Peters was 8 of 13 from the field and only missed two of his six 3-pointers.
Darien Walker added 13 points for Valparaiso (7-1). Vashil Fernandez's 10 rebounds helped the Crusaders to a 38-23 advantage.
Peters hit 3 of 3 from behind the arc in the first half and scored 15 points to help Valparaiso take a 42-20 halftime lead. The Crusaders held Portland to 7-of-24 shooting (29.2 percent) and just eight points in the final 7 minutes.
Portland (5-1) was led by freshman D'Marques Tyson's 25 points on 9-of-11 shooting, including 6 of 8 from 3-point range.