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A single-cylinder, spark-ignited engine was run on a certification test gasoline to saturate the oil in the sump with fuel through exposure to blow-by gas. The sump volume was large relative to production engines making its absorption-desorption time constant long relative to the experimental time. The engine was motored at 1500 RPM, 90° C coolant and oil temperature, and 0.43 bar MAP without fuel flow. Exhaust HC concentrations were measured by on-line FID and GC analysis. The total motoring HC emissions were 150 ppmC1; the HC species distribution was heavily weighted to the low-volatility components in the gasoline. No high volatility components were visible. The engine was then fired on isooctane fuel at the above conditions, producing a total engine-out HC emission of 2300 ppmC1 for Φ = 1.0 and MBT spark timing.

There is a recognized need in the industry to improve the quality of our CFD (Computational Fluid Dynamics) processes. One part of that initiative is to measure the accuracy of the current processes and identify opportunities for improvement. This report documents the results of a disciplined calibration process that uses statistical analyses techniques to assess CFD quality. The process is applied to UH3D, a Navier-Stokes solver used at Ford to model vehicle front-end geometry and engine cooling systems. The study is focused on a Taurus under relatively ideal circumstances to address one of the major deliverables from the analytical process, i.e., what is the accuracy of the front-end cooling airflow predictions? To address this question, high quality isothermal experiments and calculations were conducted on twenty-three front-end configurations at four non-idle operating conditions.

An electrochemical testing protocol for assessing the intrinsic corrosion-resistance of creep-resistant magnesium alloys in aqueous environments, and effects of passivating surface films anticipated to develop in the presence of engine coolants is under development. This work reports progress in assessing the relative corrosion resistance of the base metals (AMC-SC1, MRI-202S, MRI-230D, AM50 and 99.98% Mg) in a common test environment, based on a near-neutral pH buffered saline solution, found to yield particularly stable values for the open-circuit or corrosion potential. This approach was found to provide a platform for the eventual assessment of the durability of certain passivating layers expected to develop during exposure of the magnesium alloys to aqueous coolants.

Improvement of engine fuel efficiency through the use of low friction engine oils is a major task in engine lubrication research. This friction reduction can be achieved by improving the rheological characteristics and elastohydrodynamic (EHD) properties of engine oils, and by controlling boundary chemical interactions between oil-based additives and lubricated components in the engine. In order to achieve minimal frictional power loss under all lubrication regimes, engine tribological systems must be designed to effectively use advanced lubricant technology, material and surface modifications. This paper presents results of cooperative research addressing opportunities for minimizing friction through extension of hydrodynamic lubrication regime in lubricated components using various formulation approaches. A set of experimental oils has been evaluated using laboratory test rigs that simulate hydrodynamic, EHD, mixed and boundary lubrication.

This report is a contribution to the understanding of inlet aerodynamics and cooling system resistance. A characterization of the performance capability of a vehicle front-end and underhood, called the ram curve, is introduced. It represents the pressure recovery/loss of the front-end subsystem - the inlet openings, underhood, and underbody. The mathematical representation, derived from several experimental investigations on vehicles and components, has four basic terms: Inlet ram pressure recovery; free-stream energy recovered when the vehicle is moving Basic inlet loss; inlet restriction when the vehicle is stationary Pressure loss of the engine bay Engine bay-exit pressure Not surprisingly, the amount of frontal projection of radiator area through the grille, bumper and front-end structure (called projected inlet area), and flow uniformity play a major role in estimating inlet aerodynamic performance.

Exhaust valve temperatures are important in the selection of valve materials, and have strong effects on borderline spark angle and pre-ignition borderline limit. In order to support analytical modeling of exhaust valve temperatures and to correlate exhaust valve temperatures as a function of engine Reynolds number, exhaust valve temperatures were mapped as a function of spark angle and engine coolant temperatures at 2000 rpm. In addition temperatures were measured at wide open throttle at 2000, 3000, and 4000 rpm. The exhaust valve temperature was expressed as a dimensionless temperature using the exhaust gas temperature and the engine coolant temperature, then the dimensionless temperature was correlated as a function of spark angle and engine Reynolds number. The results indicate that once the temperature is known at a given speed and load condition for any one cylinder, the temperature at other speed and load conditions can be reasonably estimated.

A new, 1-D analytical engine thermal management tool was developed to model piston, oil and coolant temperatures in the Ford 3.5L engine family. The model includes: a detailed lubrication system, including piston oil-squirters, which accurately represents oil flow rates, pressure drops and component heat transfer rates under non-isothermal conditions; a detailed coolant system, which accurately represents coolant flow rates, pressure drops and component heat transfer rates; a turbocharger model, which includes thermal interactions with coolant, oil, intake air and exhaust gases (modeled as air), and heat transfer to the surroundings; and lumped thermal models for engine components such as block, heads, pistons, turbochargers, oil cooler and cooling tower. The model was preliminarily calibrated for the 3.5L EcoBoost™ engine, across the speed range from 1500 to 5500 rpm, using wide-open-throttle data taken from an early heat rejection study.

Rheological measurements were performed on a series of lubricants for flexible fuel vehicles, and blends of water or methanol in these oils. A series of measurements, including kinematic viscosity, viscosity at low and high shear rates, low shear viscosity under borderline pumping conditions, and density were performed on all oils and blends. The effects of mixing conditions, such as mixing speed and temperature on these properties were also studied. Viscosity increases when water emulsifies in oils. Methanol exhibits limited solubility in all oils, but more so in synthetic base oils. Viscosity tests at 248 K (-25°C) do not indicate the onset of critical pumping conditions, even at high concentrations of water or methanol. Tests at high shear rates at 323 K (50°C) suggest that water-oil emulsions are quite stable, while methanol-oil blends lose their methanol content either due to evaporation or shear-induced separation.

A laboratory wear test is used to evaluate the wear protection properties of new and used engine oils formulated for FFV service. Laboratory-blended mixtures of these oils with methanol and water have also been tested. The test consists of a steel ball rotating against three polished cast iron discs. Oil samples are obtained at periodic intervals from a fleet of 3.0L Taurus vehicles operating under controlled go-stop conditions. To account for the effects of fuel dilution, some oils are tested before and after a stripping procedure to eliminate gasoline, methanol and other volatile components. In addition to TAN and TBN measurements, a capillary electrophoresis technique is used to evaluate the formate content in the oils. The results suggest that wear properties of used FFV lubricants change significantly with their degree of usage.

A short engine sequence test, based on the Sequence VD procedure, was used to screen FFV oil candidates more rapidly. Since only one engine is needed to compare the wear-protection performance of several lubricants, engine hardware variability is not a significant issue in this test procedure. Several lubricants, some specially formulated for FFV engines, were tested using standard Sequence VD engine hardware which includes molybdenum top piston-rings. Results showed clear discrimination of the performance of oil candidates. These lubricants were also tested using an engine with chromium-faced top rings and exhibited similar performance ranking.

The variation of viscosity with temperature and shear rate plays an important role in the analysis of lubrication of automotive systems. In this paper, a method for predicting the viscosity of non-Newtonian fluids, such as multigrade engine oils, over a wide range of temperatures and shear rates is outlined. This expression determines viscosity parameters for shear thinning fluids in terms of easily measured viscosity values at some reference state. A comparison of predictions with experimental data suggests that viscosity for multigrade engine oils can be predicted to within experimental uncertainty. The proposed method can be used in assessing lubricant viscosity at shear rates greater than 106 s-1, which are beyond the capability of current laboratory instruments. A comparative study with multigrade oils shows that performance at very high shear rates cannot be accurately gauged from high temperature, high shear (HTHS) viscosity measurements.

This paper presents the benefits of following a disciplined thermal management process during the design and development of Ford Light Truck engine cooling systems. The thermal management process described has evolved through the increased use of Computer Aided Engineering (CAE) tools. The primary CAE tool used is a numerical simulation technique within the field of Computational Fluid Dynamics (CFD). The paper discusses the need to establish a heat management team, develop a heat management model, construct a three dimensional CFD model to simulate the thermal environment of the engine cooling system, and presents CFD modeling examples of Ford Light Trucks with engine driven cooling fans.

This paper presents the benefits of following a disciplined thermal management process during the design and development of Ford Light Truck engine cooling systems. The thermal management process described has evolved through the increased use of Computer Aided Engineering (CAE) tools. The primary CAE tool used is a numerical simulation technique within the field of Computational Fluid Dynamics (CFD). The paper discusses the need to establish a heat management team, develop a heat management model, construct a three dimensional CFD model to simulate the thermal environment of the engine cooling system, and presents CFD modeling examples of Ford Light Trucks with engine driven cooling fans.

A flow network method was developed to predict the underhood temperature distribution of an automobile. The method involves the solution of simplified energy and momentum equations of the air flow in control volumes defined by subdividing the air space between the surfaces of the underhood components and the front-end geometry. The control volumes are interconnected by ducts with branches and bends to form a flow network. Conservation of mass and momentum with appropriate pressure-loss coefficients leads to a system of algebraic equations to be solved for the flow rates through each volume. The computed flow rates are transferred to a thermal model to calculate the temperatures of the air and the major vehicle components that affect the underhood environment. The method was applied to a 1986 3.0L Taurus and compared with vehicle experiments conducted in a windtunnel.

For an automotive exhaust system, analytical evaluation of coatings, dual wall, multiwall, and blanket insulation methods indicated that the blanket insulation provided the best method for heat containment. An experimental vehicle was tested with and without a blanket insulation on the exhaust system over a demanding heat protection cycle. The exhaust gas, pipe wall, surrounding air, and adjacent component temperatures at 25 locations along the pipe are reported indicating reduced outer wall temperatures and good containment of the heat. A comparison of the heat lost through the exhaust system walls is presented.

In an automotive engine cooling system, the heat rejected to the coolant by the engine and other components is transferred to the air by the radiator. The cooling system engineer must predict the coolant inlet temperature (the top water temperature) for each operating conditions of interest. Computational fluid dynamics (CFD) computer programs have been developed to predict the cooling air flow velocities and temperatures entering the radiator. Radiator effectiveness is measured on a calorimeter with uniform air velocity and temperature entering the radiator. Computer programs have been developed to predict calorimeter performance for new radiators based on experimental data from existing components. In applying the calorimeter performance model to a vehicle, some means must be used to derate the performance slightly based on the non-uniform inlet air velocity and temperature distribution entering the radiator.

A hydrocarbon trapping system for cold start emissions was constructed and tested using two types of carbonaceous adsorbents provided by Corning, Inc. One was made by combining activated carbon with an organic binder and extruding it into a honeycomb, and the other by depositing a carbon coating on a ceramic monolith. The tests were carried out on an engine in a dynamometer laboratory to characterize the performance of the carbon elements under transient cold start conditions. Performance was evaluated by continuously measuring exhaust gas hydrocarbon concentrations upstream and downstream of the trap, using conventional emissions consoles. Samples were also collected for off-line analysis of individual hydrocarbon species using gas chromatography to examine differences in adsorption of individual species. The speciated hydrocarbon data were used to distinguish between the mass trapping efficiency and a reactivity-based trapping efficiency of the adsorbant traps.

A 1.8L turbocharged diesel engine valvetrain friction was investigated, and the effectiveness of using a solid film lubricant (SFL) coating in reducing friction was determined throughout the operable speed range. This valvetrain design features direct acting mechanical bucket valve lifters. Camshaft journal bearing surfaces and all camshaft rubbing surfaces except lobe tips were coated. The direct acting bucket shims were etched with a cross hatch pattern to a depth sufficient to sustain a SFL film coating on the shim rubbing surfaces subjected to high surface loads. The SFL coated valvetrain torque was evaluated and compared with uncoated baseline torque. Coating the cam bearing journal surfaces alone with II-25D SFL reduced valvetrain friction losses 8 to 17% for 250 to 2000 rpm cam speed range (i.e. 500 - 4000 rpm engine speed). When bucket tappet and shims were also coated with the SFL, further significant reductions in coated valvetrain friction were observed.

The effect of engine operating parameters (speed, spark timing, and fuel-air equivalence ratio [Φ]) on hydrocarbon (HC) oxidation within the cylinder and exhaust system is examined using propane or isooctane fuel. Quench gas (CO2) is introduced at two locations in the exhaust system (exhaust valve or port exit) to stop the oxidation process. Increasing the speed from 1500 to 2500 RPM at MBT spark timing decreases the total, cylinder-exit HC emissions by ∼50% while oxidation in the exhaust system remains at 40% for both fuels. For propane fuel at 1500 rpm, increasing Φ from 0.9 (fuel lean) to 1.1 (fuel rich) reduces oxidation in the exhaust system from 42% to 26%; at 2500 RPM, exhaust system oxidation decreases from 40% to approximately 0% for Φ = 0.9 and 1.1, respectively. Retarded spark increases oxidation in the cylinder and exhaust system for both fuels. Decreases in total HC emissions are accompanied by increased olefinic content and atmospheric reactivity.

Modern four-valve engines are running at ever higher compression ratios in order to improve fuel efficiency. Hotter cylinder bores also can produce increased fuel economy by decreasing friction due to less viscous oil layers. In this study changes in compression ratio and coolant temperature were investigated to quantify their effect on exhaust emissions. Tests were run on a single cylinder research engine with a port-deactivated 4-valve combustion chamber. Two compression ratios (9.15:1 and 10.0:1) were studied at three air/fuel ratios (12.5, 14.6 and 16.5) at a part load condition (1500 rpm, 3.8 bar IMEP). The effect of coolant temperature (66 °C and 108°C) was studied at the higher compression ratio. The exhaust was sampled and analyzed for both total and speciated hydrocarbons. The speciation analysis provided concentration data for hydrocarbons present in the exhaust containing twelve or fewer carbon atoms.