Race Weekend Central

Cool Heads and Cool Engines Will Win the 500

Once NASCAR issued their rule change limiting the size of the grill opening last Sunday, teams throughout the garage went to work searching for ways to maximize the smaller opening as best they could. While NASCAR put a restriction on the dimensions of the opening – to 50 square inches or 2.5 inches by 20 inches – they did not limit where the teams could locate the grill – high, low or centered.

Walking through the garage this week there seems to be no consensus as to what will work best. Defending race winner Jamie McMurray’s car appeared to have its grill opening located in the middle, as did his teammate Juan Pablo Montoya; Mark Martin, Ryan Newman, Bobby Labonte and Regan Smith all had their openings more towards the top; David Reutimann’s was as low as possible.

Richard Petty Motorsports crew chief Todd Parrott – calling the shots for Marcos Ambrose this year – acknowledged the team had been experimenting with various locations throughout the week, but when asked what he had learned over the past few days he simply said, “I can’t tell you that.”

Others in the garage were more open about the process of finding what worked best.

“It has been an ongoing test since last Sunday,” Brian Pattie, crew chief for Montoya said. He went on to explain Chevrolet had taken the dimensions and put a variety of combinations to the test in the wind tunnel, so while they were unable to do a lot of experimenting at the track, the manufacturer had done its homework.

Rodney Childers, crew chief on Reutimann’s No. 00 Toyota, explained MWR had been experimenting with various locations since the test session in January.

Gil Martin said he has not been experimenting very much on the No. 29 Chevrolet since teams are really limited as to what they can do.

“You can only do so much to last without swapping,” he said. “Peeking the grill opening out won’t do much, people are just searching.”

Martin may not have been experimenting much, but teammate Shane Wilson – crew chief for Clint Bowyer – said RCR had tested various locations in the wind tunnel prior to coming to Daytona. Trying a variety of scenarios, they found the higher location to work the best.

As one engine builder explained, the higher the grill opening, the more air you are able to capture in the draft. When their team had run with the opening lower on the nose, they found the air tended to miss the opening and thus failed to cool the engine.

After Saturday’s final practice session, NASCAR announced that due to the high temperatures seen over the past few days and expected for Sunday’s race, teams would be allowed to use larger grill openings. Making one final change prior to the 500, the grill specs are now allowed to be 3.5 inches by 20 inches.

While crews are ultimately limited as to their role in finding ways to cool the engines, the drivers may have found the key. Throughout the final two days of practice, drivers began drafting in a staggered tandem with the rear car leaning out to the right to get air to the grill opening. This has allowed pairs to stay connected for longer, limiting the need for speed-reducing swaps.

“The thing that I worry about is getting so many cars all close together, then guys having to swap. When they go to swap, there’s not room for them to move” Tony Stewart explained. “I think the Cup race tomorrow will have more packs that will be able to stay closer to the front. That’s going to make the exchanges more difficult. Getting more radiator opening will help us go a little bit further before we have to make those switches.”

By not swapping, the teams are giving up a slight speed advantage in the short term – about a half-second, to six-tenths of a second, according to Jeff Burton – but have an advantage in the long run, since swapping positions kills much more momentum. By not swapping and giving up that small amount of speed, teams are positioning themselves to gap the field and hope their efforts to breathe the car pay off at the end of the day.

“They are going to start pairing up from the drop of the green flag and for 500 miles, that’s how we’re going to run this race,” Stewart said. “I’ll change it to 100%. I’m that confident of it. There’s no doubt in my mind that’s going to happen.”

Denny Hamlin explained this new development in the two-car tandem has allowed his car to stay in line for four laps or so, pointing out the Chevrolets have more of an advantage. Dodge teams reported similar numbers.

Whereas Rodney Childers said the No. 00 Toyota could run 11 laps drafting at a stagger versus only three straight up. Fellow Toyota crew chief Greg Zipadelli said his car could only stay tucked up for two-and-a-half to four laps.

“Once you start to push water out, you start to give up horsepower and you have to pit to top it off,” he said. “Once you lose pressure, there is less water in the system and the engine begins to get hotter quicker.”

Ford teams, however, are much more confident in the new FR9 engine’s ability to cool.

“It’s a balancing act that can win or lose the Daytona 500,” said Roush Fenway Racing’s David Ragan. “If you stay tucked up [in tandem], you will be in better shape than some other cars.”

When asked how long he expected to be able to stay in tandem, staggered with another car, his answer was simple, confident and a bit surprising.

“We can go 500 miles without swapping,” he said. “I think I can go all day if I have a guy that will let me breathe.”

What is important to these engines is a combination of water temperature and pressure that will cause the NASCAR-mandated pop-off valve system to release and start blowing water from the overflow.

“The crew chief says one number, the head engineer says another number and Jack [Roush] says one number,” Ragan explained, saying they all varied by roughly 30 degrees. “Whatever Doug Yates says, that’s the gospel to me.”

Ragan’s crew chief Drew Blickensderfer explained there was not a certain temperature that he was worried about, rather than the 33 pounds of pressure that will cause the pop-off valve to open.

Teammate Greg Biffle – who also expected to run the entire race without swapping – explained building up pressure allows the engines to run hotter, but with the new rules that is not possible. Their magic number is 250-255 degrees, whereas before they would be able to run their temperatures up to as high as 270 or 280 degrees before losing water.

“I know [the limit], but I won’t say,” Roush said. “Depending on how your system functions – some systems will pop off later than others at the same pressure.”

When posed the same question as Ragan, how long two Fords could stay hooked up, he smiled and asked, “How long’s the race?”

It seems like more than ever engines and airflow into the cooling system will be the determining factor of who will win Sunday’s Daytona 500. Teams are on different pages in terms of where their grill openings are located, the temperatures at which they can push their engines and how long they can stay in the draft. Who has it all figured out? Some are confident, others reluctantly optimistic, but everyone believes they have a chance. We’ll have to wait and see how 500 miles of unknowns play out Sunday in the Great American Race.

“Contact Jay Pennell”:https://frontstretch.com/contact/28432/

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