Is there another turbo manufacturer than Holset? I wonder if ball bearing rotor systems are used when a turbo manufacturer is unable to provide a stable hydrodynamic rotor system? Just some thoughts...
I can definitely see why they would cost more…. What I don't understand is while cruzing down the road the turbo rotor speed is probably 15-30K rpm (no load). In an H1C the hydrodynamic bearing system achieves stability at a much lower rpm if it is properly balanced. With the hydrodynamic bearing system the bronze bearings are rotating ½ the rotor speed after stability and again.. Assuming proper balancing… the bronze bearings are neither in contact with the bearing housing bore nor the rotor shaft journal diameters from approximately 15K to 100K+ rpm. How could a hydrodynamic bearing system have higher friction than a contact bearing system?
Now if the rotor system does not posses the proper stiffness in a hydro bearing system and starts to bend which occurs way after initial bearing stability but at much high rotor speeds (primary contributor are compressor wheel size & amount of unbalance with respect to journal diameter) then I could see where this could be a possible solution.
I do believe they solved a problem. The ultimate question is what was the problem they were trying solve?
Imagine a engine filled with STP or straight 50 wt oil starting on a 10* day.
Only thing is, the turbo is spinning so fast, that even 5W-30 oil has a lot of "fluid friction". If the bronze bearings were lubricated with diesel fuel, they would certainly spool much faster.
Mook has it right, about what I was asking. How do we convert the crazy metric data from Holsets over to Garrett info? Anyone just install one and try it? Holsets are just not as common as Garretts, and cost much more.
Scroll down to post #18, that's the method I use to convert turbo sizing across brands. So far it's worked, but it needs tested more.
This is for sizing up the turbine side, compressor side sizing is quite well understood already.
To help ease your pain, I wouldnt use a ball-bearing turbo-unless it was givin' to me:happyfinger:
The power-gain for the cost, is in-effective in a performance application, as both would be "upgraded to another turbo" or shot by the time of needing service. In a longevity application, then maybe.....
I would have no issues running a bb turbo, they spool up quicker then a standard bearing turbo so you can get by with running a slightly larger turbo to give you a better map up top. I currently run a Holset H2e for my PSD because it has more CFM then the Garrett GP38r which is a bb. I am considering trying a Turbonetics T70 to see if it cleans up the extra fuel I still have with the H2e. I will say a bearing cartridge for a bb is a lot more expensive but I have not seen anybody need one yet.