News & Media

Debris can wreak havoc on a race car

June 14, 2014, Kenny Bruce,

A crew chief, a driver and an engine builder discuss how trash can affect a race car

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BROOKLYN, Mich. -- When a large piece of trash became lodged on the front of his race car, no one had to inform Brad Keselowski.
A quick glance at his car's gauges told the Team Penske driver all he needed to know.
With the final laps of the Pocono 400 winding down, and Keselowski in the lead, the water and oil temperature gauges on his No. 2 Ford were continuing to climb.
"Really, really hot," the 2012 NASCAR Sprint Cup Series champion radioed his team, "but I don't want to give up the win."
His best bet was to pull close enough to another car to create a break in air pressure on the front of his car, a move that often sends debris blowing off the grille.


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Attempting such a maneuver while also holding off a charging Dale Earnhardt Jr., Keselowski's speed dipped briefly as he moved up the track and momentarily behind Danica Patrick. But the move didn't take, the trash stayed put and Earnhardt Jr. went to the front and eventually collected the win.
"We're trying to maximize performance every weekend," said Paul Wolfe, Keselowski's crew chief. "We're so close to that window that you run in without being too hot, because that's how important performance is. Every little bit of tape we can put on that grille is speed.
"We're running right up against the window so we're paying attention to that. If there's any type of debris or anything, we usually know pretty quick."
The normal operating temperature for a NASCAR Sprint Cup engine varies among teams, but most run in the 230 to 260 degree range.
What happens when debris begins to collect or a piece of trash becomes lodged on the front of a race car?
Left too long, water and oil temperatures quickly begin to escalate. But depending on the size of the track, the degree of damage can vary.
"It's not always the same," said Doug Yates, who operates Roush Yates Engines. "At different tracks, it might be different things (that are affected).
"What usually happens when the temps get elevated, it increases the fatigue of the valve springs. Basically they'll break sooner. That's number one.
"The second thing, when the water temperature gets hot, the engine has a tendency to detonate. Because everything that's cooling that chamber and that piston is getting hotter."
Yates said one of the plusses coming with the move to electronic fuel injection systems is the ability to program the units "so that when the engines gets hotter, we reduce the timing and add some fuel.
"Unlike a carburetor and a distributor where you couldn't adjust that before, now we can adjust that.
"So if the engine and the system doesn't lose water, it will probably be OK. Once the water is gone, everything bad happens. Head gaskets, things like that."
Ford teams underwent a change to the front grille area of the Fusion during the break between the 2013 and '14 seasons, in large part because the previous grille, which was inset, had a tendency to collect much more debris.
The new nose features a much more flush grille and less likely to suffer from the buildup of debris.
"That's the main reason (for the change)," Wolfe said, "when you get rubber buildup and stuff can collect in there.
"The flushed-out grille helps that a lot. We've definitely noticed a difference. We can run closer to that optimal temp and not worry about getting a bunch of buildup as the race goes on. Every little bit helps."
It's not a track-specific problem -- it can happen anywhere -- but Yates said it can be more of an issue if it occurs on the larger tracks the series visits.
"The bigger tracks are the tougher ones because you're on throttle, your wide-open throttle time is (longer) so … the load on the engine is higher," he said.
"Last week, seven laps around Pocono with a bag on the front of your car is like an eternity. Seven laps at Bristol, you'd have been done and the race would have been over and we'd be in the winner's circle spraying champagne."
Drivers usually report a drop in horsepower when the temperatures inside the engine rise too high. Cooler air being sent into the cylinder means more horsepower; the hotter the air becomes, the less horsepower.
"When we go out to qualify and the water temp is low, it's making a lot of power. When it gets hot, it makes less power," said Yates.
"We kind of use the ECU to protect the engine at higher temps; that would be the power that (Keselowski) was feeling that he lost."
Yates said each team programs the units differently.
"A lot of people this week have asked me, 'How hot did it get?'" he said. "Well, really hot is my answer. Because every team out here has a different strategy on how they tune. That's their choice.
"It worked OK, it was just unfortunate. Brad was doing everything he knew to do to get the trash off; it was just unfortunate he caught the 10 car at the wrong time."
The gauges notify a driver that he might have a problem, but Brian Vickers said even without such information, a driver would likely notice a difference in the handling of the car.
"If it's a big piece of trash that really blocks off the grille, then you're going to notice it in the balance of the car," the Michael Waltrip Racing driver said. "It's going to be like putting tape on for qualifying without taping the car up.
"It's probably going to be loose and eventually as the temps climb … you would start to lose some power right until it blew up."
While it doesn't occur often, Vickers said it's probably happened to every driver in the garage at some point in his or her career. There's rarely a favorable solution; either let another driver get by to try and dislodge the trash or pit to remove it. Or ride it out and hope the engine doesn't fail.
"There are a lot of variables in our sport that are unknowns … no matter how talented you are, no matter how good of a car you have and no matter how great of a race your crew chief calls … there are factors that just happen.
"You run over debris and you cut a tire. You get trash on your grille. Things happen."



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