Electronic Fuel Injection’s Possibilities

(WOMR file photo)

The introduction by NASCAR of electronic fuel injection opens up a whole world of endless possibilities.  The new EFI  represents a profound change that goes far beyond just bringing the Sprint Cup race cars closer to the manufacturer’s showroom models.  The results will be far-reaching.

The fuel delivery system

The way fuel is delivered into the cylinders of the engine is very different.  Fuel injectors shoot fuel into each individual cylinder, as they are programmed to do so by the computer.  Unlike, in the old days, where a carburetor would mix the air and the fuel, a throttle body provides the air to the fuel that is injected into the cylinder.  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.”

The mechanism

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.

Far reaching implications

Teams can plug into the ECU (electronic control unit) 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. For more on this subject, check here this Delphi Perkins injection pump.

Extensive testing

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. NASCAR will require EFI engines to use a restrictor plate at the sport’s two longest and fastest tracks: Talladega Superspeedway and Daytona International Speedway. The plate will be placed beneath the Holley EFI throttle body and limit the amount of air made available to the engine. Unlike carbureted engines, Sunoco Green E15 will not pass through the restrictor plate openings.

So as you can see, just the mere fact that NASCAR has finally allowed electronic fuel injection to be incorporated into the race car, not only is that a reflection of the manufacturer and production reality, it will also allow the race teams access to invaluable after-the-fact data during practice, qualifying, and post race.


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