Arousing car enthusiasts' interest with a C4 can be a real challenge. Positioned in the nether region between vintage and late-model, even the nicest fourth-gens have a tough time generating the oohs and aahs of a C1 Vette, or eliciting the awe and respect the newer LS-powered models command.
So how do you make your C4 stand out among the 358,000-plus other Corvettes that were produced between 1984 and 1996? For Bob Lynn, vice president of the New South Wales Corvette Car Club in Sydney, Australia, ample horsepower and a super-rare paint color were the answers.
"My Corvette obsession began 17 years ago," Lynn says. "I found a '72 454 coupe in Sunflower Yellow advertised in the local paper. After several inspections and a long testdrive, three weeks later it was mine." Soon, it was time for a second Corvette. Lynn got a deal on an '87 coupe, and it was that car that made him fall in love with the C4 architecture. Eventually, he found a '92 coupe advertised in Australia's Unique Cars magazine, and, in 1998, he added it to his collection.
His Corvette was one of 678 painted in Yellow, the rarest color choice for a model year that produced 20,479 vehicles. "My Corvette was built in November 1991," he says. "It's the only one of its kind in Australia. It was halfway through being converted to right-hand drive when I first looked at it. Corvette Queensland, now known as Performax International, completed the conversion before I took ownership of it.
The '92 model year was a watershed sea-son in the history of the C4. Whereas all '85-'91 base Corvettes were factory-equipped with the "Gen I" L98 small-block, '92 was the first model year in which the "Gen II" LT1 engine was offered as standard fare. Although it featured a familiar 4.00 x 3.48 bore/stroke configuration and displaced the same 350 ci, its reverse-flow cooling layout-in which the heads were cooled before the block-was the first-ever such application on a production Chevrolet V-8. Other significant upgrades included a short-runner intake manifold, higher-flowing heads, and a front-mounted OptiSpark ignition system.
Factory literature states that the LT1 was good for 300 hp at 5,000 rpm. That wasn't enough power for Lynn, who sent his car to Pro-Flo Performance of Sydney for a boost in displacement and a Vortech V-1 S-Trim supercharger.
Utilizing an Eagle 3.75-inch 4340 steel crank, Eagle 6.00-inch H-beam connecting rods, and SRP forged-aluminum blower pistons, Pro-Flo stroked the LT1 to 383 ci and lowered its compression to 8.5:1. The heads were then ported and treated to Ferrea 2.02/1.60 stainless steel valves, Isky double valvesprings, and Yella Terra 1.6-ratio roller rockers. Likewise, Pro-Flo retired the factory stick in favor of a Camtech custom hydraulic roller cam.
Then came the, "bright" idea to paint the cylinder block yellow to match the exterior's coruscating color. "It was the engine-builder's idea, as he said the engine bay was a black hole and needed something to brighten it up. After a little thought, I agreed," Lynn says. Meanwhile, Peter Snell Powdercoating of Sydney applied a metallic-silver coating to the front suspension, the radiator, and other select engine components to further spruce up the underhood presentation.
The fuel, ignition, intake, and exhaust systems were next. Pro-Flo's techs added Bosch 42-lb/hr injectors, a BBK 58mm throttle body, and port-matched the factory intake to the cylinder heads. Custom, ceramic-coated long-tube headers were then matched to the exhaust ports and installed. Pro-Flo also upgraded the ignition with a Crane Fireball HI-6 CD amplifier, '96 LT4 plug wires, and NGK BCPR6ES plugs. Initial dyno testing performed at Just Engine Management (JEM) in Sydney was overwhelmingly positive. "Our testing on motor alone produced 295 rwhp," Lynn says.