Today, Garrett turbo has a wider selection of turbochargers available than they ever have before! In the catalog, Garrett product are grouped by their frame size. The turbine frame size of a turbocharger center section or �CHRA� is dictated by its inducer diameter. The bigger the turbine inducer, the larger the frame size, so any garret gt or gtx turbocharger in the GT42 or GTX42 family has a bigger turbine inducer size than those in the GT35 or GTX35 family, and so on. The model name of each turbo or Center section (CHRA), you�ll notice two digits directly after the frame size. These two digits designate the compressor exducer size in diameter, as measured in millimeters. Let�s look at the GTX4294 as an example. The unit has a GTX42 frame size turbine (82 mm) coupled to a 94 mm (exducer dia) comp wheel. If there is an �R� on the end of it, then that means the unit is a ball bearing turbo. So, a GT4294 is not a ball bearing turbo; whereas a GT4294R is a Garrett ball bearing turbocharger. If an �X� appears between the �GT� and the first number, it signifies that this turbo features a billet compressor wheel with �next generation aerodynamics�. The Garret GTX line is visually different in that the wheels typically are forged (billet), fully machined wheels rather than cast.
A Visual Guide to Garrett�s �GT� Model NumbersCourtesy of MAPerformance