Cooling the crankcase area and as such the bearings is a good idea. In 2-c's and all the YS's except the DZ you also get a better charge going to the piston. You can get more power by cooling the bottom of the crankcase. A lightened backplate spinner with big prop cut -outs helps. Air-dams/diverters seem to be the most effective.

As a datapoint, my engines run at around 78F in the lower crankcase area now that they are cooled.

Some sample pictures. Quest-2 with side and top cutouts. Temptation and Impact with side diverters. Used 1/16" balsa that clears the engne movement on the hydemount.

Regards,

Eric.