Arctic Assault 2004 Corvette conversionFrom the February, 2013 issue of Vette By Christopher R. Phillip Photography by Courtesy Of Redline Motorsports
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So it’s the last year of the sixth-generation Corvette. How do you usher out the car with the same level of excitement it enjoyed upon its introduction in late 2004? For Chevrolet, the answer was simple: a 427 convertible. But what if even that big-inch bruiser isn’t sufficiently exhilarating for your needs? What do you do? For Jimmy Page (no, not the Led Zeppelin guitarist), having one of Edelbrock’s new 720hp, 416ci LS engine packages dropped into a ’13 Grand Sport convertible was the perfect way to celebrate the C6’s spectacular nine-year production run.  01 With 325 miles on its odometer,...  01 With 325 miles on its odometer, this brand-new ’13 Grand Sport convertible is ready to have its horsepower multiplied by a factor of 1.6. That means the 436hp stocker will soon be pumping out an estimated 720 hp at the flywheel…  02 …thanks to Edelbrock’s...  02 …thanks to Edelbrock’s new 416ci supercharged package, shown here.  03 To get things rolling,...  03 To get things rolling, Redline Motorsports dyno tests the showroom-stock GS. The results—425 hp and 401 lb-ft at the rear wheels—reveal this Vette may have left the assembly line with more power than GM advertised. “Typically our dyno reports 390 to 408 rwhp on the [’12] Grand Sports, so the 425hp peak is quite a surprise,” says Redline owner Howard Tanner.  04 Tanner and his team decide...  04 Tanner and his team decide the best approach is to drop the entire drivetrain, which is how Corvettes are assembled at the factory, only in reverse. “This method requires a lift, and a good understanding of how Corvettes are constructed,” Tanner says. “The…advantages are that all the harnesses can be installed as they were from the factory, and the body is nowhere in harm’s way during the installation.” The task is more complicated than this photo shows. The electrical, fuel, coolant, and air-intake systems were disconnected, as well as the steering, the front and rear upper control arms and shock mounts, the brake calipers, the exhaust, the chassis grounds, and the center console/shifter assembly.  05 Once removed, the stock...  05 Once removed, the stock drivetrain rests safely on rolling carts. The torque tube and bellhousing will be unbolted, so that the LS3 long-block can be easily extracted.  06 Redline technician and...  06 Redline technician and head fabricator Jay Healy pins the E-Force supercharger crank pulley onto the keyed crank of the LS 416. If he tried to do this after the new engine is installed, the steering rack would be in the way. VETTE magazine caught the conversion from start to finish. We’ll share with you the highlights of the build and its results momentarily, but first the backstory. In April 2012, Page learned that Redline Motorsports had relocated from upstate New York to a new facility in Pompano Beach, Florida, just a short drive from his home. Having previously bought a 427-powered ’11 Camaro HTR-600 from Redline, he found the late-model performance tuner’s southward move especially fortuitous. He met with Redline owner Howard Tanner, and soon the two men had hatched the idea for another über-performance LS car. Within a day of that tête-à-tête, Page was on the phone to Rosner Chevrolet in Melbourne, Florida, ordering a beautiful new Arctic White ’13 Grand Sport drop-top with a contrasting red-leather interior.  07 After swapping a few more...  07 After swapping a few more of the OEM parts—including the valve covers, coils, oil pan, and water pump—Redline’s Mark Hoffman bolts up a set of American Racing long-tube headers with 17⁄8-inch primaries. Note that they were powdercoated black before installation.  08 After mounting Edelbrock’s...  08 After mounting Edelbrock’s LS 416 in the engine cradle, hooking up the factory wiring harness, and adding OE trimmings, Tanner and Hoffman bolt up the E-Force supercharger, idlers, and tensioners. When done, the men will install Siemens 74-lb/hr fuel injectors and stock fuel rails.  09 Hoffman installs a Lingenfelter...  09 Hoffman installs a Lingenfelter twin-disc billet-steel flywheel and a factory ZR1/LS9 clutch. “I like using this setup, as it easily handles the power increase, [along with] a factory-defined pedal feel and none of the chatter, which is common in aftermarket dual-disc clutches,” Tanner says. With this task complete, the men will bolt the torque tube and bellhousing to the drivetrain.  10 Hoffman swaps out the stock...  10 Hoffman swaps out the stock slave cylinder for a taller unit specifically engineered for the ZR1.  11 The Vette’s stock fuel...  11 The Vette’s stock fuel tank is upgraded with a factory LS7 pump.  12 The upgraded drivetrain...  12 The upgraded drivetrain is reintroduced to the Grand Sport’s body. Afterwards, the Redline team will reconnect the Corvette’s vital systems and install the supercharger’s cooling system. For spark, they’ll employ a set of NGK TR6 plugs, which have a colder heat range than stock to accommodate supercharged applications.  13 After the installation...  13 After the installation is double-checked, and fresh coolant and oil are added, Tanner uses EFI Live software to upload a custom calibration to the stock E38 engine-control module.  14 It’s then back to the ...  14 It’s then back to the dyno…  15 …where the blown GS puts...  15 …where the blown GS puts down 629 hp and 612 lb-ft at the rear wheels. That’s a mind-blowing increase of more than 300 horsepower. “We left the supercharger’s upper and lower pulleys stock for this project,” Tanner says. “We could have easily swapped some smaller pulleys and made over 725 rwhp. The motor can handle 12-14 lbs, versus the 8-9 lbs we fed it.” Once the car’s production week was set in stone, Tanner dialed up Edelbrock Performance and ordered one of the company’s new 416ci LS engines (PN 46720, MSRP $14,878.95), along with an E-Force supercharger (PN 1591, MSRP $8,805.95). The supercharged 416 package is brutal. It’s built by Shaver Specialty Racing Engines of Torrance, California, which has been creating competition race engines since the 1930s. Ron Shaver, a third-generation engine builder, starts with a new LS3 block, bores it to 4.065-inches, and drops in a bulletproof Manley rotating assembly—specifically, a forged-steel crank, H-beam connecting rods, and forged-aluminum pistons good for a blower-amenable 9.5:1 compression ratio. Topping this big-cube small-block are a set of LSA heads, which are outfitted with 2.165-/1.59-inch valves, Edelbrock Sure Seat beehive valve springs, and 1.7:1 rockers. Completing the package is the highly regarded E-Force blower, which uses a modified version of the Eaton TVS2300 rotating assembly found on the ZR1’s 638hp LS9.  16 With its hood pointed to...  16 With its hood pointed to the sky, the Grand Sport ’vert shows off its new supercharged mill.  17 The Vette tests its new...  17 The Vette tests its new tire-melting capabilities at Palm Beach International Raceway. According to Tanner, “The car just destroys the tires, and every gear feels strong. There’s no surging or bucking, and if the exhaust valves are closed, you can hardly tell it has a hotter cam in it.” With a “soft” launch technique, and testing subjected to oppressive 3,250 density-altitude weather, Tanner clicks off a best e.t. of 11.31 seconds at 125.65 mph. “Based upon the power we measured at the dyno, track temperatures of 130-plus degrees (F), and air temps across the blower approaching 160 at the end of the track—which pulled spark from timing—we should easily get to low 10.90s at over 132 mph in cooler weather,” he says. vette “The E-Force’s supercharger assembly is inverted, allowing for 12 inches of intake runner for maximum low-end torque. It also has a short and less restrictive intake path for improved airflow,” Edelbrock spokesman Eric Blakely says. The camshaft’s custom grind (215-/247- degree duration, 0.629-/0.656-inch lift, 121-degree lobe separation) was designed and optimized for the E-Force system. “We did extensive testing with various cams to find one that offered the best driveability along with maximum power output,” Blakely says. “We also wanted something that was going to last a long time [and provide] reliability for the life of the engine. “The whole system is designed to deliver great performance throughout the rpm range, and we rate it at 720 hp and 695 lb-ft at the flywheel,” he summarizes. Now let’s get to the action and watch how Redline Motorsports installs this ZR1-killing powerplant into an otherwise unassuming Grand Sport. Then we’ll see how this potent ’vert performs, both on the dyno and at Palm Beach International Speedway’s quarter-mile ’strip.
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