DAYTONA BEACH, Fla. -- NASCAR officials announced two technical changes Sunday evening aimed at preventing the sustained two-car drafts that dominated Saturday night's Budweiser Shootout at Daytona.
Robin Pemberton, NASCAR's vice president of competition, said the body issued a bulletin to race teams with the following specifications:
• The maximum size for the air inlet for the cooling system will be 2½ inches tall by 20 inches wide.
• The pressure release valve on the water system will be set at 33 pounds per square inch.
The intent is to set up the cars so they can't push each other in two-car tandems for extended runs without overheating. Teams try to line up drafting partners at Daytona and Talladega so they can overcome the limitations of the restrictor plates used to keep speeds down at those two tracks.
"That will bring down the temperatures so the teams can't run at 290 or 300 degrees [without overheating] on the extended push of 30 or 40 laps," Pemberton said. "This will put [the water temperature in the engines] back in the 250-degree range."
Several drivers, crew chiefs and team executives expected NASCAR to control the pressure relief valve. Jamie McMurray, who finished second to Kurt Busch in the Shootout, said many cars had valves that allowed the temperature up to 300 degrees before boiling over.
That allowed the second car in the two-car draft to push longer without overheating -- some for more than a dozen laps -- under Saturday's cooler outdoor temperatures. The weather is expected to be warmer for Thursday's qualifying races and the Daytona 500.
NASCAR officials elected not to change the size of the carburetor restrictor plates. But Pemberton said that remains an option depending on what NASCAR sees in practice Wednesday and the qualifying races Thursday.
Pemberton was asked what he thought about the two-by-two pairs racing Saturday night.
"At first I thought it was exciting," he said. "But once they reached 206 miles per hour, I stopped thinking about the race. I just thought about all the work we had to do moving forward."
John Darby, NASCAR's managing director of the Sprint Cup Series, said reducing the length of time drivers can maintain a two-car hookup is the goal moving forward.
"There's a tremendous amount of creative ideas floating around the garage," he said. "There are some limits in what we can do. If there's a real problem we'll work on fixing it because that's what we do. But at the same time you can't disturb the garage area to a degree it creates a bigger problem than what we've got."
Some have suggested reducing the size of the restrictor plate hole, in order to further slow the cars down. But that suggestion has met with mixed reviews.
Both said it would be harder to keep contact in the corners at higher speeds, which is why some didn't try it in a December tire test.
"You have to make them faster," Hamlin said. "It's the only way to stop it. We have to run like 200 [mph] by themselves. The cars are not going to handle good at 210, 215 with a push."
McMurray suggested cutting the spoilers to make cars tougher to handle.
"If you make it where you have a guy pushing you and the guy in front can't hang on, then the drivers know that and it will be tougher to do," he said. "The good part to me about last night was we could pass.
"I think NASCAR is trying to make it safe. It's not about reacting. The 200 mph [mark] seems to be the threshold of cars flying."
Darby said NASCAR hasn't closed the door on any option.
"The good thing is when you talk about restrictor plates we've got a pretty full library and a pretty good correlation of what it all equals to," he said. "Plate changes are the easiest to do. We're still looking and knowing what creates the lap that becomes a high mile an hour. ... Is that a sustained speed? How does that speed relate to what the actual pack of cars is running?
"The good thing is the way the Speedweeks schedule lays out we have some time to think more before we react."
All agree warmer temperatures will solve much of the problem.
"Absolutely," Darby said. "That'll make a huge difference. But at the same time, there is not a weather forecaster I trust well enough to put that much money in the bank. If the forecast is 80 degrees and it rains in the day and we end up running the duels at night ... It's not one you can bank on comfortably."
Reaction throughout the garage remained mixed on whether the two-car tandems created a good show. Kyle Busch watched the dramatic four-car finish on television after seeing his night end in a wreck.
"It sucked," he said. "You're watching four cars and then you have another two there and another two there. To me, it sucked."
"Interesting" and "weird" were words many drivers used.
"This is a whole different form of racing," Hamlin said. "We went from playing one type of game to an entire different game."
The finish resurrected the debate about whether the rule prohibiting passing below the yellow line rule should be waived when cars are coming to the finish line. Hamlin and Juan Pablo Montoya were adamant it should be.
"Absolutely," Montoya said. "And move the finish line to the tri-oval at Dega."
Hamlin said it should be anything goes when racing for the checkered flag, even if that means driving on the grass.
"You're racing for a line," he said.
McMurray disagreed, although he questioned why Hamlin didn't hold his line and stay above the yellow line on Saturday night.
"Hell no," he said when asked if the line should be eliminated for the finish. "That's a great rule. I watched the highlights of the races before they had that. That's a bad plan."
Nobody knows exactly what to expect in the 500. Montoya suggested drivers may line up and be conservative for 460 miles and then go all out in two-pack tandems the final 40.
Hamlin doesn't know what to expect, but says the playing field has been leveled by the two-car tandems.
"Tony Stewart and those guys really got good at Daytona and restrictor-plate racing; Jeff Gordon and all those guys," Hamlin said. "They have no advantage over me, Joey Logano, anyone. I think it's more of a level playing field."
David Newton and Terry Blount cover NASCAR for ESPN.com.