Department X: Supercharged LSX Solstice

When the Solstice show car made its debut in 2002, performance enthusiasts and tuners eagerly awaited the announcement that the concept would reach production. Many longtime Pontiac fans saw it as the spiritual descendant of John Z. DeLorean's stillborn XP-833 Banshee, while others simply saw it as raw material for building outrageous performance cars-a lightweight two-seater with a huge V-8 stuffed into it.

Essentially, both were right. As a latter-day Banshee, it also was subjected to some of the same corporate infighting from the Chevy camp, who-like their predecessors 40 years before-saw the Pontiac two-seater as a serious competitor to the Corvette.

The Solstice fared better than the XP-833 and actually reached production, but it didn't receive a V-8 engine, even though one would easily fit. The performance version of the Solstice received a 260-horse turbocharged version of the EcoTec four-cylinder with an immense amount of hop-up potential. Still, a four-banger-no matter how powerful-didn't suffice in the minds of many, who were weaned on the great V-8 thunder of the past.

Even though no production V-8 Solstice was in the making, there certainly was a demand for one. Word leaked out that the production LS-series V-8s would fit in the Solstice engine bay without any butchery. Soon, companies like Mallett were offering the car that GM wouldn't build. Sure, the cost was high, but the intangible benefits of owning such a beast ensured that many bucks-up performance freaks would line up to purchase one.

Brian Thomson, of Thomson Automotive in Redford, Michigan, took the V-8 Solstice concept a few steps further. While many of the conversions used the 5.7 or 6.0L aluminum versions, his car was built to showcase the new extreme-duty, cast-iron LSX block and the crate motors that will soon reach production. His combination is particularly fierce and punctuates what the LSX block is capable of, as well as just what kind of power the Solstice can effectively handle.

Thomson Automotive has been working with GM Performance Parts on a variety of LSX-based projects and has become one of the leading builders of these engines. It recently built the 550+ horsepower LSX V-8 engine that powered rapper 50 Cent's Pontiac G8 SEMA show car. This particular project was done independently of GMPP for obvious reasons, though they are clearly very pleased with the outcome of Brian's efforts.

The Engine Combination
Starting with the LSX block, Thomson bored it to 4.13 inches, which left enough meat for the additional cylinder pressure that a supercharger provides. A set of Diamond reverse-dome pistons provide an 8.2:1 compression ratio, while 6.20-inch Oliver forged steel rods swing on a Callies forged steel crankshaft with a 4-inch stroke.

Cylinder heads are the prototype LSX units that feature the new six-bolt per cylinder layout, which helps prevent head gasket failure. The castings feature stock LS7 roller rockers (1.8:1 ratio), titanium LS7 intake valves (2.20-inch), and sodium-filled exhaust valves (1.61-inch). These particular heads flow 380 cfm on the intake at 0.700-inch lift.

The valves are actuated with a stock LS7 hydraulic roller cam from the Z06 Corvette. It features 211/230-degree duration at 0.050 and 0.591-inch lift. A much wilder camshaft was originally used that pushed the horsepower over the 1,000 mark, but it was not at all suitable for the street.

From here, things get a little more exotic. Harrop Performance, the Australian aftermarket firm, developed a supercharger kit for the LSX that really wakes it up. A special 2,300cc (140 ci) Eaton supercharger is mated to a custom intake manifold that features an integral air-to-liquid intercooler. With a 2-inch diameter pulley, the drive ratio is 1:1 and it's driven by a 12-ribbed belt. Boost is set at 10 psi.