Kurt Busch opened up about his brother Kyle‘s sudden death in a new interview … and he’s clearly still stunned by the development — especially because he insists no one knew how sick he was.

The NASCAR star opened up about Kyle’s final days in an interview on Anderson Cooper‘s “All There Is” podcast … telling the veteran journalist that people around Kyle noticed he had a little cough — but he seemed totally fine otherwise.

He notes Kyle won a race — the 2026 Ecosave 200 Craftsman Truck Series race at Dover Motor Speedway — days before he died … and even visited an indoor go-kart track with his son two days before he passed.

Kurt says these aren’t the actions of a man so close to death … and one look at him shows he’s still shocked.

He then jumps into Kyle’s last days … detailing how his crew chief found him slumped against a wall in the bathroom during a training session — at which time Kyle asked his crew chief to call an ambulance. We published the harrowing 911 call in which the caller noted he was coughing up some blood the day before his death.

Kurt says a lot changed in the hours after Kyle was taken to the hospital … explaining that everyone thought he was going to pull through — before they received a devastating call to come and see him because he didn’t have much time.

Watch the clip all the way through to hear about Kurt’s final moments with his little brother … and why their father — Tom Busch — wouldn’t go into his hospital room.

Kyle was 41.