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Octane appetite of modern engines has changed as engine designs have evolved to meet performance, emissions, fuel economy and other demands. The octane appetite of seven modern vehicles was studied in accordance with the octane index equation OI=RON-KS, where K is an operating condition specific constant and S is the fuel sensitivity (RONMON). Engines with a displacement of 2.0L and below and different combinations of boosting, fuel injection, and compression ratios were tested using a decorrelated RONMON matrix of eight fuels. Power and acceleration performance were used to determine the K values for corresponding operating points. Previous studies have shown that vehicles manufactured up to 20 years ago mostly exhibited negative K values and the fuels with higher RON and higher sensitivity tended to perform better.

Gasoline Direct Injection (GDI) engines have been widely adopted by manufacturers in the light-duty market due to their fuel economy benefits. However, several studies have shown that GDI engines generate higher levels of particulate matter (PM) emissions relative to port fuel injected (PFI) engines and diesel engines equipped with optimally functioning diesel particulate filters (DPF). With stringent particle number (PN) regulations being implemented in both, the European Union and China, gasoline particulate filters (GPF) are expected to be widely utilized to control particulate emissions. Currently, evaluating GPF technologies on a vehicle can be challenging due to a limited number of commercially available vehicles that are calibrated for a GPF in the United States as well as the costs associated with vehicle procurement and evaluations utilizing a chassis dynamometer facility.

The diesel engine can be an effective solution to meet future greenhouse gas and fuel economy standards, especially for larger segment vehicles. However, a key challenge facing the diesel is the upcoming LEV III emissions standard which will require significant reductions of hydrocarbon (HC) and oxides of nitrogen (NOx) from current levels. The challenge stems from the fact that diesel exhaust temperatures are much lower than gasoline engines so the time required to achieve effective emissions control with current aftertreatment devices is considerably longer. The objective of this study was to determine the potential of a novel diesel cold-start emissions control strategy for achieving LEV III emissions. The strategy combines several technologies to reduce HC and NOx emissions before the start of the second hill of the FTP75.

The Scuderi engine is a split cycle design that divides the four strokes of a conventional combustion cycle over two paired cylinders, one intake/compression cylinder and one power/exhaust cylinder, connected by a crossover port. This configuration provides potential benefits to the combustion process, as well as presenting some challenges. It also creates the possibility for pneumatic hybridization of the engine. This paper reviews the first Scuderi split cycle research engine, giving an overview of its architecture and operation. It describes how the splitting of gas compression and combustion into two separate cylinders has been simulated and how the results were used to drive the engine architecture together with the design of the main engine systems for air handling, fuel injection, mixing and ignition. A prototype engine was designed, manufactured, and installed in a test cell. The engine was heavily instrumented and initial performance results are presented.

Over the last two decades, global emission regulations have become more stringent and have required the use of more advanced fuel injection systems. This includes the use of tighter tolerances, more rapid injections and internal components actuated by weaker injection forces. Unfortunately, these design features make the entire system more susceptible to fuel contaminants. Over the last six years, the composition of these contaminants has evolved from hard insoluble debris, such as dust and rocks, to soluble chemical contaminants. Recent research by the diesel engine manufacturers, fuel injection equipment suppliers and the fuel and fuel additive industry has discovered a major source of the soluble chemical contaminant that leads to injector deposits to be derived from cost effective and commonly used additives used to protect against pipeline corrosion.

A cooperative research and development program was organized to determine the critical particle size of abrasive debris that will cause significant wear in rotary injection fuel pumps. Various double-cut test dusts ranging from 0-5 to 10-20 μm were evaluated to determine which caused the pumps to fail. With the exception of the 0-5-μm test dust, all other test dust ranges evaluated caused failure in the rotary injection pumps. After preliminary testing, it was agreed that the 4-8-μm test dust would be used for further testing. Analysis revealed that the critical particle size causing significant wear is 6-7 μm. This is a smaller abrasive particle size than reported in previously published literature. A rotary injection pump evaluation methodology was developed. During actual operation, the fuel injection process creates a shock wave that propagates back up the fuel line to the fuel filter.

A technique for rapid in situ measurement of the fuel dilution of oil in a diesel engine is presented. Fuel dilution can occur when advanced in-cylinder fuel injection techniques are employed for the purpose of producing rich exhaust for lean NOx trap catalyst regeneration. Laser-induced fluorescence (LIF) spectroscopy is used to monitor the oil in a Mercedes 1.7-liter engine operated on a dynamometer platform. A fluorescent dye suitable for use in diesel fuel and oil systems is added to the engine fuel. The LIF spectra are monitored to detect the growth of the dye signal relative to the background oil fluorescence; fuel mass concentration is quantified based on a known sample set. The technique was implemented with fiber optic probes which can be inserted at various points in the engine oil system. A low cost 532-nm laser diode was used for excitation.

Despite the recent increase in fuel prices, the multi-billion dollar recreational boating market in North America continues to experience solid momentum and growth. In the U.S. economy alone, sales of recreational boats continue to increase with over 17 million boats sold in 2004 [1]. Of that share, outboard boats and the engines that power them, accounted for nearly half of all boat sales. Though there has been a shift in outboard technology to four-stroke cycle engines, a significant number of new engine sales represent two-stroke cycle engines employing direct fuel injection as a means to meet emissions regulations. With the life span of modern outboards estimated to be 8 to 10 years, a significant base of two-stroke cycle engines exist in the market place, and will continue to do so for the foreseeable future.

Radioactive tracer technology (RATT™) is an important tool for measuring real-time wear in operating engines and other mechanical systems. The use of this technology provides important wear information that is not available by other, more conventional wear measurement methods. The technology has advanced to the point where several components can be interrogated simultaneously, and new methods have extended the method to materials that are normally not amenable to radioactive tracer evaluation. In addition, sensitivity has increased so that the onset of wear can be detected long before practical with non-tracer methods. This improves the ability to measure and determine cause and effect relationships, thus providing a better understanding of wear responses to specific operating conditions and to changes in operating conditions. This paper reviews the radioactive tracer process and recent improvements that have extended its reach in both automotive and non-automotive applications.

Sulfur poisoning from engine fuel and lube is one of the most recognizable degradation mechanisms of a NOx adsorber catalyst system for diesel emission reduction. Even with the availability of 15 ppm sulfur diesel fuel, NOx adsorber will be deactivated without an effective sulfur management. Two general pathways are currently being explored for sulfur management: (1) the use of a disposable SOx trap that can be replaced or rejuvenated offline periodically, and (2) the use of diesel fuel injection in the exhaust and high temperature de-sulfation approach to remove the sulfur poisons to recover the NOx trapping efficiency. The major concern of the de-sulfation process is the many prolonged high temperature rich cycles that catalyst will encounter during its useful life. It is shown that NOx adsorber catalyst suffers some loss of its trapping capacity upon high temperature lean-rich exposure.

The objective of this study was to quantify the effect of pilot fuel injection on engine-out emissions of potentially toxic compounds from a modern diesel engine operated with different fuels including 15% v/v dimethoxy methane in a low-sulfur diesel fuel. Five diesel fuels were examined: a low-sulfur (∼1 ppm), low aromatic, hydrocracked fuel, the same low-sulfur fuel containing 15% v/v dimethoxy methane, a Fischer-Tropsch fuel, a California reformulated fuel, and a EPA number 2 certification fuel. A DaimlerChrysler OM611 CIDI engine was controlled with a SwRI Rapid Prototyping Electronic Control system. The pilot fuel injection was either turned off or turned on with engine control by either Location of Peak Pressure (LPP) of combustion or the original equipment manufacturer (OEM) calibration strategy. These three control strategies were compared over 2 speed-load modes run in triplicate. Thirty-three potentially toxic compounds were measured.

In-cylinder control of particulate emissions in a diesel engine depends on careful control and understanding of the fuel injection and air/fuel mixing process. It is extremely difficult to measure physical parameters of the injection and mixing process in an operating engine, but it is possible to simulate some diesel combustion chamber conditions in a steady flow configuration whose characteristics can be more easily probed. This program created a steady flow environment in which air-flow and injection sprays were characterized under non-combusting conditions, and emissions measurements were made under combusting conditions. A limited test matrix was completed in which the following observations were made. Grid-generated air turbulence decreased particulates, CO, and unburned hydrocarbons, while CO2 and NOx levels were increased. The turbulence accelerated combustion, resulting in more complete combustion and higher temperatures at the measurement location.

Liquefied petroleum gas (LPG) is commonly known as autogas when used as a fuel for internal combustion engines. In North America, autogas primarily consists of propane, but can contain small amounts of butane, methane and propylene. Autogas is not a new fuel for internal combustion engines, but as engine technology evolves, the properties of autogas can be utilized to improve engine and vehicle efficiency. With support from the Propane Education & Research Council (PERC), Southwest Research Institute (SwRI) performed testing to quantify efficiency differences with liquid autogas direct injection in a modern downsized and boosted direct-injected engine using the production gasoline fuel injection hardware. Engine dynamometer testing demonstrated that autogas produced similar performance characteristics to gasoline at part load, but could be used to improve brake thermal efficiency at loads above 9 bar Brake Mean Effective Pressure (BMEP).

Dedicated EGR has shown promise for achieving high efficiency with low emissions [1]. For the present study, a 4-cylinder turbocharged GDI engine which was modified to a D-EGR configuration was used to investigate the impact of valve phasing and different injection strategies on the reformate production in the dedicated cylinder. Various levels of positive valve overlap were used in conjunction with different approaches for dedicated cylinder over fueling using PFI and DI fuel systems. Three speed-load combinations were studied, 2000 rpm 4 bar IMEPg, 2000 rpm 12 bar IMEPg, and 4000 rpm 12 bar IMEPg. The primary investigation was conducted to map out the dedicated cylinders' performance at the operating limits of intake and exhaust cam phasing. In this case, the limits were defined as conditions that yielded either no reformate benefit or led to instability in the dedicated cylinder.

The influence of nozzle geometry on spray and combustion of diesel continues to be a topic of great research interest. One area of promise, injector nozzles with micro-holes (i.e. down to 30 μm), still need further investigation. Reduction of nozzle orifice diameter and increased fuel injection pressure typically promotes air entrainment near-nozzle during start of injection. This leads to better premixing and consequently leaner combustion, hence lowering the formation of soot. Advances in numerical simulation have made it possible to study the effect of different nozzle diameters on the spray and combustion in great detail. In this study, a baseline model was developed for investigating the spray and combustion of diesel fuel at the Spray A condition (nozzle diameter of 90 μm) from the Engine Combustion Network (ECN) community.

Plug flow reactors, simulating engine exhaust gas, are widely used in emissions control research to gain insight into the reaction mechanisms and engineering aspects that controls activity, selectivity, and durability of catalyst components. The choice of relevant hydrocarbon (HC) species is one of the most challenging factor in such laboratory studies, given the variety of compositions that can be encountered in different application scenarios. Furthermore, this challenge is amplified by the experimental difficulties related to introducing heavier and multi-component HCs and analyzing the reaction products.

Enhancement of fuel/air mixing is one path towards enabling future diesel engines to increase efficiency and control emissions. Air-assist fuel injections have shown potential for low pressure applications and the current work aims to extend air-assist feasibility understanding to high pressure environments. Analyses were completed and carried out for traditional high pressure fuel-only, internal air-assist, and external air-assist fuel/air mixing processes. A combination of analytical 0-D theory and 3D CFD were used to help understand the processes and guide the design of the air-assisted setup. The internal air-assisted setup was determined to have excellent liquid fuel vaporization, but poorer fuel dispersion than the traditional high-pressure fuel injections.

Spray angle and penetration length data were taken under cold start conditions for a Direct Injection Spark Ignition engine to investigate the effect of transient conditions on spray development. The results show that during cold start, spray development depends primarily on fuel pressure, followed by Manifold Absolute Pressure (MAP). Injection frequency had little effect on spray development. The spray for this single hole, pressure-swirl fuel injector was characterized using high speed imaging. The fuel spray was characterized by three different regimes. Regime 1 comprised fuel pressures from 6 - 13 bar, MAPs from 0.7 - 1 bar, and was characterized by a large pre-spray along with large drop sizes. The spray angle and penetration lengths were comparatively small. Regime 2 comprised fuel pressures from 30 - 39 bar and MAPs from 0.51 - 0.54 bar. A large pre-spray and large drop sizes were still present but reduced compared to Regime 1.

The growing usage of Unmanned Aerial Vehicles (UAVs) for aerial surveillance and reconnaissance in military applications calls for lightweight, reliable powerplants that burn heavy distillate fuels. While mass-produced engines exist that provide adequate power-to-weight ratio in the low power class needed for UAVs, they all use a spark-ignited combustion system that requires high octane fuels. Southwest Research Institute (SwRI) has embarked upon an internal research effort to design and demonstrate an engine that will meet the requirements of high power density, power output compatible with small unmanned aircraft, heavy-fuel combustion, reliable, durable construction, and producible design. This effort has culminated in the successful construction and operation of a demonstrator engine.

Because of its dominant role in diesel engine performance and emissions, the fuel injection process has become an area of very active research and development. It is now clear that location, shape, rate of development, and mass flow distribution within each fuel jet are all important in controlling fuel air mixing, wall interactions, combustion rate, and the resulting levels of emissions. The objective of this project was to develop an instrument for measurement of the instantaneous fuel mass and momentum distribution in the jets issuing from diesel injection nozzles. The goal was to develop an instrument concept that can be used in the laboratory for fundamental measurements, as well as a quality control system for use in manufacture of the injection nozzles. The concept of the instrument is based on the measurement of the instantaneous momentum of the fuel jet as it impacts on a surface equipped with pressure sensitive elements.