After the oil embargo in 1973, GM began many activities to increase the fuel economy of its fleet. These efforts included increasing powertrain efficiency and reducing vehicle mass. Another, more radical effort that I was involved with in the late 70's - early 80's while at GM Research (GMR) was to investigate the potential of hybrid vehicles that used a flywheel as an energy storage device. Much work at that time was going on in this area, some of which was sponsored/coordinated by the DOE.

GM, in the late 70's contracted the Industries Development Corporation (IDC) of Israel for the development of an engine/flywheel drive system for a G-30 Chevrolet van. The van’s V8 engine was replaced by a 2.5L 4-cylinder Pontiac engine. A low technology flywheel system coupled to a unique 2-mode CVT transmission using a high efficiency Allgaier hydrostatic unit was used.

The engine/flywheel drive system was delivered to GMR in 1980, and a G-30 van equipped with that drive system was delivered the following year. The results from tests conducted with those systems were very promising.

G-30 Van Flywheel Drive System in GMR Test Cell

In parallel, in 1979, a study was made to define the maximum potential fuel economy gains of heat engine hybrid passenger cars. “Ideal” hybrid vehicle characteristics were assumed, i.e., a vehicle which:

• utilized regenerative braking
• allowed the engine to be turned off during idle and unpowered decelerations
• allowed the engine to be operated at minimum brake specific fuel consumption

Results with these assumptions indicated the potential for dramatic fuel economy improvements across the entire vehicle spectrum.

Computed “Lower Bound” Fuel Consumption of Heat Engine Hybrid Vehicles vs. 1980 Production Cars

Based upon the above studies the FX85 Task Force was formed in early 1982. FX85 stood for Flywheel X-car for 1985 production – quite a goal!

FX85 Leadership Team with a Mock-Up of the FX85 Transmission. Left to right: Lou Hewko, Steve Rohde, Butch DeHart, Neil Schilke, Chuck Matthews, and Don Pozniak

A 44-person FX85 Task Force was assembled consisting of GMR and Hydramatic personnel. The team was charged with the design and specification of a11 transmission and flywheel components, tailoring of a 1.8 L OHC Family II engine with sequential port fuel injection for hybrid-type operation, specification of the hardware for a drive-by-wire development control system, conceptualization of a regenerative braking system, and resolution of any vehicle handling characteristics issues. The metal-belt CVT that GM was developing at that time was used. The team met its goals.

Although the EPA Urban fuel economy predictions for the FX85 system were 31% and 17% higher than a 1985 X-car and a 1985 X-car with a CVT transmission, the FX85 would only achieve a 10% improvement over the composite fuel economy of either of these competitors. This came at a considerable increase in complexity and probable cost. Hence, the FX85 Task Force was disbanded having met its objective of defining the current state of the engine flywheel hybrid technology relative to passenger cars.

Isometric Schematic of the FX85 Drivetrain

Many new concepts came out of FX85 including better CVT and engine control algorithms for a hybrid vehicle, a novel drive system design, and a new low cost flywheel design for automotive vehicles.

Besides FX85, other studies were conducted during this period that showed considerable potential for flywheel systems. These included electric and diesel engine flywheel drive systems for RTS coaches (with Truck and Bus Division), and the use of flywheel systems in military tanks (with Allison).

The year was 1982.