And in the Other Corner…

Andrew Alepa also wanted a killer Corvette, but he went about creating one in a different way. Instead of buying a base C6, he started out with a top-of-the line ZR1. However, just like Cox, Alepa found himself driving to LMR not long after returning from the dealership.

Since the ZR1 already packs 638 bhp from its supercharged LS9 powerplant, LMR didn’t need to perform a complete engine swap to make the mega power Alepa was after—but a standard tune wouldn’t cut it, either. The company’s mild Street Stalker upgrade package for the ZR1—with American Racing stainless-steel headers, low-restriction catalytic converters, an X-pipe and an air-induction kit—wasn’t enough, so it had the standard heads ported by “Slick Rick” McConathy at Naiser Racing Components in Houston. The cam was replaced by a custom grind designed by LMR and machined by Comp Cams. Most significantly, a new pulley ups the boost from 10.5 to 16 pounds. In addition, a bigger intercooler provides a denser intake charge.

The result is 753 rwhp on 93-octane fuel and 810 rwhp on 109 octane, making this the most powerful street ZR1 we’re aware of.

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—a 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.