Manufacturing for Performance Supplement: CNC Machining Improves NASCAR Cars
Hendrick Motorsports partners with Haas Automation to compete
By Jim Lorincz
Building a better race car—engine and chassis—is a daily occurrence in-season and even out-of-season on the NASCAR racing circuit. Engines in race cars that compete in the Nextel Cup and Busch Series events resemble those developed for the powertrains of muscle cars of the 1960s, albeit with horsepower ratings of 800 hp or 600 kW (Nextel Cup) and 700 hp or 523 kW (Busch Series), respectively.
Vehicle chassis are a different thing. They must fit—under NASCAR rules—into a template used to check the body shape and size that must closely resemble the factory version of cars today.
Imagine, if you will, race tracks ranging in length from 0.533 mile or 0.86 km (Bristol, TN) with a 650' (200-m) straightaway to more than two miles (3.2 km) with three, four, and even five turns (all left turns) per lap. Talladega, at 2.66 miles (4.3 km) with a front straightaway 4300' (1310-m) long and Daytona International at 2.5 miles (4 km) with a 3800' (1158-m) front stretch are so fast that engines must be fitted with restrictor plates to hold speeds down.
Of course, you don't have to imagine this. You and hundreds of thousands of NASCAR race fans trackside, and literally millions of viewers at home, watch cars running lap after lap until a winner takes the checkered flag, spins a donut or two, or does a back flip off his car.
Watching NASCAR on TV is one thing. It looks like a slow motion ballet of cars chasing one another down straightaways, taking turns banked as much as 36° (Bristol) high or low trying to find the "groove," the most efficient or quickest way around the track for a particular driver.
NASCAR race cars are high-speed, high-technology billboards that generate millions of sponsorship dollars to support race teams that have budgets and employment rolls as large as those of mid-sized manufacturing companies.
Hendrick Motorsports (Charlotte, NC), which has distinguished itself on the track, has evolved into an automotive re-manufacturer over the last decade. HMS utilizes the latest advanced manufacturing technologies to gain whatever competitive edge it can in both engine and chassis performance.
Hendrick Motorsports employs more than 500 at its 100+ acre complex where as many as 700 engines from its race fleet of 200 engines are built or re-built each year on-site for its own four race teams and, under leasing arrangements, for several other NASCAR teams.
In its 21 years of competition, Hendrick Motorsports has earned five NASCAR Winston Cup Series (now Nextel Cup) championships and challenged for a sixth in 2005, three NASCAR Craftsman Truck Series titles, and one NASCAR Busch Series crown. Chevrolet race cars entered by Hendrick in Cup Series competition have won the prestigious Daytona 500 five times and recorded 140 Cup Series victories.
The race drivers associated with its success over the years include Kyle Busch, Jeff Gordon, Brian Vickers, Jimmie Johnson, Terry Labonte, and Geoff Bodine.
HMS made its initial foray into manufacturing in 1992 with its first CNC machine tool, which was purchased from a foreign builder. It wasn't until 1996 when it bought its first CNC machining center from Haas Automation (Oxnard, CA) that it began to grow both its machining capability and its partnership with Haas.
Today, the number of Haas machine tools has grown to more than 30, including 16 VMCs, eight HMCs, and seven CNC lathes.
The partnership with Haas has also grown into a racing relationship. Hendrick Motorsports supplies engines to the Haas CNC Racing team, which began fielding its own NASCAR race car in 2002.
"It's natural that a racing operation like ours should have evolved into a full-scale manufacturing capability," explains Jim Wall, director of engine engineering, Hendrick Motorsports. "It's hard to imagine that anyone who races—even a late—model at the local track on Saturday night-wouldn't have a shop out behind his house in the garage with the tools to help campaign that car."
The Hendrick manufacturing resource is just a lot bigger in scale and more sophisticated in scope. It now includes CNC machining to support engine manufacturing (its original focus) as well as the chassis manufacturing side.
"We focus on parts that give us a competitive advantage and leave the commodity-type parts, such as spacers, brackets, and fasteners, to contract manufacturers who can make them more efficiently," says Wall.
With the increase in number of CNC machines, Hendrick is able to dedicate certain machines to one critical part, as well as machine complex parts using the four and five-axis machining capability of the Haas machines. According to Wall, one of the definite attractions of the Haas CNC machines was the availability of accessories that could readily transform them into machines with fourth and fifth axes.
"We need the flexibility," says Wall. "There are times when a team makes a change on Sunday night after a race, or a part is damaged in an accident that requires designing a part, testing it, and having it ready in three days for the next race."
Even a season-to-season change driven by a NASCAR rule revision can and did challenge this machining flexibility.
"We had a major rules change in 2000 when NASCAR legalized the use of a poly V-belt for our accessory drives," Wall says. "Until that point, we had to use a standard V-belt. Once NASCAR gave the go-ahead, we had to move quickly to convert our large fleet of engines.
"We couldn't find exactly the right design of a front system for the application, so the engineering staff designed a family of parts that were produced over the winter off-season to convert the entire race fleet to the poly V-belt. It would have just been too difficult to find a vendor who could have done that in the timeframe available."
The speed at which parts can be prototyped, replaced, rebuilt, and reinstalled in cars is a continuing challenge. "The race team will take the engine, put it in the car, take it to the track, use it up, come back to the shop, take it out, and give it to us to rebuild and remanufacture to a condition as good as it was or even better," says Wall.
During 2005, HMS rebuilt 12-15 engines a week, supplying engines for its own teams and leasing engines to two other NASCAR fulltime programs, two part-time programs in the Nextel Cup, two full-time Busch Series programs, and two part-time Busch-series programs.
The engine-build cycle encompasses new builds and the rebuilding and reuse of engines that have run in prior competitions. The Hendrick engine department consists of 20 engineers and 100 engine-shop employees.
It takes an average of about 120 hr to build a completely new engine and 40 hr to perform routine maintenance and cleaning of the engine. Everything in an engine is reused except the rotating mass, comprising the pistons, valves, and springs. An engine as a whole will run about 15 times before being retired.
Cast-iron engine blocks and aluminum cylinder heads are supplied by General Motors. The average cost to build a new "open" engine is $45,000; for a restrictor plate engine, the cost is $60,000. Rebuilding and maintenance of an engine costs about $28,000.
An open engine is one in which the carburetor has no restrictions placed on the amount of air it can intake. A restrictor plate is a 3 x 4" (76 x 102-mm) aluminum plate 1/8" (3.2-mm) thick with four holes drilled in it that is placed between the base of the carburetor and the top of the intake manifold to reduce airflow to the engine's combustion chambers.
A team takes three engines to the track each weekend: one in the primary car; one in the backup car; and one engine as a race spare.
Chassis are built using hoods, roofs, and rear deck lids, as well as front and rear fascias, produced by General Motors. The chassis frame is manufactured in-house using tube for fabrications that are shaped, welded, and polished for the best aerodynamics—not unlike the aerodynamics of a bullet. A single chassis is composed of about 200 pieces.
The Hendrick chassis team fabricates 40 cars each year on average, and has built more than 300 Chevrolet Monte Carlos and Luminas during the past ten years.
Most of the Haas CNC machines are located in the main manufacturing facility that is adjacent to the engine shop. A few are scattered in other areas of the HMS campus, including R&D.
A large Haas VS3 vertical machining center is being used in the sheetmetal shaping fabrication area that supports short-run stamping operations.
HMS is utilizing an HS-2RP twin-pallet machine with an HRT 310 mounted sideways on the machine's built-in fourth-axis rotary table for dedicated machining of engine blocks. Each pallet is set up for different operations. In the first setup, the end face is machined and the cam tunnels are bored, followed by drilling and tapping for the motor plate.
Most all of the Haas machines at Hendrick are configured to have fourth and fifth-axis machining capability. "For example, we take the HRT-210 rotary table, and use it on the VMC to gain a fourth axis or, when installed on a HMC, a fifth axis.
"We use a lot of multiaxis machining, both positional and simultaneous, to eliminate the need for multiple setups. We hold to the philosophy of trying to machine a part complete in two setups. We make a lot of complex parts with compound angles, so the capability that the rotary products give us is extremely important," Wall explains.
To facilitate manufacturability of parts, Hendrick's engineering staff does a lot of component design and works with the manufacturing group to participate in job setup for the machine tools.
HMS has moved from a few machines that were flexible for a variety of jobs to a full complement of Haas CNC machines that offer flexibility and free up individual machines to be dedicated to a particular manufacturing part.
"When we had fewer machines, we had to change the fixturing for different parts," says Wall. "But now we are able to dedicate certain machines to certain tasks that we do over and over again, such as cylinder heads and manifolds. We have four HS-1Rs and two of them are dedicated just to cylinder-head work."
One benefit of having machines dedicated to a specific part is improved repeatability and accuracy. "That allows us to turn around parts much faster. Once you get a part tuned in and the geometry is just right, you can actually have spare parts available for replacement," he says.
Intake manifolds and cylinder blocks represent some of the fairly complex parts that are being machined in one setup by using five-axis capability.
HMS is employing an HS-2RP twin-pallet machine with an HRT 310 mounted sideways on the machine's built-in fourth axis rotary table for dedicated machining of engine blocks. Each pallet is set up for different operations. In the first setup, the end face is machined and the cam tunnels are bored, followed by drilling and tapping for the motor plate.
With a stable of more than 30 Haas machines, HMS is now able to dedicate specific machines to specific parts or tasks. The two HS-1R HMCs at right are dedicated to cylinder head porting and machining; while the HS-2RP, center, is dedicated to machining engine blocks.
The second setup for the engine block on the other pallet uses the HRT 310 matched with a manual tailstock for cylinder bores, along with drilling and tapping deck holes and the main caps.
Among the newest machine additions at Hendrick are two Haas EC 400 horizontal machining centers that are being used for piston work.
Hendrick also machines its own piston blanks, about 5000 a year, out of barstock instead of using forgings. Other parts being machined include a water pump casting that HMS designed in-house, as well as rocker arms, piston pins, and rocker bars.
Tuning Up In The Hendrick Engine Department
It's a team effort as an engine progresses through the Hendrick Engine Department. Here are the stops along the way:
Engine Tuner/Dress Area: Each team, including all HMS lease teams, has a tuner who is assigned specifically to its engines. The tuner's main responsibility is to make sure that all three of the engines that travel to the track each weekend are in perfect shape. Tuners are the last people to touch a team's engine before the start of a race. They also rebuild carburetors from previously run engines. This area also houses the two Hendrick engine dressers, who do the final fittings or dressing on the engine before it is placed into a team's car.
Engine Assembly Area: Hendrick engine assemblers do in-depth analysis of each and every component in the engine. They perform fittings to ensure that the dimensions of critical components such as bearings meet rigorous specifications. Engine assemblers are also responsible for tracking where each engine and part is run throughout each season.
Machine Shop: The engine department's machine shop includes Haas Mini Mills and honing machines used to modify rods, pistons, and crankshafts to specific dimensions.
CNC Room: The CNC room houses the Haas Automation CNC machines used to manufacture and produce engine components from raw materials. More than 40% of the parts used in Hendrick engines are produced here. One of the main goals of the Engine Department is to eventually make all engine components in-house.
Head Shop: After machining in the CNC area, cylinder heads and intake manifolds are ported and valve jobs are performed.
Teardown: All incoming engines are torn down, cataloged, and then thoroughly inspected prior to returning to the engine build cycle.
Dynamometers: Using four dynamometers that measure torque and horsepower, HMS staff can test an engine in-house before it is ever put into a car. The engine is mounted onto the dyno machine that connects it to fuel, coolant, exhaust pipes, and a brake that simulates drag. Dyno machines perform two main functions. First, they serve as a quality control mechanism to ensure that the engine is properly assembled. The engine will be tested at open throttle to meet power specifications and to check for leaks in oil or gas lines. HMS also uses the dynos as a development tool for engine building, specifically in the areas of durability, power, and reliability.
Spintron: The Spintron machine measures movements within the engine's valve train. The engine is powered by an electric motor that allows the operator to control the revolutions per minute (rpm) to mimic track conditions. An operator can increase rpm to simulate a certain track's straight-aways and then decrease them to simulate its turns. The Spintron allows the engine department to observe the different types of demands placed on the valve train at the various types of tracks.
Magnaflux: The magnetic particle inspection process checks steel parts within the engine such as camshafts and connecting rods for defects like cracks. The engine is covered in a dye laced with magnetic particles that are attracted to cracks on steel parts within the engine. A UV light causes the magnetic particles to glow green and highlight the defects.
Wash Room: All used engines are cleaned, inspected, and returned to the engine build cycle.
Aerodynamic Drag: A number that is a coefficient of several factors that indicates how well a race vehicle will travel through the air and how much resistance it offers. Race crews work to get the best "drag horsepower" rating they can, determining how much horsepower it will take to move a vehicle through the air at a certain mile-per-hour rate. At faster speedways, teams strive to get the lowest drag number possible for higher straightaway speeds.
Air Pressure: With the advent of stiffer sidewalls, changing air pressure in the tires is used as another setup tool that is akin to adjusting spring rates in the vehicle's suspension. An increase in air pressure raises the spring rate in the tire itself and changes the vehicle's handling characteristics. If the race vehicle is "tight" coming off a corner, a driver might request a slight air pressure increase in the right rear tire to loosen it up.
Banking: The sloping of a racetrack, particularly at a curve or a corner, from the apron to the outside wall. Degree of banking refers to the height of a racetrack's slope at the outside edge.
Downforce: The air pressure traveling over the surfaces of a race vehicle creates downforce or weight on that area. In order to increase corner speeds, teams strive to create downforce that increases tire grip. The tradeoff for increased corner speeds derived from greater downforce is increased drag that slows straightaway speeds.
Fuel Cell: A holding tank for a race car's supply of gasoline, consisting of a metal box that contains a flexible, tear-resistant bladder and foam baffling.
Groove: The best route around a racetrack; the most efficient or quickest way around the track for a particular driver. The high groove takes a car closer to the outside wall for most of a lap, while the low groove takes a car closer to the apron than the outside wall. Road racers use the term line. Drivers search for a fast groove, which is known to change location depending on track and weather conditions.
Loose: A condition created when the back end of the vehicle wants to overtake the front end when either entering or exiting a turn. In qualifying mode, teams walk a fine line creating a setup that "frees the vehicle up" as much as possible without causing the driver to lose control. Also referred to as free or oversteer.
Push: A condition that occurs when the front tires of a vehicle will not turn crisply in a corner. When this condition occurs, the driver must get out of the throttle until the front tires grip the race track again. Also referred to as tight or understeer.
Restrictor Plate: An aluminum plate with four holes drilled in it that is placed between the base of the carburetor and the engine's intake manifold. The plate is designed to reduce the flow of air and fuel into the engine's combustion chamber, thereby decreasing horsepower and speed.
Superspeedway: a racetrack of one mile or more in distance. Road courses are included. Racers refer to three types of oval tracks: Short tracks are under one mile. Intermediate tracks are at least a mile but under two miles, and superspeedways are two miles and longer.
Template: A device used to check the body shape and size to ensure compliance with the rules. The template closely resembles the shape of the factory version of the car.
Tight: A car is said to be tight if the front wheels lose traction before the rear wheels do. A tight race car doesn't seem able to steer sharply enough through the turns; instead the front end continues through the wall. Also known as understeer
Tri-Oval: A racetrack that has a hump or fifth turn in addition to the standard four corners. Not to be confused with a triangle-shaped speedway, which only has three distinct corners.
Wedge: Refers to the relationship from corner-to-corner of the weight of the race vehicle. Increasing the weight on any corner of the vehicle affects the weight of the other three corners in direct proportion. Weight adjustments are made by turning weight-jacking screws mounted on each corner with a ratchet. A typical adjustment for a loose car would be to increase the weight of the left rear corner of the vehicle, which decreases the weight of the left front and right rear corners and increases the weight of the right front. A typical adjustment for a tight vehicle would be to increase the weight of the right rear corner, which decreases the weight of the right front and left rear, and increases the weight of the left front.
This article was first published in the January 2006 edition of Manufacturing Engineering magazine.