The GMPP LS7 Is Hand Built On The Same Wixom, Michigan, Assembly Line As The Production Engine
Remember the old saying, "There's no replacement for displacement"? The same holds true today. If you want to be a contender, and not a pretender, there's nothing shy of the $100,000 mark that packs the punch of the Z06 Corvette and its 505hp LS7 engine.
Shortly after the C6 Z06's public debut in fall 2005, GM Performance Parts (GMPP) unveiled an over-the-counter LS7 crate engine at that year's SEMA show. The widespread availability of the new top-dog LS opened the floodgates for Corvette aficionados to transplant this 7-liter monster motor into Vettes of all vintages.
"The LS7 has a lot going for it that owners of midyear Vettes can enjoy," says Dr. Jamie Meyer, GMPP's marketing manager. "Chief amongst these is that it's very light and compact, offering an engine that's the size of a small-block, yet still outperforms big-blocks of that era. [It also] offers unbelievable fuel mileage for an engine that makes more than 500 horsepower. The stock Z06 nails darned-near 30 mpg!"
Word spread quickly that the LS7 was the engine of choice for speed connoisseurs whose Corvettes had the look, but lacked the horsepower to back it up. The popularity of the LS7 is now such that Corvette owners across the world are demanding the engine for their restomod and Pro Touring time machines.
Charles Spiteri, a motor-vehicle mechanic in Albion Park, Australia, is one such enthusiast who realized a GMPP LS7 was the perfect engine for his classic Corvette. But it took a harrowing journey through the internal-combustion jungle before he saw the light for his '63 Sting Ray.
"I've always been a Corvette fan," Spiteri says. "I first saw my '63 in the 1980s, when all it consisted of was a chassis and a body." Owned by George May, an Australian hobbyist, the right-hand-drive Vette was something of an enigma. No one knew any of the details of its history, such as what had happened to its original drivetrain, or why an unknown owner had undertaken the peculiar task of removing the trademark split window from the classic coupe.
By the 1990s, the car was still unfinished, although May had "spent a lot of dollars getting parts for it," Spiteri recalls. It was then that the Ray was purchased by Bob Mayner, another local Corvette hobbyist. Spiteri was optimistic. If luck was on his side, perhaps the new owner would prefer cold, hard cash in lieu of his Corvette carcass.
"I went to see him, and he said he would think about it, because his wife didn't want him to sell. I called him a week later, and we struck a deal," Spiteri says.
With a virtual tabula rasa on his hands, Spiteri's choices for a drivetrain were virtually unlimited. Nonetheless, he chose the traditional route, outfitting the car with a 350-cube SBC mated to a Muncie M20 four-speed. Several years later, he opted for more power, and shoehorned in a supercharged 350 sourced from previous car owner May.
According to Spiteri, subsequent damage to the blower tarnished the splendor of the boosted small-block. "I was getting tired of the supercharger, but I loved the power it had," he says.
Then, in 2007, a friend of his extolled the many virtues of the LS7. "He told me I could buy an LS7 in a crate, so I downloaded all the information and said to myself, `This is the way to go,'" he remembers.
Opening the GMPP shipment, Spiteri found a shiny, new LS7, validated and backed by a full warranty. "The engine is hand built on the same Wixom, Michigan, assembly line as the production LS7," Meyer explains. "When you purchase an LS7 crate engine from a GMPP dealer, you're getting the same record-setting performance that you'll find under the hood of the Z06 Corvette."
The engine features a 4.125 x 4.00 bore/stroke combo, a forged-steel crankshaft, titanium connecting rods, CNC-ported heads with a 2.20/1.61 valves (sodium filled on the exhaust side), 1.8-ratio rocker arms, a hydraulic roller cam with 211/230-degree duration and 0.591/0.591-inch lift, and an 11.0:1 compression ratio.
As many VETTE readers know, the injected LS7 requires a compatible ECU to operate, even when retrofitted to a classic Corvette. Because no "plug and play" solutions were available at the time, Spiteri utilized a reprogrammed LS1 ECU and a Holley 90mm drive-by-cable throttle body in his project. (Seeing the exploding popularity of LS-into-vintage-car swaps, GMPP has since developed an LS Controller Kit and an LS7 Accessory Drive System, which together make the job much easier.)
To increase the LS7's output to even more sinister levels, Spiteri and his cousin, Joe, upgraded the LS7's internals with JE pistons and added a Comp Cams hydraulic roller delivering 238/240-degree duration and 0.605/0.609-inch lift.
One of the more noteworthy aspects of the swap is the car's unique dry-sump canister, which the mechanically inclined Spiteri put together himself. "It started from an old water-type,stainless-steel fire extinguisher," he explains. "I worked out all the baffles, the filler tube, the dipstick and tube, the mounting brackets, and such. Then it was TIG-welded together and mounted to the frame on the right-side inner fender. [It] works great."
Next, Spiteri designed a custom fuel-delivery system featuring three fuel pumps. After the addition of 17?8-inch custom headers welded to Corvette 3-inch side pipes, the fortified LS7 pumped out a rousing 640 hp and 570 lb-ft of torque on an engine dyno.
Realizing that the vintage M20 trans would curtail the capabilities of his 7-liter projectile, Spiteri sourced an LS7 clutch and flywheel, a Tremec T56 six-speed, and a custom-length driveshaft for the car. The Vette's stock 3.70-geared rear was deemed up to the task and left in place.
While he was at it, Spiteri also took the initiative to upgrade his Vette's ride and handling. Although the underpinnings remain mostly stock (at least for the time being), the factory A-arms were treated to Nylo-thane bushings, while Pedders lowering springs and Koni shocks stand in for their factory counterparts up front. Rear-suspension modifications include a composite monospring, a second set of Konis, and a -inch sway bar to limit side-to-side motion. For an added touch, many of the front and rear suspension components were powdercoated.
The next step was to make sure the brakes, tires, and wheels could accommodate the massive power increase provided by the LS7. Accordingly, Spiteri installed GM four-piston calipers and 11.9-inch rotors from a '66 Vette at all four hubs to provoke instant stopping power. A set of 17-inch custom Dragway wheels wrapped in Yokohama rubber provide a wide-enough contact patch to punish the pavement into submission.
Performance was Spiteri's primary goal, but along the way he found the passion to prepare his midyear missile for show duty, too. Friend Tony Roberts mixed up the batch of Corvette Red paint, and Illawarra Collision Repair sprayed the scintillating hue. The interior, meanwhile, was Spiteri's own design. It includes Recaro seats with full racing harnesses, an SAAS sport wheel, black carpet, and Auto Meter gauges in the factory pods. For added safety, Spiteri also installed a brace box behind the seats.
So, how has this heavily modded midyear been received? Since the build was completed, Spiteri's coupe has won numerous Best Car and First Place trophies in the Aussie Vette-show circuit's highly competitive '63-'67 Modified class.
"Now that the car's complete, it's great fun to drive," says Spiteri. "All I have to do is reinstall the split window, and I'll have a '63 Corvette that's exactly the way it should have been built: with an LS7 engine."
|Camshaft||Comp hydraulic roller;|
|238/240-deg duration, .605/.609-in lift|
|Rocker Arms||1.8-ratio with offset intake|
|Throttle Body||90mm Holley billet, cable type|
|Fuel Pump||Single Carter (surge tank), twin Bosch (main)|
|Engine Management||Modified LS1 ECU|
|Exhaust System||Custom, stainless-steel|
|17/8-in long-tube headers with 3½-in collectors|
|and side-pipe mufflers|
|Transmission||Tremec T56 six-speed manual|