Boosted Fun

Dominick Testa transforms his 2019 Grand Sport convertible into a blown, 700-horsepower cruise missile

Photo: Boosted Fun 1
May 16, 2024

Dominick Testa grew up in an era when fast cars had a stranglehold on the imaginations of young people, and he was no exception. “My family lived in Suffolk County on Long Island,” he recalls, “and I was surrounded predominantly by GM muscle cars: Camaros, Chevelles, GTOs, and the occasional 4-4-2. There was hardly anything else around, but there was one guy, a returning Vietnam veteran named Al Hayes, who lived around the block from where I grew up. He had a purple ‘Cuda that was retrofitted with hand controls because he lost his legs from a land mine. I fell in love with that car the moment I saw it and dreamed of a Barracuda, GTX, Roadrunner, or anything Mopar because…I had to be different.”

Testa’s desire to purchase a Chrysler product was strengthened further when his best friend got a blue-and-white 1969 Z/28, another friend obtained a green ’69 Z/28, and a third pal purchased a ’69 El Camino SS. “I homed in on a B5 Blue Roadrunner and begged my father to help me buy it,” he recalls. “He was a first-generation Italian immigrant who was 100-percent devoted to GM. The first car I remember in our family was a 1955 or ’56 Chevy sedan, then a ’63 Impala, and as he got a little more successful, he worked up the nerve to get a Pontiac. His last car was a Buick.”

The dream of the blue Roadrunner reached a crescendo when Testa got his license and was heading into his senior year of high school, and his father delivered…sort of. “My dad comes home from work one day and tells me to get into his car. He’d found a car for me, and since I was doing OK in school and wasn’t getting into any real trouble, he was going to buy it for me. I was over the moon!

Photo: Boosted Fun 2

“We drove about a half-hour and pulled into this small car lot,” Testa continues. “Of course, I’m looking around for a Roadrunner, or even a GTX or ‘Cuda. He walks up to a black-and-white ’69 Chevelle SS and tosses the keys to me. I stood there in shock and in his thick Italian accent he says, ‘Watsa matta witchoo?’ I responded that I didn’t want a Chevelle, I wanted a Roadrunner. He nearly knocked me out! Now, 50-plus years later with kids and grandkids of my own, I realize how hard it must have been for him to buy that car for me after putting away a few dollars each week until he had enough saved.”

Despite his affinity for Mopars, Testa quickly grew to love his Chevelle and made it his own by installing a few typical period mods, including Cragar mag wheels, Hooker headers, and Pro-Trac tires. A few years later he traded the Chevelle for some cash and a 1969 Firebird convertible, and in 1974 the Pontiac gave way to a ’69 440 Charger. That car was later replaced by, of all things, a Ford F-250 pickup. “A crazy song called ‘Convoy’ came out, and my friends and I all got hot for pickup trucks,” he explains.

After high school Testa was working at a Long Island speed shop called SK. There, he was surrounded by race junkies who harassed him endlessly about his pokey pickup. One day he asked the drag-strip denizens what he should be driving instead of his F-250, and they told him to buy a Corvette. “I really didn’t know anything about Corvettes—I didn’t even know where to start,” he says. “Then, one day I was driving past Nesenger Chevrolet [in Medford, Long Island] and spotted a silver-and-blue Corvette in the showroom.”

Photo: Boosted Fun 3

Testa bought that brand new ’77 Corvette, which he drove and loved for the next few years. The fun came to an abrupt end in 1980, however, when he gave in to pressure from his new bride to trade the Corvette in on a Chevy Blazer. “The dealer was on my way to work, and for about a month I would pass my Corvette on the used car lot. [It was] very sad.”

So sad, in fact, that Testa subsequently became what some might call a compulsive Corvette buyer. “In 1984 I got a new C4 and put many, many miles on it, doing regular long-distance road trips. In some ways the 1980s and ’90s were hard times to love new Corvettes, but I had a bunch of them. I also had older ones—a ’78, two ’79s, and an ’82. Now I have the 1960 Camoradi Corvette [our March ’24 cover car], a restored ’67 small-block, a restored ’69 big-block, and a 2019 Grand Sport.”

As built by Chevrolet, the Grand Sport in question was, and remains, the highest-performing Corvette Testa has ever owned. After evaluating it, Car and Driver had this to say about the ’19 edition: “The Corvette is brutally quick, handles brilliantly, and stops as if you’ve driven into wet cement. It’s basically a supercar for a fraction of the price of a Ferrari, a McLaren, or a Lamborghini.”

Photo: Boosted Fun 4

Although the C7 Grand Sport used the same LT1 engine is the base Stingray, this track-focused model was treated to a number of upgrades intended to strengthen its grip and sharpen its reflexes. The normally optional Magnetic Ride Control suspension, Brembo brakes, and NPP active exhaust came standard on the GS, as did the supplementary cooling and oiling hardware otherwise reserved for the Z51. Gummy, summer-only Michelins and aggressive bodywork similar to that of the supercharged Z06 completed what was an exceptionally well-rounded package.

And yet, as good as the car was right off the showroom floor, Testa quickly decided to modify his new C7 to elevate its performance further. To that end, he took it to JTM Motorsports in Deer Park, New York. The technicians there installed an A&A Corvette V3 Ti supercharger system. This setup uses a Vortech Engineering centrifugal head unit that can deliver a peak boost of 22 psi, with a flow rate of 1,250 cfm at its top rpm of 52,000.

Unlike the Roots-type superchargers most often favored by GM and other original equipment manufacturers (OEMs), centrifugal blowers employ a head unit that is mounted on brackets, separately from the engine, rather than being integrated into the intake manifold. The upsides of this configuration include a lower propensity for power-killing heat soak (we’re looking at you, C7 Z06), as well as a higher maximum-output potential. For the latter reason, they tend to be popular with drag racers competing in “power adder” classes. And while Roots blowers typically make more torque than do centrifugals at lower rpm levels, that’s of comparatively little importance when dealing with a big-inch V-8 like the Grand Sport’s LT1.

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To reduce the increased likelihood of detonation that can accompany forced-induction system, JTM fitted the engine with its own proprietary methanol-injection system. Such a system does exactly what you’d expect: it sprays water and methanol (usually in a 50/50 mixture) into the intake tract to cool and oxygenate the incoming compressed air.

To further free up the LT1’s breathing, the JTM techs replaced the stock exhaust manifolds with American Racing Headers pipes crafted from two-inch-diameter tubing. And finally, to optimize the package’s output, reliability, and on-road civility, JTM used HP Tuners software to calibrate both the engine- and transmission-control modules.

All that work clearly paid off: At a relatively modest 14 psi of boost, the 6.2-liter LT1 engine’s output was measured at 689 horsepower and 560 pound-feet of torque at the rear wheels on JTM’s chassis dynamometer. That’s a huge increase compared with the stock rating of 460 horsepower.

Photo: Boosted Fun 6

Just as he did with his very first Corvette, the ’77 he bought new, and the dozens of others that he’s had in the intervening years, Testa thoroughly enjoys driving his supercharged C7. “Some 40 years later, I’ve retraced with the ’19 Grand Sport all of the major road trips that I did with my 1984 Corvette, including drives to Vermont, Montreal, Cape Cod, Pennsylvania, and Florida. It’s a fantastic car, and I really love driving it.”

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