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In recent years the Government of India has supported the use of Liquified Petrolium Gas (LPG) in public and private vehicles. One of the ways to reduce emission is use of alternative fuels. Among alternative fuels, LPG is one of the most promising mainly because of its low exhaust emissions. The papers about LPG used in three wheeler, cars for SI or CI converted to SI engines had been published extensively in the last two decades. The applications of LPG to bi-fuel or single fuel engines are tried widely at this time. But the extensive study of LPG for small SI single cylinder two stroke engine of three wheeler two stroke engine is not reported in depth. This paper describes development of bi-fuel (LPG/Gasoline) concept of a single air cooled 200 CC single cylinder two stroke engine for three wheeler application.

For more than a decade there is a progressive demand for fuel efficient and high specific power output engines. Optimization of engine cooling and thermal management is one of the important activities in engine design and development. In the present paper an effort has been made to simulate the heat transfer modes of cylinder block and head for a present 4-stroke air-cooled motorcycle engine. Two and three-dimensional decoupled and conjugate heat transfer analysis has been done with commercially available computational fluid dynamics (CFD) codes. Experimental results are also presented. A complete simulation model has been developed and CFD techniques have been applied to design and optimize air cooling surfaces of cylinder head and block, for an air cooled motorcycle engine. The two dimensional analysis is an easy and fast method to predict fin surface temperature, heat transfer co-efficient and flow velocity.

The cooling system is an important engine subsystem. The air cooling mechanism of the engine is mostly dependent on the fin design of the cylinder head and block. In the present paper an effort is made to study the effect of fin parameters on fin array heat transfer. Two and three dimensional conjugate heat transfer analyses have been performed using commercially available computational fluid dynamics (CFD) codes. For a given heat flux, the fin profile and fin array parameters could be optimized in a better way by numerical simulation methods. CFD could be used to determine optimal values of the fin parameters, upstream of design process. Different trends of these parameters are observed and the values which give optimized fin surface from the thermal point of view at a given heat flux are determined.

In the recent years, considerable efforts have been devoted towards improving the performance and emissions of small 4 stroke spark ignition engines by lean burn combustion techniques. However, there are certain drawbacks associated with the lean burn engines which are, large cyclic variations, long combustion duration, unreliable ignition of the mixture in some cycles. An experimental investigation has been carried out on a 150 cc air cooled four stroke gasoline engine to improve the lean burning limits by overcoming the difficulties associated. The following strategies have been considered for the study. 1 Use of catalytic materials in the combustion chamber to accelerate combustion. 2 Pre-chamber with catalytic activation. 3 Optimization of compression ratio and valve timing to improve flame propagation. 4 By using an ignition system with high-energy spark discharge and increased spark duration, to help ignite the lean mixture. 5 Combustion chamber optimization.

It is well understood that the consumption of lube oil should be reduced to minimum due to stringent emission norms and the need to reduce visual smoke. We have used statistical methods for optimising engine performance parameters due to limited time availability for product development. In this paper, techniques that have been used to develop and optimise a small 4-stroke gasoline engine have been described. This work is focussed mainly on oil consumption due to piston assembly and cylinder block. The piston ring assembly has been modeled using simulation software (RINGPAK). Design of Experiments (DoE) tools have been used to optimise the variables / critical factors. The significant factors were identified through ANOVA (Analysis of Variance) table on the above responses. A test procedure has been judiciously finalised to evaluate the optimised parameters. The best combination of factors/levels was arrived at by using the above results and was evaluated through test rig trials.

In Two Stroke Spark Ignition engines the thermal efficiency increases with increase in compression ratio. Also, with higher compression ratios the Ican burning limit increases because of the reduction in initial combustion period. Under part throttle conditions the fuel economy can be improved with higher compression ratios. However, this is often associated with problems of knocking and roughness. The paper describes a new type of cylinder head design which allows operating at high compression ratios under part load conditions and at lower compression ratios under full throttle condition. This paper begins by discussing the necessity for developing an automatic variable compression ratio engine (AVCR engine) and continues with the explanation of working of an experimental engine developed by TVS Suzuki Ltd. The mathematical model for theoretical prediction of the pressure crank angle diagram is then explained.