at 3.3V the max recommended frequency is about 13 Mhz.
10.6Mhz But it seems like the OP wants to nicely change a ATmega/Arduino to an 8Mhz crystal and 8Mhz bootloader.
is linear between 2.7V @ 10Mhz and 4.5 V@ 20 Mhz.
16MHz...At least if I use this datasheet.
Thanks for the link, I'll try and burn a 3.3v bootloader on to one of my chips and see if it works.