Referring now to the turbocharger bearing system, Comp Turbo  turbochargers utilize the latest in high-speed ball bearing technology. The  acceleration rate of a turbocharger is a function of the rotor inertia and the  friction losses in the bearing system. Conventional commercial turbochargers  use floating sleeve bearing systems that are a result of years of experimental  development. The floating sleeve bearings have an inner and outer oil film fed  by lube oil under pressure from the engine's lubricating oil system. They must  also employ a separate stationary thrust bearing that is fed lube oil under  pressure from the engine. The friction loss attributed to a stationary thrust bearing  is proportional to the fourth power of the radius and can amount to several  horsepower at the high speed at which turbochargers operate.

The oil films in conventional floating sleeve bearings have  significant viscosity that produces appreciable friction losses due to oil film  shear when the turbocharger rotor is accelerated and running at high speed. The  friction losses in the sleeve bearing systems and in the stationary thrust  bearings result in mechanical efficiencies in the middle 90% range in conventional  turbochargers.
The Comp Turbo turbochargers use a ball bearing system that  does not need a separate thrust bearing since the ball bearings carry both the  radial load and the axial thrust loads. There is little or no oil film shear in  ball bearings that operate with rolling friction only so that Comp Turbo  turbochargers accelerate much faster than conventional turbochargers that use  sleeve bearing systems. The Comp Turbo bearing system is a proprietary design  that is unique in the industry. It utilizes full compliment angular contact  ball bearings with ceramic balls. Compared with steel balls, ceramic balls in  ball bearing have a number of advantages.
According to a prominent ball bearing  manufacturer, bearing service life is two to five times longer than steel  balls, they run at lower operating temperatures and allow running speeds to be  as much as 50% higher. Also, since the surface finish of ceramic balls is  almost perfectly smooth, they have lower friction losses and lower vibration  levels. And, since there is less heat buildup during high-speed operation, they  exhibit reduced ball skidding and have a longer fatigue life.

All these  characteristics make ceramic ball bearings ideal for use in turbochargers where  they must operate at very high speeds and survive in a high temperature  environment. The full compliment bearings do not use a cage to position the  balls and this additional feature, combined with the ceramic material, provides  a combination that has minimal friction losses. The mechanical efficiency of  Comp Turbo turbochargers that use ceramic ball bearings can approach the high  90% range and this contributes to rotor acceleration rates that have been shown  to be faster than competition.
In the proprietary Comp Turbo ball bearing system, the  angular contact bearings are mounted in an elongated steel cylinder that is  free to rotate in the bearing housing. The outside diameter of the cylinder is  fed with lube oil and this outer oil film provides a cushion against shock and  vibration. Two angular contact bearings are mounted in tandem on the compressor  end of the cylinder in an arrangement that carries rotor thrust in both axial  directions. A single angular contact bearing is mounted under pre-load on the  turbine end of the cylinder and is free to move axially with shaft elongation  when heat is conducted down the shaft from the hot turbine wheel. The elongated  steel cylinder containing the angular contact bearings represents the complete  bearing system and can be inserted and/or removed as an assembly, making the  Comp Turbo turbocharger fully serviceable and rebuildable.