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This paper covers work performed for the California Air Resources Board and US Environmental Protection Agency by Southwest Research Institute. Emission measurements were made on four in-use off-road two-stroke motorcycles and all-terrain vehicles utilizing oxygenated and non-oxygenated fuels. Emission data was produced to augment ARB and EPA's off-road emission inventory. It was intended that this program provide ARB and EPA with emission test results they require for atmospheric modeling. The paper describes the equipment and engines tested, test procedures, emissions sampling methodologies, and emissions analytical techniques. Fuels used in the study are described, along with the emissions characterization results. The fuel effects on exhaust emissions and operation due to ethanol content and fuel components is compared.

This paper covers work performed for the California Air Resources Board and the United States Environmental Protection Agency by Southwest Research Institute. Emission measurements were made on nine types of off-road equipment with small (<19kW) spark-ignited engines including handheld and non-handheld equipment utilizing oxygenated and non-oxygenated fuels. Emission data was produced to augment ARB and EPA's off-road emission inventory. It was intended that this program provide ARB and EPA with emission test results they require for atmospheric modeling. The paper describes the equipment and engines tested, test procedures, emissions sampling methodologies, and emissions analytical techniques. Fuels used in the study are described, along with the emissions characterization results. The fuel effects on exhaust emissions and operation due to ethanol content and fuel components is compared.

The U.S. EPA and the California Air Resources Board have adopted standards to reduce emissions from recreational marine vessels. Existing regulations focus on reducing hydrocarbons. There are no regulations on particulate emissions; particulate is expected to be reduced as a side benefit of hydrocarbon control. The goal of this study was to develop a sampling methodology to measure particulate emissions from marine outboard and personal watercraft engines. Eight marine engines of various engine technologies and power output were tested. Emissions measured in this program included hydrocarbons, carbon monoxide, oxides of nitrogen. Particulate emissions will be presented in a follow-up paper.

A 2001 General Motors 4.3 liter V-6 marine engine was baseline emissions tested and then equipped with catalysts. Emission reduction effects of exhaust gas recirculation (EGR) were also explored. Because of a U.S. Coast Guard requirement that inboard engine surface temperatures be kept below 200°F, the engine's exhaust system, including the catalysts, was water-cooled. Engine emissions were measured using the ISO-8178-E4 5-mode steady-state test for recreational marine engines. In baseline configuration, the engine produced 16.6 g HC+NOx/kW-hr, and 111 g CO/kW-hr. In closed-loop control with catalysts, HC+NOx emissions were reduced by 75 percent to 4.1 g/kW-hr, and CO emissions were reduced by 36 percent to 70 g/kW-hr of CO. The catalyzed engine was then installed in a Sea Ray 190 boat, and tested for water reversion on both fresh and salt water using National Marine Manufacturers Association procedures.

The primary goal of this project was to characterize particulate emissions from a snowmobile engine through measurement of particulate matter volatile organic fraction (VOF), particle size, and biological activity. Emissions were evaluated using both a mineral oil and a biosynthetic oil. Basic criteria pollutants were also measured from diluted exhaust using conventional techniques. Particulate matter volatile organic fraction was determined using a gas chromatographic method (DFI/GC). Particle size was characterized using a scanning mobility particle sizer (SMPS), and particulate matter biological activity was measured using a modification of the Ames bioassay procedure. Results revealed that more than 99 percent of the particles were ultrafine (Dp<100nm), with a peak concentration in the nanoparticle (Dp<50nm) size range. It was also observed that the use of a biosynthetic lubricant increased both volatile and total PM mass emissions compared to the mineral lubricant.

A project was conducted by Southwest Research Institute on behalf of the California Air Resources Board and the South Coast Air Quality Management District to demonstrate the technical feasibility of utilizing closed-loop three-way catalyst technology in off-road equipment applications. Five representative engines were selected, and baseline emission-tested using both gasoline and LPG. Emission reduction systems, employing three-way catalyst technology with electronic fuel control, were designed and installed on two of the engines. The engines were then installed in a fork lift and a pump system, and limited durability testing was performed. Results showed that low emission levels, easily meeting CARB's newly adopted large spark-ignited engine emission standards, could be achieved.

Snowmobile engine emissions are of concern in environmentally sensitive areas, such as Yellowstone National Park (YNP). A program was undertaken to determine potential emission benefits of use of bio-based fuels and lubricants in snowmobile engines. Candidate fuels and lubricants were evaluated using a fan-cooled 488-cc Polaris engine, and a liquid-cooled 440-cc Arctco engine. Fuels tested include a reference gasoline, gasohol (10% ethanol), and an aliphatic gasoline. Lubricants evaluated include a bio-based lubricant, a fully synthetic lubricant, a high polyisobutylene (PIB) lubricant, as well as a conventional, mineral-based lubricant. Emissions and fuel consumption were measured using a five-mode test cycle that was developed from analysis of snowmobile field operating data.

Natural gas-fueled vehicles impose unique requirements on exhaust aftertreatment systems. Methane conversion, which is very difficult for conventional automotive catalysts, may be required, depending on future regulatory directions. Three-way converter operating windows for simultaneous conversion of HC, CO, and NOx are considerably more narrow with gas engine exhaust. While several studies have demonstrated acceptable fresh converter performance, aged performance remains a concern. This paper presents the results of a durability study of eight catalytic converters specifically developed for natural gas engines. The converters were aged for 300 hours on a natural gas-fueled 7.0L Chevrolet engine operated at net stoichiometry. Catalyst performance was evaluated using both air/fuel traverse engine tests and FTP vehicle tests. Durability cycle severity and a comparison of results for engine and vehicle tests are discussed.

Small engines which are friendly toward the environment are needed all over the world, whether the need is expressed in terms of energy efficiency, useful engine life, health benefits for the user, or emission regulations enacted to protect a population or an ecologically-sensitive area. Progress toward the widespread application of lower-impact small engines is being made through engine design, matching of engine to equipment and task, aftertreatment technology, alternative and reformulated fuels, and improved lubricants. This paper describes three research and development projects, focused on the interrelationships of fuels, lubricants, and emissions in Otto-cycle engines, which were conducted by Southwest Research Institute. All the work reported was funded internally as part of a commitment to advance the state of small engine technology and thus enhance human utility.

Recent legislation including the California Clean Air Act of 1988 and the Federal Clean Air Act Amendment of 1990 will regulate exhaust emissions from small utility, lawn, and garden equipment engines. In an attempt to gain as much understanding as possible in a short time, SwRI has conducted a series of tests to investigate the effectiveness of late 1960's automotive emission reduction technology on small engines. Experiments were conducted utilizing air injection into the exhaust, exhaust gas recirculation (EGR), and ignition timing changes. The test engine was a 4 stroke generator set engine rated 5.88 Kw at 3600 rpm. Results show these technologies to be very effective in reducing hydrocarbons (HC), oxides of nitrogen (NOx), and carbon monoxide (C0).

A major gap exists in available baseline emissions data on the small utility engine population between the mid-1970's and present day. As part of the input required for a standard-setting process, the California Air Resources Board has funded limited laboratory emission measurements on a number of modern small engines, both 2-stroke and 4-stroke designs. Exhaust constituents characterized in this study include total hydrocarbons, reactive hydrocarbons (RHC), methane, CO, NOx, CO2, O2, aldehydes, and particulate matter. A total of nine engines were evaluated, spanning the range from the smallest widely-used 2-strokes (about 20 cc displacement) to 4-strokes approaching 20 hp.

The Detroit Diesel 6V-92TA engine has been redesigned to run on alcohol fuels to meet 1991 urban bus emission standards. A prototype engine was tested over the EPA transient procedure, using mixtures of methanol, ethanol (with and without water), gasoline, and ignition enhancer. Regulated and selected unregulated emissions were measured. Organic material hydrocarbon equivalent (OMHCE) emissions were significantly above the hydrocarbon emission standard; however, emissions of CO and NO, were below the 1991 emission standards for the fuel combinations used. Particulate emissions were close to the 1991 urban bus emission standard for some configurations. The method used for calculating OMHCE emissions when ethanol was used is also given.

Measurement of emissions from small utility engines has usually been accomplished using steady-state raw emissions procedures such as SAE Recommended Practice J1088. While raw exhaust measurements have the advantage of producing modal exhaust gas concentration data for design feedback; they are laborious, may influence both engine performance and the emissions themselves, and have no provision for concurrent particulate measurements. It is time to consider a full-dilution procedure similar in principle to automotive and heavy-duty on-highway emission measurement practice, leading to improvements in many of the areas noted above, and generally to much higher confidence in data obtained. When certification and audit of small engine emissions become a reality, a brief dilute exhaust procedure generating only the necessary data will be a tremendous advantage to both manufacturers and regulatory agencies.

Emissions from a Stirling engine-powered 1986 model light-duty truck were measured using current EPA (chassis dynamometer) emissions certification procedures and certain specialized tests. Three fuels were used including unleaded gasoline, a blend of MTBE in unleaded gasoline, and JP-4. City (FTP) cycles and Highway (FET) cycles were run on all three fuels, and emissions measured during the cycles included hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx). Fuel economy was also calculated for these tests. Additional pollutants measured during some of the tests included aldehydes, 1,3-butadiene, individual hydrocarbon species, and total particulate matter. In addition to the cyclic schedules, steady-state conditions were run on JP-4 and straight gasoline for regulated emissions and fuel economy. The conditions consisted of several simulated gradients at three vehicle speeds, plus idle.

The influence of fuel composition on exhaust emissions from four 1982 model light-duty diesel vehicles was studied on the FTP cycle and at two steady-state conditions, but only the FTP results are presented and discussed in this paper. Nine test fuels were blended specifically for the program, with intentional variation in aromatic content, 90% boiling point, and 10% boiling point. Limited data were also acquired with injection timing at advanced and retarded settings, in addition to the main body of data taken with the engines adjusted to recommended timing. A comparatively small effort was also made to evaluate a tenth fuel consisting of a blend of two of the original nine fuels. Of the fuel characteristics varied intentionally, aromatic content generally had the greatest effect on most emissions of major interest (hydrocarbons, oxides of nitrogen, particulate, soluble organic fraction, polynuclear aromatic hydrocarbons, and mutagenicity of extract by Ames bioassay).

Three crude shale oils were chosen from six candidates to investigate their possible use as substitutes for No. 2 diesel fuel. Satisfactory hot engine operation was achieved on the crudes using a fuel heating system, allowing emissions characterization during transient and steady-state operation. Regulated gaseous emissions changed little with the crudes compared to diesel fuel; but total particulate and soluble organics increased, and larger injector tip deposits and piston crown erosion were observed. After engine rebuild, two minimally-processed shale oils were run without the fuel heating system, causing no engine problems. Most emissions were higher than for No. 2 fuel using an SO percent distillate of crude shale oil, but lower using a hydrotreated form of the distillate.

Diesel soot or smoke has been regarded as a nuisance pollutant and potential health hazard, especially in congested urban areas where diesel buses operate. Exhaust emissions from a DDAD 6V-71 coach engine and a similarly-powered 1980 GMC RTS-II coach, fitted with a non-catalyzed particulate trap, were characterized over various Federal Test Procedures for heavy-duty engines, including an experimental test cycle for buses. Regeneration was accomplished using an in-line burner in the exhaust to raise the engines' idle exhaust gas temperature from 120 to 700°C. Trap testing included approximately 15 hours of engine operation and 100 miles of bus operation. Particulate emissions were reduced by an average of 79 percent and smoke emissions were nil using the trap. The effect of the trap on regulated and other unregulated emissions was generally minimal.

Diesel engines are adjusted to manufacturers' specifications when produced and placed in service, but varying degrees of maintenance and wear can cause changes in engine performance and exhaust emissions. Maladjustments were made on two heavy-duty diesel engines typically used in buses in an effort to simulate some degree of wear and/or lack of maintenance. Emissions were characterized over steady-state and transient engine operation, in both baseline and maladjusted configurations. Selected maladjustments of the Cummins VTB-903 substantially increased HC, smoke and particulate emission levels. Maladjustments of the Detroit Diesel 6V-71 coach engine resulted in lower HC and NOX emission levels, but higher CO emissions, smoke, and particulate.

Exhaust emission data from several fuel effects studies were normalized and subjected to statistical analyses. The goal of this work was to determine whether emission effects of property variation in alternate-source fuels were similar, less pronounced, or more pronounced than the effects of property variation in petroleum fuels. A literature search was conducted, reviewing hundreds of studies and finally selecting nine which dealt with fuel property effects on emissions. From these studies, 15 test cases were reported. Due to the wide variety of vehicles, fuels, test cycles, and measurement techniques used in the studies, a method to relate them all in terms of general trends was developed. Statistics and methods used included bivariate correlation coefficients, regression analysis, scattergrams and goodness-of-fit determinations.

Emissions from a modern heavy-duty Diesel truck engine were characterized with five different fuels during transient and steady-state operation. A control fuel (Phillips D-2) was used for baseline emissions, and as base stock in three alternate fuel blends containing EDS or SRC-II middle distillates, or used lubricating oil. The fifth fuel tested was neat soybean oil, heated to 145°C. HC, CO, NOX, and particulate emissions were similar for this engine on all fuels tested, with the exception of higher particulates for the soybean oil and higher NOX for the SRC-II blend.