It should come as a surprise to no one that for the past two decades there has been essentially nothing stock about NASCAR stock car racing. After all, when was the last time that you opened the hood on a new car and actually saw a carburetor or distributor? GM and its Detroit counterparts have at least maintained the facade with the dimensions of their engines. Although there are no parts that are common with production versions in their NASCAR powerplants, they have had the same cylinder bore and cam position.
Toyota had no production pushrod V8 upon which to base its NASCAR engine, so that meant a ground-up racing design was called for. As a result, GM has followed suit with a similar engine of its own dubbed the R07. The new engine gets wider 4.5-inch bore spacing that allows for bigger bores and redesigned cooling. The camshaft is also moved up to accommodate better performance of the valvetrain at high rpms. The potentially large bores allow for higher redlines and more power as well. The new R07 will make its competition debut at this weekend's race at Texas Motor Speedway. GM's press release is pasted after the jump.
[Source: General Motors]
Team Chevy Rolls Out New Chevrolet R07 Racing Engine
Transition to New-Generation NASCAR Small-Block V-8 Begins at Texas Motor Speedway
FORT WORTH, Texas – On the heels of the successful introduction of the new Impala SS race car in NASCAR Nextel Cup competition, Team Chevy is beginning the transition to the new Chevrolet R07 racing engine. Approved by NASCAR for competition in 2007, the Chevrolet R07 is making its debut this weekend in the Samsung 500 at Texas Motor Speedway.
The Chevrolet R07 marks another step in the evolution of the GM small-block V-8. It is the successor to GM's SB2 (Small-Block/2nd Generation) engine that was introduced in NASCAR Cup competition in 1998. The Chevrolet R07 will eventually replace the SB2 as teams turn over their inventories of engines and components.
"The GM Racing engine development team had four key objectives in mind throughout the design and development of the Chevrolet R07 engine," said Mark Kent, director of GM Racing. "Our goal was to create an engine that produces competitive power, delivers excellent reliability, enhances safety, and reduces costs for Chevrolet teams. Based on the feedback we have received from Chevy teams after extensive dynamometer and track testing, I believe we have achieved our objectives."
The evolution of the GM small-block V-8 racing engine mirrors the development of the GM small-block V-8 production engine, which is now in its fourth generation. Until the introduction of the Chevrolet R07, all of GM's small-block racing engines shared key dimensions such as cylinder bore spacing, camshaft location and deck height with the original small-block V-8 introduced in 1955.
"The Chevrolet R07 is GM Racing's first purpose-built NASCAR racing engine," said Pat Suhy, GM Racing Group Manager, Oval Track. "NASCAR's parameters for the new generation of engines provide a range of choices on key dimensions and design features. Our job was to make the critical decisions and carefully balance the tradeoffs that would enable the Chevrolet R07 to continue Chevy's success in NASCAR. In the long run, the results will show whether we made the right choices."
GM Racing supplies the major components that define the Chevrolet R07 engine package – the cylinder block, cylinder heads, and intake manifold. GM Racing also developed engineered assemblies such as the water pump, rocker covers, valley plate, and front cover. Teams and independent engine builders prepare and assemble these components using their own proprietary parts and processes, including the rotating and reciprocating assemblies, valvetrain, oil pump, fuel and ignition systems, and accessories.
"New manufacturers coming into NASCAR pushed the envelope with engines that had no links to production powerplants, while GM engines were based on the architecture of the first small-block V-8," explained Jim Covey, NASCAR engine development manager for GM Racing. "NASCAR Nextel Cup Series director John Darby addressed this issue by developing a list of parameters that define the envelope for all manufacturers, thus giving Chevrolet an opportunity to develop the R07 engine. Now with the introduction of the Chevrolet R07, Chevy teams have an optimized engine design that reflects the advances in racing technology that have been made over the last 50 years."
Per NASCAR regulations, the R07 displaces a maximum of 358 cubic inches and retains the classic two-valve pushrod design that has been the mainstay of American motorsports for more than 50 years. The R07's key technical advances over the SB2 include 4.500-inch cylinder bore centers (vs. 4.400 inches in SB2) that enhance coolant flow, 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 and eliminating external oil and coolant lines enhance safety.
GM Racing engineers created the Chevrolet R07 in-house using many of the advanced development tools employed by GM Powertrain engineers to design production engines. These included computer-aided engineering (CAE), computational fluid dynamics (CFD), finite element analysis (FEA), and solid 3D modeling. Extensive use of computer modeling accelerated the production and testing of prototype Chevrolet R07 components while reinforcing the connection to GM production powerplants.
"The introduction of the Chevrolet R07 this weekend marks the beginning of a new era for the GM small-block V-8 engine," said Kent. "The Chevrolet R07 is the heir to the winning tradition of GM production-based engines that have powered Chevy to more than 600 victories in NASCAR Cup competition. As we look to the future, we are confident that the Chevrolet R07 engine and the Impala SS race car will continue Team Chevy's winning ways in NASCAR."