Busch earned his 96th career Xfinity Series win and his fourth career win at IMS. He has four wins in seven series starts this year.
Making his last Xfinity start of the year, Busch led 46 of 100 laps from the pole.
“Really tough to pass, even when you had a run on guys,” Busch told NBCSN. “You could pass some of the guys that were built more for long-run longevity, (Allgaier) was. You could pass him on the straightaways. … Overall, we got back in traffic and just really fought the handling of this thing, even from fourth place.”
Allgaier, who led 24 laps, finished second after winning this race last year. He has not won a race since then. He has four runner-up finishes this season.
“Kyle’s great, especially on late-race restarts,” Allgaier told NBCSN. “Our Suave Men Camaro was on rails, especially on the long run. We were able to really push though guys. … We had a couple of late-race restarts that didn’t go our way and unfortunately put us behind.”
The final run to the checkered flag was set up by a wreck between Christopher Bell and Tyler Reddick on a restart with eight laps to go. Restarting on the front row, Bell got loose in Turn 2 and washed up into Reddick, which sent them both into the wall.
STAGE 1 WINNER: Brandon Jones
STAGE 2 WINNER: Justin Allgaier
WHO HAD A GOOD DAY: JR Motorsports is the first team to put three drivers in the top five of an Xfinity race at Indy … Justin Haley earned his third top five of the year and locked himself into the playoffs on points … Austin Hill placed ninth in his Xfinity Series debut … Brandon Jones bounced back from a mid-race wreck to finish sixth.
WHO HAD A BAD DAY: Austin Dillon finished 34th after he suffered a fuel pressure issue and stalled on the pit access road on Lap 15 … Brandon Brown wrecked on a Lap 36 restart. He finished 28th … David Starr finished 37th after his engine expired mid-race … John Hunter Nemechek finished 31st after he wrecked in Turn 1 with 22 laps left in the race.
WHAT’S NEXT: Rhino Pro 300 at Las Vegas Motor Speedway at 7:30 p.m. ET on Sept. 14 on NBCSN