"We contacted Guldstrand and asked if he would 'refresh' the car. He was very receptive to the project. We went with his recommendations, and the car is now virtually identical to the way he built it 20 years ago. The only differences are the upgraded rims and tires and a rollbar that was part of the original upgrade but never installed on this car."
To be sure, the true stories behind these two surviving GS80s make for exciting reading, but we want to know more. Specifically, how were these rare GS80s engines built? How was their suspension designed? And, most important, how did they perform?
According to Hurst, Traco Engineering began with a Chevrolet HD Bow Tie block, which the company's techs bored to 4.125 inches. A 3.48-stroke, forged-steel GM crank; Carrillo rods; and JE pistons brought displacement to the prescribed 372 cubes.
Next up were a pair of extensively ported GM aluminum heads. Hurst explained that the Traco-performed cylinder-head modifications were state-of-the-art for the time. "The heads underwent some 50 hours of shop work. The valve-seat work was done on a Serdi 100 valve-seat-prep machine. The valve guides were overbored and fitted with K-Line bronze inserts. The heads were machined to unshroud the combustion chamber, then valve seats were cut for larger intake and exhaust valves. The intake and exhaust ports were substantially enlarged and polished, and the valve pockets were worked on. The intakes were enlarged from 165cc to 180cc. The final modification was a top-secret Traco multi-angle valve job. A before/after dyno test with the valve job on stock heads yielded a 15hp gain; fully modified heads produced a 45hp gain over stock. Together, the head/block combo boasted a 125hp gain over the stock L98 engine configuration."
Additional engine mods included 1.6-ratio rocker arms compressing dual springs and actuating the Ferrea 2.02/1.65-inch steel valves. An Engle solid-lifter camshaft boasted 231/231-degree duration, 0.480/0.480-inch lift, and a 112-degree lobe-separation angle-relatively modest by today's standards, but significantly rowdier than the factory L98 stick. Fuel was fed from a GM heavy-duty pump to 28-lb/hr injectors, while a TPIS 52mm throttle body gulped air into a port-matched L98 intake manifold with siamesed runners.
All GS80s were further upgraded with Traco 1 3/4-inch headers; the No. 9 car also received Random Tech high-flow cats and a 2 1/2-inch Flowmaster exhaust system as part of its rebuild. Power traveled from a GM steel flywheel and L98 clutch to a factory-issue Dana 44 rear loaded with 3.42 gears.
The suspension was the second major component in the GS80's transformation. It used Guldstrand/Bilstein shocks with Guldstrand roller-bearing control-arm bushings; aluminum, Heim-jointed camber and toe-rod trailing arms; and Heim-jointed sway bars. According to Hurst, the race-bred suspension package was capable of nearly 1g lateral acceleration on the skidpad. To round out the package, GS80s were fitted with various sizes of Epsilon wheels wrapped in Goodyear rubber. (As is evident from the accompanying photos, both the No. 9 and No. 4 cars have since been modified with other wheel/tire combos.)
The resulting performance was well worth the extra money the package commanded. Dyno testing of the 372ci engine yielded 365 hp and 430 lb-ft torque at the crank-well up from the Vette's 240/340 factory rating in '87. "Guldstrand has said that the GS80 will perform as well as a C6 Vette," says Willauer. "I would be happy to have a side-by-side comparison performed." That's a tete-a-tete we'd like to get intimate with as well.