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Tarmac Twister Shootout - Part 2

Lone Star Edition, Part 2

Randall D Allen Jul 14, 2010
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Tarmac Twisters: A term not normally used to describe the essence of Corvette, but rather brutish old-school cars swilling 116-octane leaded gas and tearing up the drag-tracks of this fair land. But do superb handling and a refined driving experience necessarily mean that a Vette can't excel at drag racing? We think not, and to prove the point, we issued a shout-out to Texas-area tuners and enthusiasts to bring out their high-powered late-model Vettes and turn them loose on the 1,320. The venue for the event was Lone Star Motorsports Park in Sealy, Texas, located just west of Houston alongside I-10-squarely in the epicenter of the state's notorious C5 and C6 horsepower wars.

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A total of seven Vettes accepted the challenge, four of which remain. In our second installment, we'll turn up the power numbers and ratchet down the e.t.'s to show you an eclectic mix of brutal late-model builds. Diversity is evident in the alphabet soup on LS-series blocks on hand, with LS3, LS7, LSX, and Warhawk all represented. Twin-turbos will battle it out against heavily juiced cars and even a single naturally aspirated entry. How will the foes fare against each other, and will they put down impressive numbers or simply obliterate their tires? We're about to find out.

Author's note: LSMP is located 185 feet above sea level, and on a cool day the track can support record-shattering runs. Unfortunately, ambient temperatures on this day topped the century mark, and the combination of barometric pressure and dew point made the air similar to racing at 3,000 feet. Although we won't "correct" the e.t.'s to reflect sea-level conditions, suffice it to say that with these corrections, the runs that follow would have been notably quicker.

We'd like to thank the crew of Late Model Racecraft and Lone Star Motorsports Park, who made this event possible, as well as the great group of volunteers who kept things running smoothly throughout the day.

'06 coupe
Peek beneath the hood of R.C. Cox's screaming-red Z06 clone, and it's obvious that the car is a technological wonder. With street-legal power as his goal, the self-employed electrical contractor teamed up with Late Model Racecraft (LMR) in Houston to put together one unique boosted warrior.

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The stock LS2 was replaced by a World Products Warhawk LS7X aluminum block displacing a gargantuan 440 cubic inches. All Pro LSW race heads offer tremendous flow while dropping compression to a boost-safe 9.2:1, allowing the intercooled APS twin-turbo system to cram in upwards of 20 psi of boost. An RPM Transmissions 4L80-E automatic and a full Pfadt suspension makeover help keep the power in check. After some initial teething problems, the combo put down more than 1,030 hp on the LMR chassis dyno on a mere 15 psi of boost.

For obvious reasons, Cox and the LMR crew were concerned that traction would be the limiting factor at LSMP. Simply stomping the go-pedal off idle resulted in a 60-foot time of 1.73 en route to a jaw-dropping 9.40 at 155.23 mph. A second off-idle run brought another 9.40. With those numbers in the books, Cox decided on his next pass to release the trans brake at 2,500. Things were looking great, with a 60-foot time of 1.66, before the drag radials lost purchase and spun. The car eventually recovered to run a 9.79 at 153.58 mph.

With the heat of the day taking over, and track temps soaring, Cox would prove unable to better his first three passes. Still, it's worth pondering what his C6 would be capable of with a pair of slicks and some cool, dense air.

'01 Coupe
After owning his '01 C5 for a little over a year, Austin Hickman decided to take the mildly modded Vette to a new level and employed Gary Harmon and Horsepower Engineering (HPE) in Houston to do it. HPE is well known for wringing maximum power out of LS engines, so the shop was well suited to the task of building a nasty LS7 stroker inhaling copious amounts of nitrous oxide.

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The 440ci engine features Trick Flow GenX 235 heads that provide a compression ratio of 11.5:1. A custom Nitrous Outlet direct-port nitrous system is set to kill with a 300-horse shot and an FJO progressive controller. A look beyond the engine reveals adjustable QA1 shocks at each corner and a battle-hardened Dynotech Engineering rear that receives power via an RPM Transmissions Level 6 4L60-E automatic. On the dyno at HPE, the LS7 put down 550 rwhp on motor alone and a tad more than 850 with the juice flowing. Having already ripped off a 9.67 on drag radials prior to our event, Hickman's C5 looked like a real contender for low-e.t. honors.

Hickman started by setting the progressive controller on a 70-300hp ramp, dialing in the shocks (10 clicks up front and 5 in the rear), and launching at 1,500 rpm. The result was an impressive 60-foot time of 1.61 en route to a 9.69 e.t. at 145.73 mph. Hickman kept tuning the suspension and nitrous settings, and by the fourth run the car had improved to a 9.56 e.t. at 149.5 mph. The final run was the most aggressive of the day, with a 120-300hp nitrous ramp yielding a 9.54 e.t. at 149.55 mph.

Hickman had smashed his previous best while managing the impressive feat of getting consistently faster as the day wore on. With future plans calling for a dual-stage 500hp nitrous shot, this C5 should be a legitimate 8-second contender in better weather conditions.

'08 Coupe
Tommy Young describes his Velocity Yellow '08 as "basically a stock car built to murder built cars." And with a prerace timeslip showing a 9.92 at 142 mph, the 25-year-old asphalt paver doesn't appear to be engaging in hyperbole. The journey began at Late Model Racecraft (LMR), which installed its C6 Street Stalker package featuring stainless-steel headers, a high-flow exhaust, an air-induction kit, and custom tuning. While the Vette got a significant bump in power, up to 475, Young knew there was much more work to be done to reach his e.t. goals.

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The C6 went back to LMR, where it received a Cold Fusion Nitrous dual-plate kit employing a 100hp shot in the first stage, followed by a 175hp shot in the second. Rear-wheel output jumped to 570 hp and 659 lb-ft on the LMR dyno. A dedicated fuel system for the nitrous-featuring a Holley "blue" pump and fuel cell-allows the stock fuel injectors to remain untouched. Other than an MSD window switch that actuates the first stage at 3,000 rpm, the rest of the car stayed stock, right down to its automatic transmission.

Young lined up the car, planning to drive it like he had on his previous 9-second run: foot-brake to 1,800 rpm, spray the 100hp shot in First, then manually spray the 175hp shot right after the car shifted into each successive gear. But something clearly wasn't right on the first pass, and Young pulled the nitrous back to the 100hp setting through the end of the run. The board flashed a 1.65 60-foot, along with a 10.98 at 132 mph.

The same thing happened on the second pass, yielding a 10.974 at 132 mph. Worse, it was apparent that the 6L80-E six-speed automatic was starting to slip. Undeterred, Young decided to try spraying it in First, then getting deep into Second gear before enabling the 100hp shot again. He did, and trap speed increased to 137 mph on a 10.971 e.t.

Since our track outing, Young has installed an RPM Transmissions Level IV trans and a Circle D billet torque converter, mods that enabled him to run in the 9.80s. Murderous indeed.

'06 Coupe
Owning Corvettes runs in Jason Thornhill's family: In addition to his Le Mans Blue '06, Thornhill's mother and father both pilot Z06s. After driving his Vette for about a year, the 27-year-old business owner decided to vastly improve its performance with one of LMR's LSX-based 750hp Punisher Packages.

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After machining the GMPP block to 440 ci, the LMR techs topped it with Trick Flow's new GenX 245 Cylinder Heads, which flow upwards of 390 cfm. Combine that with a 12.5:1 compression ratio and a rowdy custom hydraulic roller cam, and you get 612 rwhp and 553 rwtq on the LMR dyno while running a conservative tune. Equipped with a T-56 manual and a race-ready RPS Street Twin Carbon clutch, Thornhill's flashy C6 would be the lone stick-shifter in this edition of our shootout.

Even with 10 years of racing experience under his belt, Thornhill had trouble getting the torque-laden C6 to hook up at the track. A conservative first-pass launch at 3,000 rpm decimated the tires, yielding a 2.65-second 60-foot time en route to a 12.1 at 126 mph. For the second pass, Thornhill dropped the rear-tire pressure from 20 to 18 psi, resulting in a much-improved 2.28 short time and an 11.83 e.t. at 126.

After cooling the car, Thornhill dropped the tire pressure another 2 psi and let LMR co-owner Steven Fereday make a pass. While Fereday could only marginally improve on the 60-foot time, with a 2.26, his shifting mastery became evident as the C6 screamed to an 11.49 at 128.2 mph. With the engine heat soaked and the session running late, Thornhill decided to call it a day.

Although his 440/T-56 combo couldn't best the automatics on this day, it won't be long before Thornhill gets his launch procedure sorted and starts cracking off some high 10s. Until then, he can take solace in the knowledge that the thrill of manually shifting this beast at 6,800 rpm on the open road will never fade.



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