DAYTONA BEACH, Fla. -- NASCAR officials will continue the have-at-it-boys theme Saturday night after opting not to change the restrictor plates for the Budweiser Shootout.
But there have been changes to limit how long drivers can maintain the two-car drafts that create speeds of more than 200 mph.
Typically, when speeds cross the 200-mph barrier at Daytona or Talladega, NASCAR goes to a different restrictor plate that causes less air flow to the engines and slows the cars, as it did after a December tire test at Daytona.
But NASCAR vice president of competition Robin Pemberton said there are other factors that led to an increase in speeds since December, including gains of about 3 horsepower with the switch to ethanol fuel, the switch to a new nose, and air hoses that were added to reduce overheating.
"They couldn't lock up [in December] because they couldn't run more than two laps together,'' Pemberton said. "The reason they couldn't run more than two laps together is because their water would [pour] out all over everything. They had a bladder problem.''
So instead of shrinking the size of the plate hole, as it did after the December test, NASCAR is disallowing one of the air hoses that a majority of the teams added to reduce overheating.
NASCAR also is looking at putting a limit on the pressure relief valve that reduces water temperature, said Richie Gilmore, chief operating officer at Earnhardt Childress Racing Engines.
"The biggest thing we saw is we could run probably as long as anybody, 10 to 12 laps and then you've got to switch,'' Gilmore said. "They're gonna cut that in half.
"Now they're talking about limiting the PRV valve, which is the pressure you can run in your water system. And that basically is like a radiator under your car. It's a pop-off valve. What that's going to do is limit how much water temperature you can run, the same thing they did with the oil.''
Teams have reached higher speeds by lining up in two-car breakaways in which the rear car pushes the front car. That move quickly causes the rear car to overheat after a few laps, so teams were allowed to add additional air hoses to help cool the engines.
NASCAR hopes removing one of those hoses will cause the rear car to back off after a few laps.
Pemberton said shrinking the size of the plate hole is not on the table heading into the Feb. 20 Daytona 500. Gilmore said the next step likely would be enlarging the hole because it was harder for drivers to stay in the two-car hookup at higher speeds at the December test.
"These guys are dragging their brakes so guys can stay up with them,'' Gilmore said. "A lot of people say go to a smaller plate. I say go up with the plate. When they were down here at the test with the other plate on it was harder to stay with each other with a bigger plate.''
Dale Earnhardt Jr. agreed, saying slowing the cars will make it easier to maintain two-car draft and top 200 mph.
"We were trying to do that bump draft [stuff in December] and it wouldn't work in the corner,'' he said. "We would get in the corner and almost wreck. Just that little bit. If you slow it down it's not going to stop it.''
"If they slow us down we'll just be able to do this better. It possibly could become a situation where even three or four cars could get together, and we'll get back to 205.''
Gilmore said the increase in horsepower from ethanol caught teams by surprise, but the biggest concern is fuel mileage. He said there is a 4 percent drop in mileage, which could translate into three to four laps.
"We'll be monitoring all those things in the Shootout,'' he said.
David Newton and Terry Blount cover NASCAR for ESPN.com.