Indianapolis ? Perfect track conditions unleashed a dazzling speed show Friday with defending Indianapolis 500 champion Helio Castroneves leading 13 drivers surpassing 230 mph at Indianapolis Motor Speedway.

The fast laps, with 33 of 47 cars beating last year’s pole-winning, four-lap average of 226.037, set the stage for a great qualifying show today should the weather hold.

The National Weather Service forecast called for a 90-percent chance of afternoon rain for the first of three days of time trials for the race May 26. Qualifying was to start at 11 a.m. local time.

“Hopefully, we can get out before the rain hits,” said Castroneves, who got around the 21/2-mile oval Friday at 232.087. “I think everybody will be lined up and ready to go.”

Several drivers had flirted with the 230 mark earlier in the week, but Bruno Junqueira was the first to surpass it.

The 25-year-old Brazilian the successor at Chip Ganassi Racing to 2000 Indy winner Juan Montoya got everyone buzzing when he turned four consecutive laps above 230 mph. His best was 231.526.

The simulated qualifying run was most impressive because it came at 3:30 p.m., the hottest part of the warm, sunny afternoon.

“I thought I could do 230 and did 231,” said a grinning Junqueira. “The team is working hard to keep improving the car.

“The first day, I did 226 and I thought that was fast. There is no limit in racing. Every day you try to go faster.”

Junqueira opened the floodgates. As the track cooled, 12 other drivers eclipsed 230.

Castroneves did one lap over 231 and his fast one over 232 before deciding to call off the run after he felt something change in the car.

“I was like, ‘Whoa, 232,’ and I tried to keep going but, unfortunately, the car started to go away,” said Castroneves, who started 11th last year.

When the session ended, Robbie Buhl was second-fastest at 231.603, followed by rookie Tomas Scheckter at 231.600, Eddie Cheever Jr. at 230.882, Felipe Giaffone at 230.865, Sam Hornish Jr. at 230.683, Al Unser Jr. at 230.489, Tony Kanaan at 230.419, Raul Boesel at 230.147, Gil de Ferran at 230.092, Kenny Brack at 230.074 and defending polesitter Scott Sharp at 230.024.

Arie Luyendyk set the track qualifying records of one lap at 237.498 and four laps at 236.986 in 1996, but the speeds Friday were by far the fastest since the IRL eliminated turbocharged engines in 1997.

All of the drivers over 230 could battle for front row spots in the 33-car field that will be determined in qualifying sessions today, Sunday and on May 19.

Not everyone found the secret to going fast on the historic track, though.

The uncertainty of the weather adds to the pressure on the drivers, especially those such as teammates and CART regulars Paul Tracy, Dario Franchitti and Michael Andretti. They have struggled to get up to speed this week for the rival IRL’s biggest event.

“Usually, when we show up at a track, I jump out and go fast right away,” Tracy said. “But I haven’t had any time in these cars and I haven’t been here in six years. The car is completely different from the CART car.

“There’s a big learning curve for our team and to try to do it in one week, versus guys who have done it for six years, isn’t easy.”

While others soared above 228 quickly after practice began Sunday, team owner Barry Green’s trio of drivers worked hard to run considerably slower until all got above that speed Friday.

Andretti, son of 1969 Indy winner Mario Andretti, actually returned to the speedway a year ago with Green’s Team Motorola and finished third in the race. Tracy and Franchitti, who drive under the Team Kool Green banner, joined him this month.

Tracy drove here four times from 1992-95, never finishing better than 20th. Franchitti came to CART after the IRL began competition in 1996 and the top CART teams and drivers began boycotting Indy.

Ganassi’s team began the trickle of CART drivers back to Indy in 2000. Roger Penske with Castroneves and de Ferran and Green followed last year. Now most of CART’s biggest names are here, and some are struggling.

“This is a big race,” Tracy explained. “Every day, there’s pressure to go well. You’ve got seven days practice and, if you’re not up to speed, every day people are asking, ‘What’s wrong with you?’ “