1990 Corvette ZR-1 Bonneville Salt Flats Racer
Chasing a Bonneville Record in a 1990 Corvette
Jeffrey Conger - August 01, 2011 09:00 AM
When describing the excitement of rocketing down the salt-covered racetrack at 400 feet per second, Dave Hlebichuk of Texas said, “It feels like you are driving on hard-packed snow. The crosswind changes a lot in the three-mile, and it can easily move the car 50 feet either way. If you need to do too much correction … well you’re pretty much done!”
Making it through the 4- and 5-mile markers are essential for any record-breaking attempt in this class. Lightheartedly, he added, “Sometimes your right leg gets tired pressing constantly on the gas for three minutes.”
Bonneville is an alluring racetrack with its list of speed-drenched heroes and iconic saline surface. After attending his first Speed Week three years ago as a spectator, Dave explained, “I had only been on the salt for about half an hour before I began building a racecar in my head!”
Returning home to Conroe, near Houston, he immediately contacted his friend Rick Harden and divulged his plan. Not long after that, they were flying west to buy a rough 1990 ZR-1 Corvette that Dave found on eBay. With its wider rear body and 24-hour endurance record notoriety, the ZR-1 was the perfect donor car for the project. This particular coupe had been driven hard, but fortunately had the original Lotus-designed 5.7-liter aluminum V-8 with its innovative DOHC and four-valve per cylinder configuration still under its long sculpted hood.
Familiar with the complete Corvette product line, Dave has logged over half a million miles in one body type or another. Relying on the relatively smooth aerodynamic shape and affordable cost of a C4, they decided to pursue a record in the Grand Touring Sport or GT class, using the newly acquired ZR-1. Setting their sights on a record in the “C” engine category, which has a maximum displacement of 6.1 liters using a naturally aspirated motor, Dave assembled an experienced team and began the task of modifying a sports car designed with a 180-mph top speed and pushing it to exceed 230 mph.
With Rick as crew chief, they utilized his professional automotive garage for all the heavy lifting that is required to transform a sports car into a racecar. Dave selected Corey Henderson of New Braunfels, Texas, who has a reputation for precision Corvette engine work and owns a ZR-1 himself. At his shop, Henderson Performance Technologies, Corey was able to extract more power from the stock block by increasing the displacement to 372 cubic inches, bumping the compression to 12.4:1 and installing four race-prepped camshafts.
Most realize chasing a dream at Bonneville is similar to hitting a moving target. In 2008, when Dave decided to build a Corvette to compete on the salt, the C/GT record was 222.572 mph, established by the Carter family. By the time Team ZR1 completed their rookie year in 2009 with a best run of 218.768 mph, Russell Duffin of Jan Berry Motorsports had bumped the C/GT record to 230.545 mph. As Corey candidly confided, “When you are already theoretically at the limit, a 10-percent increase is a lot!”
Over their second winter, the team rebuilt the ZR-1 drivetrain. Rick and Dave bolted a Jerico five-speed transmission into the C4 frame. Corey upped the compression to 14.1:1 and fabricated velocity stacks and fuel rails to feed the thirsty V-8. Next, they dumped a bunch of money into reducing the valvetrain weight by 40 percent and removed the alternator and power steering pump to reduce drag on the engine. Ultimately, the 20-year-old naturally aspirated aluminum block delivered 730hp on the stand and 605hp at the wheels, which is considerably more horsepower than a new 2011 supercharged ZR1.
To oversimplify the GT class, the stock body must remain the same as production specs. In the case of this
ZR-1 Corvette, that includes small details like a functioning third brake light mounted above the rear window. The only body modifications that are permitted are the addition of roof rails for aerodynamic safety, removal of the side mirrors and modifications to the hood. Forgoing the solution of adding a large hood scoop used by other GT class record holders, Team ZR1 chose to implement a low-profile induction inlet at the front of the stock hood, which adds natural boost when the car exceeds 200 mph.
With the modifications complete, the original 3,500-pound Corvette had grown to a healthy 5,000 lbs. Adding to the weight was 120 feet of 1.75-inch mild steel tubing carefully bent and welded to form the SCTA-mandated roll cage. A complete fire suppression system was also installed. Looking inside, it is evident that the luxurious Corvette interior had been gutted. With the exception of a few minor dashboard gauges and some vent buttons, an assortment of hand-labeled toggle switches have replaced the stock controls, while a large four-inch Auto Meter tachometer is centered on the dash.
At the 2010 Speed Week, Dave made several successful passes on the long course with the best of 224.825 mph. Later that week, Rick jumped behind the wheel and earned his A and B licenses. With extensive drag racing experience by Thursday, Rick had pushed the Corvette to an impressive 225.948 mph in the measured mile.
It gave them a timing slip with an exit speed of 227.207 mph, thus making their stock body Corvette the world’s fastest ZR-1. Even better, the exit speed was only three mph off the C/GT class record!
A race program with this level of conviction requires support from several, including engine tuner Kevin Neuse, mechanic Dave Trumbo, fire systems manager Jack Andrews, engineer Jack McClanahan and a remarkably long list of family members, including spouses and children. Everyone has a job during Speed Week, from stowing the driver’s helmet and firesuit between runs, to selling T-shirts in the pits. Even the team’s generous decision to support the Texas Children’s Hospital on the race car speaks volumes. Through their assistance, they have raised over $25,000 for this remarkable institution, while giving the kids back in Texas a racecar to cheer.
As the team preps for their next attack on the salt, discussion of lowering the stance of the C4 is at the top of the list. Making the Corvette ride even 1/8-inch lower could mean a record-breaking difference.