Engine woes fuel questions

It was hard to determine what impact NASCAR's switch to unleaded fuel had on Sunday's Auto Club 500 at California Speedway. But the number of engine problems in the race suggests Nextel Cup Series crew chiefs might have some homework.

Engine problems sent Kasey Kahne and teammates Dale Earnhardt Jr. and Martin Truex Jr. to the garage within the first 70 laps of the 250-lap event.

Kahne couldn't say if fuel was a factor but he could sense something was different. "It's definitely different the way it runs, the way it takes off on restarts and how it shifts," he said. "I think the unleaded fuel is fine. We've just got to learn how to make it work."

Mark McArdle, director of Evernham Engines, expressed a degree of trepidation before the race. "The greatest concern we have with the fuel change is the durability consideration," he said. "Our greatest concern is with valve guide and valve seat wear."

Sunday's cool temperatures had engines running faster than normal at a track traditionally tough on engines. Four cars, including those of potential winners Greg Biffle and Tony Stewart, failed to finish because of motor failures last year. This year Truex's engine lasted seven laps. More at USA Today