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FIGURE 1 The 200 HP high performance 4.3L Vortec V6 engine has been developed to satisfy the need for a fuel efficient performance powerplant in the General Motors small truck platforms. Marketing requirements included strong low and mid range torque, relatively high specific power, smoothness and noise comparable to the best competitive six cylinder engines, excellent driveability, and a new technology image. Maintaining the 4.3L engine record of high reliability and customer satisfaction was an absolute requirement. Fuel economy and exhaust emission performance had to meet expected customer and legislated requirements in the mid 1990's.

The turbo/intercooled Syclone engine is the latest variant off the famed GM 90° small block engine platform. Application is specifically to the Syclone short wheelbase all wheel drive pickup truck to be marketed by GMC in 1991. The engine project was a joint venture between General Motors Powertrain Division and PAS TRIAD of Troy, Michigan. Engine manufacture will originate at the GMPD Romulus 4.3L plant with final assembly at the Shreveport vehicle assembly facilities of GMC Truck and Bus and PAS TRIAD. Features of the engine include: High specific performance (1430 KPa BMEP) Air to water intercooling with an independent cooling loop. Electronically controlled wastegate for boost and knock control. High dynamic range multi-port fuel injection. Communization with standard 4.3L engine where possible to facilitate manufacturing process and quality management.

Mathematical modeling of conventional automotive type cooling systems has been developed at Chevrolet for vehicle design and evaluation. Solution methods are based on system air and coolant side interrelationships. The computer program utilizes either experimental, analytically derived, or empirically calculated steady-state performance characteristics for system components. Typical examples of application to design problems and parametric studies are included in the presentation.