Forget the King of the Hill. Meet the God of the Mountain

By Daniel Pund, Senior Editor, Detroit Email

Date posted: 12-19-2007


You've waited long enough to hear the real deal on the 2009 Chevrolet Corvette ZR1, right? The nonstop, server-frying deluge of speculation, hoaxes, misinformation, wild-ass guessing and publicity-stunt silliness has dragged on just short of three years now.

In anticipation of the ZR1's introduction at the 2008 Detroit auto show in January, Chevrolet at last has opened the proverbial hood on this, the most powerful, most expensive and most highly anticipated Corvette in the model's half-century history.

Here, finally, is the real story.

"Greater Than 620 Horsepower"
All right, so there's one thing that we can't put a final figure to and that's the important one: the ZR1's power output.

But Ron Meegan, the assistant chief engineer for the new 2009 Chevrolet Corvette ZR1's supercharged V8 (and formerly a member of the original ZR-1's engine team from 1990-'95), says he expects that once the new car's supercharged 6.2-liter V8 is certified, it will produce "greater than 620 horsepower at 6,500 rpm and 595 pound-feet of torque in the 3,600-to-4,000-rpm range, depending on some last-minute tuning items."

So even GM doesn't have a final power figure yet. Although you can be sure that if Meegan's superiors allowed him to mention any figure to us, they're not worried about making those numbers. Remember, when the current-generation Z06 was unveiled, it came with a claim of 500 hp, and when the production car arrived it had a rating of 505 hp.

Whether the ZR1 is rated at 625 hp or 633 hp or whatever, it won't just be the most powerful Corvette production vehicle ever (including ones measured by the grossly overstated "SAE gross" figures of pre-1972), it won't even be close. The power produced by the ZR1's LS9 engine will be roughly the equivalent of three 1980s-era Corvette small-block V8s bolted together. It'll produce more power than the Corvette C6.R that races at the 24 Hours of Le Mans.

The Nordschleife on Chrome Rims, Y'all
ZR1 chief engineer Tadge Juechter says, "If a buyer really wants them, he can get chrome wheels on it," although he's letting us know that he would never do such a thing and he thinks you shouldn't either. But the ZR1 isn't a racecar.

Think of the Corvette lineup in Porsche 911 terms. The base coupe and convertible Corvette are analogous to the standard Carrera and Carrera S. The Z06 is the GT3 — the loud, hard-core choice of the performance junkie. The ZR1 is the Porsche Turbo. It's devastatingly fast, but it's also intended to be civilized. It's available with a head-up instrument display, power-adjustable seats, high-end audio and Delphi's smooth-riding MagneRide suspension dampers. It's no raw-boned racer. Hell, at 3,300 to 3,400 pounds, the ZR1 is almost 300 pounds heavier than a Z06.

Juechter adds, "It's sort of like the Turbo but for less money and with performance — more like the Carrera GT."

That's big talk. But, while Chevrolet is not yet making specific performance claims, Juechter notes that the ZR1 will be faster, quicker and more responsive in every way than a Z06. "You won't see a huge difference in 0-60 mph because even the Z06 is traction-limited through most of that," he says. "But in the quarter-mile and tests from zero to 100 mph to zero, there will be big differences."

And just to up the ZR1's chest-puffing quotient, Juechter notes this car "will be able to take the production-car track record at any racetrack." Ex-squeeze me? And no, the company has not done an officially timed run at the Nürburgring yet.

As for top speed, Juechter says only that the 200-mph speedometer of the standard and Z06 Corvettes has been replaced with a 220-mph unit, because the standard one is "grossly inadequate."

Hot Wheels
By now you probably have noticed that the ZR1 looks like, well, a C6 Corvette. The silhouette is, of course, the same and the overall dimensions are essentially identical to a Z06.

But there's a goodly helping of racecar bluster applied to this vehicle. It's hard to miss the hole in the hood that measures roughly 19 by 16 inches, for example. A clear polycarbonate window lets you see the intercooler cover with its fancy script. This is the ZR1's signature styling flourish. Truth be told, it's a bit Hot Wheels for our tastes. The hood is made from carbon fiber, and while the exterior has been painted, the underside retains its carbon-fiber's undressed matte finish.

The front fenders with their ZR1-specific twin-port gills are also made from carbon fiber. The prominent aerodynamic front splitter is — you guessed it! — carbon fiber. It sticks out proud of the nose by 4 inches at the edges, making it a dandy place to rest your Hummel figurine collection. Clear-coated carbon rocker extensions make the vehicle look almost subterranean. The top and B-pillar are covered in clear-coated panels of the stuff as well. This car will look wicked in black.

According to Juechter, GM has used a special super-secret additive to the clear coat to protect the unpainted carbon from the sun's ultraviolet rays. (UV rays can break down the resin that helps give carbon fiber its stiffness.) He claims that the substance costs $60,000 per gallon. But since the clearcoat needs only 3 percent of the stuff, the resulting clearcoat costs merely an absurd $2,000 per gallon. This mystery material was originally designed to protect circuit boards from UV. Juechter acknowledges only that the substance has no chemical similarity to mayonnaise and says, "We should probably not imply that it is edible anyway."

The front aero splitter is matched in the rear by a spoiler of a relatively modest height that is taller at the edges than in the center, a measure to combine an optimum balance between a decrease in aerodynamic lift and an increase in aerodynamic drag.

The wheels are a new design produced by Speedline, measuring 20-by-12 inches in the rear and 19-by-10 inches up front. They are covered (barely) by Michelin Pilot Sport PS2 tires, specifically formulated for this vehicle. At 335/R2520, the rear tires resemble something you might find in a steamroller; the fronts are a not-much-more-modest 285/R3019.

The interior is essentially identical to the regular Corvette. ZR1 badging and a boost gauge in place of the voltmeter are the only changes to the cabin.

Traction Limited
Even with the gigantic meats bolted to the backside, the ZR1 will be what is euphemistically called "traction limited." In other words, all that power just goes up into expensive smoke when you try to lay the power down.

And since launching a car with so much horsepower can become a violent, axle-hopping mess, Chevrolet has come up with two novel countermeasures.

First are the rear shocks. When you're stopped and the clutch pedal is depressed and you pile on some revs, the car assumes you want to launch it hard. It automatically softens the compression damping of the rear shocks, and this allows the rear end to squat and effectively shift more weight to the rear of the car for added traction. At the same time, the rebound damping of the rear shocks goes up to 99 percent of full stiffness. This means that the rear cannot spring back up under power in the up-and-down monkey motion of axle hop.

All this is perhaps the cleverest use of adjustable shocks that we've ever heard of. Also, according to Juechter, the standard magnetic shocks allow the ZR1 chassis team to use softer springs than the Z06 for a more compliant ride. To further mitigate power hop, Chevy has also fitted the ZR1 with axle half-shafts of different diameters (33mm on the right and 40mm on the left).

We'll see how all of this works next year when we finally get to drive the thing. We might just try a hard launch or, you know, several.

Stop, I Say
There should be no dispute about the effectiveness of the ZR1's brakes. The rotors are as large as or larger than most wheels were just a decade ago.

In what must be a very sweet moment for a longtime Corvette engineer, Juechter notes that the monster 15-inch Brembo carbon-ceramic rotors fitted as standard to the ZR1's rear wheels are the brakes originally designed for the front of Ferrari's 650-hp Enzo supercar. In the front of the ZR1, you'll find even larger 15.5-inch carbon-ceramic units.

Juechter says, "The only vehicle I know of that has these brakes as standard equipment is the 1,000-hp Bugatti Veyron." Then he adds with a grin, "Although I think you can get them as a $20,000 option on the Ferrari 599." We get the sense Juechter will be using these laugh lines many, many times in the near future.

The Price of Production
Chevrolet isn't about to tell us the price it intends to charge for the 2009 Chevrolet Corvette ZR1. But it tells us that the prime motivator for the project has been GM honcho Rick Wagoner, who asked, "What would a $100,000 Corvette look like?" The ZR1 is apparently the answer and we expect the car's list price will be near enough to the $100,000 mark.

Chevy says it is constrained by production of the carbon-fiber bits to only 2,000 ZR1s per year, and since it seems to us as if we've met almost as many Corvette nuts in our career with the funds to bid up the price significantly, we think the list price might be strictly academic in the first year's production.

So that's it. There's no more mystery Corvette. We'll have to just go ahead and go through the arduous task of driving the thing and testing it.

Shortly thereafter we'll begin speculating on the C7 Corvette and the circle of life will continue.

Hell, at 3,300 to 3,400 pounds, the ZR1 is almost 300 pounds heavier than a Z06.

Inside the Supercharged 620-hp LS9 V8

By Daniel Pund, Senior Editor, Detroit Email

Date posted: 12-19-2007


GM isn't just kidding around with the supercharged 620-horsepower V8 that's at the heart of the 2009 Chevrolet Corvette ZR1.

It'll produce more urge than the absurdly powerful twin-turbocharged Mercedes V12 or the race-bred V10 of the Porsche Carrera GT or nearly any other internal combustion engine ever produced for vehicular transport. Most important, the 2009 Chevrolet Corvette ZR1's V8 makes more horsepower than the Dodge Viper's new 8.4-liter V10.

And it will carry GM's 100,000-mile powertrain warranty when the ZR1 goes on sale next fall as a 2009 model.

That's Just Super!
The secret to this ridiculous power output figure is no secret at all. It is in large part the doing of the Roots-type supercharger, one of the oldest tricks in the engine builder's book. More than a century after it was devised, this fundamentally simple air compressor helps Chevy's pushrod small-block (itself devised more than half a century ago) develop at least 100 hp per liter.

For those challenged by arithmetic, this means the displacement of the ZR1's engine is 6.2 liters, the same size as the V8 of the standard 2008 Corvette. But, you say, "Why wouldn't they throw the supercharger on the 7.0-liter Z06 motor and make, like, a million horsepower?" But Ron Meegan, the assistant chief engineer for the new 2009 Chevrolet Corvette ZR1's supercharged V8, replies, "The LS7 is a pretty polished beast. There's not much more to be had there."

Also there's the little issue of block strength. As it is, the 6.2-liter block, which is the same physical size as that of the 7.0-liter, had to be substantially strengthened for supercharged duty. Overall, the LS9's block is 20 percent stronger than that of the standard LS3.

Why not turbocharging? "Well," says ZR1 chief engineer Tadge Juechter, "we built a turbo car and it burned. We didn't want to get into turbo lag or any drivability issues. We wanted it to be quicker than hell but still fun to drive."

More Lobes, More Power
Juechter tells us that supercharging has been more important to the project than you might realize. He says, "Honestly, had Eaton not come up with this new, more efficient, sixth-generation supercharger, we might not have done the car at all."

Meegan tells us that Eaton's Twin Vortices Series (TVS) supercharger uses four-lobe rotors in place of the conventional three-lobe units, making it quieter and more efficient. The parasitic loss to drive the supercharger is around 70 or 80 hp, but it would have been more like 120 hp with the old supercharger, Juechter says. For the LS9, the supercharger cranks out 10.5 psi of boost.

And for those of you who dream of swapping out the stock supercharger pulley to make like a billion horsepower, be aware that Meegan says, "We don't want people to do that. We have not made that easy."

Wild Ride
The air molecules lucky enough to get sucked into the ZR1's V8 take a pretty straight shot through the intact tract, through the air filter, throttle body and into the supercharger inlet, nestled between the V8's cylinder banks. After that, things get a little circuitous.

The intake air molecules then get squeezed through the counterrotating rotors that look like gigantic black licorice twists. It then gets pushed up through a triangular hole in the top of the supercharger housing in between two long, narrow intercoolers. A 90-degree turn either left or right leads our molecular heroes to an intercooler that Meegan claims can lower the air temperature by 140 degrees F. The intercoolers are connected to a heat exchanger in the car's nose and filled with standard-issue antifreeze.

Once through the intercoolers, the now-chilled air takes another 90-degree turn down into the left or right cylinder bank of the engine. Here it will enter a combustion chamber (the compression ratio is 9.1:1) through intake valves that have the same diameter as those in the heads of a standard LS3 V8. The LS9's intake valves are made with lightweight titanium, however, and are set in cylinder heads made from high-strength aluminum.

Sandwiched between the heads and the block are head gaskets twice as thick as standard LS3 gaskets in order to cope with the upward force that's trying to send the heads through the hood. Upgraded fuel injectors are connected to a dual-pressure fuel delivery system (low pressure for low throttle load situations; high pressure for high load). New forged-aluminum pistons (cooled by oil squirters) are connected by titanium rods to the steel crankshaft.

Spent air exits through exhaust manifolds identical to those on an LS7 motor and through 3-inch exhaust pipes capped off by vacuum-actuated flaps as seen on the Z06. The LS9's oiling system is similar to that of the Z06's LS7 as well. It uses the same dry sump as the LS7 but has an additional 2.75-quart auxiliary tank that helps keep oil where it needs to be in a car that Juechter says can post lateral acceleration figures "comfortably over 1g."

It might seem strange, but the LS9 uses a lower-lift cam than the one used in the LS7, resulting in an idle that Meegan says is 11 percent smoother. Isn't this the baddest, leanest, most extreme, track-scorching, widow-making Vette from hell? Well, apparently, no.

Power Delivery
The monster motor is backed by a six-speed manual transmission that is a strengthened version of the TR6060 transaxle used on the standard '08 Vette.

This is a true close-ratio unit, unlike those of other Vettes, and 6th gear is no longer a fuel-saving ratio but instead the gear in which top speed can be achieved. "This buyer says, 'I can buy the gas. Just give me the performance,'" says Juechter.

A twin-plate clutch replaces the standard single-plate of all other Corvettes to handle the extra power and keep clutch pedal effort roughly equal to that of the Z06.

Show and Tell
Chevrolet is sufficiently proud of this supercharged small-block to give it its own window in the hood of the 2009 Chevrolet Corvette ZR1. In fact, the ZR1's signature feature is this clear polycarbonate porthole that reveals the LS9's integrated supercharger/intercooler unit. That should leave no doubt about which element of the ZR1 is most important.

We would imagine that the company could find more uses for this admittedly expensive powerhouse. Maybe GM should put it into all the Cadillac CTSs, Cadillac XLRs, Chevrolet Camaros, Pontiac G8s and — what the hell — everything else the company builds. If you believe Mr. Robert Lutz, GM's product potentate, future CAFE standards will kill all but the lowest-volume, highest-priced performance cars in the world.

Neither Meegan nor Juechter gave us fuel-economy estimates on the ZR1 and we didn't bother to ask.

The ZR1's hood is made entirely of carbon fiber, a strong lightweight material. A clear polycarbonate window allows a view of a cover over the intercooler, which cools air coming in to the supercharger, allowing for higher compression and more power.
When the hood is open, the black weave of carbon fiber is visible on its underside. Carbon fiber is also used in the car's widened fenders, and it can be seen on the car's roof.

Think of the Corvette lineup in Porsche 911 terms. The base coupe and convertible Corvette are analogous to the standard Carrera and Carrera S. The Z06 is the GT3 — the loud, hard-core choice of the performance junkie. The ZR1 is the Porsche Turbo. It's devastatingly fast, but it's also intended to be civilized. It's available with a head-up instrument display, power-adjustable seats, high-end audio and Delphi's smooth-riding MagneRide suspension dampers. It's no raw-boned racer. Hell, at 3,300 to 3,400 pounds, the ZR1 is almost 300 pounds heavier than a Z06.

9. ZR1 will offer one upgrade package, consisting primarily of the hand-sewn Draexlmaier leather interior and navigation, priced around $10,000