2009 Chevrolet Corvette ZR1 - Auto Shows
Head for the fallout shelter: The beastly Corvette ZR1 is gonna wreak some havoc.
The ZR1 is the most expensive and most powerful production Corvette in history, with a price of about 100 grand ($110,000 for the loaded 4LZ trim level) and an estimated 620 horsepower at 6500 rpm and 600 pound-feet of torque at 4000 rpm from its supercharged LS9 6.2-liter V-8.
It is the first factory-built Corvette to feature forced induction, and it will also be the first Corvette to top 200 mph off the showroom floor. The idea that such a Vette could exist is certifiably bonkers.
And yet here it is. Thank you, Rick Wagoner. Thank you, Bob Lutz. And thank you, Corvette vehicle lead engineer Tom Wallace.
The Heart of the Beast
Spearheading the myriad mutations needed to turn a run-of-the-mill Corvette into a ZR1 is, of course, that blown hunk of aluminum residing between the front wheels. Contrary to what you might think, the LS9 isn't based on the Z06's 7.0-liter LS7 but rather the base Vette's 6.2-liter LS3 (the LS3 has 76-percent carryover parts) with which it shares a 4.06-inch bore and a 3.62-inch stroke. The LS7's cylinder walls were deemed too thin to reliably handle the extra grunt of the supercharger. The LS9 has been validated to 150,000 hours and had no piston, rod, or crank failure in 6800 cumulative dyno hours. The hand-assembled engines come from GM's Performance Build Center in Wixom, Michigan, and each one is hot-tested before it goes out the door.
The all-new blower is provided by Eaton and is the sixth in its series of Roots-type superchargers. This Twin Vortices Series rides between the cylinder banks, making max boost of 10.5 psi, and Chevy claims an increase in efficiency and noise reduction over past superchargers. An air-to-liquid intercooler sits on top of the supercharger. By lowering the engine inside the car, engineers were able to avoid the telltale hood bulge required for most superchargers. As a result, hood height only increases an inch, although there is little space between the outside of the hood and the engine.
Other less noticeable changes were made under the hood, too. The LS9's heads are made of an alloy meant to handle higher temperatures, and they sit on four-layer steel gaskets rather than on the two-layer ones found in the LS3. The intake ports have swirl wings, which increase the efficiency of the combustion process but unfortunately also cramp airflow. The supercharger's forced air, however, mitigates the airflow problem, according to Corvette engineers.
The LS9 uses a forged steel crank and pistons and has a lower 9.1:1 compression ratio compared with the 10.7:1 ratio of the LS3. The connecting rods are titanium, like the LS7's. The LS3 and the LS9 have identical valve diameters, but the blown engine gets titanium intake and sodium-filled steel exhaust valves.
The Rest of the Voodoo
As the LS9 does its work, its many, many ponies invade the transmission, where they encounter a beefed-up six-speed Tremec unit with closer ratios than the one found in the Z06. However, first gear will still be good for 60 mph, ensuring insane performance stats. A dual-plate clutch offers enough feel and modulation, according to Chevy, to make launches a snap. We expect 0 to 60 in 3.5 seconds or better and the quarter-mile in 11.0 seconds.
The spring rates have been softened from those of the Z06, and the ZR1 will get as standard equipment the second generation of Delphi's auto-reactive magnetic shocks tuned to produce a docile ride around town in a car that required a new speedometer to 220 mph. The footwear is fat. The ZR1 gets 285/30-19s up front and 335/25-20s at the rear. By comparison, the Z06 uses 275/35-18s in front and 325/30-19s in the rear. As GM vice-chairman and head of global product development Bob Lutz puts it, "It's wonderfully easy to drive, but once in it, Clark Kent turns into Superman."
The Corvette uses the same Brembo carbon-ceramic brakes as the ones found on the million-dollar Bugatti Veyron supercar. Vented and cross-drilled discs measure a whopping 15.5 inches at the front and an even 15 at the back. The front calipers utilize six pistons and the rears four. Essentially, everything was brought up to the level needed to handle the rush of power the car can create, says Lutz.
The ZR1 will likely weigh 150 more pounds than the roughly 3200-pound Z06, despite the liberal use of carbon fiber for the hood—which has a see-through panel in the middle for an excellent view of the top of the intercooler cover—front fenders, sill extensions, front splitter, and roof. The car has eight major panels of carbon fiber compared with six made of other materials. GM says the ZR1 will be first to offer clear-coat carbon-fiber exterior panels designed to last the life of the car. The chemical additive in the clear-coat costs more than $60,000 a gallon, officials say.
The weight gain was inevitable, given all the extra hardware under the hood. "It's literally like being fired out of a slingshot in a time-warp continuum," Lutz says, but with stability enhancement to help keep the tail straight when nailing the throttle while exiting a corner.
Production starts in July, and the ZR1 will be on sale in August or September. GM can build about 2000 ZR1s a year with a choice of seven colors. Each car will have a unique VIN that incorporates the sequential build number, which should please collectors.
The Vette to End All Vettes—Literally
Since its launch, the Z06 has always been "the best dollar-for-dollar sports car on the planet," but that's kind of like being called the "best pound-for-pound fighter" in boxing. You might be very good, but there are still bigger, stronger opponents out there who'll knock you flat on your rear. In the case of the Ferrari 599-baiting ZR1, however, it doesn't look as though we need any qualifiers whatsoever—it's going to rock, plain and simple.
And with the fear that high-performance vehicles like this may be legislated out of existence in the future because they can't meet emissions standards, we plan to enjoy every minute we can, just in case.
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