News & Media

At 'Dega, drivers aren't only things under pressure

October 22, 2011, David Caraviello,

TALLADEGA, Ala. -- At Talladega Superspeedway, restrictor plates get all the attention. The polarizing pieces of metal have helped define this place since 1987, when an airborne crash involving Bobby Allison led to their implementation at NASCAR's two biggest tracks. The plates are at issue once again this weekend, given that series officials have slightly widened the openings to provide drivers with some additional horsepower that may curtail the amount of two-car drafting.

"We've learned too much, and we know that it works and we're going to do everything we can to continue to make it work until we get to one other's bumpers and we spin one another out. That's when we'll stop doing it. Then we'll still do it down the straightaway."


But it's another rule change that could have the bigger impact on Sunday's event on the 2.66-mile Alabama oval, and it involves a piece that's far less controversial and far lesser known. If anything is going to force cars to break out of their two-car drafts at Talladega, it won't be the revised restrictor plate -- it will be a recalibrated pressure-relief valve that could lead to overheating and blown engines if the trailing car doesn't get enough clean air.

"It's probably going to be a bigger deal, because it's going to affect how long you can stay hooked up in that two-car draft and push," said Jimmy Makar, a former crew chief who is now senior vice president of racing operations at Joe Gibbs Racing. "You're going to tend to blow off a little bit quicker, so you're not going to push as long. You'll have to swap out, or stick your nose out and get the temperature back down before you can get back to a solid push."

The cooling systems in Sprint Cup cars operate under pressure, and as the engine temperature increases, so does the pressure within the cooling system. If that pressure reaches a certain point, it has to vent -- first in the form of air, and then in the form of steam, producing one of those small geysers that erupts from under the cowl on the right side of the car. For the Daytona 500 in February, NASCAR mandated a pressure-relief valve setting of 33 pounds per square inch, meaning that if the pressure within the cooling system got higher than that, the valve began to vent.

At Talladega, that limit has been lowered to 25 PSI, meaning that the valve is apt to vent sooner. For drivers, that change represents a challenge -- stay hooked up in the two-car draft as long as possible because it's the fastest way around the race track, but at the same time manage an engine that is more susceptible to overheating and failure. Everybody knows their limits, which range between 245 and 275 degrees. Any hotter, and they have to pull out or switch to the front position in the two-car draft to prevent the pressure-relief valve from going off.

"It's definitely challenging [in] that you have to make sure to not overheat your engine," Kyle Busch said. "You've got 500 miles to race here, so you've got to make sure you're taking care of it for 495 miles of that. It will last running hot in the last five miles. You'll be fine with that, no problem. You just have to make sure that throughout the midpoint of the race or any point of the race, that until you get to that point, that you're not pushing any water. ... You really do have to work hard at that. You have to stay out from behind the guy in front of you to get enough air into the grille opening to make sure that you keep your temps down. Other than that, will it change our cars much? Probably not."

When what drivers call the "pop-off valve" pops off, it begins to empty the radiator of fluid. Empty enough of that water, and the engine gets hotter and hotter until it blows up. Seeing that small geyser erupt from underneath the cowl isn't a point of no return, but a warning, according to Denny Hamlin. "You've got to react to it pretty quick when it does pop off, basically," he said. "... You get to a certain temperature that activates it, then you have to react to it."

Once the valve begins to vent, Hamlin said drivers usually have only a few laps of water left in the radiator. Teams are able to refill the cooling system using a hose that forces more water back through the valve, and Talladega is so large that crews can perform that kind of quick-fix without their driver losing a lap. The goal, though, is to prevent the thing from going off in the first place, which at Talladega likely means drivers swapping positions more often. That makes some a little nervous, given that switching is the most delicate part of the tandem draft, and that the cars involved lose a lot of speed compared to the rest of the field in the process.

"If we are going to push each other around the race track, we are going to have to swap more often," Dale Earnhardt Jr. said. "... Say you are working with your partner out there, and you've got to change more often. That is when it is going to get crazy, because you lose a lot of speed and the guys that are not changing that are behind you come flying up on you really quick, and if they do not have a lot of room and everybody doesn't know what is going on, bad things can happen.

"The change in the radiator to make us change more often, I don't really see what we are trying to accomplish there and how that can bring about any good. I think that will just put us all in difficult situations more often, because when you make a swap, it is a difficult situation for the other drivers that aren't swapping that have to dodge you, and hope they know where you are going and what you and your teammate are trying to do, because you lose so much speed in the process of making that swap. Everyone is sort of making a lot of calculated guesses out there if that is happening more often. That is a little bit troublesome, but I don't think it will be that big of a deal. But I just don't know what that change was really for other than to make us swap more."

Which may very well be the goal, given how many fans view the two-car draft. When the rule changes for Talladega were announced last month, NASCAR said the intention was to provide exciting and competitive racing. The balance falls on the driver, who has to manage the changes and still go as fast as he can, all while trying to keep the pop-off valve from popping off.

"You cannot allow that pop-off valve to go off, so you have to switch, and you have to do it right then, and there could be six cars coming hard," Jeff Gordon said. "That's the part that I don't necessarily agree with, because I think that while we're going to take steps here toward not having the two-car draft working, we've learned too much, and we know that it works and we're going to do everything we can to continue to make it work until we get to one other's bumpers and we spin one another out. That's when we'll stop doing it. Then we'll still do it down the straightaway."