Steele Jantz passed for 133 yards and a touchdown for the Cyclones (5-5, 2-5) but was under constant pressure from the Texas pass rush.
Ash had his second stellar game after getting pulled late in Texas' 21-17 win over Kansas two weeks ago. Against Iowa State, he rarely had to throw into coverage because Longhorns wide receivers seemed to get wide open on almost every play. Jaxon Shipley had eight catches for 137 yards and Davis had seven for 113.
Royal coached Texas to national championships in 1963 and 1969, a share of a third in 1970, and won 11 Southwest Conference titles. He was inducted into the College Football Hall of Fame in 1983. Flags flew at half-staff inside the stadium that bears his name and Royals' "DKR" initials were on burnt-orange logos at midfield and on the Texas players' helmets.
Texas coach Mack Brown, who was very close to Royal, had promised Texas would line up in the wishbone on its first play. But instead of a fullback dive up the middle, Texas dialed up some 21st-century razzle dazzle with a pitch to Shipley, who threw back to Ash, who connected with tight end Greg Daniels for 47 yards.
The rest of the game was something Royal gave Texas fans for 20 years: methodical domination of an overmatched opponent. Texas rolled up 609 yards of offense and held the ball for nearly 40 minutes. The Longhorns pounded out 222 yards on the ground.
Texas led 7-0 on Gray's 5-yard touchdown run before Ash connected with Davis on a perfect deep post route for a 61-yard touchdown. It was Davis' third TD catch in two weeks and his fourth of the season of 44 yards or longer.
Ash was 15-of-16 passing for 245 yards in the first half and his 3-yard scoring toss to tight end Barrett Matthews made it 20-0. Iowa State, which upset Texas in Austin in 2010, finally responded with a long drive to a 14-yard TD pass from Jantz to Quenton Bundrage.
Iowa State had three other drives push inside the Texas 40 in the first half, but they ended in a punt, an interception and a missed field goal.
Texas led 23-7 in the third on a 37-yard field goal by freshman Nick Jordan, who replaced Anthony Fera after a blocked field goal and missed extra point in the first half. By then, Texas was starting to wear down the Cyclones up front and turned to bruising running back Joe Bergeron with smashing rushes up the middle.
Bergeron finished with 86 yards on a 12 carries. Gray scooted 13 yards early in the fourth to push the lead to 30-7 before Jordan kicked a late 25-yard field goal for the final score.