High-Speed Pursuit

If you have a life and aren't completely distracted by cars, then you might not have heard of open-road time trial competitions such as the Silver State Classic and the Pony Express 100. Briefly, these competitions are sanctioned by two different organizations purely for the joy and thrill of driving as fast as you possibly can within the confines of your speed bracket. Your speed bracket is defined by the amount of required safety gear to run that speed. Rick Doria competes in the highest speed class, generally known as the Unlimited class, which means the only limits are those of the car and courage.

Rick currently holds the average speed record of 194 mph for Roger Ward’s C.A.R.S. Pony Express 100 set at the June 1997 race. This competition is held on a stretch of Nevada State Highway 305 south of Battle Mountain. During the run, the car was caught on radar doing 211 mph at the top of the course. Further into the event, after timing the car using GPS and landmarks, the personnel inside the aircraft reported a top speed of 218 mph for that portion of the course. That is one brutally fast Chevy, and brutally fast cars make for brutally hot stories.

Rick’s tale really begins when he bought the car from Sean Rowe, who campaigned it in the IMSA supercar series. It was an LT1 fuel-injected, small-block car, and in the nearly stock trim of the racing class, it had managed top speeds in the high-160-mph range. That wasn’t nearly fast enough for Rick. To be competitive in the Unlimited division, the car had to be capable of reaching top speeds into the 210-plus-mph area.

Rick isn’t a fan of electronic fuel injection, at least not yet. So he pulled the LT1 and planted in its stead a carbureted small-block engine that had been scheduled to power an offshore race boat. The engine doesn’t make a tremendous amount of power. According to Rick, it twists 450 hp to the rear wheels, which equates to roughly 525 hp at the flywheel.

He doesn’t like to talk much about his engine combination because there isn’t much to talk about. It’s just a basic aluminum-headed 355 with good rods and a good crank, 12.0:1 compression, an Edelbrock Victor Jr. intake, and a 750-cfm Holley carb and headers. Nothing exotic, just a reliable combination that makes peak power in the high-6,000-rpm range. He’s using a 3.07 final-drive ratio and pulls top speed with the Vette’s ZF six-speed, 0.75 overdrive ratio in Fifth gear. Assuming a 24.9-inch rolling diameter for the Hoosier P275/40ZR17 tires, that puts the engine at 6,600 rpm at 212 mph.

The engine’s power stats were taken at sea level, not at the rather steep Nevada altitude. The Pony Express course starts at 4,000 feet and climbs to 6,000. Some performance theorists believe that between 3,000 and 4,000 feet is the ideal altitude to get the best tradeoff between reduced aero drag and loss of engine power. That may or may not be precisely true, but there are performance gains to be had by driving through less-dense air as far as the aero horsepower is concerned. Engine power suffers, but it’s possible to reduce the effects of altitude on the engine by taking full advantage of ram air at 200-plus mph. You have to be attentive when you design a ram-air ducting system. One can just as easily design a low-pressure system. The trick to Rick’s intake is that both sides of the hoodscoop are open and both openings are in high-pressure areas.

Even with proper ram tuning, the new motor only pushed the car up to 174 mph. This still wasn’t fast enough to be competitive, but because the speed was drag-limited and not rpm-limited, Rick massaged the aerodynamics to find that extra speed. His first aero move was to install side windows, which were good for 8 mph, pushing the top speed up to 182 mph. He then tried a hard chin spoiler that extended nearly to the ground. This helped tremendously, pushing the car’s top speed close to 190 mph. The chin spoiler worked its magic by preventing the air stream from tumbling underneath the Corvette’s very busy chassis, which would create drag. A bellypan similar to the one used in the 1995 Ferrari F355 not only reduces drag to increase top speed, but it also improves high-speed stability. Other areas of aerodynamic improvement included removing the side mirrors and trimming the rear wing.

This last piece on the car is also crucial to achieving the ultimate speed. The rear wing is a high-drag component but necessary to prevent rear-body lift at high speed. The rear wing is the only adjustable aerodynamic control surface on the car, but at speeds of over 200 mph, you must be exceedingly careful when making adjustments. Adjustments are always a matter of compromise. Adding downforce also increases drag. But there must be sufficient downforce to keep the car glued to the ground at these incredible speeds. Too much rear wing downforce can also create lift in the front.

This racer doesn’t have onboard data acquisition, so Rick videotapes the car at high speed in order to fine-tune his combination. He changes the angle of attack a few tenths of a degree at a time until the car, while running its fastest, feels stable. Get this: He checks stability by making 200-mph lane changes! If he can toss the Vette around at that speed, then, he says, "It’s tuned properly." Having the opportunity to tune the aero and chassis before the race is one of the reasons he prefers to compete in Roger Ward’s Classic Auto Racing Society (C.A.R.S.) events. C.A.R.S. always arranges a practice course to allow racers time to set up their cars and, perhaps more importantly, get acclimated to the extremely high speeds they travel during the competition.

Now you may think that the ultrahigh speeds and the time spent up there is the scariest part of this kind of automotive thrill. Certainly that’s a major portion, but perhaps the scariest thing about this kind of racing is really tire choice. Tire choice can make or break the race and perhaps the car. Rick chose Hoosier DOT road-race tires for the Corvette, while setting the toe to zero to avoid heat and drag-inducing scrub. The tires are Z-rated, and he runs them strictly within the weight limits of the tire. Tire-inflation pressures are also crucial. The tire manufacturers recommend maximum-inflation pressure (as noted on the sidewall of the tire) for top-speed use, and Rick checks these pressures religiously before the competition

Despite his careful attention, Rick knows how a tire failure at speed feels. Fortunately, the car remained stable when the tire let go, though the car did move over about half the width of the road. He has a video of the incident and has watched it in slow motion. The first rotation of the tire shredded the entire left half of the hood. In the next revolution, the tire separated from the wheel, cracking the windshield before sailing over the top of the car. On its way out, the tire also cleaned off the power-brake booster, all the wiring from the main harness on the engine side of the firewall, the chin spoiler, the lower skirt, and the rear quarter-panel. About the only thing left untouched on the left side of the car was the door.

Rick says the tire lost air before it exploded, probably the result of a puncture. He felt it go flat, then detected the thinnest whiff of burnt rubber. Almost immediately the car picked up a vibration, and within a few seconds he was driving through a storm of fiberglass and tire smoke at 190 mph.

You’d think that experience would slow Rick down, but instead he plans to improve his Highway 305 record to a 200-mph average. "It’ll be tough," he says, "but if I can average 211 mph in the rest of the course other than the area of relatively tight turns--that should do the trick." That’s a feat Rick performs at more than 300 feet per second, so don’t blink.