Xona Rotor has made several major innovations with its XR line of performance turbochargers with features that enhance performance and durability. Among them is Xona’s proprietary variable-preload ball bearing cartridge system. Traditional bearing systems that lack adequate preload can experience ball sliding and scuffing at high shaft speeds, leading to fretting of the bearing races and ultimately the life of the bearing will be cut short. Xona engineered their way around this issue with aplomb.
Xona Rotor’s second-generation turbine wheel has arrived. Known as UHF (Ultra High Flow), its mission was to maximize flow capacity and raise efficiency. UHF is Xona Rotor’s most advanced wheel yet. Among other details, UHF’s patent pending splitter-blade design allowed the blade loading to be fine-tuned in order to achieve its performance objectives. Turbine design is a multi-variable juggling act. One feature that heavily influences a turbine’s mass flow “swallowing capacity” is the throat region located near the exit of the wheel. An effective method to increase the throat area is to decrease the number of blades. While reducing blade count tends to increase the turbine’s flow capacity, efficiency typically suffers. Introducing splitter blades provides an elegant solution to the trade-off between flow and efficiency. The splitter blades alleviate the blockage in the throat area while preserving the fluid momentum at the wheel inlet. The result is that UHF has the swallowing capacity of a low blade-count turbine with the efficiency of a high blade-count configuration. Its improvements were observed analytically, validated experimentally on a gas stand and then confirmed in on-vehicle testing.
The high-strength stainless steel bearing housing itself is a fully-machined component equipped with an extended water jacket. By encompassing the turbine seal ring land area, this advanced cooling feature combats heat soakback, which in turn prevents piston rings from collapsing and contributes to enhanced setup durability at higher temperatures.
Xona Rotor has left nothing on the table when it comes to their revolutionary bearing system. Xona XR turbochargers use hybrid (ceramic balls and steel races) ball bearing cartridges unlike those found elsewhere. These precise ABEC 7 angular contact ball bearings feature advanced M62 high-speed powder metal steel races, silicon nitride ceramic balls and metallic ball cages for decreased friction and increased temperature tolerance, which makes a tremendous difference in preventing a melted ball cage. Over standard ball bearing systems, these features deliver significantly enhanced strength and durability at extreme temperatures.
While most performance turbochargers today use a single piston ring for sealing the shaft at each end, Xona XR turbochargers employ twin rings at the compressor as well as the turbine. This feature dramatically reduces oil leakage and gas intrusion at both ends of the rotating assembly. Furthermore, since the sealing load is spread across two rings, wear rates are reduced and seal life is extended. Complementing this are large-diameter oil slingers incorporated into both ends of the shaft, further reducing splash oil at the piston ring seal location within the bearing cartridge.
The compressor register of the CHRA features an overbuilt compressor backplate and cover interface system for extremely high external load tolerance, limiting possible structural distortion that can lead to rubbing of the compressor wheel and premature turbocharger failure.
At the oil inlet, XR turbochargers offer a choice of 7/16" inverted flare or straight M12x1.25 connections. Built into the oil inlet cavity of the CHRA is a large volume “last ditch” oil filter element that prevents oil contaminants from entering the bearing system and plugging oil passages within the turbocharger. At the other end of the Xona XR’s bearing housing, a modular oil drain flange allows for a variety of bolt spacing.
Xona XR6557S Turbocharger Features:
- Rated for 350-680 horsepower
- 57.5mm/79mm compressor wheel
- 64mm/57mm turbine wheel
- 65lbs/min max compressor flow
- Choice of Xona X2C and X3C compressor housings
- Compatible with Xona XR57S Series turbine housings
