Kyle Busch Honored During Lap 18 of Indy 500

Kyle Busch received a tribute in the middle of the Indy 500 Sunday ... with the crowd falling silent out of respect for him during lap 18 -- a nod to his former number.

Check out the clip ... racers turn out of corner 4 on Lap 17 -- and, as they pass the scoring pylon, a picture of Kyle Busch "1985-2026" flashes on a screen at the venue.

The Indy 500 crowd -- usually a raucous bunch -- falls into a subdued silence ... while pit crew members can be seen standing at attention.

Lap 18 is one of just many tributes at the Indy 500 to Busch ... whose former teammate, Jimmie Johnson, appeared during Fox's pregame show.

Johnson talked about the respect Busch had from everyone about the sport ... while fellow driver Danica Patrick reflected on Busch's love of racing.

As you know ... Busch passed away Thursday after a bout with severe pneumonia that progressed into sepsis, according to his family.

KB won his final race on May 15 -- a Truck Series race ... and the No. 7 vehicle he used was back in action Sunday as well, though it didn't have the happy ending sports fans might've hoped for.

Driver Corey Day ended up in a hard crash during lap 47 when he received contact from Gio Ruggiero. It's a scary-looking crash ... but Day was able to walk off the track under his own power.

Day said, "I just hate it for the No. 7 guys. This is exactly what I didn’t want to do today. I just wanted to deliver them a good run. I feel terrible."