In our product catalog, all offerings are grouped according to their turbine wheel frame size. The frame size of a turbo or CHRA is dictated by its turbine wheel inducer diameter. The larger the turbine inducer, the bigger the frame size, so any turbo in the GT42 family has a larger turbine wheel inducer than those in the GT35 family, and so on.
In the model name of each turbo or CHRA, you’ll also notice two digits after the frame size. These two digits refer to the compressor exducer diameter, as measured in millimeters.
Let’s use the GT4294 as an example. This unit has a GT42 frame size turbine (82mm) coupled to a 94mm (exducer diameter) compressor wheel.
If there’s an “R” on the end of a model name, this means the unit is ball bearing. So, a GT4294 is not ball bearing; whereas a GT4294R is ball bearing.
If an “X” appears between the “GT” and the first number, it signifies that this turbo features a compressor wheel with next generation aerodynamics. The GTX line is visually different in that the wheels typically are forged, fully machined wheels rather than cast.