New GM Racing Engine to Power Team Chevy in NASCAR Nextel Cup Series in 2007
New GM-Designed R07 Is Next Step in Small-Block V-8 Evolution

DETROIT - It's all change for Team Chevy in the NASCAR Nextel Cup Series in 2007. In addition to the scheduled introduction of the Impala SS Car of Tomorrow in March, GM Racing is introducing a new small-block V-8 racing engine that was specifically designed for NASCAR competition. The new powerplant - designated R07 - has been approved by NASCAR for competition in 2007. Chevrolet teams are expected to begin the transition from the current SB2 (Small-Block/2nd Generation) engine to the new R07 in March.

"The introduction of the new R07 small-block V-8 represents another milestone in GM's continuous evolution of the small-block V-8 engine," said GM Racing director Mark Kent. "It is the successor to the production-based engines that have made GM the most successful manufacturer in NASCAR. The R07 is our first purpose-built NASCAR racing engine, and it was created using GM's in-house technical resources. Our goal was to develop an engine that will continue Chevy's winning ways in NASCAR for years to come."

Work on a successor to the SB2 began shortly after the SB2's introduction in NASCAR competition in 1998. The R07 retains the pushrod/two-valve layout that has been the mainstay of American motorsports since the introduction of the first-generation GM small-block V-8 in 1955. It is a highly advanced racing engine that meets NASCAR's specifications.

"GM Racing worked within the parameters established by NASCAR officials to optimize the R07's performance, reliability, and durability," said Jim Covey, NASCAR engine development manager for GM Racing. "We also worked with our key Chevrolet teams, GM Powertrain (the section of GM responsible for the design, development and manufacture of GM's engines and transmissions), and our suppliers to design an engine that would reduce engine assembly time and cost and improve safety."

Per NASCAR regulations, the R07 displaces a maximum of 358 cubic inches. In contrast to the SB2's "mirror port" cylinder heads, the R07's cylinder heads resemble production LS-series small-block cylinder heads with alternating intake and exhaust valves. While production small-block V-8 engines employ electronic fuel injection, the R07 port layout is optimized for the single four-barrel carburetor mandated by NASCAR.

"NASCAR officials provided a 'box' of parameters such as specific design features and minimum and maximum dimensions for key engine components," Covey explained. "By using technology such as computational fluid dynamics (CFD), finite element analysis (FEA), and solid 3D modeling, GM Racing was able to evaluate and analyze various designs in computer simulations. This extensive use of computer modeling also accelerated the production of prototype parts after the specifications were finalized."

The R07's key technical advances over the SB2 include 4.500-inch cylinder bore centers (vs. 4.400 inches in SB2), a raised camshaft that improves valvetrain dynamics, a new six-bolt head bolt pattern that reduces cylinder bore distortion, and a targeted cooling system that minimizes temperatures at critical locations. A cast camshaft tunnel, integral piston squirter galleries, and overhead oil feed galleries reduce engine assembly time. Relocating the fuel pump to the inboard side of the car and eliminating external oil and coolant lines enhance safety.

Although the R07 is a purpose-built racing engine, it has strong ties to production powerplants. "The concepts and processes that are used to improve the performance of our racing engines is shared with the production engine designers to improve the efficiency of our production engines," said Tom Stephens, group vice president of GM Powertrain.

-credit: gm racing