Kentucky is famous for horsepower of the four-legged variety, but the focus at this weekend's Belterra Casino Indy 300 at Kentucky Speedway will be on the horsepower of the new Gen IV Chevy Indy V8.

Just four weeks after the Indy Racing League's approval of the Gen IV engine on July 19th, all six Chevrolet drivers in the IndyCar Series will race with the new powerplant for the first time.

The roster of Gen IV Chevy racers includes: Sam Hornish Jr. (No. 4 Pennzoil Panther Dallara/Chevrolet/Firestone), Buddy Rice (No. 52 Red Bull Cheever Racing Dallara/Chevrolet/Firestone), Vitor Meira (No. 2 Menards/Johns Manville Dallara/ Chevrolet/Firestone), Buddy Lazier (No. 91 Delta Faucet/Life Fitness Dallara/ Chevrolet/Firestone), Robbie Buhl (No. 24 Purex/Aventis/Dreyer & Reinbold Dallara/Chevrolet/Firestone), Sarah Fisher (No. 23 GMAC/AOL/ Dreyer & Reinbold Dallara/Chevrolet/Firestone).

The Kentucky event is the final step in the phased introduction of the Gen IV Chevy Indy V8 prescribed by the series. Following successful tests of the new engine package under racing conditions by Panther Racing at Michigan International Speedway (July 27) and Red Bull Cheever Racing at Gateway International (Aug. 10), all Chevrolet teams are now eligible to use the new engine.

"The race at Kentucky Speedway will be a significant milestone in the evolution of Chevrolet's IRL program," said GM Racing IRL program manager Joe Negri. "The conversion to the Gen IV Chevy Indy V8 has been very smooth, thanks to the exceptional efforts of our teams and suppliers.

"We still have a long road to travel during the development of this new engine specification, and there will certainly be some unexpected bumps along the way. With six engines on the track this weekend, we can accelerate our learning and continue to build a strong foundation for Chevy's IRL program in 2004 and 2005."

While IndyCar Series teams routinely change engines in less than an hour during a race weekend, the conversion from the Gen III Chevy Indy V8 to the Gen IV version is much more complex. Although the Gen III and Gen IV engines share the same general specifications - 3.5-liter displacement, eight cylinders, dual overhead cams and electronic fuel injection - they have no parts in common. Kevin Bayless, GM Racing's chassis and aerodynamics specialist, is assisting Chevrolet teams as they make the transition to the new powerplant.

"The IRL rules require that all engines use the same attachment points, so the Gen IV block bolts to the tub and the bell housing just like the Gen III engine, but that's where the similarities end," Bayless said. "Virtually every component on the car that interfaces with the engine must be changed in the Gen III to Gen IV conversion.

"All of the engine support systems - the cooling system, the lubrication system, the exhaust system, the electronic engine management system, the airbox, the clutch, the throttle cable, the bell housing and the gearbox input shaft - have to be replaced or modified. Forty major chassis components have significant changes."

GM Racing and Chevrolet teams operated on a tight timetable to have the cars ready for the Kentucky race. Several teams were able to get a head start by converting their spare cars; others had to make the conversion after last Sunday's race at Gateway International Raceway.

"The Panther Racing team did an outstanding job when they converted the first test car," Bayless said. "Based on their feedback, we modified the prototype parts and used them as patterns for the production run of parts. The experience we gained with each successive conversion meant that the process became progressively faster and easier.

"All of our suppliers made a monumental effort to get parts to us as quickly as possible. I think that Sam Hornish's performance at Michigan got everyone's enthusiasm up - not only the Chevy teams, but also the vendors as well."

While Chevrolet officials are excited about the Kentucky race, so are the drivers.

"To say that we're looking forward to racing this weekend is the understatement of the season for our team," Buhl said. "Chevy's been working hard to level the playing field, and now it's up to us to prove ourselves all over again. Am I anxious? Yes. Am I ready to race? More so than ever."

Toyota leads the Engine Manufacturers Championship 104-79 over Honda. Chevrolet is in third place with 59 points.