Although the Corvette's history is long, rich, and heavily laced with glory, there are still chapters waiting to be written. For example, even in the days of laissez-faire power ratings, no production Corvette engine has ever produced 100 horsepower per liter, or topped 600 horsepower. Nor has there ever been a production Corvette capable of going more than 200 mph. The current Z06, according to Chevy, can only -- only! -- attain 198.
None of these shortfalls, if that's what they are, has kept us from calling recent Corvettes the best high-performance sports-car buys on the planet. Nevertheless, when the car you see here reaches Chevy showrooms this fall, those little blanks in the Vette's performance résumé will be filled in.
Is this really important? To the Corvette team, absolutely. For one thing, there's that new 600-hp Viper. But that's a subtext. In the big picture, the global extreme-performance ballgame, this is about -- with apologies to
Aretha -- R-E-S-P-E-C-T.
Here's how Corvette vehicle line executive Tom Wallace sums it up: "We want to push the technology envelope into the supercar realm. We want a Corvette that can take on any production car in the world."
A Corvette with no "for the money" asterisk. A Corvette capable of dancing with stars like the Porsche 911 GT2 and Ferrari 599GTB. Although "for the money" will still be an element. "It'll be a real bargain compared to cars like those," says Wallace.
Back story: According to chief engineer Tadge Juechter, the '09 ZR1 traces its origin to a 2004 meeting with General Motors CEO Rick Wagoner. Dave Hill was then the Corvette's high priest, and the meeting was to acquaint Wagoner with the formidable performance credentials of the Z06, which was approaching 2006 showroom readiness.
"Rick was really impressed," Juechter recalls. "He said, 'If you can do this for about $60,000, what could you do for $100,000?'?"
Hill treated Wagoner's question as an informal directive. A Z06-based development mule materialized, along with a code name: the Blue Devil. The Duke University athletic teams bear that nickname. Wagoner is a Duke graduate. Coincidence?
Blue Devil was considered as a name for the actual production car, as were Stingray, Corvette SS, Z07, and Z08. The ZR1 name was revived, minus the hyphen, recalling the then-radical Corvette of 1989-95. According to Wallace, "It came closest to representing a car with leading-edge technology and all-around everyday drivability."
It takes more than horsepower for a car to top 200 mph, but without big horsepower the subtleties are irrelevant, so let's start with what's under the carbon-fiber hood. You can see part of it without even raising the bonnet, thanks to the plexiglass window faired into the middle, but we want to see more than the intercooler.
Yes, intercooler -- a force-fed production Corvette. You could say the Corvette has been there before, via the Callaway Twin-Turbo of 1989, but that one was a dealer option. This one will come right off the Corvette line in Bowling Green, Kentucky.
The Blue Devil project started with a twin-turbo V-8 in a Z06, and it was an inauspicious beginning. After one week at GM's proving ground in Milford, Michigan, the mule burned to the ground.
Meanwhile, Eaton had developed a sixth generation in its series of Roots-type superchargers. Its impeller has four vanes, rather than three, with a tighter helix (160 degrees) to the spiral. It's not only more efficient but also much quieter than previous units, according to Chevy.
The Eaton blower -- R1900 -- nestles between the cylinder banks, straddled by an air-to-liquid dual-brick Behr intercooler. It's driven by an 11-rib belt that also turns the water and power-steering pumps. Max blower speed will be 15,300 rpm, and max boost for the ZR1 will be 10.5 psi.
The engine has a new designation -- LS9 -- but it shares the LS3 aluminum block used in the standard Corvette, with a 4.06-inch bore and a 3.62-inch stroke. Chevy chose the 6.2-liter rather than the 7.0-liter LS7 that powers the Z06 for durability reasons. The cylinder walls in the LS7 are too thin for comfort with forced induction. And achieving 100 horsepower per liter with the LS7 would equal 700 horses.
The LS9's aluminum block is the same alloy as the LS3's. The aluminum heads are essentially the same design as the LS3's, but the alloy -- A356-T6 -- was chosen to handle higher temps, and the casting process takes special pains to eliminate porosity. A departure from the LS3 is intake port swirl wings, a feature that promotes better combustion efficiency. It also reduces airflow, but the engineers note that this isn't a big problem in a boosted engine.
Although similar, there are detail differences between LS3 and LS9. For example, the valves are identical in dimension -- 55.0mm intake, 40.4mm exhaust -- but the LS9's intakes are titanium, and the exhausts are hollow-stem stainless steel. The ignition system is essentially LS7 -- same coils, same plugs -- but the coils are mounted directly to the rocker covers to save space. The head gaskets are four-layer steel versus two-layer in the LS3, with heftier (12mm) head bolts. The LS7 exhaust manifolds and catalytic converters are a straight bolt-on.
Below the banks, the LS9 uses forged steel pistons with a 9.1:1 compression ratio versus 10.7:1 for the LS3 in the '08 Vette. As with the LS7, the connecting rods are titanium, and the crank is forged steel. The oil system is dry sump but with additional provisions to combat oil starvation during episodes of extended side loading (e.g., the long carousel turn at Road America).
So what's the bottom line? We've heard rumors as high as 650 horsepower, but at this writing Chevy isn't talking specifics. According to Ron Meegan, assistant chief engineer on the LS9 project, the goal was a minimum of 100 horsepower per liter, and "we're definitely in the hunt to meet our target." How about torque? "We expect it to be close to 600 pound-feet." You can also expect a big percentage of this massive thrust to be on tap just beyond idle. And you can expect this to be the first Corvette subject to a gas-guzzler tax.
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