Lunt threw three late touchdowns for Illinois. The second was a 15-yarder to running back Josh Ferguson that put Illinois up for good 21-17.
Lunt finished the day 24 of 38 for 285 yards and four touchdowns. He used nine different receivers.
Lunt's highly anticipated debut after his transfer from Oklahoma State started slowly. The Illini had seven first downs by halftime and clung to a 7-6 lead.
The Penguins took a 17-14 lead with 10:57 left in the game on a 2-yard Brian Ruiz touchdown and a 2-point conversion by quarterback Dante Nania.
Ruiz finished with 32 carries for 116 yards and one touchdown. Nania was 11 of 24 for 177 yards.