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This paper reports its findings in three separate parts. First, a comparative study is made among existing commercial dual clutch automatic transmission fluids (DCTFs). Significant differences in fluid torque capacity, friction material compatibility and copper corrosion performance were found among the fluids. Second, both a new vehicle chassis dynamometer durability test and a SAE#2 durability procedure are offered, specifically designed for DCTs. A 2008 VW GTI did well in the severe 60,000 mile chassis dynamometer procedure. Third, a new DCT fluid is discussed.

The effects of the cetane improvers* 2-ethylhexyl nitrate (EHN) and di-tertiary-butyl peroxide (DTBP) on regulated exhaust emissions from a 1993 Detroit Diesel Series 60 heavy-duty diesel engine were studied. EHN and DTBP were added to two commercially available fuels at concentrations ranging from 500 to 12,000 ppm by volume. Both additives reduced CO, NOx, and particulate emissions as measured in the hot start portion of the FTP heavy-duty transient emissions cycle. A comparison of the emissions response of the two additives shows that the nitrogen in EHN does not contribute to NOx emissions at typical treat rates.

A 1000-hour test was conducted to determine the durability effects of 2-ethylhexyl nitrate (2-EHN) cetane improver on heavy duty diesel engines. Two identical 1993 DDC Series 60 engines were run side-by-side on a severe duty cycle. Both were fueled with a commercial low sulfur fuel. The fuel in one engine was treated with 7500 ppm of 2-EHN cetane improver. At the end of the test, engine wear and deposit comparisons were made to determine the effect of high cetane improver treat rates on engine durability. After 1000 hours of operation, the engine running on fuel treated with 2-EHN cetane improver exhibited lower engine wear and deposits than the engine run without cetane improver. Analysis of oil samples drawn every 100 hours indicated no difference in wear metals or other physical properties when cetane improver was used. Fuel analyses demonstrated that 2-EHN did not degrade under the high operating temperatures of this modern heavy-duty diesel engine.

A program to explore the effects of natural and additive-derived cetane on various aspects of diesel performance and combustion has been carried out. Procedures have been developed to measure diesel engine fuel consumption and power to a high degree of precision. These methods have been used to measure fuel consumption and power in three heavy-duty direct-injection diesel engines. The fuel matrix consisted of three commercial fuels of cetane number (CN) of 40-42, the same fuels raised to CN 48-50 with a cetane improver additive, and three commercial fuels of base CN 47-50. The engines came from three different U.S. manufacturers and were of three different model years and emissions configurations. Both fuel economy and power were found to be significantly higher for the cetane-improved fuels than for the naturally high cetane fuels. These performance advantages derive mainly from the higher volumetric heat content inherent to the cetane-improved fuels.

A number of factors have contributed to a growing awareness of diesel fuel quality. Recent regulations promulgated by the California Air Resources Board and the U.S. Environmental Protection Agency have emphasized the importance of diesel fuel properties on vehicle performance and emissions. This has created an interest in premium diesel fuel in the United States. Premium diesel has long been used in Europe to address the performance needs of the passenger car diesel market. Studies show that additives can improve the quality of diesel fuel. A new application of cetane improvers is to reduce emissions from diesel engines. Other combustion improvers may also be employed. Diesel detergents are used to insure that these low emission levels can be maintained over extended periods. Engine tests recently developed by OEMs are being used to quantify the performance benefits of these additives.

Four commercially available low-sulfur diesel fuels were additized with two chemically different cetane improvers. Both neat and additized fuels were evaluated in a 1991 prototype heavy-duty diesel (HDD) engine using the EPA Hot Start Transient Cycle. Hydrocarbon (HC), carbon monoxide (CO), nitrogen oxide (NOx), and particulate emissions were determined for each of the 18 fuel formulations tested. Results show that cetane improvers lower HC and CO emissions and, in some cases, NOx and particulate emissions. CO and HC emissions decreased as cetane number increased. The use of cetane improvers should help refiners design diesel fuel formulations which meet California requirements and assist original equipment manufacturers (OEM's) in meeting their emission targets.