We won't say Nick Yoskin's '06 Corvette intimidates dynamometers; it just destroys them.
"Now that the word's gotten around that my Vette puts 1,437 hp to the rear wheels, many dyno operators just send me away. Their rollers can only handle up to 1,000 hp," he says.
Yoskin's appetite for high-horsepower, twin-turbo Corvettes began in 2006, when he installed an off-the-shelf PTK Turbo system on the transplanted LS7 in his '03 convertible. "Working with that turbo kit was a like earning an engineering degree," he recalls. "I became an expert in top-mount twin-turbo systems for the C5, amongst my peers on Corvette forum. I learned about proper parts and material, heat management, and custom tuning to make a reliable street car."
In 2008, Yoskin started his search for an unmodified, low-mile, manual-trans C6 coupe, which would serve as a test bed for his autodidact's engineering skills. "Most guys would have opted for a Z06, but I had my doubts about its aluminum frame," he explains. "I purposefully sought out a base coupe with the entry-level 1LT interior. It was Le Mans Blue, which was the color I wanted, and it was in perfect condition. Since I liked the wide-body look of the Z06, I bought Z rear quarters and had them painted and installed. I also had Pfadt Feather Light Generation Coilovers, Z06 calipers and rotors, and Modular Concept three-piece wheels wrapped in Nitto Invo rubber bolted on."
Having learned from his experience turbocharging the LS7 in his C5 ragtop, Yoskin says he had serious reservations regarding the stock LS2's ability to handle sustained amounts of extreme boost. "I did extensive research to find the right LS engine builder, and chose ERL Performance in New Albany, Indiana," he says.
Specifically, he had his mind set on ERL's Superdeck six-bolt block. This piece starts life as an off-the-shelf GM LS block, from which ERL's technicians remove the stock liners, then install ductile iron sleeves, aluminum trusses, and billet main caps with carbon-steel dowel pins. Finally, they weld an outer rail and a lifter-bore-area boss to the block to convert it from four- to six-bolt clamping.
"The trusses we install are one of the most unique things about the Superdeck system," ERL's Seth Schaeffer says. "These are not in the factory blocks or any other aftermarket blocks that we're aware of, and they really help [the block] obtain a good bit of its rigidity. This truss absorbs torsional load that high-horsepower LS blocks see across the deck, and relieves the sleeves and cylinders from having to take all that abuse. The Superdeck short-block accommodates up to 2,000-plus horsepower with other added options."
Commissioned with Yoskin's long-block build as well, ERL stuffed the Superdeck with a Callies Dragonslayer forged-steel crank, Oliver I-beam billet connecting rods, Wiseco forged-aluminum pistons, and a Cam Motion hydraulic roller cam, then bolted up a set of Total Engine Airflow (TEA)/Trick Flow 245cc heads. When all was said and done, Yoskin had 427 vicious cubic inches just waiting to ingest double digits of boost.
Meanwhile, Yoskin enlisted RPM Transmissions of Anderson, Indiana, to build a Stage 6 six-speed gearbox for his car: Starting with an over-the-counter ZR1 TR-6060, RPM installed carbon blocking rings on First through Fourth gears and bronze fork pads, micropolished all of the internal components, and hand-fitted the slider and hub assemblies. "We haven't a found a limit yet to what our Stage 6 trannies can endure," RPM's TJ Strange says.
Yoskin--with help from his friend David Riddell--installed the engine and trans in his home garage. The pair didn't forget about how much abuse this severe-duty build would dole out aft of the crank, either. In went a SPEC ST-trim clutch, a ZR1 rear differential and halfshafts, and Driveshaft Shop's HD propshaft and Ovaka 300 output shafts. (Later, after destroying the ZR1 halfshafts, Yoskin installed Driveshaft Shop's Level 5 Ovaka 300 units, which are rated to a stupefying 7,200 lb-ft.)
For the second part of his Corvette's transformation into a land-speed missile, Yoskin turned to Marty Danko and Mike Korn of MD Customs in Warminster, Pennsylvania.
"[They] used high-alloy 321 stainless steel to fabricate the exhaust, turbo piping, and necessary brackets," Yoskin says. "I then sent the 'hot parts' [the turbo downpipes and manifold] to Advanced Thermal Products and had them fitted with Alloy Racing Shields. The turbo insulation shields keep the radiant heat to a minimum, and allow more exhaust gas energy to transfer to the turbo. I sent the 'cold parts' [the airbridge and intercooler-to-throttle-body pipe] to Bonehead Performance in Warminster for powdercoating, which closely replicates the OE look."
The custom turbo setup was installed next. The system comprises Turbonetics TC78 78mm billet-compressor ball-bearing turbos, Turbosmart 44mm wastegates, and Race Port blow-off valves (all supplied by Forced Inductions); a Turbo Technology intercooler (mounted behind the front fascia); and a Howerton Engineering Aquamist methanol-injection system (housed in the intercooler-to-throttle-body pipe).
One Aeromotive 340 and two Walbro GS 341 fuel pumps (all attached in-tank via a custom bulkhead/hanger assembly) feed the Fuel Injector Connection 200-lb/hr high-impedance injectors. "The two Walbros are constantly on, and the Aeromotive automatically powers on via a Hobbs switch when boost reaches 10 psi," Yoskin says. Amazingly, the engine retains its stock LS2 intake and throttle body.
Other engine-bay upgrades include a Dewitts radiator, a powdercoated sheet-aluminum engine cover (complete with "Bam Bam" badges, reflecting the six-two, 270-pound Yoskin's nickname), and custom ductwork from the factory foglight locations to the airbox.
The tuning? Yoskin plugged in with HP Tuners and uploaded a custom 2.5-bar speed-density tune to his Corvette's factory ECM.
Aesthetically, the cabin remains a cool contrast to the extreme capabilities of the engine package. Yoskin installed a Blitz i-Color boost controller into the driver-side A/C vent, a custom A-pillar gauge pod (housing an Innovate Motorsports XD-1 digital gauge and an Aquamist HFS-6 flow gauge), a four-point rollbar, a carbon-fiber-style radio bezel, and an aftermarket stereo system. The thrones, door panels, carpet, and headliner remain factory stock.
The exterior, however, leaves onlookers guessing whether this C6 is a base coupe, a Grand Sport, or a Z06. For that, Yoskin thanks Extreme Corvette in Hatboro, Pennsylvania, which painted and installed C6 Grand Sport fenders, along with a Z06 front fascia and rear lip.
Yoskin's next task was finding a dyno shop daring enough to measure his Corvette's prodigious output. "Luckily, Injection Connection in Horsham, Pennsylvania, has a Dynocom dynamometer rated to 2,000-plus horsepower," he says. "The first dyno pull--dialing back the boost to 13-14 psi--produced 980 hp at the wheels. Subsequent pulls at 27 psi made 1,437 hp and 1,320 lb-ft of torque."
Yoskin's future plans for his Corvette include participating in the 2012 Texas Mile competition, where he hopes to reach terminal velocity of 230-plus mph. "I'm hoping it will be the fastest 25 seconds of my life."
Rest assured, his twin-turbo Corvette won't be sitting still in his garage waiting for the opportunity to join the "Over 200" land-speed club. "I didn't want to build a one-dimensional drag car with [poor] street manners. I wanted something I could still take the wife out to dinner quickly... make that very quickly."
|HEADS||TEA/Trick Flow six-bolt 245cc|
|CAMSHAFT||Cam Motion hydraulic roller (232-/228-deg duration, 0.610-/0.600-in lift, 110-deg LSA)|
|ROCKER ARMS||Yella Terra 1.7:1 ratio|
|PISTONS||ERL Performance custom-selected Wiseco forged aluminum|
|CRANKSHAFT||Callies Dragonslayer forged steel|
|INTAKE MANIFOLD||Stock LS2 composite|
|THROTTLE BODY||Stock 90mm|
|FUEL INJECTORS||Fuel Injector Connection 200-lb/hr (2000cc) HiZ|
|FUEL PUMPS||Single Aeromotive 340 and dual Walbro GS 341|
|IGNITION||Stock coil-near-plug, NGK TR7 plugs|
|ENGINE MANAGEMENT||Stock ECU using HP Tuners custom 2.5-bar OS|
|POWER ADDER||Custom twin-turbo system (Turbonetics TC78 turbos, Howerton Engineering Aquamist methanol injection)|
|MAXIMUM BOOST||28 psi|
|INTERCOOLER||Turbo Technology custom sheetmetal using Bell cores|
|EXHAUST SYSTEM||Custom 321 stainlesssteel manifolds with 13.4-in primaries and Advanced Thermal Products covers|
|TRANSMISSION||'11 ZR1 six-speed manual, built to "Stage 6" specs by RPM Transmissions|
|DRIVESHAFT||Driveshaft Shop HD|
|FRONT SUSPENSION||Pfadt Feather Light Generation coilovers (single adjustable)|
|REAR SUSPENSION||Pfadt Feather Light Generation coilovers (single adjustable)|
|REAREND||'11 ZR1 with Driveshaft Shop Level 5 Ovaka 300 output shafts|
|FRONT BRAKES||C6 Z06 calipers and rotors|
|REAR BRAKES||C6 Z06 calipers and rotors|
|WHEELS||Modular Concept threepiece forged aluminum (19x10.5-in front, 20x13-in rear)|
|FRONT TIRES||Nitto Invo 285/30ZR19|
|REAR TIRES||Nitto Invo 345/25ZR20|
|BEST 60-FT. TIME||TBD|
|MILES DRIVEN WEEKLY||Approximately 50|