This weekend, Richard Childress Racing will be the first team to utilize Chevrolet's new R07 motor when Scott Wimmer hits the track with the #33 Holiday Inn Chevy on Friday afternoon at Atlanta Motor Speedway. 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 the 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. RCR will be the first team in the Nextel Cup ranks to utilize Chevrolet's new engine combination.(RCR PR)(3-14-2007)