One thing that we noted was that there were bits of welding wire and stuff that looked like machine turnings stuck in the runners. This sort of stuff can damage your turbine if it breaks loose. We spent a few minutes with a die grinder knocking it out. Not a big deal but it’s wise to inspect the insides of your runners before installing.
The 20/52 uses an efficient TO4B compressor housing with a 0.60 A/R and a 0.85 A/R exhaust housing with an internal wastegate. The CHRA or center section uses a low friction dual ball bearing floating cartridge. Ball bearings can reduce transient response time by as much as 20% over conventional sleeve bearings.
With a floating bearing cartridge, the rotating assembly has vibration damping due to its suspension on a thin layer of the lubricating and cooling oil trapped between it and the housing. Typically found only in OEM turbo designs, this helps control shaft motion caused by higher order harmonics that can be damaging.
The bearing cartridge uses twin ceramic bearings which are longer lasting and lower friction than the typical steel bearings with dual oil seals at each end of the shaft. The ball bearings use steel bearing separators so the center section can be run dry for racing use. Great if you are trying to simplify your underhood plumbing.
The CFD goes hand in hand with FEA (Finite Element Analysis) stress analysis which enables Turbonetics engineers to pare down the hub size and thin the blades as much as possible. This improves aero without sacrificing burst or fatigue strength. FEA thus works hand in hand with CFD to maximize flow, broaden the operating range and minimize rotating inertia. This means more power, less lag and better durability.
Like the compressor side of the turbo, the turbine and housing make extensive use of CFD and FEA analysis for performance optimization. What we really like is that you can easily see that the turbine housing and wastegate will flow so much better than the typical T25 based designs that are common with this size turbo.
The turbine discharge diffuses into a large chamber with a 3″ V-band exit. It has a straight free flowing exit with a diffusion ring right at the exit to prevent odd flow mixing from the wastegate discharge disrupting the flow. The wastegate flow is introduced at an angle so as to be less turbulent. We feel that the design of this area alone will account for a decent bit of power and less lag than common legacy T25 related designs.