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The constant demand regarding vehicle efficiency and emissions improvement is a consequence of the expected very restrict emission regulations in the whole world. Despite the vehicle market being changing due to several new powertrain configurations options, such as hybrid and electric, internal combustion engines will still play an important role in future global vehicle market, due to its applicability in powertrain systems. Among other engine parameters, the geometric compression ratio has an important impact on the engine thermal efficiency and vehicle performance, however such parameter requires deep investigations in order to avoid operation with pre ignition and combustion knocking events. Vehicle simulation is widely used to select powertrain adequately, with respect to fuel consumption and performance.

The need to reduce greenhouse gas emissions by the automotive sector has demanded an increase in the efficiency of internal combustion engines as well as the use of renewable fuels, with ethanol being one of the most promising fuels. In SI PFI engines, the quality of the air-fuel mixture formed during the injection event is dependent on several factors, such as: physical-chemical properties of the fuel (density, viscosity, surface tension, latent heat of vaporization), interaction between fuel spray and gas flow / pipe walls / back surfaces the intake valves.