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Jay Penske risked his whole Indianapolis 500 race program on finding two new engines before qualifying began.

The risk paid off for his team -- and race organizers.

A deal made Thursday in Indy will give Penske's two drivers, Sebastien Bourdais and Katherine Legge, the dominant Chevrolet engines for the rest of the season and was a big step toward making sure the Indy 500 will start with its traditional 33-car field.

Penske did it by ending his contentious relationship with Lotus, including dropping a $4.6 million lawsuit against the engine manufacturer. He was released from his contract with Lotus and got approval from IndyCar officials to make the switch.

After a week of negotiating, it's all done.

"It was nice to see them push it out of the pit box and we all cheered when he was pulling out," Legge said after Bourdais shook down her car early Thursday. "It was definitely a step in the right direction."

Penske did not provide additional details about the agreement.

He said Chevy jumped in when it realized there may be a problem and helped the team get league approval to make the switch. The two engines, Penske said, arrived at his team garage overnight.

But that leaves Penske with no backup engine or plan if something goes awry between now and when the track closes Sunday afternoon. It's a gamble worth taking because Indy now has driver-car combinations on the track, enough to fill the traditional starting grid -- but no more -- for Sunday's Bump Day.

"We are pleased to see this issue resolved as we head into the final practice days in advance of qualifying," IndyCar CEO Randy Bernard said in a statement. "I have to thank all parties for working together to help preserve the traditions of the Indianapolis 500."

Penske said the two sides had been close to an agreement for the past week, though final details weren't worked out until Thursday morning. Most in Gasoline Alley thought Penske's father, Roger Penske, would help him get something worked out with Chevrolet. The younger Penske said that never happened.

"As he much as he wanted to help, he stayed on the sidelines," Jay Penske said.

The move also ends a frustrating week for Bourdais and Legge, who were relegated to studying tape and asking questions to prepare for IndyCar's biggest race of the season.

Penske's garage was empty last week when the originally scheduled rookie orientation program began and stayed that way until crew members moved tire sets into the garage Sunday afternoon. On Tuesday evening, Legge's No. 6 TrueCar entry and Bourdais' No. 7 car moved in and by the next day crew members had covered the embroidered Lotus name and logo on their shirts with black tape.

Series officials wanted Legge, a rookie, and Bourdais, who last drove at Indy in 2005, on the track before drivers get a boost of power for Friday's practice and this weekend's qualifying. It finally happened Thursday morning.

Legge all second of the three phases of her rookie test after series officials kept the track open for an extra 45 minutes. She turned a fast lap of 212.796. Bourdais also made it onto turned 21 laps in his own car, with a fast lap of 214.715.

"It's been a rough ride this week," said Bourdais, the four-time Champ Car champion. "It was very complicated."

Lotus has been a distant third among IndyCar's three engine manufacturers all season.

Lotus officials have acknowledged they got a late start in testing the twin turbocharged engine, leaving them far behind Chevy and Honda. Last month, Lotus released Dreyer & Reinbold Racing and Bryan Herta Autosport from their contracts.

Penske became the third team to ditch the engines after another sub-par showing at Brazil, but Lotus wouldn't initially let him out of the contract. Six days before the Brickyard opened for rookies and refresher programs, Penske filed suit against Lotus, claiming the company damaging his team's reputation by spreading "especially outrageous" falsehoods about the IndyCar team while failing to deliver two chassis and hurting its ability to be competitive.

Indy rookie Jean Alesi and Simona de Silvestro are the only two drivers attempting to qualify with a Lotus engine and they have consistently been the two slowest cars all week. Alesi, who made 201 career starts in Formula One, couldn't even pass the final phase of his rookie test until series officials gave him a boost of 40-50 horsepower Monday. That allowed him to finally run sustained laps at 210 mph or more.

Without the boost, Alesi posted a fast lap of just 205.389 mph on Wednesday -- more than 17 mph behind the day's top speed of 222.785. De Silvestro's best lap was 205.009.

Alesi even said he felt "unsafe" and was "concerned" for the other drivers because he was "quite slow in the middle of the track."

They were only slightly better Thursday. Alesi's top speed was 207.489, while de Silvestro went 205.690.

IndyCar officials say they're "monitoring" the situation, seven months after two-time Indy winner Dan Wheldon was killed in a horrific crash at Las Vegas.

"I can sympathize with the situation," John Judd, the IndyCar engine project manager for Lotus, said Wednesday. "I can only comment on what I know about the engine, and we do have some work to do, for sure. I think we would all benefit from more testing."

Penske and his drivers did not discuss any safety concerns. Instead, the Dragon Racing team remained focused on trying to find an engine and a strategy that would make the team more competitive on race day.

"We're not even worried about qualifying," Legge said. "If we just get it in the field, we'll get ready for the race. Realistically, we've not had too much time in the car, just like all year, and we're coming in here with really no testing."