News & Media


EFI opens a wealth of possibilities to competitors

February 07, 2012, NASCAR Wire Service, NASCAR.com

CONCORD, N.C. -- Simply put, NASCAR's move to electronic fuel injection hasn't gotten the press it deserves.

There have been more pressing concerns. The sanctioning body and Sprint Cup teams were so focused on rule changes designed to break up sustained two-car drafts during mid-January tests at Daytona International Speedway that the impending competitive debut of EFI went virtually unnoticed.

Nevertheless, the introduction of EFI represents a profound change that goes far beyond bringing Cup race cars closer to models found in the showroom. Here are the basics:

New era


Electronic fuel injection will make its NASCAR debut at Daytona. Mark Aumann gives an in-depth look at how the new EFI will work and what changes it brings to the sport.

-- The fuel delivery system is fundamentally different. Injectors shoot fuel into each individual cylinder, as they are programmed to do by computer. Instead of a carburetor that mixes air and fuel, a throttle body provides airflow to the engine. As Sprint Cup series director John Darby put it during a meeting with reporters Monday at NASCAR's research-and-development center, "The engine architecture is the same. We're squirting it (fuel), instead of sucking it."

-- There are more parts and pieces. To run the EFI system, NASCAR has contracted with McLaren to provide an electronic control unit, powered by software from Freescale. An array of sensors provides performance data to the ECU, which is mounted on the engine. With a few keystrokes on a laptop computer, engine tuners can construct an ignition timing map that will regulate fuel flow to the cylinders based on input from the sensors.

The implications for Cup racing are far-reaching. Teams can plug into the ECU post-race and use the after-the-fact telemetry to make performance decisions. Traditionally, NASCAR has taken a firm stance against real-time data acquisition, and that won't change.

But teams will be allowed to download data after practice and qualifying and make adjustments to the EFI system. What they won't be able to do, however, is read data during a race, and -- realizing that fuel mileage may determine the outcome, for example -- reset their systems to a mapping more conducive to fuel conservation.

Accordingly, plugging into the EFI system adds an additional layer to NASCAR's inspection process. Before a race, the ECUs will be "locked" to one configuration for the duration. After the event, NASCAR will inspect the top five and random cars.

In keeping with its tradition of an open garage, NASCAR will also collect data and share it among the teams. But when Roush Fenway Racing, for example, sees information from a Hendrick Motorsports ECU, it will be broad-brush data rather than examination of minutiae.

In other words, RFR won't be able to compare where Carl Edwards lifts on corner entry as opposed to Jimmie Johnson. Each team will have specific information about its own cars but much more general data about its competitors. Nevertheless, the information should prove useful, particularly, as Darby says, "to get the little guys up to speed quicker."

Before its debut at Daytona, EFI has been tested extensively. Based on those tests, and on a critical mass of issues that have surfaced in a chat room established by McLaren, there have been approximately eight software revisions since NASCAR began testing the system.

Though McLaren has a history in Formula One and other forms of racing, the company had never dealt with a NASCAR engine, which Darby characterized as "the biggest, most bad-ass thing in motorsports, other than drag racing."

McLaren has never had a competition failure with one of its ECUs, but neither has the company dealt with a racing series that puts as much stress on its engines.

"If it's going to fail, we're going to fail it -- I guarantee you that," Darby said.

Though there has been much discussion of fuel economy with the switch to EFI, the consensus is that savings will be negligible. Nevertheless, EFI will allow tuners to achieve a higher level of efficiency in their fuel-saving measures.

One thing won't change: the inverse relationship between fuel economy and horsepower. To save gas, you have to give up power under the hood. But EFI, particularly as teams become more familiar with its nuances, will allow the engine to be tuned to a particular competitor's driving style, thereby enhancing the performance of both man and machine.

Last Tango at Daytona?

NASCAR fans spoke loudly. More than 80 percent of fans polled by NASCAR either hated the two-car drafts at Daytona or said they preferred pack drafting to the tandems.

In mid-January testing at Daytona, NASCAR instituted rule changes designed to break up sustained two-car hookups. The efforts didn't stop there.

When the cars return to Daytona next week, the grille openings will be higher on the front bumper and the rear bumpers will be extended down two inches. NASCAR determined that cars were still able to get airflow to the grille from underneath the lead car and took measures to counteract that.

"Our goal was not to eliminate the two-car pushes," Darby said. "Our goal was to change the look of the race back to more of a conventional drafting but not to take away the tool of the two-car draft."

If NASCAR and its fans get their wish, which seems likely, you'll see a lot more conventional pack drafting in the Daytona 500. But the race is likely to be won with a two-car push, whether it's one car pushing another to the win or one car trying to slingshot past another as they approach the finish, as Clint Bowyer did to Jeff Burton at Talladega last October.

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