smoother engine bearings
Ceramic bearings are available from Boca Bearing.
The Nelson and Jett engines probably dont use them die to the fact that two bearings are worth more than half the price of a new Jett! Not many guys will part with the $250 or so for a Jett 46 or 50 allready, if it cost an additional $120 they wouldnt sell many. (by the way I own and run Jett's and think they are the best engine for rc use)
There are many benifits to ceramic bearings, longer life, smoother operation and yes they can take the heat. But, in an internal combustion engine, the bearings wont even see a fraction of that heat, and are not necessary. The higher quality prescision bearings with the phenolic cages (which are allready 3X the cost of a normal bearing replacement) are super, and you wont lose a cage at high rps either.
Just my experience and $.02...
Andrew Coholic