660-HP 7.7 Liter LS7 Stock Block Corvette Z06 Time Attack Monster

After two years of autocross and time trials in his modified Nova, Feras Abuqartoumy was growing worried. Regularly doing some 150 miles an hour in his budget build didn’t sit too well with him. It was a lot of risk to be taking, especially since the heavyset Nova was, to put it politely, far from a competitive front-runner.

Though it worked to foray Feras into racing, the Nova wasn’t exactly a dedicated track car. He’d outfitted it with an LY6 engine, a built 4L60E transmission, and a set of Bilstein shocks, but even with the essentials for circuit fun, it was still far from a safe and reliable road racer. Within four road course events, he realized the climbing rates of speed were something that he ought to be doing in something better suited to the task.

After a brief period of rumination, he came to the conclusion he may as well move into something that could take him to the sharp end of the pack safely. After writing down a list of reasonably priced sports cars which could wet his whistle, he started browsing the classifieds for something new. It didn’t take him long to whittle the list of potentials down to two.

The Porsche Cayman S, being a mid-engined car, was plenty enticing. However, he’d been accustomed to around 500 horsepower in his Nova, so he felt it a downgrade to move to about 300 horsepower, even if it was that extra potent type of Porsche power. For the money, the only modern alternative in his eyes was the C6 Z06. For roughly $35,000, there really aren’t many production cars with comparable performance, something which we’ve delved into before.

Unfortunately, the promise of cheap performance proved to be a fantasy. After picking up his Z06, a lifter came apart, which destroyed a piston and a cylinder wall. So much for a cost-effective start. Some might’ve thrown the towel in then and there, but Feras—even though he was operating on a limited budget—was unfazed by the setback. He took the opportunity to start planning out the modifications he’d need to get this car to the pointy end of the grid.

A Monstrous Motor

His build straddles the fence between dedicated racing car and compliant road car, and proves that with the right selection of bolt-ons, one can take a punchy production car to the top of the time attack sheets. The masterminds behind this build were the LS experts at Horsepower Research (HPR) who started with a Darton-sleeved 5.3L Gen IV short block, fitted with one of K1‘s forged, long-post 4.250-inch stroke crankshafts, a set of Wiseco‘s 6.125-inch forged H-beam connecting rods finished to HPR’s specifications, and HPR-designed Wiseco forged pistons. They also use their own proprietary ring pack, which has been developed as a result of the research performed by Erik Koenig of HPR on some of the Houston area’s quickest LS/LT powered machines.

Since the valvetrain from the old engine was wrecked, a new package was selected to work with the existing WCCH cylinder heads. HPR spec’d out one of their custom camshafts, which features .655-inch lift on both intake and exhaust lobes to go with 254 degrees of duration on the intake side and 260 degrees on the exhaust.

The additional displacement changed the driving experience considerably.

In frugal fashion, he used what he could from the old motor’s top end before tacking on the WHCC heads, a Horsepower Research custom cam, conical springs, American Racing stepped headers, an MSD intake manifold, and a Nick Williams throttle body. Proving the potential of the LS7 platform and E85 fuel, this short list of simple modifications brought output to a frightening 660 horsepower and 620 lb-ft of torque at the rear wheels—though some of those gains have to be attributed to the skilled men at Peitz Performance Tunes.

Most of that latter figure is available from zip, so Feras had to tread carefully in his first tentative laps—even at higher speeds. “I think we added 100 pounds of torque [with the new motor], so the biggest challenge was anticipating when the torque would kick in and how fast I needed to react to it.”

With plans for 1.5-G cornering in this Corvette’s future, he had to ensure the new motor wouldn’t be starved of oil. With the help of a Katech oil pump, he was able to reuse the factory dry sump system with the new bottom end.  He’d already taken a few painful hits to his limited budget and had to modify wisely.

Aside from the gold insulation, the 660-horsepower motor looks near-stock.

Trimming Heft From the Corvette’s Frame

Running quickly at fast tracks like COTA—where’s he’s lapped in 2:18.5 on street tires—requires strong acceleration, and the Corvette’s svelte figure only helped in this regard. To trim some heft from the C6’s haunches, Feras first tossed out everything that wasn’t essential. Scrapping the air conditioning, heater, carpet, and passenger seat was followed by replacing the hood and the trunk with carbon items. A Lexan hatch, a lightweight OMP seat, and a homemade titanium exhaust were the next obvious steps, but getting more out of the car required some ingenuity. By cutting his bumper in half, then gutting the headlights, he shed another twenty-three pounds. The extensive weight loss program brought the overall weight down to 2,700 pounds, even with a Sharkbar 4-point rollcage in the cockpit.

The snug cockpit isn’t a pure racing cockpit, nor is it a cushy road car’s cabin.

So, with plenty of power and little weight, the Corvette had all the straightline ability that a time attack car could hope for. A set of Alcon six-pistons on either end of the front axle, as well as four-pistons in the rears—all of which clamp 14″ rotors—provides the braking power. Incidentally, these dropped another forty pounds from the car. When complemented by the aerodynamic grip offered by the homemade front splitter, a Dusold Designs rear diffuser, and a Kognition rear wing, the Corvette can brake at 1.5 G. For a middleweight production car with minimal aerodynamic modifications, that’s quite impressive. 

A squat stance and the bold aerodynamic additions leave nobody guessing at this Corvette’s intentions.

Best of all, this setup has been very reliable. Though it doesn’t see much street driving—hard to see this Corvette being too comfortable or inconspicuous—it hasn’t been very problematic for Feras. The only real issues were cooling related, and he solved those by adding a bigger Dewitts radiator, then relocating the oil coolers to the front of the car, which are fed cool air with TIKT carbon ducting. While he used to worry on warm Texan afternoons when the oil temperatures climbed as high as 300 *F, he now rests easy knowing he never has to deal with anything much over 250 *F.

Duct-fed oil coolers keep the motor humming on warm Texan afternoons.

With the addition of a Quartermaster 8.5″ twin-disc clutch and a Button flywheel, the factory driveline is stout enough to handle the bump in grunt, so he wasn’t force to spend any more on a pricey gearbox. Though the driveshaft did explode on his second lap at the first Super Lap event, that was the extent of the driveline-related headaches, and he wasn’t too surprised. With that much power driving the wheels, something must give eventually.

The relatively modest Dusold diffuers and Kognition don’t stretch further than the car’s haunches—quite conservative in the time attack world.

Though he got off easy with the gearbox, getting the suspension needed up to par took a great deal of work. Top-shelf Penske coilovers, coupled with Hyperco springs, PFADT swaybars, GSpeed spherical bushings, and SKF race hubs gave Feras the ability to administer that power without converting the rears into a cloud of useless smoke—and that was worth every cent.

Of course, so much of the car’s traction comes down the choice of rubber. Depending on what series he’s competing in—he’s currently contesting three—he wraps his Forgestar CF5 wheels in one of three different types of tire. For Super Lap, he runs Kumho ACR tires; for Optima Ultimate Street Car Challenge, he runs BFG Rival S tires; and for NASA Unlimited, he runs Hoosier A7 slicks. It’s only on the slick tires that he’s able to put the power down comfortably, since this Corvette is happy to break sideways at speed, and every outing is an exercise in throttle-related restraint.

Homemade aerodynamic elements help the Corvette navigate the esses at COTA.

Using The Tidal Wave of Torque

To get the most out of the car, it takes serenity at speed and a sensitive right foot. This is for several reasons. “There’s so much torque, it catches me off guard sometimes,” Feras begins. “I realized after my first couple outings with the new motor that I had to be much smoother with the throttle.” Still, even Prost-like smoothness can’t always keep the car from sliding wildly.

It’s a raw car, and that’s part of the appeal. Without TC, and with ABS depending on the situation, Feras always needs to have his wits about him. Regular throttle oversteer is something which Feras simply has come to realize is only part of the process of getting a good lap out of this C6. “I’ve gotten so used to sliding, I don’t even really think about it any more. You’ve just got to have quick hands!” he adds.

Fortunately, that power surplus is controllable if treated with care. With strong engine response and a powerband that stretches across the entire rev range, Feras is able to balance the car and easily settle the rear with maintenance throttle. Additionally, that torque helps keep minimum speeds up, and allows him compensate for minor errors. With a power surplus in even the fastest corners, it wouldn’t be a stretch to call this Corvette the opposite of a momentum racer.

A new splitter of Feras’ own creation.

It’s not just a Can-Am levels of torque which makes this car so capable—there’s a manageable chassis making good use of that power. It’s clear from the footage above that the car neutralizes slightly when the rear tires aren’t as torque-limited as they clearly are in hairpins and second-gear corners. The car never looks so planted it’s simply a matter of holding on, but the mild understeer it exhibits at speed shows is typically the quicker way through faster corners.

“To be honest, I’m still not entirely comfortable leaning on it. The damn thing is scary and the slightest pressure on the throttle will get the car loose. I don’t run traction control, so it’s always a battle knowing when I’m at the limit of the tire. In fact, I find myself going to higher gear a lot more; second gear is currently useless,” he adds with a nervous chuckle.

He’s spent two years getting to grips with this intimidating Chevy, and now, fairly confident in the car, he’s placed four titles in his crosshairs. With Gridlife, Optima, SCCA, and NASA events keeping his calendar full, he’ll be extending himself to keep the car competitive and try and clinch all four championships in the remaining twelve events this year. The regular travel hasn’t drained him, however, since he’s been floating on confidence—he’s won all of the three events he’s entered this year, and expects to achieve more.

Balancing a family life with a busy racing schedule and events taking place all over the country, Feras certainly has been spread thin. Fortunately, he chose a platform which has served him well. Powerful, reliable, and receptive to modifications, the Corvette has proven its a stellar grassroots racer with the right sort of touch. With the confidence-inspiring car underneath him, the support of Race Ready Motorsport, and a few new GSpeed modifications on the horizon, there’s a good chance he’ll hit all his targets.

Feras posing with his proud family.

 

About the author

Tommy Parry

Tommy Parry has been racing and writing about racing cars for the past seven years. As an automotive enthusiast from a young age, he worked jobs revolving around cars throughout high school, and tried his hand on the race track on his 20th birthday. After winning his first outdoor kart race, Tommy began working as an apprentice mechanic to amateur racers in the Bay Area to sharpen his mechanical understanding. He has worked as a track day instructor and automotive writer since 2012, and continues to race karts, formula cars, sedans, and rally cars in the San Francisco region.
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