For all the engineering expertise that goes into building a powerful motor and designing a sleek car, the key to winning at Daytona International Speedway revolves around an elusive ingredient. It is the art of racing the air.

No one is better at it than Dale Earnhardt, NASCAR's seven-time Winston Cup champion, whose peers -- love him or hate him -- credit him with the ability to "see the air" and, in turn, know how to make it pull him through traffic and pass like a slingshot, leaving them shaking their fists in frustration.

The aerodynamic draft, as the phenomenon in known, is just one factor, of course. But at Daytona, host of the Pepsi 400 Saturday night, it is the critical factor when all other components -- horsepower, chassis design, body style and plain luck -- put a driver in position to win.

The draft plays a role in all stock-car races, but nowhere more dramatically than at Daytona and its sister track, Talladega (Ala.) Superspeedway -- NASCAR's giant, high-banked ovals, 2.5 and 2.66 miles around, respectively, built in an era that didn't anticipate the speeds of today.

The air that dances around a race car has powerful effects, the worst of which is "drag," slowing the car like an anchor. Drag is created because high air pressure pushes on the front of a speeding car, while low air pressure tugs on the back.

The effect of drag is sharply curtailed, however, when two race cars link up, one behind the other. That's because the lead car punches a hole in the air and blocks it from hitting the front of the trailing car. The trailing car, in turn, reduces the air pressure on the back of the lead car. Both cars go faster in the aerodynamic draft that results. The effect is compounded as more cars fall in line.

"You get some of that sensation when you ride down an interstate highway and come up behind a transfer truck," explains two-time Daytona 500 winner Dale Jarrett. "As you get closer to the truck, you'll realize that it'll pull you along, and you're able to ease off the gas. That's because the truck is making such a big hole in the air, and it's going around your car and actually sucking you up. The vacuum is pulling you along."

At Daytona and Talladega, no car wins a race alone. The driver needs help from a buddy, more often than not, to "push" his car to the front.

Jeff Gordon probably wouldn't have won the 1997 Daytona 500, gifted though he is, without help. He got it from his two Hendrick Motorsports teammates, Terry Labonte and Ricky Craven, whose Chevrolets pushed him past Bill Elliott for the win. The Hendrick cars finished 1-2-3 that day, shuffling Elliott back to fourth.

What makes drafting especially critical at Daytona and Talladega is the use of carburetor restrictor plates, which reduce horsepower (and speed) by constricting the flow of air to the carburetor. The plates, used only at these tracks, are a safety precaution to keep cars from getting airborne. They "max out" the engines and keep speeds under 200 mph, NASCAR's unofficial threshold for the fastest possible "safe" race. Without them, speeds would likely top 220 mph.

But restrictor plates heighten risk in another way. Because horsepower is essentially equalized, the cars run in dense packs. If one spins, it's likely to trigger a wreck that snares a dozen.

Deprived of that extra bit of horsepower, drivers must find power in the air.

"It's strange racing," said Ford racing executive Preston Miller. "You accelerate as a virtue of momentum -- and of finding a spot behind another car that allows you to run into air that has less drag. Driving these cars is a lot like a chess game. And any car that is running in line and then gets out of line and can't get back in will go straight to the back."

Enormous work goes into building the fastest possible "chess piece" for Daytona. To engine builders, a gain of 2 horsepower is considered a major breakthrough, shaving one-tenth of a second off a lap time, which translates to less than .5 mph.

NASCAR regulates body styles so strictly that there's scant room for creativity in building an aerodynamically superior car. The trick, then, is to "hide" the rear spoiler, which adds to drag. And you do that with smaller springs and heavy shocks, which make the car sit lower on the track by keeping it from bouncing back up when it hits a bump. It's a brutal ride for the driver, basically stripping away the suspension.

"The cars drive very, very badly in that condition," said crew chief Jimmy Makar, whose Pontiacs have put driver Bobby Labonte on the pole at Daytona three times. "But it's a fine line how far you want to go in the comfort zone and give up speed. If you get the car driving like a Cadillac, it won't be quite as fast on the race track."

The final step is testing the car in a wind tunnel, where giant fans, powered by 9,000-horsepower electric motors, simulate speeds of 200 mph. Teams experiment with various car configurations -- fiddling with the spoiler, shocks and springs -- then measure the drag that results. It's an expensive inquiry, with an eight-hour test costing $16,000.

Once refinements are made, the driver straps in.

It's not easy playing chess at 200 mph.

Jarrett learned by first asking his father, Ned, a two-time Winston Cup champion, to explain the draft. Then he went to a wind tunnel to watch as colored smoke was blown over a car, and he formed a picture in his mind of what the air did. Out on the racetrack, he traced Earnhardt's tire tracks on the pavement every chance he got. "It was hard to keep up because I didn't have the equipment or the experience," Jarrett said. "But I tried to get behind him and watch where he made the passes, how far back he needed to be from the other cars to get them to pull him and be able to go by. He has such a good feel that he realizes at exactly the right moment when another car is going to help him get that little bit of extra momentum that it takes to make a pass."

Jarrett also videotaped races and studied what moves worked and what didn't. "I think there's an art to it," he said. "There are a lot of guys who have fast cars, but a lot of times they're not exactly sure how to take advantage of the situations they put themselves in."

Jarrett's homework paid off on the last lap of the 1993 Daytona 500, when he used a push from Geoff Bodine to whip around Earnhardt for the win.

"When you beat the best, that's what makes it exciting," Jarrett said, "because he is the very best at drafting that there is."

But even Earnhardt can't explain the draft or account for his record at Daytona, which includes 34 wins in short sprints, 125-mile qualifying races, 300-milers, 400-milers and, finally, after 19 unsuccessful attempts, the Daytona 500 in 1998.

"It's hard to explain, hard to put into language," Earnhardt said. Like Jarrett, he studied drivers he considered the best: David Pearson, Bobby Allison, Cale Yarborough, Buck and Buddy Baker.

"That's where I got started understanding the air and the draft: What it does, how to win, how you get beat and how to use that to your advantage," Earnhardt said.

He also studied races on tape. "If you finish second at Daytona enough," as he did seven times, "you get to see a lot of those replays," Earnhardt said.

But there's no substitute for time on the track, where lessons are high-stakes and high-stress. Kyle Petty's stomach was in knots this February watching his son, Adam, then 18, run his first race at Daytona.

"You're a lot more nervous [at Daytona] because everybody runs in a pack, and you know that to run well, you've got to stay in the pack," Petty said. "From a father's point of view, you'd like to say, `Get out of that pack! You don't need to be running in there!' But you know that as soon as you get out of line, you lose."

Rusty Wallace, NASCAR's 1989 champion, was sure he had Earnhardt outfoxed in the IROC race at Talladega in April. He had seen Earnhardt pass Mark Martin on the last lap to win February's IROC race at Daytona. So with the lead in hand and the laps winding down, Wallace plotted his strategy. "I'm talking to myself for 10 laps, thinking there's no way Earnhardt's going to pass me," Wallace recalled. Once the white flag waved, signaling one lap to go, Wallace eased off the throttle ever so slightly, slowing just enough to jam Earnhardt so close to his back bumper that Earnhardt couldn't get a run on him. Suddenly, from nowhere, Martin's Ford came flying around the fourth turn, giving Earnhardt just enough of a surge to scoot around Wallace for the win.

"I was up high, up low -- trying to block him," Wallace said. "I swear to God, I can't understand how he passes you."

CAPTION: Sometimes being out in front isn't such a good thing, because the trailing driver can use the draft to help him pass.