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2005 Chevrolet Corvette - At the Crossroads

Pushing The Limits With A 700-RWHP Stock-Block LS2

Randall D. Allen Apr 26, 2007
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The C6 Corvette is quickly becoming legendary in its quest for domination on streets and racetracks across the globe. With the aftermarket pumping out all forms of power-producing hardware-including superchargers, turbochargers, and stroker packages-tales of otherworldly output from the Gen IV LS2 are rampant. But while horsepower levels that were once reserved for dedicated race engines are increasingly common, high-power stock-block applications remain an enigma to all but the most talented tuners in the land. Put simply, the question that eventually has to be answered is this: "How much power will the engine produce without disastrous consequences?"

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Baer Eradispeed rotors and Carbotech Panther XP pads offer exceptional braking, but the real show-stoppers are the I-Forged Classic wheels optioned with anthracite centers.

After dreaming about a Corvette as a kid, David Gianechini of Missouri City, Texas, went about life as many of us have, dedicating himself to establishing a career and settling into a suburban lifestyle with the obligatory-if dull-four-door sedan. After a few years, David and his wife decided that some Corvette excitement was in order before the banality of suburban life engulfed them completely. After months of frustrating searches for a pristine C6, a silver '05 with a six-speed and a scant 7,000 miles was finally purchased on eBay. Given that David is a personal friend of Motorsport Technologies operating officer David Coates, it was a fait accompli that the C6 would be modified. Unbeknownst to both men was just how much power could reliably be extracted out of the car's LS2 engine.

According to Gianechini, "The C6 is a daily driver to my Houston-based accounts-receivable management firm. As such, it has to be dependable. Determining how to modify the car to be fast, yet reliable, while on a budget became a challenge." With seemingly endless experience modifying the Gen III and IV engines with power adders, Motorsport Tech was up to the task.

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"As soon as the LS2 hit the market, we began research into creating engine packages that would handle extreme horsepower," Coates tells us. "We can offer the customer a full range of choices, including stroker packages that can take the LS2 out to 455 ci as well as stock-block combinations that will handle 800 crankshaft horsepower. By pushing the envelope, two things became crystal clear: The LS2 block is very stout, but in order to handle the rigors of a power adder, tuning and heat management are critical."

With a goal of 800 hp on the stock block-exactly twice the factory rating-Motorsport Tech turned to ProCharger and its own in-house cylinder-head and camshaft-design teams to create a suitable powertrain package. The combo's big hitter is a ProCharger H.O. Intercooled supercharger kit, which was outfitted at the factory with an upsized D-1SC head unit to facilitate boost levels of up to 12 psi.

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A seemingly factory-fresh cabin meets the owner upon ingress. Clues to the true performance of this C6 are subtle, with only an Auto Meter peak-and-hold electronic boost gauge and an AEM wideband air-fuel gauge on the front pillar as clues.

In order to pump that much air into the engine, the original LS2 heads were treated to Motorsport Tech's Stage II-E head-porting regimen, which is designed to work optimally with stock displacements. Oversize Ferrea stainless valves help flow in excess of 300 cfm on the intake, courtesy of fully hand-ported runners, bowl work, and a performance valve job with proprietary valve angles. Those valves are actuated by a custom-ground "G1" cam measuring 228/232 degrees of duration and 0.588-/0.575-inch lift on a 113-degree lobe-separation angle. A set of stock-bore Cometic multi-layer gaskets and ARP head studs keep the 10.9:1 compression mill strong against the rigors of forced induction.

A stock LS2 intake and LS2 90mm throttle body send copious amounts of air into the engine, while Mototron 60-pound injectors and a Kenne Bell Boost-A-Pump work in conjunction with the stock C6 fuel pump. An Alky Control electronic methanol kit injects straight meth just before the throttle body to help manage intake-air temperatures.

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Fuel, air, and exhaust are the keys to big power in a supercharged combination. Gianechini's engine relies on Motorsport Tech Stage II-E heads and a highly efficient exhaust system to fill and evacuate the cylinders in rapid fashion. A boost-referenced Kenne Bell Boost-A-Pump and Mototron 60-pound injectors feed fuel to the stock-cube LS2, while MSD 8.5mm plug wires, NGK TR-6 plugs, and a Yellow Top Optima battery work overtime to support the audio and electronics suites guiding this silver missile.

Hours of LS2 Edit tuning found Motorsport Tech owner Jayson Cohen tweaking the car's ECM both on a chassis dyno and on the street. As with other tuning packages for power-adder cars, this one presented challenges. Says Cohen, "In order to provide a tune that would extract the maximum safe power from the engine, we had to ensure that as parasitic heat from the blower built up, we maintained a delicate balance of timing and fuel. On these types of combinations, there is little to gain and everything to lose if the PCM starts pulling timing or leans out. The combination of the excellent ProCharger intercooler [and] supplemental assistance from methanol injection keeps the intake-air temperatures from ever exceeding 120 degrees, even when hot-lapped."

Exhaust is expertly expunged via a set of Kooks 1 7/8-inch stainless headers and a Borla 3-inch mid-pipe with high-flow metal-matrix converters. A Borla "Stinger" 2 1/2-inch Cat-Back exhaust provides a civilized tone until the pedal is pushed to the carpet and the whine of the supercharger aurally exsanguinates nearby soccer moms with unmitigated ferocity. Shifting duties are handled by a stock T56 six-speed transmission that utilizes an LS2 clutch and flywheel to transmit power to the pavement. Other than a Dynotech hardened output shaft, the rear differential remains stock, right down to its 3.42 gears.

To allow the addition of wider rear tires, Z06 rear fenders were purchased and shot in the factory Machine Silver Metallic by Richey Collision. The suspension is unaltered, other than being lowered 1 inch on each end via the stock suspension bolts. I-Forged Classic wheels finished with anthracite centers are perfect complements to the silver C6's low-slung body panels. Super-sticky Michelin Pilot Sports get the call for tractional adhesion; they measure 275/35-18 in front and a bulbous P345/30-19 in the rear.

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Says Gianechini, "[My wife and I] love driving the car around. By getting the C6 with the standard suspension, the car is always comfortable to drive, whether dodging potholes in the city or taking a trip out of town. Combine the power of the blown LS2, the luxurious ride, and a high-powered audio system, and you have a powerful dual-purpose car. Although the amenities are nice, the addictive nature of the ravenous motor's sound really gets me going. The boost from the ProCharger is almost instantaneous, and once the cam gets into the heart of the wide torque curve, the car is a handful. Even with the extremely high heat and humidity of Houston, the car has been a paragon of reliability."

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Massive Z06 rear fenders and 3.5-inch Borla exhaust tips should provide ample visual and auditory warnings that this Chevrolet supercar means business.

Whether driving on the clogged arteries to and from Houston or displaying the potential to turn mid-10-second e.t.'s at the local dragstrip, this C6 manages the balance between all-out race car and luxury cruiser with aplomb. Thanks to the expert building and tuning skills of Motorsport Tech, the car has stepped firmly into the crossroads of C6 performance and come out with its soul-and its stock-block engine-intact.

Remember, when you approach the intersection of your life, forget the mysticism of Hoodoo and those intoxicating Robert Johnson blues riffs. You need only delay your gratification as long as it takes to hit the dash-mounted proximity fuse on your own C6.

The author would like to thank David Gianechini for "composing" the crossroads photograph at George Bush Park in Houston, Texas.



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