Breaking Technology on the Circuit

Mazak's Consistency Keeps Rusty Wallace Rolling
Some months ago, Penske Racing South Inc. (Mooresville, NC) began preparing ten new 1996 Ford V-8 Thunderbirds for this year's National Associaltion for Stock Car Auto Racing (NASCAR) season. The first step in an extensive modification process was to tear down each car completely, gutting the interiors and replacing them with welded metal cages and other safety equipment (Notice the MAZAK Logo on Rusty's roll bar to the right!).

Because each race course is unique, Penske South engineers also must design the suspension, and specify the shock absorber arrangement and power-train elements for the conditions at the track. They also must determine the best torque for each race, and then match this output to the drivetrain.

9,000 RPM Screamer
To prepare the power-plant, the most critical of the mechanical parts, designers begin with a naturally aspirated Ford V-8 engine with a four-barrel carburetor. When the engine is ready, the cast iron block is about the only element that remains of the original equipment. "This is a never-ending battle," says Rusty Wallace, team driver and part owner of the operation. "We are always experimenting with new aluminum piston configurations, compression ratios, and intake and exhaust passages, trying to coax out just a little more power than the last design." The present engine design delivers a maximum of 740 HP at 8,800 RPM, burning 108 octane fuel. An unmodified engine would deliver only 200 HP.

Despite all the work, the team designs the engine to live just slightly longer than the race distance. "If it's a 500 mile race, you can expect the engine to blow at about 550 miles," says Wallace. Even so, the team discards only the pistons after each race. They rebore the blocks, which may last four years or more. Crank shafts and aluminum cylinder heads last 3,000 miles and connecting rods, 2,000 miles.

Reproduction Problem
Building one winning engine is not the ultimate solution, however. "The first problem in racing is winning," says Wallace. "The second is understanding what you did right and wrong. It's important to be able to duplicate those features that resulted in the win."

For a while, the team was having problems doing that. Engineers would get an engine performing just the way they wanted, but when they tried to duplicate that engine, using manual machine tools, there were unpredictable and unacceptable variations in the parts.

A few years ago, to ensure the necessary accuracy and repeatability, the Penske team started using two CNC machines from MAZAK CORPORATION: an H-630N Horizontal Machining Center and a Super Quick Turn 15MS Multi-tasking Turning Center. This flexible equipment gave the team the ability to create and modify the block and pistons precisely and quickly. The horizontal machining center chiefly bores the block, levels the decks, and modifies the manifold and oil system. The H-630N has 6,000 RPM and 30 Horse Power. A double row of cylindrical bearing at the front of the spindle and a double row of angular contact bearings in the back provide ultra rigidity.

"The Mazaks' biggest contribution to our racing program is the machining of cylinder heads," says President and Team Manager, Don Miller. The 5th axis on the H-630N allows precise definition of combustion chamber contours, including porting and relieving. Porting is the shaping of the exhaust port or runner, and relieving is the blending of areas from the combustion chamber to the inlet and exhaust channels. Both operations are designed to help the engine "breathe" better. The Penske Team engineers use a dynamometer in a nearby test cell to quickly verify the output per cylinder of the new design. After confirming a design, engineers use the powerful Mazatrol M-32 CNC to duplicate the design across the entire cylinder head. This process means uniformity from cylinder to cylinder, eliminating the labor-intensive trial-and-error method still used by most other race teams.

With the Super Quick Turn 15MS, a multi-tasking turning center with a 25 HP main spindle, 10 HP secondary spindle, 12 position turret, and 5 HP rotary tools at any postion, Team Penske machines precision pistons. With the SQT, complete parts hit the floor in a single set-up, whereas in the past the same parts had taken four to six fixture changes on manual milling machines.

Problem Solver
The new Mazaks also helped solve a problem unique to the Ford blocks. Under high torque, the inner four cyliners respond differently than the pairs at either end. For optimum performance, therefore, the engineers have to design two different piston shapes for a single engine. Until the Mazak machines came on-line, the repeatability the team was looking for was not available. "When we were making our parts one at a time on manual machines, we were getting inconsistencies, even with good machininsts," says Miller. "The Super Quick Turn with its milling capabilities gives us the speed we need. For example, we can make eight pistons in just 30 minutes to an accuracy of 0.001".

Mazak Precision-- A Consistent Part of Rusty's Winning Ways
Thus far for '96, Rusty Wallace has won 3 major Winston Cup NASCAR races, and he is confident he can surpass 10 wins to beat his personal best. Mazak CNC machines are at the root of Rusty's success, and Team Penske will continue to call upon the Florence, KY machine tool builder for the best equipment available to consistently place them in the winner's circle.

Bobby Rahal is a Mazak user, too!

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