Servicing of turbochargers

More power means more of burned fuel and air. In order to create the conditions for that, it is necessary to increase the volume of cylinders, and thus increase the weight and production costs, with an increase in fuel consumption and non-compliance with strict environmental standards. The turbocharger offers a solution!

Turbo servicing

The Pinjušić Service Center repairs all types of turbochargers(Garrett, BorgWarner, Holset, Mitsubishi, IHI, Toyota), including electronic actuators for the control of charging pressure Garett-Hella and others.

The process consists of the following steps:

1/ Disassembly and cleaning of turbochargers

After having received the turbocharger for repairs, it is disassembled and thoroughly degreased and cleaned from burned oil, soot and corrosion. In this process are used the injector sandblasting cabins with different media, depending on the type of material (steel, aluminum).

2/ Inspection and measurements of turbochargers

After visual inspection, the damaged parts are replaced with new ones, and before assembling, we carry out precise measurements in accordance with the factory tolerances, paying special attention to the radial and axial impeller clearance in the bearing assembl

3/ Balancing of turbochargers

Balancing is the most important step in the process of turbocharger repairing. The reason is simple, and it is connected to a number of revolutions that is achieved (more than 200.000 revolutions per minute at temperatures between 600-1050 degrees). At that speed, even the slightest unbalance can cause a complete breakdown of the turbine subassembly. Balancing of turbocharger includes three steps: 

• Separate balancing of rotating parts. For a properly balanced turbo, it is fundamental to perform a dynamic balancing of shaft and compressor turbine rotor in both areas (left and right).

• Balancing of the entire rotor. Since the rotor consists of additional parts that could cause unbalance, it is also necessary to carry out the second stage of dynamic balancing in both areas (left and right).
   
• Balancing of the turbo assembly. After putting together the parts that are already balanced, we carry out the final balancing and checking the oil sealing on the VSR device (Vibration Sorting Rig). This test up to the maximum number of revolutions (0 – 200.000) ensures proper operation in all modes, without well known "whistling" caused by vibration.

4/ Assembly and calibration of actuators

A tested turbo assembly is installed in the casing in order to check the actuator. If the actuator is pneumatic, the overall stroke and running in several positions is checked and adjusted, using the electronic deviceGATETEST12.

Principle of the turbocharger operation

Using turbochargers, we compress the air into the engine and thus generate more power per unit volume.

In the engine cylinder burns a mixture of fuel and air. The exhaust gases, exiting through the exhaust manifold, with its kinetic energy drive the turbine wheel of turbocharger. It is connected with a common shaft to the compressor wheel. The compressor wheel rotation sucks the air and compresses it towards the engine. By opening the intake valve, the compressed air enters into the cylinder and provides the pressure "boost" in the first stroke. This creates conditions for further fuel burning, when compared to the conventional "atmospheric" engine.

Advantages of turbochargers:

• Getting more power from less volume
• Reduction in fuel consumption
• Better combustion with reduced environmental pollution
• Downsized engines
• Power available at lower number of revolutions with more driving pleasure

From the history of the turbocharger

The first turbocharger was designed by a Swiss engineer Alfred Bücki in mid-1905. Very soon began its installation in combat aircrafts and racing cars. First mass-produced car with a turbocharger was an American Chevrolet Corvair from 1962. On the European market, this concept experienced its baptism by fire in the BMW2002 turbo from 1973, where the power was increased from 100 or 130 hp (in the Tii version) to 170 hp. Two years later came the Porsche 911 Turbo with 301 hp, and the first turbo commercial success was achieved in 1977 with the Saab 99Turbo.

The engine power of 1971 ccm increased to145 hp. The first diesel car with a turbocharger was the Mercedes 300 SD from 1978, and in the beginning of 1979 the Peugeot 604 turbo diesel was first to arrive to the European market.

Modern turbo diesel engines are equipped with variable geometry turbochargers, namely, with the rotary turbine stator vanes. This considerably improves its drivability and flexibility. In order to achieve an adequate gain of energy from intake gases, they must flow on the impeller blades under the optimal angle, which depends on the peripheral velocity of the blades, that is, on the number of the rotor revolutions (which climbs to over 250.000/min), and it is defined by the position of the resultant (input) gas velocity in so-called triangle of velocities. By rotating the stator blades, changes the direction of the gas input into the turbine rotor. Thus it is compensated the change of peripheral rotor speed and achieved the optimal angle of the gas flow in whole working area, as well as prevented a local sonic boom at the top of the rotor blades (which causes congestion at the rotor entrance). The stator blades are rotated by lever mechanism connected to the diaphragm assembly that responds to the increase in gas pressure at the compressor exit. In the stator is created so-called Venturi effect of the gas flows, which achieves its acceleration and additional increase of the compressor efficiency.

The Porsche 911 Turbo from 2007 was the first petrol car with turbocharger with rotary stator vanes. The turbocharger has proven itself in all internal combustion engines, especially in diesel engines. It provides better performance, balanced drivability and low fuel consumption. The turbocharger has enabled undreamed development of diesel engines and it is rightly said: if turbo- then diesel, if diesel-then turbo.