On the 12th August 2010, the Formula SAE UQ Racing car was finally dyno tuned after 3 years of development, producing 51.5 kW at 9210 RPM and 50.4 Nm at 7846 RPM.
Formula SAE is a worldwide engineering competition for university students, which involves the design and manufacture of a small, open-wheel style race car. The cars are judged at various competitions around the world.
This thesis critically analysed the 2010 Formula SAE UQ Racing powertrain system while detailing findings that will contribute to future engineering developments and improvements recommended for the 2011 Formula SAE UQ Racing entry. The Powertrain System comprises of;
2. Exhaust Manifold (or Headers)
3. Exhaust Tailpipe
5. Throttle body
6. Restrictor (note it is not common in passenger vehicles)
7. Plenum Chamber
8. Intake manifold runners
9. Fuel rail
10. Fuel injectors
A great deal of literature was examined to develop and an understanding of the intake and exhaust tuning influences present in an engine. Using dyno data obtained, an empirical method was used to determine the intake ramming coefficients for a given engine speed (RPM) and intake length. Blair (Blair, 1999) suggests the intake system be designed first, and the exhaust system be designed to counter act the tuning troughs created by the intake.
The geometry and design of the intake and exhaust systems greatly influence the performance of an engine, which also directly relates to the drivability of the engine, where the driveability refers to the ability to control the engine, and thus power. Drivability is considered critical within the FSAE competition. Generally, a driveable car is one that has a linear or flat torque over the engines. operating speed range. High-end power cars (for example drag cars) comparatively differ and see a pronounced torque peak at high engine speeds (revolutions per minute, RPM).
To determine the baseline of the 2010 Formula SAE UQ Racing Cars drivability and improvements moving forward; the intake and exhaust lengths were calculated using the empirical methods describe by Blair (Blair, 1999) and outlined in section 3.3.2. The tuned lengths are summarised below;
The major design flaw identified with the current exhaust system was its vertical height, limiting the location of the engine and engine subsystems. The presented 2011 exhaust system allows the engine to be lowered by 45 mm and has an estimate weight of 5 kg, which is 2 kg lighter than the current system. The CAD and data for manufacture completed by this author during this thesis will be passed onto the UQ Racing team.
To facilitate analysis and future design, flow bench data was obtained for the current intake system. The intakes system results show that there is even flow to within 1% over the 4 cylinders. Results of the two restrictors tested, identified the flow bench data agreed with viscous flow theory (White, 2006).
The most notable result of the testing is the restriction of the throttle body, which is greater than the restrictor. SolidWorks flow simulation was used to analyse the current intake system, with aim of producing comparable results. Unfortunately the results did not compare. When comparing the volumetric efficiency with the data obtained the simulations greatly over estimated the performance. The intake showed a 55% difference, the restrictor analysis showed a 32.5% difference.
There are a number of recommendations for the 2011 intake system to over comes the presented issues. The recommendations are as follows;
• Implementing a new throttle body with a 34 mm throat and progressive throttle cam
• Modifying the current intake system to confirm the empirical analysis
• Move the injector location to the top side of the intake system to improve fuel/air mixing.
• Continue simulations using SW Flow Simulation to improve the volumetric efficiency and examine the use of Ansys CFD package to compare results.
• Strongly encourages team to use Ricardo Wave simulation software to develop greater understanding of the engine systems.
It is believed that if the recommendations are implemented; the 2011 Formula SAE UQ Racing Car will be greatly enhanced in both design and performance; meeting the Society of Automotive Engineers (SAE) pressure on FSAE teams to improve the fuel efficiency while maintaining reliability and performance.