Harrell was replaced in the second half by backup Chris Todd, who completed a 48-yard pass to Jarrett Hicks on his first play. It was the first game back for Hicks, Tech's top receiver. He missed the first three games before the NCAA granted him an academic eligibility waiver Friday.
Three plays later, Shannon Woods scored on a 5-yard run to put Tech up 49-0.
The Lions (1-3) allowed 106 yards rushing and 403 yards passing, and their offense sputtered throughout. Southeastern Louisiana finished with only seven first downs and 119 total yards.
The Lions' longest drive came in the first quarter and lasted only nine plays.
The Red Raiders (3-1) were trying to rebound from last week's measly offensive outing in a 12-3 loss to TCU. Tech had more total yards in the first half Saturday night (315) than it got the whole game (242) against the Horned Frogs.
Harrell was flustered last week by TCU's pressure, but this time he threw touchdown passes of 9, 5, 7 and 6 yards. He completed 20 of 29 passes, and Todd was 10-of-12 for 151 yards.
The TCU loss knocked the Red Raiders out of the Top 25 and Tech coach Mike Leach promised to make changes for what he called the "sorriest offensive effort" he'd ever seen. For the first few plays, he kept receivers Joel Filani, Robert Johnson and Todd Walker on the sideline.
Once they got in, though, they made their presence known. Walker caught a 9-yard pass from Harrell on Tech's first possession, and Filani caught touchdown passes of 5 yards and 7 yards in the first half.
The shutout was Leach's seventh and is the most for a Tech coach since Dell Morgan, who had 20 from 1941-50.