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Vehicle mission simulation is one component of a system designed to optimize selection and operation of on-highway vehicles. The focus of vehicle mission simulation is on equipment specification. It can predict the physical and financial performance of equipment alternatives, identify opportunities and correct problems before a truck is purchased.

A Cummins B55 in3 350 bhp heavy-duty, turbocharged diesel engine was tested in fully cooled and uncooled modes over the EPA transient emission test cycles for comparison of gaseous and particulate emissions. The results are presented at the same fuel injection timing and at similar NOx emission levels. Also, steady state emission measurements and analysis of real-time transient emission data of selected runs are discussed. The uncooled engine does not represent an adiabatic (insulated) engine in its emission characateristics, but may indicate some trends. It may be useful in identifying design and/or operating parameters that need optimization.

A survey is made of compression brake noise levels in heavy duty diesel trucks, using test procedures based on the ISO and EPA driveby acceleration noise tests. The data shows that compression brake noise levels are very high if worn out or open stack exhaust systems are used. Compression brake noise is also audible with OEM exhaust systems and, in at least one case, potentially objectionable. Two methods for reducing brake noise are investigated: improved mufflers and the use of an exhaust brake with the compression brake. Both techniques demonstrate a potential for reducing compression brake noise.

This paper documents the successful operation of a modified Cummins T46 turbocharger with a ceramic rotor. This turbocharger is modified to incorporate a 4.6 inch diameter ceramic turbine rotor (pressureless sintered silicon nitride) on the hot end. These results document the most complete ceramic turbine rotor performance map, for a large ceramic turbocharger rotor, available to date.

The EPA Heavy Truck Driveby Noise test is used to regulate trucks over 10,000 pounds GVW. The EPA test procedure is based on SAE J366. The EPA/J366 procedure is used both as a regulatory compliance tool and as a development tool. When the test procedure is used as a development tool, the goal is to determine the most cost effective means of meeting the legal requirement. Since J366 was not intended as a development tool, it can be difficult or misleading to use it to make decisions on product configuration. In order to use J366 successfully in vehicle or engine development, one must understand and properly account for the inherent variability of the J366 driveby test procedure. This paper examines both the extent and some of the sources of J366 driveby test variability. Strategies are proposed to ensure the proper interpretation of test results. Several repeat tests are required to accurately determine a small change in driveby noise level.

Data link interfaces are a very important part of the heavy duty vehicle industry; sharing information between subsystems is vital. SAE Recommended Practices J1708, J1587 and J1922 were developed to provide standards for proprietary communications, general information sharing, diagnostic definition and early powertrain controls. The industry realized, however, that these standards would not accomplish the ultimate goal-that of a high speed control and communications network. The development of more capable serial data communications for the heavy duty vehicle industry was prompted by the following: the desire of component suppliers to integrate subsystems for improved performance; the advancement of technology; customer expectations; and government regulations.

High Velocity Oxygen Fuel sprayed face coatings have shown great promise for piston rings used for High Power Density Diesel Engines. Various coatings have been tested on both wear test rigs and in engines. A highly dense HVOF cermet coating was developed with reasonable crack resistance during service. The HVOF coated piston rings wore three to six times lower than chrome plating. Cylinder liner (counter face) wear was found to be one to three times higher than chrome. However, engine oil consumption and blow by were within normal values. The HVOF coating is considered to be an excellent replacement for chrome plating. The coating process is more environmentally friendly than the chrome plating process. Also, the coating has potentially lower or equivalent production cost when compared to chrome.

This paper discusses the various process changes, engine improvements, and equipment evolution that have contributed to significant increases in test productivity for heavy duty engines over the past several years. It deals with the development of short test cycles, methods of diagnosing operating problems, methods of maintaining test accuracy and discusses systems for minimizing test equipment down time. Finally it presents historical overview of the changes as they occurred at Cummins Engine Company and how performance improved over that transition period.

In this paper, a procedure for the measurement of noise produced by compression brakes on heavy duty trucks is proposed and evaluated. The test procedure is an adaptation of the ISO exterior vehicle noise regulation, ISO 362, to measure compression brake noise. The test consists of two parts, a driveby test and a stationary brake test, which are both developed to accentuate compression brake noise. The proposed test is demonstrated to provide results that are indicative of on-road compression brake noise. The sensitivity of the test results to variations in several test parameters is also examined.

The advantages and disadvantages for the current oil consumption measurement systems, including the real-time oil consumption measurement and traditional weight methods, are reviewed. Based on the review, the Smart Oil Consumption Measuring System developed by Cummins Engine Co. in an effort to resolve some of the disadvantages of the systems developed earlier, especially compared to the Gravity Fed oil consumption measurement system, will be discussed. In addition, the uncertainty analysis of the Smart Oil Consumption Measuring System will also be briefly discussed here. The Smart Oil Consumption Measuring System has proven to be an effective tool to measure the oil consumption at almost any engine test conditions, including the steady and cyclic tests in a shorter time than most of traditional oil consumption measurement systems.

Evolving diesel engine design trends are expected to include fuel systems operating at significantly higher pressures and temperatures than in the past. Accordingly, meaningful laboratory tests are needed to help guide this development. Two candidate test methods were evaluated in this exploratory study. Scuffing Load Ball-on Cylinder Lubricity Evaluator (BOCLE) and Modified High-Frequency Reciprocating Rig (HFRR) test results covering a range of operating temperatures were compared with fuel property data. Correlations of the Modified HFRR test data with BOCLE results were also made.