of turbocharger pressure and the engine speed wastegate duty cycle percent. These figures are larger at lower revs, indicating that the wastegate valve is closed in this location to spool the turbo quicker. The turbocharger increases in speed as the engine boost speed increases, and when it reaches the specified pressure according to the turbocharger pressure table, the duty cycle decreases. The wastegate valve opens, allowing the turbo boost to be adjusted. The wastegate opens more when the duty cycle numbers are smaller.

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