From the 3.5 FAQ (if desired):
"Does the powerful build racial trait change the damage
the character deals with unarmed strikes and natural
weapons?
No. The powerful build racial trait allows the character to
“use weapons designed for a creature one size larger without
penalty” but doesn’t say anything about changing the damage
dealt by his unarmed strikes or natural weapons."
"Does the powerful build racial trait change the damage
the character deals with unarmed strikes and natural
weapons?
No. The powerful build racial trait allows the character to
“use weapons designed for a creature one size larger without
penalty” but doesn’t say anything about changing the damage
dealt by his unarmed strikes or natural weapons."