Kyle Busch’s engine failures at Darlington and Bristol were related.
Busch had engine problems in two of the first three races of the playoffs and ended up getting eliminated before the second round because of them. Busch missed out on the second round by two points after he had to retire early at Bristol because of that engine problem.
Toyota Racing Development president David Wilson told NBC that Busch missed a shift at Darlington and that NASCAR’s gear ratios were partially to blame at Bristol. He said that Toyota has been dealing with stability issues with their engines when its drivers hit the NASCAR-mandated rev limiter. Busch’s engine hit the limiter and over-revved in the Darlington incident and Busch was hitting the limiter a lot at Bristol because of NASCAR’s gear ratios.
Before Darlington, Busch had been forced to exit a race early because of an engine problem just twice since 2016.
“We have some sort of an instability in our valve train and it seems to be triggered by us running into NASCAR’s mandated rev limiter, interestingly enough,” Wilson said.
At Darlington, Busch missed an upshift from fourth to fifth gear, contributing to the engine failure. “He buzzed the rev limiter hard,” Wilson said, “and a lap-and-a-half later, his engine let go. Now, just to be clear, our stuff should be durable enough. It should be tough enough to handle that.
“At Bristol, NASCAR miscalculated the gear ratio. It was too short. When Kyle, particularly when he was running that upper groove in fifth gear, he was hitting the rev limiter, almost every lap. The fact is that right now we just don’t have enough durability margin in our valve train. That’s on us.”
NASCAR's mandated gear ratios have been a test for teams and drivers throughout the 2022 season with the new Cup Series car. The gear ratios have even led drivers to shift in the corners at a few oval tracks and there was discussion ahead of the Bristol race that some drivers would downshift in the corners.
Busch is the only active Cup Series driver who has more than one title. Busch won the 2015 and 2019 Cup Series titles for Joe Gibbs Racing and became the first driver to win a Cup title for Toyota with that 2015 championship.
2022 was Busch’s last chance at a title with JGR and Toyota. He announced a week ago that he was heading to Chevrolet and Richard Childress Racing in 2023. Busch left JGR after longtime sponsor M&M Mars said 2022 would be its last season as his sponsor and he couldn’t come to an agreement on a contract extension with the team without a new sponsor in place.