Sunday, August 31, 2008

2009 Chevrolet Corvette ZR1

2009 Chevrolet Corvette ZR1

Chevrolet will pay for every new ZR1 owner to attend a high-performance driving school, probably at Bob Bondurant in Phoenix or Spring Mountain in Pahrump, Nevada, both of which feature Corvettes (and may end up getting the preproduction ZR1s we're driving today). A lapping session with ace development engineer Jim Mero at the helm is equally instructive and credits the Brembo brakes and Pilot Sports as the underappreciated heroes of this package. Mero initiates braking where mortal drivers accustomed to ordinary performance cars would be trailing off the brakes. Their power and fade-resistance seems infinite, and they're said to have glowed red while still providing confident retardation during 24-hour racing durability tests. He points out that with 638 horses on tap and a torque curve as wide as Montana, you can upshift early at convenient locations on the track without losing time.

Mero also carries way more speed through the turns than seems possible on a run-flat tire good for 20,000 miles of tread life and boasting reasonable rain performance. An asymmetric tread design with cornering rubber on the shoulders and rain channels inside, a special tread compound, and unique internal architecture conspire to deliver maybe 80 percent of a Pilot Sport Cup racing tire's peak grip with real-world liveability and more forgiving limits. (They're so grippy it took an hour for a ZR1-team driver to nail our smokin' sideways shots.) Our next ZR1 encounter will include testing, but here are some more Chevy-supplied numbers to chew on in the meantime: 1.01 g steady-state lateral acceleration, more than 1.2 g braking grip, and a 0-to-100-to-0 mph time of under 11.0 seconds, besting the Dodge Viper and Shelby Cobra benchmarks by at least a second or two. Oh, and let's not forget Mero's production-car Nurburgring lap record time of 7 minutes 26.4 seconds.

Having witnessed the true power of this chassis, speeds build quickly with increasing confidence during the next lapping session. The low hood affords a perfect view of every corner apex and accurate, nicely weighted steering helps keep a laser lock on the driver's intended line, but with 52 percent of the car's reasonably light 3350 pounds pressing down on 285/30R19 tires in front, the steering feel will never be confused with that of a mid- or rear-engine car, and exceptional care must be used when exercising the loud pedal if the various safety nets are all disabled (it's very forgiving in full nanny mode). Many of the same tech tricks that Porsche uses to make its rear-heavy 911s handle safely and neutrally have been employed just as effectively by the ZR1 team to tame this front-heavy ultra-powerful rear-driver.

Pit again to let the adrenaline subside, and then let's take a spin on some bumpy public roads to sample the suspension's Tour setting and assess the car's general commuting demeanor. A bit of supercharger whine can be heard before the exhaust opens, but aside from that the ZR1's as demure and docile as any other Corvette. The short sidewalls exact a ride-harshness penalty that's beyond what the magnetic shocks can entirely smother, but it's not punishing, and it's considerably less flinty than the Sport setting. Variable-ratio steering (now on all Vettes) makes low-speed parking maneuvers easier while ensuring sneeze-proof high-speed stability.

Okay, so we're shocked (and more than a little proud) that America's sports car established a lap-record at the Nurburgring. We're awed by its high handling limits and overall tractability. And 15 or 20 hot laps of a circuit like the Lutzring could probably convince any skeptic that $30K worth of hardware value has been added to the already impressive Z06. But will the Corvette faithful take our word for it without benefit of that track time and plunk down $105,000 for a base ZR1-let alone $10K more for the package that makes the car feel expensive (hand-stitched leather, full-power/memory seating, and Bose Nav/audio system)? Let's hope so, because it'll be way tougher convincing the Ferraristi or Lambophiles that they'll be happier in this better performing, more fuel-efficient, probably more reliable but-let's face it-less exotic looking and feeling Chevy. Maybe the ZR1 driving school needs to happen before the sale...

The difference between the 7.0-liter Z06's basso rumble and the ZR1's baritone roar is striking. Sure there are bigger lungs on the Z06, but the difference has more to do with what happens in the tunnel. Both use two big pipes with a crossover, but the Z06 has an H-configuration with a short connector pipe that simply allows the reverberations to bounce between pipes. The ZR1 uses an X connection that comingles the actual exhaust. The H-pipe setup tends to preserve a slightly rougher second-order sound in each pipe, while the X (or any single-exhaust system) results in a higher fourth-order sound. Both variants use an exhaust valve in the muffler, but the Z06's opens at 3500 rpm and still includes some sound-attenuating perforations, while the ZR1's opens more of a straight shot at 3000 rpm.

Hot-lapping the ZR1 makes it hard to imagine owners feeling the need to add power to this setup, but you know it will happen. And it won't be hard. Hack the engine-control chip to run more boost with slightly higher engine or supercharger revs and the power will come. But the team cautions that any additional power will drive temperatures up dramatically resulting in spark retardation unless a larger cooling circuit is installed, along with a taller intercooler poking through the hood and blocking the clean sight lines. Durability is also likely to suffer. As it is, to keep from blowing the heads off the team switched to four-layer gaskets, strengthened the heads, and fitted larger bolts torqued for 25 percent higher clamping loads.

Source: motortrend

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