New GM Racing Engine to Power Chevy in Cup

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. 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. 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. 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. GM Racing PR