VTG Rings VTG Rings All ‘VTG Rings’ are manufactured using centrifugal casting method. PAC Turbo Charger parts are manufactured to American and German material standards. PAC Turbo Charger parts have least thermal expansion and highest thermal conductivity properties. MethodOuter Diameter (mm)Internal Diameter (mm) Centrifugal Casting65 To 270 mm26 To 100 mm