1991-02-01

Saturn DOHC and SOHC Four Cylinder Engines 910676

This paper describes two 1.9L four cylinder engines developed for the new Saturn vehicles introduced in the Fall of 1990.
A single overhead cam (SOHC) 2 valve/cylinder single point fuel injected (TBI) design is utilized as a base engine with a dual overhead cam (DOHC) 4 valve/cylinder multi-point fuel injected (MPFI) configuration selected for an optional derivative. Market objectives for the SOHC engine included exceptional driveability achieved by high torque at low engine speeds combined with excellent fuel economy. Objectives for the DOHC engine included excellent driveability characterized by high torque at low engine speeds as well as good high speed power and good overall fuel economy. Both engines were developed in conjunction with specific automatic and manual transmissions to achieve fully optimized powertrains.
One of the strategic technologies selected was the lost foam casting process. This process was used with aluminum alloy for the cylinder block (a world first) and cylinder heads, and with ductile iron for the crankshaft. Significant advantages of this process include flexibility to optimize component mass and the ability to minimize machining requirements.
A high degree of integration during the design process with all aspects of manufacturing, supplier partners and UAW technicians resulted in achieving the aggressive reliability, mass, packaging, cost and investment targets for both engines.

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