[Cp1]

ceramic though extremely durable is also extremely brittle and cant put up much of a fight with the forces of the rotating engine mass but they are ideally suited to the high wear and low rotating mass of a turbo turbine.

If you take any engine even a rotary for that matter and remove any possibility of compression (take out the sparkplugs) you can quite easily spin it by hand (so long as it is in good condition) the most resistance you will feel is not due to friction but by the rotating mass.

I have seen rollerbearing cranks and engines before and the cost for the bearings because they either have to be assembled during the build (which is painstaking to do because they all have to be done simultaneously) or have to be designed in halves (to accomodate putting them in) all of which makes for an extremely costly build with minimal at best gains.

As a machinist i can tell you that on some things the old ways are the best ways. this has been thought of countless times by many people and yet in this day of age even a bugatti veyron with no price ceiling opted for a journal bearing.

I would start with trying different materials like i mentioned before, or trying helical oil grooves on the journals like ive done on a mkiii supra (it worked JUST AS WELL cant say it was better or worse but it did give a bigger contact patch from which to draw oil.)