1994 Chevy Corvette Convertible - Rocket Science

Want To Build An 11-Second C4 The Right Way? One Reader Shows You How

William Wolfe Aug 2, 2010 0 Comment(s)
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I graduated from high school in 1964, at the very beginning of the muscle-car era. After being honorably discharged from the United States Navy in 1969, I purchased a '69 Pontiac GTO automatic rated at 350 hp. My best time at the dragstrip was 14.5 seconds at 101 mph, and I actually won many drag races. Today, there are V-6 family cars that would give that GTO a run for its money and still get 28 mpg on the highway. There was a time when everyone thought the '60s were the Golden Age of performance cars. I now realize that today is the pinnacle, and I am a willing participant.

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I've always admired the Corvette for its timeless style and performance. I remember being 13, looking over a '60 Corvette roadster, and thinking it was the hottest car I'd ever seen. I knew then I wanted to own a Vette; I just didn't realize how long it would take. Finally, on June 15, 2004, I purchased a 1994 Chevy Corvette convertible with 58,513 miles. The car met all my criteria: it was very clean, it had a six-speed, and it was Torch Red. My first trip to the dragstrip that summer netted a 13.801 at 101.12 mph-respectable, but not particularly fast.

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In September of 2006, I decided to build a C4 that could match the quarter-mile performance of a new Z06 without using a power adder like a turbo or a nitrous system. It also needed to be reliable and fun to drive. Selecting and ordering parts was nearly as much fun as actually working on the car. Each component had to be carefully selected and matched in order to achieve 11-second e.t.'s. My project was completed April 2007, after I spent the entire winter in the garage.

I started with the drivetrain. A 6,500-rpm redline with 6,300 to 6,400-rpm shift points seemed reasonable and should have enabled an 11-second car to achieve about 120 mph in the quarter. The rolling circumference of my tires was measured to be 79.8 inches, so to go through the lights at 6,300 rpm in Fourth gear would require a 3.91 differential and result in a trap speed of 121 mph. I had the differential rebuilt with all new bearings, seals, clutches, and 3.91 gears. I also replaced the U-joints in the halfshafts with heavy-duty units. The driveshaft had 0.013-inch run-out on the differential side and 0.006-inch on the transmission end. Using 3.91 gears, the driveshaft would spin at 3,880 rpm at 75 mph; this was way too much run-out for that speed. As a solution I purchased a lightweight, custom-built carbon-fiber driveshaft that measured less than 0.001 run-out. Gear changing is done via a B&M Ripper shifter that reduced the 3-to-4 shift distance from 6.25 to just 2 inches.

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My next step was to select a suitable rotating assembly. I chose an Eagle stroker kit that included a forged 3.750-inch 4340 steel crankshaft, forged 4340 H-beam rods, and 0.030-inch oversized SRP 4032 forged pistons with full floating pins. This increased the displacement from 350 to 383 ci. These parts were bolted into the line-bored block using billet-steel four-bolt bearing caps and ARP Pro Series studs and nuts. On the transmission side, I used a 12-pound, SFI-certified Ram aluminum flywheel and hydraulic release-bearing conversion kit to replace the heavy dual-mass flywheel. The other end of the crank uses an SFI-certified ATI aluminum Super Damper. Oil pressure is provided by a Melling high-performance pump. The oil pan is an oversized Milodon unit equipped with a Diamond Stripper windage tray. The rotating assembly of this motor could safely reach 9,000 rpm and still hold together.

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