GM Racing

Portland Grand Prix Is Pivotal for Corvette Racing

Chevrolet Factory Team Seeks Reversal of Fortune at Portland International Raceway

Portland Grand Prix Portland, Ore. - The Portland Grand Prix, to be contested at Portland International Raceway on July 22, will kick off the second half of the ALMS season for Corvette Racing. The first half of the season was highlighted by Corvette victories in Sebring, Houston, Mid-Ohio and Le Mans. But back-to-back losses in Lime Rock and Salt Lake City in the wake of rule changes will provide strong motivation for Chevrolet's factory road racing team in the sixth round of the ALMS series.

"In the five previous ALMS events, we haven't run under the same rules twice," said Corvette Racing program manager Doug Fehan. "Now after two defeats, I think it's imperative that we get a direction from the sanctioning body on the specifications that we are going to run in the second half of the season."

"When you look at the current performance differential, it is a huge challenge for us to overcome," Fehan continued. "We are hopeful that the series will maintain the spirit of competitive balance and not be in the business of manufacturing outcomes. There are many unknowns going into this event, but that's what creates the challenges that motivate this team."

The X factors at Portland International Raceway will include a 113 dB sound restriction, a narrow racing line, and hot temperatures.

"We're going into the Portland race with the same performance restrictions we had in Salt Lake City, and that's going to make it very difficult for us on the two long straights," said Oliver Gavin, driver of the No. 4 Compuware Corvette C6.R. "It's usually quite warm there and the track surface doesn't offer much grip, so you really have to work hard on the setup to make sure you're getting the most out of the car."

"Portland can be a very frustrating track because there is a long section of infield where you just have to be patient," Gavin explained. "If you are aggressive and try to hustle the car, you just end up going slower. It's very narrow, so most of the overtaking happens on the front straight. You get one shot at passing going into the chicane, so you have to make it count."

Last year's Portland Grand Prix marked the beginning of a record-setting streak of eight straight ALMS victories by Gavin and his teammate Olivier Beretta. Beretta also won there in 1999 and 2000 with his former team.

"Portland has always been a great track for me since I started racing in America," said Beretta, a native of Monaco. "Last year the organizers improved the course by opening up the chicane. We will try to do our best as always and see what happens."

The Portland round will see the Corvettes' LS7.R small-block V-8 engines equipped with 30.8-mm (1.2-inch) intake air restrictors, 6 percent smaller in area than the 31.8-mm restrictors used in the first four ALMS races. These restrictors, which are approximately the diameter of a half dollar coin, limit the volume of air that enters the Corvettes' 7-liter racing engines.

"An engine is basically an air pump, and the amount of horsepower it produces is a function of how much air you can move through it," explained John Rice, trackside support engineer for the Corvette engine program. "The restrictor limits the airflow and therefore limits the horsepower."

"NASCAR requires restrictor plates on superspeedways to limit performance, and the restrictors used in ALMS are similar in principle," Rice continued. "They allow different types of engines to run against each other. For example, different restrictor sizes are specified for naturally aspirated and turbocharged engines, depending on the displacement and number of valves per cylinder."

"An unrestricted 7-liter two-valve endurance racing engine would produce 850 to 900 horsepower. With the 31.8 mm restrictors the Corvettes used previously, the LS7.R produced approximately 600 horsepower. The restrictors we are currently required to use are 6 percent smaller in area and they reduced power by 34 horsepower, or almost 6 percent. The smaller restrictors also affected the torque at lower rpm and required the drivers to change their shift points."

With the weather forecast predicting temperatures in the 100s on race day, Corvette Racing will have to cope with a tricky track and a performance disadvantage. But overcoming obstacles is just another day's work for America's team.

The two-hour, 45-minute Portland Grand Prix, the sixth round of the 10-race 2006 American Le Mans Series, is scheduled to start at 6 p.m. PDT (9 p.m. EDT) on Saturday, July 22. The race will be televised tape-delayed on CBS Sports on Sunday, July 23, at 3 p.m. EDT.

Release Date: July 19, 2005