Mechanical Engineering - Research Publications
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ItemDevelopment of a 430cc constant power engine for formula SAE competition(SAE Technical Paper Series, 2006)This paper describes the design and development of an engine with constant power for SAE’s student Formula race-car competition, allowing the avoidance of gear shifting for much of the Autocross event. To achieve constant power for over 50% of the speed range, turbocharging was adopted with a boost pressure ratio of 2.8 at mid-range speeds and applied to an engine capacity of 430 cc. This engine was specifically designed and configured for the purpose, being a twin cylinder in-line arrangement with double overhead camshafts. Most of the engine components were specially cast or machined from billets. The capacity was selected to minimise frictional losses and thus increase delivered power along with dry sump lubrication and a three speed gear box. The engine manifolds and plenums were designed using a CAE application and proved to be well suited to the task resulting in excellent agreement between predicted and actual performance. One of the major challenges of the experimental development was overcoming the turbocharger oil consumption under throttled operation at part load conditions and at full power when the FSAE restrictor is choked. For the 2004 Australian competition the engine was run with slightly reduced mid speed power to avoid excessive use of the traction control system and was very competitive finishing first in the fuel economy event.
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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.
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ItemComparing the performance and limitations of a downsized formula SAE engine in normally aspirated, supercharged and turbocharged modes(SAE International Technical Paper, 2006)This paper compares the performance of a small two cylinder, 430 cm3 engine which has been tested in a variety of normally aspirated (NA) and forced induction modes on 98-RON pump gasoline. These modes are defined by variations in the induction system and associated compression ratio (CR) alterations needed to avoid knock and maximize volumetric efficiency (hVOL). These modes included: (A) NA with carburetion (B) NA with port fuel injection (PFI) (C) Mildly Supercharged (SC) with PFI (D) Highly Turbocharged (TC) with PFI. The results have significant relevance in defining the limitations for small downsized spark ignition (SI) engines, with power increases needed via intake boosting to compensate for the reduced swept volume. Performance is compared in the varying modes with comparisons of brake mean effective pressure (BMEP), brake power, hVOL, brake specific fuel consumption (BSFC) and brake thermal efficiency (hTH). The test engine used in experiments was specifically designed and configured for Formula SAE, SAE’s student Formula race-car competition. A downsized twin cylinder in-line arrangement was chosen, which featured double overhead camshafts and four valves per cylinder. Most of the engine components were specially cast or machined from billets. Experimental results showed BSFC or hTH values in the order of 240 g/kWh or 34% could be achieved. TC BMEP values in the region of 25 bar were also achieved, the highest recorded for small engines on pump gasoline [1]. The engine was installed into successive Melbourne University Racing (MUR) vehicles in 2003 and 2004, where it was very competitive, finishing first in the fuel economy event at the 2004 Australasian competition.