you must alter SYSTEM set timed_statistics=true not alter session or else it is meaningless as the statspack spans eevery session database wide. And it must stay on for entire duration not just when you take a snap or its totally useless

If you have been running that same stuff against 8i then you have been doing it wrong and not following the doco's.

Also your snapshot interval is wwwaaayyy too long, the data will just be meaningless after 4 hours. You really should read Tom Kytes book or follow any piece of Oracle advice which advises a 15 minute window.

Suggest you do some reading on this tool