The aero characteristics affect the lines the drivers take through the corners. Busch says being off the preferred line by as little as six to 12 inches at New Hampshire Motor Speedway can kill a lap, and the same is true at Pocono Raceway's tri-oval. Because the Cup engines can pull 9,400rpm, vs. 8,800 for the less powerful engines, gearshift points on restarts vary.
At Phoenix International Raceway, for example, the driving approaches vary, especially between the No. 18 Kyle Busch Motorsports Toyota Tundra and the No. 18 Joe Gibbs Racing Toyota Camry Busch races in the Cup Series.
“In the Cup car at Phoenix, you really have to come up off the corner straight before you can apply the power,” says Busch. “There's so much horsepower in a Cup car that you really need to have the load of the horsepower working on both rear tires, rather than just the right rear. If you don't, you're going to burn off the right rear way too quick.”
That means a nice square exit to Turn 4, with the Cup car exactly parallel to the frontstretch wall.
“However,” Busch continues, “with a truck, you can really round the exit of the corners. One reason is that there's not a lot of power there so you're not going to burn off the right rear, and reason No. 2 is because there's so much side force on a truck, you can really lay up against the wall. It's like you've basically got a piece of plywood – the flat, slab-like side of the truck – that you can lean up against the cushion of air that's being created between the truck and the wall.”
At the high-speed, 1.5- and two-mile ovals, the handling characteristics are so pronounced that they influence lane choices on restarts.
“In the truck, you want to go to the outside,” says Busch, “because typically when you're on the inside, it's easier for you to get sucked around [into a spin] by the draft of the guy alongside you or for that guy on the outside to get right on your door and make it hard for you to get by. So you have to do it in a hurry.
“With the Cup cars, you like to restart on the inside, usually, because it's the shortest way around and you can force the guy beside you to go high and take the longer, slower line. But you have to be conscious of what kind of track you're at for the exit of the corner. If you're somewhere like Charlotte, and the guy at the top gets big momentum down the straightaway, he'll blow right by you.”
And at restrictor-plate tracks, the draft can play havoc.
“The truck's definitely not easiest in the draft,” says Busch. “It moves around a lot more. You can be going down the straightaway and if somebody pulls alongside you, it almost turns your truck sideways on the racetrack. It will really move you around. You can be in control of another guy's truck more than he is in control of it, depending on how you move the air around it. The hole that's punched in the air – the trucks are the biggest, then it's the Nationwide cars, then it's the Cup cars. They're the slickest of all three, even though they've got that boxier look.”
So where does Busch feel as though he has the most success?
“I feel like I'm pretty good at all of them, but I think it's all competition-relative, as to where the success comes from, you know?” he says. “I won eight races in the Cup Series in 2008 and I won eight races in the Truck Series last year. I won 13 in the Nationwide Series, so I've had plenty of success in a given year in each series. I would say I'm really good at Nationwide, for some reason. The Nationwide Series is probably the easiest and comes to me the best, but I'd still like to say I'm successful at Cup and Trucks.”
The biggest delineation might be this: A great driver can win in a not-so-great truck. That's not the case in Nationwide or Cup.
“When you're in the Cup Series and you have a bad car, you're not going to carry it very far,” Busch says. “I think it's all competition-related. The Cup Series, you have to be so precise and so perfect with your vehicle and that's the only way you're going to run good. In the truck, it can be off by a little bit and you can still hustle it, manhandle it and you can actually win with something that doesn't drive that great.”
Well…Kyle Busch can, at least.
• For the full version of this feature article, plus much more, check out the April 2011 issue of RACER magazine. CLICK HERE to subscribe.