Technology Creep

Automotive evolution stretches the performance envelope on Jason Harding’s 860-hp C7 Z06

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November 5, 2017

In his 1970 book Future Shock, Alvin Toffler argued that rapid, technologically driven changes caused psychological problems. Today, one glance at a typical Twitter feed furnishes evidence of his prescience.

But while smart phones and Web-based media effected rapid, disruptive change in the way we conduct our daily lives, a more subtle form of advancement commonly known as “technology creep” has been at least equally influential. The term refers to the way one thing leads to another through small degrees of alteration. You used to run out on Friday night to rent movies on video cassettes and then DVDs, before having them delivered by mail. Now, you call them up on your television. It’s a fundamental transformation based on evolution, not revolution.

The Corvette itself has been a notable beneficiary of this phenomenon. Twenty years ago, the LS1-powered C5 ushered in a new era of performance, leading to the 385- and 405-horsepower Z06 models. From there, the LS2-powered C6 offered comparable performance to the specialized C5 Z06, and later the LS3 C6 offered even more, with 430 horses. The 505-hp C6 Z06 and 638-hp C6 ZR1 pushed the bar even higher, and now we’re basking in the Michelin PS2–induced haze of the 650-hp C7 Z06. A year or two, or 20, make all the difference.

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Where do you go from there? That’s the question Jason Harding and his cohorts at Katech spend their days answering. Building on 40 years of experience, they poke, prod and cajole the performance envelope to build on the latest factory technologies. “It’s a bigger challenge every year, because the level of capability straight off the showroom floor just keeps getting higher,” says Harding. “A decade ago, a 500- or 600-horsepower engine in a street car was a big deal. Now, it’s not even the price of entry. You’ve got to exceed the factory, and increasingly our customers are looking for a dual-purpose car—one that’s track-capable with excellent street manners.”

That’s where Harding’s C7 Z06 comes in. Serving as a rolling test bed for the company’s latest performance parts, it is intended balance street and track capability on the sharpest of edges. “We’re much more confident building and recommending performance packages when we’re experiencing them ourselves,” says Harding. “We find what works and what doesn’t before offering it to our customers.”

With the Z06, Harding says it’s pretty easy to zip up to 750 hp. Well, at least it is for Katech. Accommodating the direct-injection fuel system of the supercharged LT4 engine, while working within the confines of the C7’s advanced E92 powertrain controller, requires specialized knowledge and an application-specific approach.

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Building on its extensive tuning experience, Katech was able to extract an additional 210 horses and 227 lb-ft of torque from the LT4 in Harding’s car, bringing it to a stunning 860 hp and 877 lb-ft—delivered with exceptional drivability. We’ll vouch for that personally, per our experience during our time with the car during this photo shoot.

“We’ve been working on the LT engine family from the moment it was introduced, including the tuning, so we’re already more than four years into knowing what works and what doesn’t,” says Harding. “This was racecar power only a few years ago, and now it’s available with the refinement that makes it suitable driving to work every day.”

At the heart of the specialized “Stage 4” engine system are a set of CNC-ported cylinder heads, a higher-lift camshaft, a smaller-diameter supercharger pulley that increases boost pressure to 15 pounds and a flex-fuel conversion that allows to engine to ingest higher-octane E85 or any combination of E10 premium gas and E85.

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The ported heads flow about 12 percent more through the intake ports and 8 percent more through the exhaust, while the camshaft—a collaborative effort with Lingenfelter Performance Engineering—holds the valves open a little longer to let that greater airflow pack into the combustion chambers. It’s worth noting the chambers and the top of the pistons are unchanged from the factory design, as their respective shapes are crucial to optimal combustion with the direct injection system. Also, the LT4’s stock bottom end has proven admirably stout, so Katech didn’t touch the crank, rods or pistons.

Complementing engine components include GM high-speed lifters, PAC valve springs, Katech titanium valve-spring retainers (on the intake side), a C5-R timing chain, a ported supercharger and supercharger snout, a 103mm throttle body, ARP head studs and American Racing 2-inch headers. The engine draws its breath through a Halltech Stinger RZ carbon-fiber air intake, while Katech’s signature cast-aluminum valve covers and relocated coils deliver visual distinction under the hood.

The E85 conversion ratchets up the engine’s potential because more-aggressive ignition timing can be used with the fuel’s approximately 105-octane rating. It also has an important intercooling effect on the boosted air charge. A pair of 350-lph DeatschWerks fuel pumps in Harding’s car—one boost activated and both residing in Katech’s approximately 1.6-gallon fuel-surge tank at the rear of the car—keep the alcohol flowing like a couple of taps at a busy pub. No, fuel economy is not one of this car’s strengths, but on the other hand the sharp tang from the exhaust outlets makes it smell like a real racecar.

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“Fortunately, E85 is plentiful in my area,” says Harding. “But because of the flex-fuel sensor, I can always run 92-plus-octane E10 premium fuel if necessary. I highly recommend E85 for anyone wanting to make big power in a boosted car like the Z06. The engine responds really well to the lower boost temperature, as well as the higher octane.”

Cooling is of paramount importance for any vehicle making 860 hp, and an elaborate TIKT intake-cooling system keeps this higher-pressure Z06 from blowing its supercharger lid. It consists of twin heat exchangers in the corners of the fascia, a carbon-fiber grille bezel and ducts, screened air outlets in the wheelhouse liners, a pair of independent coolant circuits that are served by their own pumps and two surge tanks hidden under the fenders. There’s also a larger-capacity DeWitt’s aluminum radiator, a TIKT oil cooler and Katech’s own carbon-fiber radiator exit duct.

To supply the necessary airflow to the TIKT system’s heat exchangers, the car’s front fascia was sliced open and fitted with a larger grille. At around $12,000 installed, this system is by no means inexpensive, but the cooling capability it offers is an absolute must for road racing with this kind of horsepower.

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TIKT also supplied the carbon-fiber rear wing, which is anchored to the chassis for strength and stability, the carbon front splitter and an underbody closeout panel with a huge tunneled under-tray. Harding added Katech’s Stage 3 splitter end plates, wickers, side skirts and straked rear diffuser, all of which are made from lightweight carbon.

The car rolls on Katech KT1 19×10-inch front and 20×12-inch rear wheels in satin black. These lightweight rims were developed in conjunction with and manufactured by Forgeline. The fronts weigh only 27 pounds apiece, while the massive rears tip the scale at only 30.5 pounds apiece. They’re all wrapped in Michelin Pilot Sport Cup 2 rubber, measuring 285/30R19 in front and 335/25R20 in the rear, and they’re held in place with featherweight titanium lug nuts.

The rest of the mechanical bits are a mix of stock and aftermarket enhancements, including Katech’s lightweight billet-aluminum flywheel, which is used with the stock clutch. The flywheel is nearly 25 pounds lighter than the stock unit, which reduces inertia to help the engine rev quicker.

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Already equipped with the optional Z07 package, the Z06 also relies on the stock and highly capable carbon-ceramic brake rotors, which are complemented with Carbotech XP10 front pads. There’s also a DSC Sport suspension controller used with the factory Magnetic Selective Ride system, giving Harding another tool to dial in that street/track balance. He says it’s “like HP Tuners for the suspension,” with g-force– and velocity-based tuning for the shocks. “You can keep it soft and smooth at 0g, driving down the street, but throw it into a corner on the track and the magnetorheological shocks go from street to race in milliseconds.”

Harding rides that edge all the time, putting the car through its paces often as an instructor on M1 Concourse’s 1.5-mile road course outside Detroit. He’s logged a fast 1.12:67 lap there, where the car can hit 133 mph on the 1,800-foot-long straight. The car is fast on the street, too—as fast as you might image an 860-hp Z06 would be, but also surprisingly docile between the stoplights. “I ‘work’ this car all the time, pushing it to find its limit and validate the parts and engine packages we’ve developed,” Harding says with a grin. “I guess you could call it one of those tough jobs that someone just has to do.”

Only few, short years ago, he was working dual-purpose cars with around 600 horsepower. Now it’s more than 800 horses and there’s no end in sight. That’s technology creep, and it’s not such a bad thing.

Also from Issue 118

  • '67 427 Tri-Power
  • C5 Buyer's Guide
  • Zora's C1 Prototypes
  • Restored '62 Roadster
  • '75 Convertible Driver
  • Ex-Vintage Racer '56
  • Racing: Tommy Milner
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