Development of fuel efficiency improvements for a single cylinder internal combustion engine. An investigation and implementation of five fuel efficiency improving technologies on an Eco Marathon engine.

Sammanfattning: This thesis describes the work of developing a technology demonstrating single cylinderengine for Chalmers Vera Team. The engine was to display five different technologies thatcould be of use to Chalmers Vera Team in the continued development of their fuel efficientengine.The first technology investigated was the use of ceramics and low-friction materials in thecombustion chamber in order to reduce heat and friction losses and hence increase thethermal efficiency.Using the ideal thermodynamic Atkinson cycle was the second technology investigated asit has a higher thermal efficiency than a conventional Otto cycle engine and can be utilizedby relatively small mechanical changes of the Chalmers Vera Team existing engine.Replacing the conventional electric spark plug with a laser ignition system to achieve amore efficient combustion and lower the engine heat losses were investigated as a thirdfuel efficient technology.The fourth technology was the use of variable compression in the combustion chamberto achieve an optimum compression ratio over the full speed operating range of the engine,in order to get a constant high thermal efficiency.Direct injection was investigated as a fifth technology and a possibly more fuel efficient method of fuel injection, specifically the air assisted direct injection system, as theChalmers Vera Team is limited, by competition rules, to a low pressure fuel system.The different technologies were implemented into a complete technology demonstratingengine, where only the laser ignition never was actualised with a physical component.The different technologies never got tested on the engine due to lack of time, but they allshowed potential to decrease the fuel consumption.