700-hp supertrucks go bumper to bumper and door to door at over 190 mph
Some of the body sheet metal is torn off. I’m standing here looking through the truck,” exclaims driver Jimmy Hensley. The damage is the result of an especially rough bump and grind race at Nashville’s 5/8-mile oval track. That day Hensley took his first checkered flag for the Petty truck team, beating out Tony Raines by only 0.540 sec. What’s more, he became the first driver in the world to win a race from a provisional starting position. A provisional position lets certain drivers who don’t qualify on speed to start, usually near the back of the pack. Hensley began the 250-lap race from 30th position. But even more impressive is that he drove to victory in a hastily prepared backup truck.
During qualifying rounds, the team’s primary truck snapped a ball joint sending Hensley into a retaining wall. “The right front tire was up in the dash,” remarks crew chief Fred Wanke. Luckily, Hensley escaped with only bruises. The truck, unfortunately, was junk.
Roll cage not optional
While professional drivers keep the shiny side up most of the time, accidents do happen. Slamming into a retaining wall at 190 mph can be deadly. Remarkably, most drivers involved in these high-speed crashes escape serious injury. “Racing chassis are designed to absorb huge amounts of energy on impact,” explains Mike Laughlin of Laughlin Racing Products, Simpsonville, S.C. If the chassis is too rigid, much of the energy transfers to the driver. To provide resiliency and maintain rigidity, chassis are built from cold-drawn, mild-steel, seamless tubing.
Drawing on 17 years experience building Winston Cup car chassis, Laughlin currently supplies chassis to over 40 supertruck teams. From their newly expanded facility, the company turns out several hundred chassis per year with backlogs at times exceeding 100 units. Offerings range from basic and rolling chassis to finished turnkey racers. So called rollers include a basic chassis, roll cage, floor pan, steering linkage and suspension parts. “You bring your wheels and springs and roll her away,” says Laughlin.
While his company supplies chassis, customers bring back race-proven data on components and chassis geometry. The telephone, Laughlin says, is their most important tool. Running a close second to the phone, though, is computers.
Laughlin credits advances in manufacturing techniques, along with higher volume, with keeping costs in check. Computer-aided manufacturing is the biggest single influence in our business in the last five years, he remarks. The flexibility, accuracy, and efficiency afforded by the equipment makes feasible customizing production parts. Such quick-change design can give teams a competitive edge.
Despite all the automation, humans are still in the loop. Welding is done manually while rigid fixtures hold components in the correct orientation. Thermal distortion is their worst enemy. To assure dimensional consistency, chassis are checked using coordinate measurement equipment. After fabrication, each chassis must pass rigorous inspection by Nascar officials. Those that make it are stamped with an identification number. Besides having to meet regulation, Laughlin gives the best argument for quality workmanship. “Drivers are betting their lives on the integrity of our products.”
While drivers rely heavily on “bulletproof” chassis and personal skill to save their hides, they’re betting the farm on their pit crews. After Hensley’s mishap in Nashville, for example, crew members had just 30 min to prepare the team’s backup truck for the upcoming race. Several components had to be changed including the entire suspension system. After passing a preflight check, and a quick three laps, the backup was deemed race ready.
Teamwork is essential
Supertrucks hold 22 gallons of 108 octane racing fuel and get about 3 mpg. In a 150-mile race, drivers must stop at least three times for fuel. Crews that get their trucks out on the track faster have a decided edge. Pit stops continue to get quicker year after year. Weight training and agility drills keep crews in top form, while improved equipment such as lightweight jacks make their job easier. Supertruck crews can change two tires and refuel in about 13 sec.
Another factor that can separate the winner from losers is the truck’s setup. Setup refers to the combination of springs, shocks, tires, brakes, engine tuning, and weight distribution. Different tracks and conditions require different setups. Previous experience helps since Nascar rules allow teams only 135-min track time per race to test and tweak the equipment. Drivers must efficiently and accurately convey problems to crew chiefs so they can instruct the crew to make proper adjustments. But certain quirks are too subtle for a driver to detect.
Mechanical sensors replace human senses
Onboard many of the trucks are sophisticated data-acquisition systems. Sensors monitor speeds, accelerations, steering input, and engine parameters. Information stored in onboard solid-state memory can be downloaded to computer and analyzed using special software. In general, the faster the track, the more useful is computer data, claims Wanke. At higher speeds, truck aerodynamics play a larger role. Critical to going fast is the angle the truck nose makes with the airstream. Tiny deviations from optimal pitch angle can greatly reduce top speed. If truck setup is correct, though, pitch stays nearly constant over the speed range. Sensor data help crews tune the chassis for best performance. While onboard data loggers can give teams an edge, Nascar prohibits their use during races. Moreover, teams can use the systems only five times per season.
Superior aerodynamics help trucks go fast, but to lead the pack requires another ingredient: raw horsepower.
700 horses at a full gallop
Supertruck engines may look similar to their Detroit cousins but they’re miles apart. For example, hit the starter button in the Petty racing team’s No. 43 Dodge Ram — the engine roars to life then settles into an anxious-sounding, 2,000-rpm idle. That’s where it likes to run, much slower and it cuts out, says Timmy Petty of Maurice Petty and Associates. A tap of the throttle sends engine speed skyward almost instantly along with decibel levels from unbaffled header pipes. Supplying the ground-pounding noise is a highly modified 5.9-liter V8 Dodge Magnum engine.
At its core is a special race engine block. Such blocks are designed to hold cylinder bores round and aligned in the stroke direction even during wide-open-throttle operation. To accomplish this, cylinder bores are machined while the block is in a prestressed condition. Honing plates bolted to the cylinder decks stress and distort the block as would actual cylinder heads. Also bolted on during the operation are main bearing caps which simulates having the crankshaft in place.
Installed in the block are billet steel connecting rods, crankshaft, and camshaft. Billet steel components are stronger than stock cast iron units. Pinned to the connecting rods are domed-head pistons that give the engine a 9.5:1 compression ratio, the highest allowed by Nascar rules. Each moving part is carefully weighed and balanced with respect to one another. Finally, the entire bottom end is dynamically balanced as an assembly, which helps ensure nearly vibration-free operation.
The rotating machinery all ride in special trimetal bearings lubricated with oil from a high-flow-rate pump driven by a cog belt. The pump maintains engine oil pressure at 60 to 80 psig. Oil comes from a separate tank, not from the crank pan like in conventional engines. This dry-sump system helps the engine survive the rigorous conditions by keeping oil temperatures relatively lower. Another advantage of storing oil outside of the pan is decreased power loss. Crankshaft and connecting rods splashing through pooled oil robs horsepower. With dry-sump oiling, power loss is virtually eliminated. The combination of precision balancing, high-strength components, and good lubrication, make the bottom end “pretty indestructible,” remarks Fred Wanke.
On the top end, CNC-ported aluminum heads sit on the block’s two cylinder banks. A high-rise aluminum manifold spans the cylinder heads. At the center sits a massive four-barrel carburetor that can gulp fuel and air at 830 cfm. The cam that opens and closes intake and exhaust valves has a lobe profile featuring high lift and long duration. Unlike a stock cam whose profile has a gentle ramp and lower peak, lobes on these competition cams are nearly square. Lift is about double that of a stock cam. Such a radical cam profile lets the engine breathe better at higher speeds, but it also puts added stress and strain on valve-train components.
To help take the abuse, rocker arms and valve lifters are fitted with roller bearings at contact points. Rollers make the system more reliable by reducing friction and heat build up.
A major challenge is keeping lifters in contact with the cam surface at high engine speeds. To accomplish this, multiple valve springs with different spring rates are used to damp out harmonics and provide adequate force. Still, springs are the weak link in the train. Broken valve springs are the major cause of engine failure. Besides springs, racing takes it toll on other parts. After running only 400 to 500 miles, the engines must be entirely rebuilt. It’s not surprising considering they turn 9,000 rpm and make over 700 hp. We’re pretty much squeezing all we can out of them right now, says Petty.
Besides envelope-pushing technology, a lot of what it takes to win comes from trial and error and driver skill. The longer you’ve been in it, and the more you can remember, the better off you are, says Wanke. He credits the Nashville victory to lessons learned from races spanning five previous years. Still, winning races these days is harder than ever before. More money is being poured into the sport all of the time. Teams with bigger budgets can afford better equipment and talent.
Another factor that can influence competition is public perception. In a popularity contest, Nascar’s Winston Cup car racing beats supertruck racing by a wide margin. For drivers, greater popularity means more prestige, endorsements, and money. Many younger, inexperienced drivers start out racing supertrucks, hoping to move up to Winston Cup cars. This could be one reason there’s more beating and banging in truck racing.
Though some drivers can be overaggressive, most act professional. For example, when Hensley was leading in Nashville, many drivers of slower trucks gave him plenty of room to pass. Hensley, a 30-year veteran of the sport, says he feels safer on a race track than on the highway. “At least you know who you’re dealing with.”
A great advertising vehicle
Most racers will tell you they’re in it for the love of the sport. But how can they afford it? Supertrucks can run $100,000, with a good motor costing $40,000 to 50,000. And that doesn’t include spare parts. Sure, some teams get by on a shoestring and do quite well. But in the long run, those teams who are better funded end up in the winner’s circle more often. That’s where sponsors come in.
Companies pay teams to put their product stickers on the trucks. Remuneration, it seems, is directly proportional to sticker size. The most predominant sticker is often from a primary sponsor. The primary may pay for everything from payroll to petrol. Smaller stickers can be from what are called contingency sponsors. If say a filter company supplies a team with air and oil filters, and the truck finishes a race in the top ten, they pay a small cash prize to the team. Often, several contingency sponsors link up with one team. Contingency awards are in addition to regular prize money. But what’s in it for sponsors is exposure.
Racing is gaining popularity every year. Television beams the action to millions of viewers who watch as sponsors’ logos flash by, stuck to high-speed, rolling billboards. Fans in attendance buy expensive official merchandise emblazoned with sponsor logos. “This is probably the only sport in existence where the fans sponsor the sponsors,” says Jim Fritz of Cummins Motor Sports. Racing gives companies such as Cummins good bang for the advertising buck. Cummins sells diesel truck engines to Dodge for exclusive use in their pickups. Truck racing has been a way for Cummins to strengthen their relationship with the dealer. In the end, though, advertising dollars spent must increase sales. Fritz puts it in perspective. “Racing is great,” he says, “but if it doesn’t have any business fundamentals to it, you’re not going to get it past the board of directors or shareholders.”