The development of alloys, coatings, surface treatments, and lubricants for improved cylinder liners and rings has historically included friction and wear testing. The correlation of results from motored engines or laboratory-scale tribotests with those from full-scale, fired engines remains a subject of contention. Attempts to develop valid engine wear simulators have met with varying degrees of success. Complexities in understanding and duplicating the relevant contact conditions in fired engines have challenged the designers of sub-scale, simulative laboratory tests. The current paper describes one aspect of this problem; namely, simulating the cylinder bore surface finish for use in bench tests. A rapid method to prepare cast iron test specimens that have similar surface roughness parameters to a production cast iron cylinder liner has been developed. To compare the sliding response of simulated liners with actual liners, cast iron specimens were friction-tested in both new and used 15W40 commercial diesel engine oil, in mineral oil, and without liquid lubrication. A reciprocating, ball-on-flat testing machine was used with test lengths that ranged from 100 to 20,000 cycles. Kinetic friction coefficient data compared favorably between the simulated cylinder liner specimens and actual cylinder liner segments. The friction coefficients obtained in tests with different lubricants on the simulated surfaces were related through a second-degree polynomial to the change in arithmetic average roughness that occurred during running-in. Additional elements of the fired engine environment will be added in the next stages of this research to determine the degree of complexity that is needed to obtain increasingly better simulations.

The ring-pack lubrication is a complicated physical process involving multiple physical phenomena. This paper presents an attempt to model the ring-pack lubrication in three-dimensional space, considering the ring-bore structure interaction, bore distortion, ring-twist, piston secondary motion, non-Newtonian lubricant behavior, and ring/bore asperity contacts. The physics of the model includes the interface between the structure of the ring, oil lubricant, and the structure of the cylinder liner. The ring is modeled as a three-dimensional FEA model with the nodes along the ring circumference. The ring face orientation changes circumferentially depending on ring geometry as well as piston tilt angle and three-dimensional ring twist angle at every crank angle degree. The oil lubrication is modeled with the Reynolds equation with shear thinning and temperature dependent oil viscosity and with or without the flow factors. The cylinder liner description allows three-dimensional bore distortion and ring/liner asperity contact to be modelled. The key of the analysis is solving simultaneously at every crank angle increment a set of coupled linear and non-linear equations of ring structure, ring face lubrication, bore distortion, and asperity contact. The model predicts variations of the ring-pack lubrication in the axial and circumferential directions. Using the hydrodynamic lubrication model coupled with the asperity contact model allows calculations of the friction forces due to asperity contact (boundary and mixed lubrication) and oil film interactions (hydrodynamic and mixed lubrication). The transition from hydrodynamic lubrication to boundary lubrication through mixed lubrication is determined interactively based on ring / liner surface properties, ring loads, and lubrication properties. The new friction sub-module calculates axial and circumferential variation of both types of friction forces as well as total friction. The asperity contact induced friction forces and asperity contact pressure can further be used for ring wear calculations. The developed model has been applied to determine the performance of a production engine ring-pack. The influence of different phenomena affecting the ring-pack performance has been analyzed and compared.

Electrical efficiency is an important factor for most of the owners of gas engines. To reach a high electrical efficiency, engine manufacturers use four valve cylinder head technology on new designed engines. The change from two valve to four valve technology, in combination with optimized charge motion, can achieve an increase of electrical efficiency up to 2.5%. A significant number of engines in the market are only equipped with two valve cylinder heads, thus leaving potential to reduce carbon emissions and fuel consumption. The scope of the paper applies to the modernization of an already well established gas engine series available on the market with a power range of 500–1100kW [1]. In the first step, the potentials were considered purely in the context of a change in configuration of the spark plug, to pre-chamber spark plug. As second step an optimization of the ports was examined. Due to the pre-existing high level of development of the combustion stage, combined with an adaption of the boost charging system, an improvement of almost 2.5% was achieved. According to data sheets, modern gas engines within this power range have efficiencies in the range of η e ∼ 44%. The project team therefore proceeded to develop a new cylinder head along with new design leading to a better combustion. Minimizing changes around the periphery of the engine was a prerequisite in order to complete these on site as part of the 30.000-hour service. Intake- as well as exhaustport geometries were optimized with the aid of CFD tools, such that swirl and flow capacity values achieved their specified objectives. The geometries of the water jacket and valve train were also optimized through a similar methodology. These changes led to a 7% reduction in gas exchange work, which directly reflect within improved efficiency levels. Altogether, the various measures (including combustion optimization) resulted in an efficiency improvement of about 2.5% leading to an electric efficiency of 42.9%. The first endurance run shows that the mechanics match the expected technical requirements. Very low wear rates despite the increased masses of the valve train could be reached due to higher qualities in terms of materials. The paper focuses particularly on the flow optimization in conjunction with the variables surrounding the mechanic design. Finally, the test results of the pilot engines are presented alongside an economic analysis.

Composite pistons are often used in heavy duty diesel engines due to its good reliability and durability. Owing to the alternating loads, fretting wear usually happens on the mating surfaces between piston crown and skirt. In this paper, a fretting wear finite element model is developed to analyze the mating surface wear of composite piston of heavy duty diesel engine. The fretting wear model predicts the wear depth evolution for each working cycle based on Archard model and mesh updating technique, which is validated by previous pin and disk contact experiments. The wear evolution of the top contact surface of piston skirt is simulated according to engine operating condition, and fretting wear life is estimated by the decreasing process of crown-skirt connecting bolt preload. Effects of the shape of piston skirt top surface is also evaluated. In the end, the rationality of fretting wear model is validated by durability tests of diesel engine.

Chromium nitride (CrN) is the main protecting coating applied to top rings for gasoline and diesel engines, due to its excellent wear resistance, low friction and minor environmental impacts, especially in modern engines operating with low viscosity oils. Recently, diamond like carbon (DLC) coatings reported improved tribological performance, but at a higher cost. Therefore, in the present work, wear and friction of CrN and DLC coated rings were evaluated on reciprocating and floating liner engine tests running on 0W-20 and 0W-16 lubricant formulations, which additives tailored for different markets (Japanese, European and Emerging). DLC outperformed CrN for both friction and wear when running on lubricant formulations without molybdenum additives. On opposite, with high molybdenum content additives, CrN presented synergic effects that significantly reduced friction and wear, whilst DLC did not. Same comparison on floating liner engine tests demonstrated again superior performance of CrN by 9% reduction on friction losses, running on oils containing molybdenum additives, whilst DLC lowered 6%. From that, it can be estimated 0.4% fuel saving at urban conditions by combining Japanese lubricant oil formulation and CrN top rings.

The automotive industry is subjected to increasing pressure in order to improve fuel efficiency and reduce the CO 2 emissions of internal combustion (IC) engines. The power cylinder system (piston, piston ring, and liner) contributes significantly to the friction losses, engine oil consumption and gas leakage called blow-by. The role of cylinder bore shape in engine performance has been the subject of several studies in recent years. High bore distortion must be avoided because it can lead to ring conformability issues, which leads to inadequate sealing resulting in increased blow-by and oil consumption. It also leads to asperity contact between the piston skirt and cylinder bore increasing friction causing abnormally high surface wear. Although bore distortion cannot be eliminated, engine manufacturers strive to contain it within acceptable limits. Therefore, numerical analysis of the power cylinder with physically based mathematical models becomes very essential to the engine and component manufacturer in order to reduce engine development lead time and minimize the number of engine tests. The integrated ring-pack modeling methodology developed by the authors [1] is used to investigate the piston ring-pack performance. Although the modeling approach can be used for extensive parameter analysis of piston, piston rings and lubrication oil consumption, the influence of the bore distortion on the ring conformability and its impact on blow-by, friction and wear is highlighted in this study. Piston tilting, piston ring twist and surface roughness of the piston ring and liner have been taken into consideration.

Two-stroke engines are capable of providing very high power density levels in a cost effective, easy-to-maintain package. They are, however, typically susceptible to higher levels of hydrocarbon emissions, lower durability, and a shorter lifecycle when compared to four-stroke engines. These detriments are easily overlooked in some military applications where power density is paramount, but most commercial two-stroke engines require specialized consumable lubricant. Typical military applications strive to minimize their logistics “trails,” which includes minimizing the variety of fluids they require. As a result, there has been very limited success in fielding small two-stroke engines for military use. As a preliminary study, MIL-PRF-2104K Single Common Powertrain Lubricant (SCPL, a four-stroke heavy diesel engine oil) was utilized as the consumable lubricant (in place of conventional two-stroke oil) in a liquid-cooled, semi-direct fuel injected, spark-ignition, two-stroke engine. Empirical data was collected to study the impact of the oil on deposit build-up, power, wear, combustion stability, and fuel conversion efficiency. Over 147 hours of operation were logged and analyzed. The performance of the engine on SCPL was consistent with conventional two-stroke oil and showed no degradation over the test duration. Brake specific fuel consumption was not negatively impacted with SCPL. Increased deposit build-up in the exhaust ports and on the spark plugs were the primary negative impacts of the SCPL oil. Spark plugs with hotter classifications and modification of the oiling rate resulted in a reduction of soot accumulation and spark plug fouling.

Slow-steaming operation and an increased pressure in the combustion chamber have contributed to increased sulfuric acid (H 2 SO 4 ) condensation on the cylinder liners in large two-stroke marine diesel engines, thus causing increased corrosion wear. To cope with this, lube oils are formulated with overbased detergent additives present as CaCO 3 reverse micelles to neutralize the condensing H 2 SO 4 . In this present work, a mixed flow reactor (MFR) setup aims to investigate the neutralization reaction by varying Ca/S molar ratio, stirrer speed, H 2 SO 4 inlet concentration, and residence time. Lube oil samples from the outlet of the MFR were analysed by use of Fourier Transform Infrared Spectroscopy (FTIR) and a titration method. The MFR results indicate that the CaCO 3 -H 2 SO 4 reaction is very fast in a real engine, if the cylinder liner is well-wetted, the oil-film is well-mixed, and contains excess of CaCO 3 compared to the condensed H 2 SO 4 . The observed corrosion wear in large two-stroke marine diesel engines could consequently be attributed to local molar excess of H 2 SO 4 compared to CaCO 3 reverse micelles on the cylinder liners.

Recent engine developments towards higher loads (downsizing) and thinner oil films have increased the severity of plain bearing operating conditions 1 . These factors, combined with lower viscosity oils, have resulted in a greater sensitivity of bearings to damage by foreign debris particles. Traditional highly embeddable materials, such as lead, are being progressively phased out. This lead-free trend observed in the passenger car market is likely to spread to the truck market in the future. As a result, it is becoming increasingly challenging to balance the conflicting hard and soft requirements of bearing materials. Although new generations of bearing materials, particularly polymeric overlays, have shown excellent fatigue and wear capabilities 2 , they would benefit from enhanced embeddability properties. This demand has led MAHLE to take a new approach with the development of a polymeric overlay material that has both hard and soft characteristics. This newly developed soft-phase co-polymer resin has been synthesized from monomers selected to give the desired properties. Conventional Polyamide-imide (PAI) monomers have been combined with Polydimethylsiloxane (PDMS) macromonomers. PDMS was selected to improve embeddability as it is softer and offers more flexibility than PAI. Via a polymerization reaction, chains of hard, fatigue resistant PAI are alternately combined with short chains of PDMS. This produces a polymer matrix which has a very fine distribution of soft phase due to the micro-phase segregation created as the soft and hard segments of neighboring polymer chains preferentially align with each other 3, 4 . The relative lengths of the hard and soft sections can be ‘tuned’ to produce domains of differing size and therefore adjust the balance of properties. Experiments have been carried out varying the overall percentage of PDMS and also with the molecular weight of the PDMS segments. Initial embeddability testing has shown an improvement in embedment over current polymer products and further work is ongoing to optimize this new resin system.

Anaerobic digesters are capable of producing methane-rich biogas from animal manure and also offer the advantages of controlling odors, reducing pathogens, and minimizing the environmental impact of the waste. Unfortunately, biogas is contaminated with hydrogen sulfide (H 2 S), a highly corrosive gas that is not compatible with many stock engine component materials. As a result, conventional engines can fail after several months of exposure to raw biogas. No small or medium piston engine-generators (<100 kW e ) are currently available that can use this fuel without pretreatment to remove the H 2 S — a process that adds complexity, cost, consumables, and maintenance. As a result, many smaller digester installations simply flare the biogas rather than extracting any useful work from the fuel. Mainstream Engineering is developing a biogas-tolerant engine-generator (BTEG) that can use raw biogas without pretreatment to remove H 2 S. The development program involved a combination of approaches — materials replacement, coatings, engine control strategy changes, lubrication system changes, and additional sensors. A prototype 25 kW BTEG has been developed using a Ford DSG 2.3 L natural gas engine as the demonstration platform. In this paper, we report on performance testing of the baseline unmodified engine-generator and the BTEG. Measurements of fuel consumption, exhaust temperature, in-cylinder pressure, and exhaust gaseous emissions were made using several synthetic biogas mixtures (60–80% CH 4 /balance CO 2 ) and pure methane. Because the methane fraction in biogas can change with digester conditions and weather — a method of estimating the biogas composition on the fly and adjusting the spark timing to compensate for the variability has been demonstrated. We also report on limited (100 hr) durability testing of the modified engine using fuel containing 3,000 ppmv of H 2 S. During this test, the oil was analyzed to track acidification of the engine oil and monitor the accumulation of sulfur or any wear metals.

Piston ring wear is a major factor determining a diesel engine’s life. A ring is subjected to wear between its front face and the cylinder wall as well as at the interfaces between the ring and groove top and bottom flanks. In many modern engines, ring and groove wear are becoming more of a limiting factor for ring durability than face wear. The focus of this paper is on ring to groove side wear only. In this paper two fundamental mechanisms for ring/groove side wear are identified: (1) wear due to piston secondary motion and (2) wear due to ring twist. The time in the cycle where each of these mechanisms results in maximum wear is shown. Then the effect of ring static twist and the resulting effect on the pressure distribution around the ring are studied. The pressure distribution affects the force acting on the ring that causes the ring/groove side wear. It is also shown that the pressure distribution and the resultant wear can be influenced by the land diameter below the piston ring. Progressive wear is also studied, showing a good correlation between predicted wear and measured wear on both ring sides and groove sides. It is noted that as the corner of the ring/groove wears, the ultimate wear of the ring side can accelerate by a phenomenon named pressure infiltration. Pressure infiltration occurs because the bottom side of the ring groove wears exposing more of bottom side of the ring to lower pressure force. This ultimately causes a higher difference between the high pressure above the ring and the low pressure below the ring. As a result, the net force acting on the ring increases and wear increases. In addition to the study of the first ring, the second ring wear was studied. A comparison was made between the top ring and second ring groove side wear (RGSW) predictions. Also the effect of the second ring static twist on both top and second ring/groove side wear is described in detail.

For the efficient virtual development of combustion engine cylinder heads in terms of high cycle fatigue (HCF) it is highly important to have a reliable development process that represents reality in the best possible way. Most of today’s standard HCF procedures are capable of delivering high quality results for a specific load combination. However, loads are usually subject to variation. This is also valid for loads the cylinder head is subjected to. Assembly loads and operating loads considered during the virtual development process are widely determined by the production process which again is subject to variation due to certain tolerances, wear of the tooling equipment etc. As it is highly important to ensure the fatigue design of a cylinder head, there is the need for new analysis models capable of capturing every possible load variation. Within the framework of this paper the influence of different variable loading parameters on the cylinder head HCF margin of a heavy duty diesel engine will be discussed. A design of experiments (DoE) analysis is used together with the 3-d finite element method (FEM) for the investigations. Furthermore a methodology for the probabilistic assessment of the cylinder head HCF margin based on stochastic loading data is introduced. At the same time an effective methodology for the identification of the worst case boundary conditions for HCF analysis will be presented. With the presented probabilistic method it is possible to achieve a highly accurate prediction of the HCF design margin. Due to the probabilistic approach a better understanding of the entire system is possible, as the interaction between input and output parameters can be illustrated. Therefore HCF optimization problems can be encountered more effectively. Furthermore the presented methodology can be used for error estimation of analysis results and assessment of the result sensitivity. Thus, a borderline layout of the cylinder head can be achieved. Also the minimum input information quality, which is required for a profound HCF analysis, can be assessed by using the sensitivity analysis presented. Therefore the proposed methods enable a fast and reliable development of cylinder heads and other combustion engine components.

Increasing durability, preventing knocking combustion, improving fuel efficiency and reducing pollutant emission characterize the needs for modern internal combustion engine design. These factors are highly influenced by the power cylinder system design. In particular, the piston ring to cylinder bore contact force distribution around the circumference of the piston rings must be optimized under all running conditions. To accomplish this, the ring manufacturers make the ring curvature non-constant along the circumference. Most existing analytical tools are not able to simulate the variation along the ring circumference. In order to improve the understanding of this contact distribution and provide a high-fidelity ring design tool, a three-dimensional finite element piston ring model was developed to accomplish this variation. The modeling procedure and results are presented in this work. Experiments using a commercially available ring with negative ovality were conducted to validate the model. The ring free shape profile and the ring cross-section geometries were used as inputs to the model. Typical piston ring groove and cylinder wall temperatures were also model inputs to characterize thermal influences on the ring/bore interface forces. The ring/bore conformability was analyzed as a function of the ring radial displacements, cylinder bore constraint forces and thermal load changes to the ring. The model output showed radially separation gaps between the ring front face and the bore. This analysis provides an insight to evaluate the piston ring design. Together with an optimizer, the model can be used as a ring design tool to predict the ring free shape with a specified constraint force distribution pattern. Examples are given to demonstrate the capabilities of this numerical analytical tool. In addition, the 3D ring model can be used to improve the accuracy of existing lubrication, friction and wear analysis tools and therefore improve the entire internal combustion engine power cylinder system design.

Piston top compression rings utilized in North American Spark Ignition (SI) passenger car and light truck engines have undergone a significant migration driven by desire to reduce axial height, mass, radial thickness, wear, incidence of risk of foundry defects and to enable utilization of a consistent, global material independent of manufacturing location. Second rings utilized in similar applications are now in the earlier stages of a similar migration. This paper will present product development of an innovative steel second ring including engine testing (blowby, and lube oil consumption via radiometric tracer method), supplemented by simulation modeling utilizing MIT code, including several more conventional ring cross sectional alternatives.

The heavy duty diesel (HDD) engine market continues to strive for improvements in engine efficiency and durability which places ever increasing development demands on the power cylinder unit. One of the methods being developed to help meet these demands is coated cylinder bore technology. By applying a coating to the inner diameter surface of a cylinder liner the wear on the liner can be significantly reduced. The reduction in liner wear is not however the only advantage that this technology can offer. Liner coatings can also offer corrosion protection, reductions in wear on the running surface of the rings, improved scuff resistance, and enable improvements in the efficiency of the engine. New piston ring technologies will be valuable in maximizing these advantages and their contribution will be detailed. The system must be properly designed to take full advantage of all of these opportunities. In this paper both the advantages and difficulties coated liners present will be explored by evaluating the impact on the liner, rings and the fuel consumption. This paper will additionally provide details regarding the different liner coating technologies being developed today. To support these recommendations the system’s performance characteristics will be demonstrated through rig testing and engine performance measurements.

For certain applications in the world of internal combustion engines (ICE), it has been found that nitrided valves have a better performance against wear than those which are seat hard faced and chrome plated. This alternative has not been significantly explored in the Medium Duty (MD) and Heavy Duty (HD) markets. Fully nitrided MD/HD valves, mostly hard faceless, would be less expensive than chromed ones. They may become a cost effective product with better tribological performance, higher fatigue strength and improved resistance to thermal shock. In addition to this, a proper selection of the counterpart materials, those of the valve seat insert (VSI) and the valve guide (VG) will have a synergetic effect on the valve set performance, also leading to its cost improvement. Not less important is the replacement of the well-known salt bath nitriding by the gas nitriding technique, an environmentally friendly process that maintains valve performance with the advantage of employing a lower nitriding temperature providing a higher tip end and seat hardness combined with a lower distortion level in the final product. The aim of this work is to present the development and introduction of fully nitrided valves as a reliable solution for nowadays MD/HD applications. It is based on a deep process and product validation including the development of the gas nitriding process, wear, fatigue and engine tests.

Material selection for engine internal components, e.g. bearings, is becoming increasingly more complex and demanding as the operating environments become more aggressive with the introduction of new technologies for the reduction of CO 2 emissions. Historically, engine bearings contained lead, which has excellent fundamental bearing properties such as compatibility (run satisfactorily under conditions of marginal lubrication), conformability (deform and accept small scale geometrical inaccuracies of the crankshaft), and embeddablity (tolerance to dirt and other foreign materials) whilst being readily alloyed to achieve good wear and fatigue resistance. However, facing new challenges, many Original Equipment Manufacturers have started development programs to replace lead-containing with lead-free engine components in order to comply with new end-of-life vehicle directives or anticipated future directives. For more than fifteen years, MAHLE has been successfully supplying the light, medium and heavy duty market, with premium electroplated leaded composite bearings, which are designed to improve wear resistance. Some of this market now demands a switch to lead-free materials, while maintaining or exceeding its aforementioned requirements on bearing material properties. Composites of hard particles in a softer metal matrix are in this context ideally suited bearing materials as they can be tailored to obtain the optimal mix between soft and hard properties for the individual application. Typical hard particles that are commonly used comprise of metal oxides, nitrides or carbides. In addition to higher load carrying capabilities and longer service life, new engine technology trends demand that bearings also must operate under mixed or boundary lubrication conditions without having any adverse effect on the performance and integrity of the engine system. Boundary lubrication is commonly observed upon starting the engine before the elastohydrodynamic oil film is fully established. In this state, load is carried by surface asperities rather than by the lubricant. So far, the incorporation and even distribution of the hard particles into an electroplated lead-free matrix was not achievable using conventional direct current electroplating techniques. MAHLE, therefore, has developed a patented pulse plating technique in order to incorporate hard particles into the overlay metal matrix. The refined and modified crystal structure of the resulting lead-free overlay, with incorporated hard particles, yields a premium electroplated bearing with superior wear and fatigue resistance. Corresponding rig and engine test results have been completed to support the material development.

Recent in Two-stroke engine development for marine applications mainly deal with better and increased overall efficiency hereby reducing the CO2 emissions. Besides a mechanical design change the service conditions play a major role in enhanced efficiency. The so increased engine parameters with higher maximum pressure during combustion will inevitable increase the load on the bearings of the reciprocating parts. Since an increase in the bearing area is not possible due to the engine design parameters the object is to increase the specific load bearing capability of the bearing alloy while keeping the tribological benevolence. In particular, the fatigue properties and the strength of the used tin based alloys, commonly known as whitemetals or babbitts. This class of alloys stands out due to its emergency running capabilities, embedability and its high flexibility under edge load. Existing Al-based alloys like AlSn40 have improved fatigue properties but they fall behind on the named essential properties. Also, the dimensions of the AlSn40 bearings are limited due to the roll bonding process by which they are produced. On the other hand spin casting as standard production process of Babbitt bearings is limiting the alloying elements due to centrifugal segregation while solidification of the lining alloy. While tin based alloys are used in an environment of 90°C the homologue temperature is 0,7 which means that classic strengthening mechanisms like work-hardening and grain size effects are only shortly employable. Another restricting fact is the requirement of solid solubility for solid solution strengthening which also includes precipitation hardening. Hence there is a limited amount of elements dissolvable and not environmentally hazardous in tin this mechanism is already used to its maximum in the standard babbitts. In this paper a possible way to circumvent these limits will be presented. The use of high melting elements, compared to Sn, like Co, Ni, Mn, Al and Zn which are partly dissolvable in molten Sn, where used to improve the microstructure and therefor the overall performance of the bearing alloy. These trace elements serve as grain refinement for the primary precipitation of SbSn and CuSn during solidification. The high melting point of these elements anticipates relaxing processes in the alloy caused by diffusion at the high homologue temperature. Due to the smaller precipitations and the finer structure a better performance can be seen during tests. This leads in a higher strength while maintaining its ductility. Alternate bending tests as well as specific bearing test runs show a significant better fatigue, wear and embedability performance than standard alloys.

Over the last couple of decade, biofuels have shown a lot of promise in terms of relatively higher combustion efficiency and lower emissions vis-à-vis conventional fuels. If mineral diesel is to be replaced by an alternate fuel in existing IC engines, compatibility of the fuel injection equipment (FIE) with these new fuels need to be ascertained because engine performance, combustion and emission characteristics are greatly affected by the FIE. It is reported that FIE components face issues such as injector deposits, injector blockage and pump plunger wear with biofuels. To experimentally investigate the compatibility of FIE with biofuels, a fuel injection simulator was developed to experimentally simulate the engine conditions as closely as possible, outside the engine environment, without the need for combustion of fuel. This simulator was operated for 250 hours with different Karanja oil blends (K100, K20, and K5) and baseline mineral diesel. New fuel pumps and injectors were used for every set of experiment. After every experiment of 250 hours, fuel injector and pumps were dismantled to assess the deposits, wear and surface texture of different components of FIE. Wear was measured by weight loss, dimensional changes and surface texture changes (analyzed by optical microscopy) of the component. For K100, injector blockage was experienced after 185 hours. During inspection, injector nozzle needles using Karanja oil blends showed higher deposits compared to mineral diesel. Dimensional changes of the plunger were highest for K100 compared to mineral diesel. Karanja oil at lower blends provided superior and improved lubricity compared to mineral diesel. In summary, FIE sub-components were damaged to a higher degree with K100, especially pump plunger. Karanja oil blends showed higher deposits on nozzle needle.

Rising fuel prices and more stringent requirements in the field of emissions such as nitrogen oxides, particulate matter and carbon dioxide are increasing the pressure on the engine manufacturers to utilize technologies that contribute to a reduction in these emissions. As a result, interest in cylinder surface coatings has risen considerably in the last three to four years, and particularly in the SUMEBore ® coating solution from Sulzer Metco. Such coatings are applied by a powder-based atmospheric plasma spray process (APS). The APS method is very flexible and can also process materials to which wire-based methods do not have access, particularly high chromium containing steels, metal matrix composites (MMCs) and pure ceramics. The compositions can be tailored to the specific challenges in an engine, e.g. excessive abrasive wear, scuffing or corrosion caused by adulterated fuels and/or high exhaust gas recirculation rates (EGR). Over the past four to five years cylinder liner surfaces from trucks, diesel locomotives, marine and gas engines, for power generation and gas compression have been coated with such materials. These engines have been tested successfully. Most of the tested engines achieved significant reductions of lubrication oil consumption (LOC), sometimes in excess of 75%, reduced fuel consumption, very low wear rates and corrosion resistance on the liner surfaces. As an example the paper will highlight the coating of cylinder surfaces in a 4,000 hp EMD 16-710G3 locomotive diesel engine. Details of the application of a corrosion resistant MMC will be shown, together with results obtained with the Da Vinci DALOC measurement technique in an engine test where the lubricant oil consumption was accurately quantified at 4 steady-state operating conditions typical of North American freight locomotive and which clearly showed the significant contribution of the liner ID coating to reduction of lubricant oil consumption (LOC).