The Aviator

Mark DiLullo builds an aerospace-grade homage to the high-flying ’63 Grand Sport racer

Photo: The Aviator 1
September 22, 2022

“Takeoff” can mean a couple of different things—for example, a jet rapidly rising off a runway or a craftsman drawing inspiration from an original creation. In Mark DiLullo’s case, the term is equally apt in both instances. As a military-trained pilot and owner of Threshold Aviation Group, Inc., DiLullo has throttled up hundreds of jets over the years. So maybe it’s no surprise that he brought this same sort of neck-snapping performance down to Earth for a tribute to the legendary ’63 Corvette Grand Sport.

DiLullo’s background also helps explain why the car shown here is not an exacting reproduction, but rather a heady “takeoff” from the original. The starting point for the project was a wrecked, big-block ’67 Sting Ray, into which he would ultimately invest seven-plus years and approximately 6,000 hours of meticulous workmanship.

The engine is just one example of the many upgrades and modifications inspired by the original Grand Sport’s history. Looking back at that glorious era, the powerplant used in 1963 was typically a 377-ci small-block, but in the car’s later years it was fitted with the overwhelming L88 (sometimes spelled with a hyphen, as on DiLullo’s car).

Photo: The Aviator 2

While officially rated at 430 horsepower, the L88’s output was purposely misrepresented, with the actual number estimated at around 560 hp in racing trim. Additionally, this monster motor was not offered with air conditioning or other popular options, the idea being to steer casual customers toward a tamer engine choice. (For comparison, the ’67 Corvette’s L71 427 was rated at a slightly higher 435 horses and cost less than half as much.)

DiLullo’s project would engage in no such numerical chicanery. In building his tribute to the Grand Sport’s pinnacle of power, he selected a specific period in the evolution of the car: late 1964 for the body, and 1967 for the L88 engine and M22 four-speed. “I envisioned living in that period and having a desire to compete,” he explains.

Working in concert with Threshold’s lead designer and head fabricator, Mike Guillen, DiLullo analyzed every factory part in an effort to enhance its performance. All while keeping in mind that in the days when the Grand Sports were competing, there weren’t any competition parts—they were either factory or fabricated components. “I wanted to stay true to the era and the ‘small team’—yet highly competitive—mentality,” he explains. “I wasn’t going for the fun of the sport. I was going to win, and win with an American icon.”

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DiLullo knew from his aircraft experience that heat is the enemy of everything mechanical—indeed, this issue accounted for many of the Grand Sports’ racing losses—so he addressed the problem by adding two large oil coolers to the engine. Mounted in aluminum boxes, the coolers are fed fresh, pressurized air from scoops in the front fenders. The air then flows out through the “shark fin” cutouts on the lower rear quarter panels.

The rear end and the M22 trans have independent oil coolers as well, built by Paul Cavallo at American Made. The former is equipped with a custom, oversized spring cover that mounts the pumps and fluid-drive system. The pumps circulate fluid whenever the car is moving, which helps maintain safe temps in the gearbox and 4.11-geared Posi differential.

During a search for an original L88 to power the car, DiLullo came across one of the rare beasts (block casting 3904351) through one of his aircraft mechanics, who had sourced it from a boat. Going one better, he hired Rob Stark of the aptly named Stark Terror Racing Engines to make it even more diabolically powerful. (Note the Tasmanian Devil mascot on the valve covers.)

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Stark started by punching out the L88’s displacement, increasing it from 427 to 441 cubes. And while the block is topped with original-equipment heads, intake, and Holley carburetion, the internals include a high-performance roller cam. For evacuating the blast of the engine exhaust, Corey Ballard of CB Design Concepts fabricated two-inch stainless-steel headers and four-inch side pipes. A ’67 M22 “Rock Crusher” transfers the intense twist of the stroker motor to the rear wheels via a custom aluminum driveshaft.

The rims are’64 Corvette “knock-offs” that have been split-sectioned and widened. They’re fitted with Goodyear Eagle Stock Car Specials measuring 26.5 × 8 R15 in the front and 26.5 × 10 R15 in the rear. Stopping duties are handled by Duntov Motor Company racing brakes with cold-air ducting.

The suspension was all reworked in-house—or, more correctly, in DiLullo’s aircraft hangar—using heavy-duty Corvette shocks and springs, plus four pushbutton air jacks actuated by a handle at the rear driver’s side. This latter feature was installed on the Grand Sport Corvette through various iterations, as it helped cut down on time spent swapping tires in the pits.

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As for the fuel system, the thirsty L88 gulps down high-octane race gas from an aluminum 36-gallon tank, as well as an 8.5-gallon reserve tank with dual pumps and twin Pit Stop fuel fillers. A custom fuel-distribution module with AN fittings is mounted at the rear of the cabin.

More modifications are obvious on the car’s exterior. The hood’s massive ducting is all new, pulled off of a custom mold, and displays aggressive aircraft styling. The removable cove panels were custom made as well. Both the door handles and trunk lid were installed per race-classification rules. The rear valence was ventilated to reduce drag, and brake-cooling scoops were added, along with engine oil-cooler “gills” in the rear quarter panels.

While the rough, non-running ’67 Corvette that served as a donor was originally red in hue, DiLullo created a modernized color combo featuring Dark Blue and Porsche Red shades from Valspar 829, along with Sherwin Williams Titanium Metallic. Inside the cockpit, he went with 1964-spec Al Knoch Daytona Blue seat covers fitted on aircraft-style racing buckets. The jet-inspired toggles and gauges feature a racing treatment crafted in-house at Threshold Aviation Group.

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Even though the dash clearly has a custom setup, DiLullo stayed true to the Grand Sport era with factory gauges. “But we removed the ignition and headlight switches, and installed additional gauges,” he points out. “We added a gauge that will look at [either] trans temp or axle temp with the flip of a switch.” For an engine-oil temp dial, DiLullo’s crew used authentic Corvette gauges and senders with re-screened printed dials.

Overall, the structure of the dash itself was reduced in size by trimming the “brow.” The glove box was also removed, and an aircraft/racecar circuit-breaker panel installed in its place. That panel also houses an intercom and radio system for team communications. The center area of the dash houses controls for the ignition, windows, lights, start switch, and jack-position indicators.

Considering the car’s astonishing level of detailing and upgrades, it comes as no surprise that DiLullo describes it as having been built to be judged to “Total Badass” standards. Why invest so much effort and expense? “Corvettes serve as a welcome distraction in my busy lifestyle,” he explains. “I love the idea of restoring or modifying cars, airplanes, and residential construction.”

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Turns out this project is a family affair, as DiLullo and his father, Ralph, also a former military pilot, share the same passion. (Mark DiLullo was almost literally born in a Corvette. After he was delivered at the hospital, Ralph drove him home, swaddled, in a Fuelie model.)

“My father collected Corvettes, and we were always…fixing, maintaining, driving, and showing [them],” the younger DiLullo shares. “We have restored numerous Corvettes over the years to Bloomington Gold Status. However, the Grand Sport is currently the ‘masterwork.’”

And that’s no idle boast, given that the car recently won the prestigious Grand National Roadster Show’s First Place trophy in the Track & Performance class. DiLullo’s favorite moment was displaying the car there and seeing the excitement of others when they looked at the end product.

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“My love of performance cars, especially the Corvette brand, led to my desire to demonstrate our company’s design, fabrication, and technical expertise [in building] the Grand Sport,” says DiLullo. “As the new guys [at the GNRS], we were thrilled to display our car with the best of the best. Obviously, we were ecstatic to win this award, which complements the whole Threshold team.”

But there was more to this project for DiLullo than showcasing his team’s skills. It was a way to help keep the remarkable history of the Grand Sport alive. “I wanted to channel Zora Arkus-Duntov and build a vehicle that could credibly compete with other fine race cars [of that era]. Our goal was to build a winner.”

As part of that process, DiLullo recognized the shortcomings of the original Grand Sport and corrected those issues with numerous innovations. “I believe if we could go back in time, we would be very competitive while racing the Cobras, Ferraris, and other marques,” DiLullo says.

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Referring to the jungle-cat striping on the rear deck, he adds, “Nothing eats the tiger.”

Also from Issue 157

  • Greenwood-Bodied C3 Autocrosser
  • Market Report: C7
  • "Old and New" 427 Pair
  • Top Flight ’63 Coupe
  • History: Refining the '69 Stingray
  • Racing: Le Mans and Beyond
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