NASCAR CHEVROLET IMPALA SS ‘CAR OF TOMORROW'
Racing teams in NASCAR's premier series began racing an all-new racecar design at several venues during the 2007 season. Dubbed the Car of Tomorrow (COT), this 'universal' racecar was designed to bring new safety innovations to the drivers while also improving the competition during races. The COT also is aimed at driving down costs for race teams, as its basic design makes it adaptable to a variety of tracks, meaning teams can build fewer cars for the season.
Chevrolet displayed an Impala SS racecar at SEMA, highlighting a successful season that, to date has seen victories at 12 of the 15 races where the COT was implemented – starting wîth Kyle Busch's win at Bristol on March 25. Chevrolet has secured its 31 st NASCAR Nextel Cup manufacturers championship, has won more than 600 NASCAR Nextel Cup races—more than any other manufacturer—and has won a record-setting five straight Daytona 500 races. Car of Tomorrow enhancements and highlights include:
• Driver's seat moved four inches inboard
• Roll cage shifted three inches rearward
• Exterior dimensions are two inches taller and four inches wider
• Additional 'crushability' built into the car sides
• Front lower splitter used to produce downforce
• Adjustable rear wing
• Fuel system capacity reduced by 4.25 gallons Source - GM
NASCAR ENGINE TECHNOLOGY: SB2 INSIGHTS
On March 26, 1955, the world of stock car racing changed forever. On that memorable day, Fonty Flock drove Frank Christian's 1955 Chevrolet to victory in a 200-lap Grand National race on a dusty half-mile oval in Columbia, S.C. It was Chevrolet's first NASCAR victory and the first major win for the legendary GM small-block V-8. It would not be the last.
GM has produced nearly 90 million engines based on the small-block design – and a fair number of them ended up on race tracks. In fact, the GM small-block V-8 is the most successful production engine in motorsports history. This lightweight, high-revving engine dominated stock car competition for decades, eclipsed only during
periods when the rulebook favored big-block powerplants.
GM engineers kept the small-block V-8 forever young wîth a steady flow of new heavy-duty components. Improved blocks, free-breathing aluminum cylinder heads and forged-steel crankshafts maintained the little Chevy's place on the cutting edge. But as the all-conquering small-block approached its 40th birthday in 1995, GM Racing engineers realized that the venerable motor was reaching its limits.Work began on the small-block's successor, designated 'SB2' – shorthand for 'Small-Block – Second Generation.'
First presented to NASCAR officials in October 1995, the SB2 finally won approval for Nextel Cup competition at the start of the 1998 season. The SB2 was subsequently introduced to the Busch Grand National and Craftsman Truck series. The SB2 is a comprehensive engine package that was designed by GM Racing to improve durability,
simplify preparation procedures and reduce the overall cost of building and maintaining a stock car racing engine. In short, the SB2 makes state-of-theart technology affordable and accessible.
'The SB2 marked the first time in the history of the GM small-block V-8 that a package of engine components was specifically developed for NASCAR racing competition,' said Jim Covey, NASCAR engine development manager for GM Racing. 'GM had never designed a cylinder head specifically for a single four-barrel stock car engine. When the SB2 project began in earnest,we had an opportunity to make a significant improvement over existing engines.'
The SB2's valves and intake runners are positioned to provide a direct line-of-sight path from the carburetor to the combustion chambers. All eight intake ports are angled toward the center of the engine; the runners that supply the front cylinders are a mirror image of the ports that feed the rear cylinders. This innovative valve layout led to corresponding revisions in the small-block's camshaft, intake manifold, pistons, headers and valvetrain.
The SB2's two-piece intake manifold comprises separate castings for the plenum/runner assembly and a lifter valley cover that incorporates the water crossover,water outlet and distributor mount. This two-piece design simplifies at-track service because the manifold section can be removed without draining the coolant or removing the distributor.
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When GM Racing engineers set out to build a better small-block, they enlisted the aid of NASCAR teams who build literally hundreds of competition engines every season. This partnership between racers and engineers benefited both groups. 'By working wîth GM teams from the very beginning of the project,we were able to meet their concerns about service and reliability issues that we may not have considered as designers,' Covey noted.
Although the SB2 is firmly rooted in the classic small-block architecture, it is a purposeful and thoughtful revision designed specifically for NASCAR stock car racing.Working within the boundaries established by the rule makers, GM Racing created a two-valve pushrod V-8 for the 21st century.Source - GM