Pierson Williams opened the game with a 3-pointer and CSUDH (4-5) never saw the lead again. Chris Eversley's layup at 18:26 gave Cal Poly (4-5) a 4-3 lead and the Mustangs pulled away with runs of 9-0 and 10-0 for a 42-22 halftime advantage.
Nwaba scored 16 points in the first half on 8-of-9 shooting, and Cal Poly finished shooting 49.3 percent from the field to 39.1 percent for CSUDH.
Cal Poly extended its lead to 26 points on a layup by Nwaba at 9:43 then to 36 points a 4:45 on a dunk by Michael Bolden.
Kyle Odister and Taylor Sutlive each scored 14 for Cal Poly, with Sutlive 4 for 4 on 3-pointers, and Eversley added 10.
Williams led the Toros with 16 points, including four 3-pointers.