Stewart-Haas Racing teammates Tony Stewart and Danica Patrick blew engines during Daytona 500 practice Saturday.
HScott Motorsports driver Bobby Labonte also had an engine failure, creating concern that Hendrick Motorsports may have motor issues. Stewart, Patrick and Labonte all lease engines from Hendrick, which also fields cars for Jimmie Johnson, Jeff Gordon, Dale Earnhardt Jr. and Kasey Kahne.
Stewart says he's "not really concerned about it. ... Pretty confident it'll be fine."
After changing engines, Stewart, Patrick and Labonte will have to start at the rear of the field in their qualifying races next Thursday.
Though Hendrick drivers had no engine problems, Johnson, Gordon, Earnhardt and Kahne seemed to be down on horsepower.
The fastest Hendrick driver during the first practice was Gordon, who was 21st on the speed chart.