The moment the new Impala SS models hit the ground in 1994-after eager enthusiasts begged, pleaded and threatened Chevy brass to build a production version of the wildly popular SEMA show car on which they were based-they became cult sensations. The enthusiast base for the rear-wheel drive B-body star continues to thrive, even though production lasted a scant three years.
Over the years, countless modified Impalas have hit the street and strip, but there's never been an Impala quite like the one GM Performance Parts (GMPP) recently built. The folks there started with a '96 engineering mule that had been collecting dust, and under the direction of Mike Copeland of GM Performance Division, they transformed it into an Outlaw 10.5-style door-slammer.
Tube chassis. Funny car-style cage. Narrowed rear end. Lenco transmission. The whole megillah.
And while all that sounds impressive enough, the real point to it all was building a suitable validation vehicle for a twin-turbocharged LSX engine designed to explore the upper range of GMPP's LSX cylinder block capability. Built in conjunction with Thomson Automotive (thomsonengines.com), with assistance from Turbonetics and ACCEL-DFI, the one-off, twice-turbo'd power plant dynoed at an astonishing 2,048 hp-and the engine displaces only 400ci! (See Super Chevy's September 2009 issue for a complete look at the engine.)
That's what a pair of 88mm turbochargers, 27 pounds of boost, and some great cylinder head clamping will do for you.
"Like everything in GMPP's portfolio, the LSX block was subjected to 50 hours of full-load durability testing prior to its public release, but this was something special," says Dr. Jamie Meyer of GM Performance Parts. "There have been more than 200 dyno pulls on the engine without a problem and we don't know what the maximum power capability of the engine is. We had to pull it off the dyno in order to finish the car."
When viewed on an engine stand or on the dyno, it looks as if there's no way the turbo LSX will fit in, say, a monster truck, let alone a B-body. But Copeland and his crew designed it to do just that. Surprisingly, only the top part of the tunnel ram-style intake system protrudes from the hood. The turbochargers, their 3-inch-diameter intake and outlet pipes, as well as the custom headers all fit beneath the lightweight, aftermarket hood.
"With so much power to contend with, we needed an appropriate chassis to handle it," says Copeland. "Regardless of whether we head to the LSX Shootout and aim for a 6-second time slip, the foundation-and most importantly, the safety equipment-is there to support it."
Vanishing Point Race Cars (www.vpracecars.com) contributed expertise and one of its "three-quarters" chassis kits to help frame the Impala. The car uses the original front frame clip, with the Vanishing Point chassis behind it built to NHRA 25.5 specifications. The Telford, Pennsylvania-based chassis shop also designed the car's roll cage on a computer, while Copeland's staff GM's Milford Proving Ground assembled the chassis and built the cage from Vanishing Point's schematics.
To the chassis, a four-link rear suspension was hung, along with an X-link, stabilizer bar, QA1 double-adjustable coilover shocks and Wilwood brakes. The front suspension features Speed Tech tubular control arms, QA1 adjustable coilovers and a steering rack from Vanishing Point. The GM crew machined a set of wheel spindles from a billet of 7075 aluminum. They're designed to hold a C6 Corvette hub and bearing assembly. Brembo brake components are used up front, too.
The car rides on Weld Alumastar wheels and Mickey Thompson ET Drag tires all around.