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Rising energy demands, ecological deterioration and diminution of fossil fuels has necessitated the researchers to search for alternatives. With alternate fuels like Liquefied Petroleum Gas (LPG), hydrogen and alcohol based fuels, it is easier to substitute with the present engine without many alterations. Excellent chemical properties of these fuels make them favorable for lean burn operation which makes it a cost effective option to achieve goals of better fuel economy and controlled emissions. In this regard, experimental studies were carried out to examine the effects of LPG with different proportions of alcohols like ethanol and methanol (5, 10 and 20%) on the performance, emission and combustion characteristics of a single cylinder SI engine operated at a constant speed of 1500 rpm with a optimized compression ratio of 10.5:1 under full throttle opening conditions at varying equivalence ratio.

The desire for higher fuel economy, improved performance and driveability expectations of customers from engines are gradually increasing along with stringent emission regulations set by the government. Many original engine manufacturing companies are prompted to consider the application of higher function variable valve actuation mechanisms in their next generation vehicles as a solution. The VVA is a generalized term used to describe any mechanism or method that can alter the shape or timing of a valve lift event within an internal combustion engine. The VVA allows lift, duration or timing (in various combinations) of the intake and/or exhaust valves to be changed while the engine is in operation. Engine designers are prompted to consider Variable Valve Actuation (VVA) system because of the inherent compromises with fixed valve events. The major goal of a VVA engine is to control the amount of air inducted into the engine which is a direct measure of torque.