A Guide to Garrett's "GT" Model Number

GTxxyyzz

• Positions "xx" refers to the frame size of the turbine wheel inducer.
  
  For example the "GT28" in "GT2860RS" refers to its turbine wheel frame size family. All GT28 units use a turbine wheel with 53.85mm inducer diameter
  
  As a rule of thumb, the larger the number, the larger the turbine wheel.

 

• Positions "yy" designate the compressor wheel exducer (major) diameter in millimeters
  
  The "60" in the GT2860RS example above has a 60mm compressor wheel exducer diameter.
  
  Note: Wheel sizes 100mm and over omit the "1" (hundreds digit)
  Example: the 02 in a GT4202 refers to its 102mm compressor wheel exducer diameter

 

• Positions "zz" may be used to designate special features of a particular turbocharger where applicable
  
  Example: GT2860RS
  "R" = this is a Ball Bearing unit
  "S" = used for units which require some differentiation from units in the same family
  
  Compare a GT2860R to a GT2860RS. While both are ball bearing and externally similar, the GT2860RS is better suited for higher-flow applications than the GT2860R. In this case, the S reflects the higher-flowing nature of the GT2860RS