Turbocharger FAQ

HOW DOES THE TURBOCHARGER WORK?

The way a turbocharger works is based on the simple principle that the performance of an internal combustion engine increases when a larger amount of air (oxygen) is available for combustion. The turbo does nothing else than provide the engine with a larger air mass than it can suck in itself. To do this, air is compressed in a compressor and fed directly into the cylinder's intake tract. The exhaust gas turbocharger uses the hot exhaust gases from the engine to drive the compressor: a turbine wheel is operated by converting thermal into kinetic energy. This lies on a shaft with a compressor wheel and sets it in motion. The rotation causes fresh air to enter the compressor, which is then compressed and fed to the motor.

WHAT IS TURBO LAG?

Since the exhaust gases in low speed ranges are not sufficient to drive the turbine wheel of the turbocharger and thus build up sufficient boost pressure in the compressor, the full effect of the turbocharger only takes place in medium speed ranges. Since the amount of fuel injected is adapted to the boost pressure, the driver feels as if the car is only accelerating slowly (turbo lag). In today's common turbocharger, the VTG charger, this turbo lag is almost completely eliminated by adjustable guide vanes on the turbine. The turbine blades adapt to the respective speed range, which enables a high torque of the turbines even at low speeds. The biturbo works differently, counteracting the turbo lag with two turbochargers: a small high pressure charger for low speed ranges and a low pressure charger for high speed ranges. With the electric biturbo, the small charger is additionally supported by an electric motor.

WHAT IS THE DIFFERENCE BETWEEN AN EXHAUST GAS TURBOCHARGER AND A COMPRESSOR?

The compressor works in a similar way to the turbocharger: by compressing the air drawn in. However, it is directly connected to the motor via chain, belt or gear drives and is thus driven by it. Thanks to the mechanical drive, the compressor has the advantage that it responds immediately even at low speeds. Thanks to the VTG technology and the use of two turbos, this problem is largely eliminated with the exhaust gas charger. In addition, it is more efficient than the compressor due to the use of exhaust gas.

HOW LONG IS THE SERVICE LIFE OF A TURBOCHARGER?

Where turbochargers used to be prone to problems and required extreme care, modern turbochargers are more robust and have a service life equivalent to that of an engine. However, care should be taken to ensure that the manufacturer's service instructions are followed. That means having regular and professional oil and filter changes made. If you want to benefit from your turbo engine for a long time, you should also refrain from changing settings. As a rule, the compressors are optimally configured for the respective motors at the factory. For example, if the boost pressure is increased, the engine can be seriously damaged.

WHAT DOES TUNING WITH A TURBOCHARGER MEAN?

When tuning by installing a previously non-existent turbocharger, there is a lot to watch out for. In the vast majority of cases, it is necessary to go to a specialized workshop. Before installing the turbo, check whether all components in the engine can withstand the increased power. The amount of fuel to be injected must be adapted to the additional amount of air that the turbocharger pushes into the combustion chambers (cylinders). In the best case scenario, the exhaust gas path must also be optimized, as modern naturally aspirated engines are matched to the dynamic pressure in the exhaust system. The following rule applies to turbo engines: the faster and more exhaust gases are removed, the better. Attention: In an engine that is filled via a charger, the combustion temperatures are higher, which also depend on the set boost pressure. Partly correct is: The higher the boost pressure / filling level, the higher the performance. However, the service life of all engine parts present at the origin is greatly reduced. At this point a compromise has to be found between performance and service life.

Greatest susceptibility to defects: Turbo engines can be quickly tuned using the boost pressure. The possibility of increasing the boost pressure with very simple means in order to generate significantly more power is not advisable for most engines without further measures. Using a more powerful charger (to replace the original charger) also has limited advantages. The response behavior can be improved, but coordination and adjustment to the motor should always be carried out by a specialist.

WHAT CARE DOES A TURBOCHARGER NEED?

Oil lubrication is the be-all and end-all of a turbocharger. After starting the engine, it takes about 30 seconds for the oil to be evenly distributed and for the compressor to be optimally lubricated, so you should avoid high speed ranges during this time. The situation is similar when switching off the engine: If you were driving at high speed, you should let the engine run for about 20 seconds at low speed, as the turbo continues to work. Adequate lubrication is only guaranteed when the engine is running. It should also be noted that only the oil specified by the manufacturer should be used.

WHICH DEFECTS CAN OCCUR WITH THE TURBOCHARGER?

Most turbocharger defects are the result of insufficient lubrication. There is a risk that the compressor or turbine wheel will rub against the housing and thus also affect the motor. Further dangers arise from contaminated oil or foreign bodies from a defective air filter. This can damage the turbine and compressor wheels and ultimately damage the turbocharger bearings. In general, it is best to switch off the engine immediately in the event of unusual noises, oil leaks or vibrations in the turbocharger, as otherwise there is a risk of engine damage.

WHAT SHOULD BE CONSIDERED WHEN REPAIRING THE TURBOCHARGER?

Repairs to the turbocharger should only be carried out by trained specialists, as special tools and machines are usually required. When parts need to be replaced, it is important that only material that meets the requirements of the manufacturer is used. In the worst case scenario, there is a risk not only of engine damage, but also the expiry of the guarantee, operating license and insurance cover.

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