Mechanical Engineering - Research Publications
Permanent URI for this collection
Search Results
1 - 2 of 2
-
ItemHighly turbocharging a restricted, odd fire, two cylinder small engine: design, lubrication, tuning and control(SAE Technical Paper Series, 2006)This paper describes the mechanical component design, lubrication, tuning and control aspects of a restricted, odd fire, highly turbocharged (TC) engine for Formula SAE competition. The engine was specifically designed and configured for the purpose, being a twin cylinder in-line arrangement with double overhead camshafts and four valves per cylinder. Most of the engine components were specially cast or machined from billets. A detailed theoretical analysis was completed to determine engine specifications and operating conditions. Results from the analysis indicated a new engine design was necessary to sustain highly TC operation. Dry sump lubrication was implemented after initial oil surge problems were found with the wet sump system during vehicle testing. The design and development of the system is outlined, together with brake performance effects for the varying systems. Tuning an odd fire engine with an intake restriction and upstream throttle location was explored together with varying injector locations and manifold geometry. To improve engine efficiency, turbocharging and specific engine downsizing were employed in conjunction with a lean burn strategy at low brake mean effective pressure (BMEP). This engine package and tuning strategy resulted in the Melbourne University Formula SAE vehicle being very successful in competition, finishing first in the fuel economy event at the 2004 Australasian competition. Peak BMEP values of 25 bar, believed to be the highest recorded for small engines on pump gasoline were also achieved.
-
ItemDesign and development of a gasketless cylinder head / block interface for an open deck, multi cylinder, highly turbocharged small engine(SAE Technical Paper Series, 2006)This paper describes the design and development of a gasketless interface, which was used successfully to couple an aluminium cylinder head to an open deck design cylinder block. The cylinder block was manufactured from aluminium, featuring shrink fit dry cast iron liners. Extensive CAE modelling was employed to implement the gasketless interface and thus avoid using a conventional metal or fiber based cylinder head gasket. The engine was specifically designed and configured for the purpose, being a 430 cm3, highly turbocharged (TC) twin cylinder in-line arrangement with double overhead camshafts and four valves per cylinder. Most of the engine components were specially cast or machined from billets. The new design removed the conventional head gasket and relied on the correct amount of face pressure generated by interference between the cylinder head and block to seal the interface. This had advantages in improving the structural integrity of the weak open deck design. Extensive FEM analysis determined the correct amount of interference needed for successful operation under all operating conditions. Extensive thermal analysis concluded that removing the conventional gasket had the advantage of improving the heat path between the cylinder head and block, as the gasket behaves as an insulator. The possibility of gasket failure due to abnormal combustion is also eliminated. The design proved successful in operation, withstanding knock amplitudes of 30 bar, in-cylinder pressures exceeding 100 bar and high combustion temperatures. The engine completed extensive static and transient testing with no interface problems after initial development, recording 25 bar brake mean effective pressure (BMEP) on pump gasoline.