At what point should you go to an H bearing?
Is it RPM based, or power?
For instince, a blower motor could conceivalby make twice the power of a na motor at 6k rpm.
Would one of those really hard aftermarket cranks be better off with an H?
Or does the large fillet radius require an H?

Scott,
The large radius does not "require" an "H" style bearing, but they are the ones that will work without modifying them to clear the radius. SOme of the differences in the performance bearings are that they do not have the cosmetic "flash" coating on them, which can tend to "flake" (for lack of a better term) under extreme loads. Also, the performance bearings usually have a bit more clearance at the parting line. There are advantages to both types of bearings, the Clevite catalog is very good reading on the subject. Talk to 50 engine builders and you will probably get 50 different answers on this one smile.gif
Hope this helps,