Fork in the Road

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Since the ZR1 already has world-class Magnetic Selective Ride Control suspension and one of the best carbon-ceramic braking systems around, the running gear was left stock, as were the interior and bodywork. For drag-strip use, though, Alepa did buy a set of custom-offset 18-inch CCW SP 18 wheels shod with Mickey Thompson drag radials in back and M&H fronts. LMR’s Ledford says the ZR1 could use Driveshaft Shop halfshafts if serious drag racing was contemplated, but other than that the ZR1 chassis is up to the extra muscle.

Ready, Aim, Fire!

So how do the two compare? Alepa’s best quarter-mile time is a sizzling 9.93 seconds at 140 mph, while Cox has ripped off a 9.40 at 155 mph using only 1,000 of his 1,200 horses. We expect the turbo Vette to be in the low nines when all the power is deployed. But the raw numbers only tell part of the story.

We test-drove the two LMR cars at Lonestar Motorsports Park near Houston. While they both accelerate explosively, the experience of getting them off the line is very different. The ZR1 has been upgraded with a twin-disc clutch that requires a fine touch to operate; it’s almost like having an on-off switch mounted on the floor. The C6’s automatic makes it easier to launch, and it also allows you to keep both hands on the wheel‚Äîa reassuring attribute when confronted with this much horsepower.

Both cars sound like top-fuel dragsters at idle, particularly when their muffler are bypassed; that steadily rising staccato rumble has to be every Viper and Shelby owner’s worst nightmare.

The blown ZR1 is definitely happier at low speeds than the more radical C6 turbo, but the two Corvettes feel very similar at higher velocities, with prodigious amounts of instantaneous power. In the end, the twin-turbo does cover ground more quickly, but it is also more of a handful to drive than the ZR1.

Not surprisingly, the C6 doesn’t make as comfortable a street cruiser as the ZR1. It runs warm on hot days. Also, Cox only feeds his monster racing fuel, although Ledford says 93-octane pump gas could be used as long as the boost was dialed back, dropping output down to around 900 horsepower. As already mentioned, the ZR1 loses roughly 60 horsepower on standard fuel.

The Final Tally

So how do the two approaches compare in terms of dollars spent? Well, a new C6 coupe starts at around $50K. Bringing it up to the spec of Cox’s Corvette would set you back another $100,000, for a total price of $150K‚Äîgive or take a grand or two. Lopping over 3 seconds from a standard Corvette’s quarter-mile time is an impressive feat, but it comes at a high cost.

A new ZR1 lists for around $107,000. Our featured car had about $20K in upgrades performed on it, for a total expenditure of roughly $130K. Its quarter-mile time dropped about 1.4 seconds, so not only is the ZR1 conversion cheaper overall, it provides a higher performance return on each tuning dollar spent. The supercharged car is also more civilized. But in the end, it is at least a half second slower through the quarter than the sizzling red turbocharged C6.

You make your choice, you pay your money‚ but you win either way.

Also from Issue 59

  • C6 show car
  • State of the collector-car market
  • Interview: Jim Campbell
  • 1972 LT1 coupe
  • Pratt & Miller LS7/LS9 engine
  • History: 1960 24 Hours of Le Mans
  • Racing: Laguna Seca ALMS
  • How To: C2/3 frame repair
  • 1965 small-block coupe
  • 1972 LT1 coupe
Buy Corvette magazine 59 cover
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