FONTANA, Calif. (AP) – Unleaded gasoline made its NASCAR Nextel Cup debut Sunday to mixed reviews.
There were several blown engines during the race, including those belonging to Dale Earnhardt Inc., Chevrolets driven by Dale Earnhardt Jr. and Martin Truex Jr., as well as the motor in the Evernham Motorsports Dodge of Kasey Kahne.
Asked if he thought the unleaded fuel had anything to do with his engine letting go, Kahne said, ''I don't know. It's definitely different the way it runs, the way it takes off on restarts and how it shifts.
''We've got some things to work on and figure out, but I think the unleaded fuel is fine. We've just got to learn how to make it work.''
Earnhardt also said he didn't know if unleaded fuel had anything to do with his team's troubles.
''I know the guys will figure it out,'' he said. ''This unleaded fuel has sprung a little bit of a surprise on us – a little bit of a curveball. But I have all the faith that DEI will get it figured out.''
Teammate Truex said he had no warning before his engine went up in smoke.
''We had a restart there and I was running behind (Stewart) and the car was really good,'' Truex said. ''Then, just out of the blue, the motor let go.''
NASCAR has been using the unleaded fuel in its Busch and Craftsman Truck Series since last season, but the engines used in Cup make more power and have to last longer because the races are longer.
''The biggest challenge is the reliability and durability of the valves and valve seats,'' explained Jim Covey, engine technical director for General Motors Racing. ''Leaded fuel has lubricity; unleaded fuel does not. Therefore, with the unleaded fuel, they have experienced wear issues with the valves or valve seats.''
Covey said the Cup engines turns as much as 9,500 rpm, which means the valves are opening and closing more than 75 times per second.
''Leaded fuel provides a cushion, whereas unleaded fuel does not,'' he said. ''The other thing that effects the wear is that the valve motion controlled by the camshaft is different from engine to engine and from team to team. Therefore, it might react differently from one team to another.''
The engine in Dave Blaney's Toyota also seized up, but his team said it happened after a belt came off the oil pump.