Diesel Engine Turbocharger Rebuild and Experimental Testing

The objective of the 2006–07 Virginia Tech Turbocharger Project was to obtain and analyze vibrations data from different bearing designs. The supporting tasks were divided amongst various sub-teams; a turbocharger team, an engine test operating team, a dynamometer team, and an ADRE software team. The turbocharger team has successfully developed a procedure for disassembly and reassembly of the turbocharger. A consistent and well-documented assembly procedure has ensured turbocharger operation free from human error. Consistency in the rebuild process is vital to properly compare vibration data with the different shaft bearings. The most important aspect of this reassembly is the torque applied to the tie-bolt nut. This torque causes the tie-bolt to stretch, and this stretch must be accounted for because it is a measure of preload force on the compressor wheel. The team designed and made a stand to carefully apply this torque on the tie-bolt nut without creating a bending moment. The original stock bearings were used for the first turbocharger rebuild to see if the rebuild procedure would lead to similar data. Two other bearings have been tested and analyzed. This paper will give a brief overview of the results to date.