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A new turbocharged 60° 2.7L 4V-V6 gasoline engine has been developed by Ford Motor Company for both pickup trucks and car applications. This engine was code named “Nano” due to its compact size; it features a 4-valves DOHC valvetrain, a CGI cylinder block, an Aluminum ladder, an integrated exhaust manifold and twin turbochargers. The goal of this engine is to deliver 120HP/L, ULEV70 emission, fuel efficiency improvements and leadership level NVH. This paper describes the upfront design and optimization process used for the NVH development of this engine. It showcases the use of analytical tools used to define the critical design features and discusses the NVH performance relative to competitive benchmarks.

Powerplant NVH decisions are sometimes made looking only at how the change impacts either the source radiated noise level or the source vibration. Depending on the engine configuration, those can be good approximations, but they can also be very misleading. By combining both noise sources into a vehicle equivalent noise level a much better analysis can be made of the impact of any proposed design change on the customer perceived loudness. This paper will investigate several different scenarios and identify how the airborne and the structureborne paths combine for I4, V6 and V8 engine configurations. Similar relationships will be shown for path as well as the source contributions.

Idle Combustion Stability has previously been difficult to predict prior to prototype engine development. This paper describes an empirical modeling approach to predicting upfront idle combustion stability. The model outputs are the combustion torque harmonic magnitudes and %LNV. The paper describes the modeling methodology and provides correlation results for different engine configurations.

Getting Powerplant NVH Benchmarking right is a key first step in knowing where your design stands relative to its competition and what needs to be improved in order to achieve or maintain NVH leadership. It is through benchmarking that you can define industry trends, who gets it right, who doesn't, and why. A good benchmarking database also lets you estimate the improvements or deterioration due to engine architecture changes or design features. This paper describes a methodology used for selecting, measuring, and comparing powerplant NVH attributes.

Smooth Vehicle Idle operation requires Engine Combustion events that are extremely repeatable from cylinder to cylinder and from engine cycle to engine cycle. This paper will explore the analysis of engine idle combustion focusing in on the typical metrics, examining their strengths and weaknesses, and proposing new metrics which can help to gain a deeper understanding of what is Idle Combustion Smoothness.

Ford Motor Company has developed a new 3.5L V6 engine. The engine, called the Duratec35, represents a new architecture for Ford Motor Co. that will eventually power one in five Ford vehicles. The goals of the engine design were high output, fuel efficient, low emissions, and excellent NVH. This paper will describe the NVH process for the development of the engine, the NVH features included in the design, and the final results relative to the benchmarks.

An engine's radiated noise level is a very important attribute required for delivering customer satisfaction. Having an accurate radiated noise prediction capability during the planning, target setting, and initial design phases is critical to making the up-front decisions that enable the timely and cost efficient delivery of an engine that meets its radiated noise goals. This paper describes a simple radiated noise model that is based on a combination of regression modeling and simplified analytical modeling. The regression model uses measured data from multiple tests that can be broken down to noise sources such as mechanical, combustion, and accessory components. The simple analytical models are used to determine the parameters that the decomposed noise data is regressed against. The model developed in the paper is then compared to previous models suggested in the literature and to measured data from engines.

Low levels of Engine Idle Shake are required to produce a vehicle that delivers to the customer the overall perception of quality. Some previous metrics used to measure idle shake, e.g. SDIMEP, LNV, etc. have not always been good discriminators of engines that produced low levels of idle shake and those that did not. This paper will propose a new metric, Combustion Uniformity, that does a better job of describing the phenomena that creates idle shake. This new metric will then be used to describe how different distributions of cylinder-to-cylinder variation create different levels of Combustion Uniformity and how those levels of Combustion Uniformity compare to previous metrics.

Piston slap is a problem that plagues many engines. One of the most difficult aspects of designing to eliminate piston slap is that slight differences in operating conditions and in part geometries from build to build can create large differences in the magnitude of piston slap. In this paper we will describe a design for robustness CAE approach to eliminating piston slap. This approach considers the variations of the significant control factors in the design, e.g. piston pin offset, piston skirt design, etc. as well as the variation in the noise factors the system is subjected to, e.g. assembly clearance, skirt collapse, peak cylinder pressure, cylinder pressure rise rate, and location of peak cylinder pressure. Using analytical knowledge about how these various factors impact the generation of piston slap, a piston design for low levels of piston slap can be determined that is robust to the various noise factors.

To address the conflicting goals of minimal piston friction and minimal piston noise, a dynamic power cylinder model was developed to predict piston motion and side loads within the cylinder. This correlated model was the basis of a comprehensive analytical design of experiments (DOE) where both piston noise and piston friction were monitored. The results of the DOE were used to generate metamodels for piston friction and for piston noise. To insure design robustness, variability was introduced into the surrogate models via First Order Reliability Method (FORM). A Pareto curve using 99% probability was constructed and a piston robust to both noise and friction was selected.

Engine excitation forces have been studied in the past using one of two methods; a lumped sum or a totally distributed approach. The lumped sum approach gives the well-understood engine inherent unbalance and the totally distributed approach is used in engine CAE models to determine the overall engine response. The approach that will be described in this paper identifies an intermediate level of sophistication. The methodology implemented considers single cylinder forces on the engine block, piston side thrust and main bearing forces, and decomposes them into their order content. The forces are then phased and geometrically distributed appropriately for each cylinder and then each order is analyzed relative to know distributions that are NVH concerns, V-block breathing, block side wall breathing, and block lateral and vertical bending.