Thruster EFI And The ZZ572
The GM Performance Parts ZZ572 uses a four-bolt iron block and aluminum rectangular-port heads with 2.25/1.88-inch valves. Typically, it breathes through a Dominator-type carburetor, but in Orzetti's Corvette, it's been swapped for the Thruster EFI injection setup. The sheetmetal intake for the injection system is similar in design to a tunnel ram, with a large plenum on top and a gaping throttle body feeding long intake runners that house the injectors and fuel rails. The intake was designed to fit beneath a subtle, 1.5-inch-taller hood from AC Products.
The Thruster EFI sequential fuel-injection system is partnered with ACCEL DFI 63-lb/hr injectors that are fed by an ACCEL DFI in-tank fuel pump. Adapting the Thruster's distributorless system to the ZZ572 gives it a uniquely modern twist and surprising efficiency.
Thruster EFI is a high-feature, affordable system that is adaptable to just about any automotive engine and popular ignition systems. It's suitable for engines ranging from 200 to 2,000 horses and running superchargers, turbochargers, or nitrous. Like production-style systems, it's volumetric-efficiency-based, allowing for excellent startup, idle, and driving characteristics. And like many OEM systems, it uses crankshaft- and camshaft-position sensors-instead of a conventional distributor-to trigger the ignition system.
The Thruster EFI system offers wide-band O2 tuning in closed-loop operation, via a laptop that can be plugged into a communication port inside the Corvette's interior. The system features real-time ECU programming for instant operation and performance changes. It also provides many OEM-type features, including knock control, torque-converter lockup, and self diagnostics. It even offers a "limp home" mode and data acquisition.
When it comes to firing the Thruster EFI-controlled ZZ572, the job falls to ACCEL DFI's recently introduced 8 Channel Programmable Multi-Strike CD ignition, which utilizes a coil-on-plug system. Like a modern LS engine, the ACCEL DFI system allows the mounting of individual ignition coils on the valve covers, over each cylinder. With 150 millijoules of spark energy available at the plug, the 8 Channel CD module can fire almost any engine combination producing up to nearly 2,000 hp.
The ignition controller is wired to the Thruster EFI's Dual-Sync replacement for the conven-tional distributor. It contains both crank- and cam-position sensors, and it mounts in the original distributor hole in the intake manifold. It's an ingenious development for classic Chevy engines, giving them greater ignition and timing control without sacrificing space or aesthetics.
The Thruster EFI system broadens the torque curve of the ZZ572 engine's already healthy output, but more importantly it delivers a modern driving feel, easy tuning capability, and an unmistakably exotic aura. Another benefit is a significant increase in fuel economy-a much-appreciated attribute for any enthusiast looking to squeeze a few more miles per gallon from his or her performance car.
Additional underhood modifications to Orzetti's Corvette include a custom cold-air induction system, Corvette Conspiracy-built headers, a March serpentine accessory-drive system, a three-row Be Cool aluminum radiator (with dual electric fans), and a Corsa exhaust system.
The engine is backed by a performance-built 700R4 overdrive transmission equipped with a 3,000-stall torque converter and a custom shifter configured to fit the Corvette's center console. The transmission channels nearly 700 lb-ft of torque to a tough Dana 44 rearend filled with a "just right" 3.55 gearset.