SEBRING, Fla.—Acura Motorsports is counting on rubber to counteract horsepower this year as it moves up in class to the American Le Mans Series (ALMS) LMP1 prototype category.
Acura's new entries—developed by Honda Performance Development in California in association with Wirth Research in England—were designed to compete with the diesel-powered Audi Sport prototypes, which claimed the last three LMP1 season championships.
To offset the raw power of the Audi turbodiesels, Acura designed the ARX-02a chassis to use nearly identical 18-inch tires front and rear—a radical change from the norm—in order to take advantage of maximum downforce on the front of the car and generate higher cornering speeds and braking power.
“The goal of this new program was to try and create the fastest and most agile P1 car that's been built,” said chief designer Nick Wirth, “and also try and find a fundamental advantage that would offset the diesel's raw power. This car has the same technology on it, apart from carbon suspension, as a Formula 1 car.”
The ARX-02a—being campaigned by de Ferran Motorsports and Patron Highcroft Racing—features an open-cockpit design and is powered by a 4-liter, normally aspirated V8 fueled by unleaded E10 gasoline generating more than 620 hp.
Both teams are using 37-71-18 Michelin radial racing tires—roughly equal in size to a 405/40/R18 street tire, according to Carl Koenigstein, Michelin North America Inc.'s ALMS technical team leader.
Honda Performance Development President Erik Berkman said that the new race car took two years of design before the initial product was produced in late 2008.
“We were working on the Acura LMP1 car while we were racing in the LMP2 class,” Mr. Berkman said.
“We understand the requirements of moving to the LMP1 class. It has been very challenging. Working with an all-new chassis and engine can be a daunting task for any manufacturer and team. But HPD and Wirth Research stepped up to the challenge.”
The wider, taller front tires yield about a 7-percent larger contact patch, Mr. Koenigstein said, vs. the standard front tires other LMP1 cars are using in the series.
Acura Motorsports approached Mich¬elin North America Inc. nearly a year ago with its innovative idea to maximize the vehicle's tire contact patch, Mr. Koenigstein said.
The new chassis uses an adaptive power steering to help the drivers control the grippier front end. Mr. Koenigstein declined to comment on whether the tires being used on the front are identical in construction to the rears, saying only the front tires are being asked to perform a different function than the rears.
Ironically, Acura's benchmark—the Audi diesels—won't be around much this season. As of early 2009, Audi Sport plans to compete only once this year in the ALMS, at the 12 Hours of Sebring, leaving the two Acura teams to compete against each other and a smattering of privateer entries for the rest of the season.
The concept worked well enough at Sebring for the de Ferran team to claim pole position. In the race, the Acuras fell out with mechanical problems.
Acura entered the ALMS in 2007 with three ARX-01a LMP2 cars. In 23 starts, the Acura LMP2 cars recorded seven class wins and two overall wins, to go with six overall pole positions.