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Previous investigations have shown that fuel economy gains are possible in vehicles with increased compression ratio engines that meet 1978 Federal emission standards using oxidizing converter-EGR emission control systems. There has been no incentive to raise compression ratios, however, since the vehicle gains are offset by energy losses in the refinery due to refining the higher octane unleaded fuel required by high compression ratio engines. This paper discusses the application of an electronic closed loop knock control system to a higher compression ratio engine to allow operation on 91 Research Octane Number fuel. Two cars with different compression ratios are compared with both oxidizing converter - EGR and 3-way oxidizing-reducing converter-EGR closed loop carburetor emission control systems.

Three production cars and seven cars with various experimental exhaust emission control systems were tested to determine the effect of winter weather ambient temperatures on exhaust emissions. All of the cars were tested at 70, 40, and 20°F, and one was tested at 0°F using the 1972 EPA test schedule. Modal and bag emission data as well as catalytic converter temperature data were obtained. The results of these tests are presented in this paper. There was an increase in HC and CO emissions as ambient temperature was reduced. Most of the increase came from the first cycle of the 18 cycle test and was the result of additional time required to reach operating temperatures. NOx emissions did not vary substantially with ambient temperature.

Catalyst durability tests were run to gain additional information on the effects of contaminants on catalyst deterioration. Six different fuels were used with two oxidizing bead catalysts-platinum and palladium. In addition, a special oil was evaluated with both catalysts. Both catalysts showed deterioration with miles, but the platinum catalyst had least deterioration. Increasing lead in fuel increased deterioration. Increasing sulfur did not. Phosphorus, however, was harmful, more so with the platinum catalyst than the palladium.

An exhaust emission control system has been developed for used cars of the 1955-1967 model years. Average exhaust emissions were reduced on 194 cars by 53% HC, 33% CO, and 31% NOx. The package consists of increased idle speed, leaner idle mixture, and retarded ignition timing. A thermostatic vacuum switch provides engine cooling protection with the retarded ignition. For maximum effectiveness of the control, the engine must be in good running condition.

Tire brake force characteristic data are presented that should be helpful in the design of wheel slip control systems. Correlation of these data has been established with antilock system performance. Experimentally measured μ-slip curves are given for a large number of tire/road pairings. These measurements cover a wide range of commercial tire types on dry and wet road surfaces and glare ice. It is shown how wet road characteristics are affected by road construction, water cover depth, and tread wear. The measuring system used to obtain these data is described and variability of the experimental measurements is discussed.

The use of a laboratory simulator to evaluate the performance of wheel slip control systems under controlled operating conditions is reported. It is shown how an analog computer can be interconnected with a hydraulic brake system and wheel slip control hardware to form a hybrid simulation of a vehicle installation. An analog computer can also be used to simulate vehicle dynamics and tire-to-road friction characteristics. Simulator accuracy is established by correlating laboratory results with road data. Advantages and disadvantages of using the simulator in lieu of experimental road testing are pointed out.

Spring rate is one of several factors that affect the ride performance of passenger car tires. A technique has been developed for obtaining precise spring rate measurements in the laboratory under conditions approximating road operation. The spring rate properties of many different tire designs have been measured. The effect of wear and several tire construction variables on spring rate is presented. A correlation between the laboratory measurement of spring rate and vehicle ride evaluations is discussed. It is necessary to measure tire spring rate for the rolling condition with a resonance test technique in order to generate data that are useful for ride performance analyses.

A design guide for bolt engagement in cast iron has been developed. The design engagements are sufficient to insure that if a bolt is overloaded and failure occurs, either at assembly or in service, the bolt will break rather than strip the bolt or cast iron threads. In addition to the design guide, this report presents information concerning: 1. The ratio of gray cast iron shear strength to tensile strength. 2. The ratio of shear strength to tensile strength for SAE Grade 5 and Grade 8 bolts.

An integrated heating and air conditioning system that would automatically bring the passenger compartment to a comfortable temperature and maintain this temperature under all climatic and engine operating conditions has long been a goal of many automotive engineers in this field. Fulfillment of this objective was realized with the introduction of the Comfort Control system on the 1964 Cadillac. This paper presents a brief history of General Motors’ experience with automatic climate controls, describes the preliminary design and development of the Cadillac system, and explains how the Comfort Control system operates.