They would carry a model designation like GTxxxxR. When I left Garrett we were just starting to develop those bearings. We used ceramic ***** since they are lighter than steel and can withstand higher temperatures. Interestingly, the highest loads in the bearings come from gyroscopic loads from their own ***** running in angular contact, not from the rotating group (compressor and turbine) unbalance.
These bearings need surprisingly little oil ... in fact it is more to carry heat away than for lubrication. You do not want to flood rolling element bearings, hence Garrett recommends a .040 orifice in the oil feed line to limit oil flow.
So here's my question; assuming you or your installer did use the orifice, has anyone experienced issues with the scavenge pumps that drain the turbo reservoirs? I'm not all that familiar yet with the turbo motor oil circuit ... do those scavenge pumps also drain some other parts of the engine so they wouldn't be much affected by the reduced turbo flow? Knowing the folks at Porsche they probably sized them to exactly match that circuit.

Ken

 

I don't know the part number but I do have GT3076r's the .040 inlet on a -4 feed line. My turbos are from mid 2007 with about 22,000 miles on them now, no water cooling either. I never gave any thought to the scavenge pump. The scavenge pump is only for the turbos. There is a vent line that comes out of the turbo tanks and goes to the dry sump vent which is then plumbed with a check valve to the plenum for vacuum, so the scavenge pump will not pull a vacuum on the turbo. When I installed the turbos I left the return loose to make sure that oil was flowing. There is quite a bit of oil that get pushed passed the .040 metering orifice. Don't know if that helps..

 

Tial has been usging garret cartridges/compressors and their updated k24 style housing for a long time. i have gt28's on my car (non billet style wheels)