How can I set block size on Oracle 11 when creating a database instance Is there any way to configure Oracle 11g's default block size on installation?
I have tried Oracle 11g r2 and r3, during both installations block size is 8k and it is disabled (and can not be modified).

I shall restore a data-pump backup from a 16k block size database, so I need to make mine 16k too.

I know I can do this by assigning block size to individual tablespaces (data files), but I am looking for a way to set the default data file size on the whole oracle instance.
You need to choose "Custom Database" in the "Select Template" screen of the Database Creation Assistant, and not one of the templates that includes datafiles as in those the block size is fixed and cannot be changed.