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Low-speed-pre-ignition (LSPI) presents a great challenge for developing smaller, more efficient internal combustion engines. Current research focuses on understanding the causes of LSPI and developing strategies to mitigate its intensity or eliminate it completely. On this paper, the effect of different LSPI mitigation strategies on emission levels is evaluated. For this purpose, a 1.0 naturally aspirated port fuel injection (PFI) engine was used. The research engine suffers from LSPI phenomena under rotation speeds below 1000 rpm and high loads. Operation parameters were controlled using a fully instrumented dynamometer cell with incylinder pressure monitoring. The occurrence of LSPI was determined by using in-cylinder pressure data paired with in-cylinder light intensity using an instrumented spark plug with optical access to the combustion chamber. The emission levels of CO, CO2, NO, NO2 amd HC were measured using a real-time emission analysis stand.

Variable Valve Actuation system (VVA) is a technology developed for improving fuel economy, reducing emissions, and enhancing engine performance mainly by reducing pumping losses. Many automakers have used VVA in their engine projects with excellent results. Usually, VVA systems are built to control the valve events in four different ways: changing the amplitude of the valve lift, the valve opening angle, the valve closing angle or a combination of those modes. A special attention at the calibration activity is needed to reach the optimum performance of this system, beyond this, it was necessary to develop a different way to calibrate, much more focused on the development of the combustion and the gas exchange process requiring an intense use of a pressure indicating system. This work presents a comparison between different way of actuation in combustion analysis of a VVA system on a spark ignition engine.

Exhaust Gas Recirculation - EGR - is a well-known technique to reduce NOx and it’s been applied on Diesel engines for a long time. Later studies and application found that other benefits can be achieved with PFI and GDI gasoline engines, such as pumping loss minimization and efficient knock control. Variable valve actuation valve-trains brought broader application possibilities as it enables full internal EGR control without external paths, high precision and response, as required on transient work modes. Comprehensive investigation on PFI and GDI Spark Ignition engines with external Hot EGR and Cooled EGR are widely available. However, variable valve actuation EGR control review on a flexfuel application is not well explored, and this paper is aimed at doing such.

Port fuel injection - PFI - engines are widely available and the calibrations of fuel models are well defined. Modern flex-fuel engines are designed to work with different fuels and a mix of them. However, Brazil’s ethanol is composed of anhydrous Ethanol mixed with 8% distilled water, making it distinct in relation of composition. In a PFI, the fuel mass is mixed to the air mass before entering the combustion chamber in order to keep the mixture most uniform as possible. In this process, heat exchange and partial pressure variation are present and this may lead to volumetric efficiency modification. However, measurement errors may be introduced from the indirect measurement method if it does not considers water content and combustion efficiency to determine volumetric efficiency.

The development of a four-stroke engine, spark ignition, with direct injection of fuel into the combustion chamber was an important initiative for the global automotive market. The thermodynamic potential of this type of engine and its significant improvement in fuel economy have meant this technology as focus of a large number of research projects, with the objective to understand, develop and improve the system of direct fuel injection. However, to meet new emission limits set by Euro 5 specification, it was necessary to reevaluate the geometry design of the injector, which resulted in the development of a new component with a larger number of holes and with a diameter reduction (multi-holes injector). This change in the project aims to ensure a better spray, optimizing air / fuel ratio and, consequently, a better process of combustion inside the combustion chamber, satisfying the emission limits established by the applicable norms.

To attend the new tendencies of the automotive market, new technologies must be used throughout the engine conception. One way of improving the project is to use computational numerical simulation, predicting engine behavior in a wide range of situations. This paper presents a methodology to estimate the engine characteristic parameters necessary to numerical simulation. Morse test was used to determine friction power, mean effective pressure friction and friction torque, considering the engine behavior during cylinder ignition cut-off. In this test all the results were compatible with manufacturer data, which validates the methodology. To define the moment of inertia, it's also proposed a fuel cut methodology, associated with the Morse test, because the torque values measured by dynamometer after the fuel cut did not correspond to the real value. Thus, plausible values of engine moment of inertia, very close to values obtained by software, were obtained.