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Silent
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Discussion Starter #1
From my understanding of turbochargers, most of them use (used to use?) a floating bushing bearing design.

This means that you have the outer bearing race (generally aluminum) with a oil film inside. Then there is another ring of material (rubber or similar material) with another oil film between it and the shaft.

People these days always seem to want ball bearing turbos. Are these the bearings that are actually inside the housing on the shaft stopping it from vibrating? And now they are using ball bearings instead of oil film? I would assume the ball bearings are still bathed in oil, but I fail to see what makes this more stable or better than the oil film bearings. Is it because at high shaft speeds (read 150krpm +) the oil will compress more and the metal ball bearings don't?

Can anyone shed some light or point me in the right direction? I haven't been able to find an adequate answer.
 

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no

simple reason, less friction. The floating bushing will have a lot more friction due to the direct contact of the oil with the shaft. Laminar flow and turbulance increase friction considerably (see airplanes and top speed)
 
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