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Recent engine design trends towards increasing power, reducing weight, advancing of injection timing and increasing of injection rate and pressure could result in increased incidence of liner pitting. Liner pitting due to coolant cavitation is a complex function of many engine design parameters and operating conditions as described in reference [1]*. Traditionally, liner cavitation problems were not detected early in the development cycle. Traditional liner vibration and coolant pressure measurements in conjunction with a numerous amount of expensive engine endurance tests were then needed to resolve cavitation problems. A method newly developed by the author and described in reference [2] for cavitation intensity measurements was successfully utilized to map out engine operating condition and develop limit curves. This method could also be applied in a non intrusive fashion.

Cummins Engine Company is developing a low heat rejection 450 kW engine under contract for the US Army Tank & Automotive Command. This paper discusses progress made toward achieving the program goals of 6.6 kcal/kW-min brake specific heat rejection and 200 g/kW-hr brake specific fuel consumption. Methodology for measuring heat rejection on a low heat rejection engine is presented. Design improvements of the base engine are discussed along with their effect on improving fuel consumption. Performance test data is assessed in terms of the first law energy balance and cooling load distribution. The heat rejection data provides insights on the performance of insulating components and two cooling system designs. Diesel cycle simulations are compared to the test data and are used to predict the effect of ceramic insulation on engine heat rejection.

This paper presents the design philosophy and the technical capabilities of a new technical center built by Cummins Engine Co. The center was built primarily for development of diesel and similar engines, but also has broad capability for development of a variety of advanced power systems. The facility includes 88 instrumented test cells for testing power units up to 2000 hp under a complete range of environmental and special test conditions. Additional research laboratories support development activity and perform advanced studies in analytical techniques, materials development, and basic engine mechanisms.

Joint development of the adiabatic engine by Cummins Engine Company and the U. S. Army began with a feasibility analysis ten years ago. The effort was initially driven by the expectation of substantial performance improvement, a reduction in cooling system size, and several additional benefits. Program emphasis turned quickly to experimentation with the goal of demonstrating the feasibility of the adiabatic engine in working hardware. Several significant achievements were realized as have been reported earlier. Further development of the adiabatic engine is expected to be more evolutionary, paced by available technology in the areas of materials and tribology. Analysis capability necessary for insulated engine development has been found to be inadequate. Additional effort has gone into the development and validation of insulated engine analysis tools, both for cycle simulation and structural modeling.

A range of noise reduction hardware is described for three production engine models, as well as the rationale for selecting noise reduction methods. Noise reductions up to 6 dB(A) were achieved with this hardware in the test cell. In many cases the modifications are more effective in vehicles. The success of the hardware in reducing overall vehicle noise is illustrated.

The increased use of on-board and off-board electronic systems with medium duty and heavy duty trucks and buses presents challenges with compatibility and proper integration. The vehicle architecture is taking shape to establish three areas of computer control-the powertrain, the cab instrument panel, and the cab operations center. The critical element of pursuing proper integration of these systems requires established and clear standards and test methods. Clear roles and responsibilities, a defined system architecture and common test methods are required between subsystem electronic product suppliers and vehicle manufacturers. The electronics integration challenges are presented in the context of the U.S. medium duty and heavy duty automotive industry but have broad applicability to other heavy vehicles and markets worldwide. SAE and ISO forums are needed to address these issues.

AISI-4140H steel has been used as articulated piston crown material in heavy-duty engines. With the driving force for reducing manufacturing cost, microalloyed steel (MAS) was identified as a low-cost material to replace 4140H steel. In order to determine the feasibility of using MAS to replace 4140H steel, a test program was initiated to fully evaluate the material properties of MAS and to compare them to those of the baseline 4140H steel. The physical and mechanical properties of both materials from room temperature to 550°C were evaluated. The effect of long term thermal exposure on the material properties was also studied. Some engine tests were also conducted to evaluate the performance of the articulated pistons made with both materials. The inherently lower strength of MAS as compared to 4140H steel, requires a total re-design of the piston for the utilization of MAS as a low-cost replacement material for 4140H steel.

The production of pollutants and an increasing need for pollution management are an inevitable concomitant of a society with a high standard of living. The automotive diesel engine is used more than any other type of engine for transporting freight over highways. Two kinds of pollution to be considered with regard to the diesel engine are the dark exhaust smoke and odor, of which the public is quite cognizant, and the less obvious but possibly toxic carbon monoxide, oxides of nitrogen, unburned hydrocarbons, and trace compounds of other toxic materials. This paper discusses sampling, measurement techniques, and established standards for exhaust smoke and odor. Examination of diesel exhaust shows it to be less offensive in terms of harmful effects than the invisible exhaust from other types of engines. The major problem is exhaust color and odor.

A series of comparative evaluation tests to determine the effect of various full-flow and combination full-flow and bypass filter systems on diesel engine piston ring and crankshaft bearings was made using radioactive tracer wear measurement and component weight loss techniques. The results of these tests indicate that bypass lube oil filtration combined with good full-flow lube oil filtration result in lowest engine wear rate and lowest total cost for the engine user.

The development of smoke measurement procedures and instruments has been one of the significant factors contributing to the reduction of smoke from diesel-powered trucks. There is a need, however, for better information on the relation between measurements and the appearance of the smoke plume, for improved smokemeters, and for common international test procedures. Studies of smoke plumes using jet theory, alumina tracer, and hydraulic analog techniques indicate that the plumes are sometimes unstable and subject to large-scale shedding in the region where free-plume smokemeters are located. This introduces a significant random variation into smoke measurements made in this location. A future test procedure based on smoke measurements made with a long path (500 mm) in-line smokemeter during a dynamic cycle is suggested for consideration. Smoke limits would be based on tests similar to those conducted by MIRA to relate smoke levels and engine size to human response.

A new telemetry system has been developed for temperature or strain measurements on a spherical joint piston. The system includes a piston mounted signal multiplexer and transmitter. A patented, piston mounted power generator operates in conjunction witii a modified cylinder liner. The telemetry system is robust, having high inertia load capability and high environmental temperature operating capability. The telemetry system was installed and operated on an engine motoring test rig. Temperature signals were transmitted at engine speeds from 400 rpm to 2100 rpm. Over 100 hours of high engine speed testing with oil sump temperatures up to 122°C were completed.

Fundamental aspects of performance and regeneration of a porous ceramic particulate trap are described. Dimensionless correlations are given for pressure drop vs. flow conditions for clean and loaded traps. An empirical relationship between estimated particulate deposits and a loading parameter that distinguishes pressure drop changes due to flow variations from particulate accumulation is presented. Results indicate that trapping efficiencies exceed 90% under most conditions and pressure drop doubles when particulate accumulation occupies only 5% of the available void volume. Regeneration was achieved primarily by throttling the engine intake air. For various combinations of initial loading level, trap inlet temperature and oxygen concentration, it was found that regeneration rate peaked after 45 seconds from initiation.

RAPID CORROSIVE WEAR OF COPPER ALLOYS caused by a friction reducing additive was encountered in field tests of experimental lubricants. This oil soluble molybdenum, sulphur, and phosphorous containing additive subsequently was used in several commercial heavy duty diesel lubricants although the additive manufacturer did not recommend it for such applications. Numerous engine failures occurred due to the aggressiveness of this additive toward copper. Standard laboratory engine test methods or standard bench test methods did not predict the severe field problem. A new laboratory engine test method has been shown to duplicate the field failures. Bench test methods to duplicate the field failures are discussed. The mode of failure is shown and described.

Diesel engine manufacturers have traditionally done most engine noise development work under steady: state operating conditions. However, truck driveby noise tests are acceleration tests, and engines exhibit different noise behavior under accelerating conditions. Acceleration noise can be affected by engine performance parameters which may have no influence on steady state noise levels. In this study, a test cell simulation of the truck driveby procedure has been developed and evaluated. Test cell simulation and truck driveby results are compared for a naturally-aspirated and a turbocharged engine. This simulation procedure has been shown to predict reliably results measured in vehicles. As a result, the simulation can be used to evaluate engine modifications during the development process without requiring a vehicle installation.

Testing procedures to evaluate new coolant pump seal face materials and new coolant pump seal designs were evaluated. Rig testing of materials and seals followed by engine dynamometer testing enabled changes in the seal materials or design to be validated prior to field testing and limited production. These procedures were used to test and implement a coolant pump seal face material change to silicon carbide versus carbon. The change resulted in higher reliability for the coolant pump seal and reduced warranty cost for the engine.

A Minimum Cooled Engine (MCE) has been successfully run for 250 hours at rated condition of 298 kW and 1900 rpm. This engine was all metallic without any coolant in the block and lower part of the heads. Ring/liner/lubricant system and thermal loading on the liner at top ring reversal (TRR) as well as on the piston are presented and discussed. Ring/liner wear is given as well as oil consumption and blow-by data during the endurance run. Another engine build with a different top ring coating and several lubricants suggested that a 1500 hours endurance run of MCE is achievable. Rig test data for screening ring materials and synthetic lubricants necessary for a successful operation of a so-called Adiabatic Engine with the ring/ceramic liner (SiN) interface temperature up to 650°C are presented and discussed.

The effect of eight installation and component parameters on cooling system heat rejection and air flow were examined in detail in a wind tunnel facility. A quarter-replicate, two level factorial test plan was followed. Within the ranges of each parameter tested, the fan characteristics and the projection of fan into the shroud are highly significant parameters. The fan to radiator distance, the radiator characteristics, and the fan tip to shroud clearance are significant parameters. The fan to engine block distance and the type of shroud are not significant parameters.