2015 Engine Team Thomas Carpenter, Jim Hoffmeister, Cyrus Jordan, Brian Phung, Lyndon Wixom, Vinh Nguyen Advisor: Dr. Samuel Drake, Department of Mechanical Engineering Engine Performance Data: To benchmark the engine’s performance, a chassis dynamometer was used. This method for testing the powertrain provided horsepower and torque figures from the rear wheels. During testing, a peak horsepower of 41 [HP], and a peak torque of 34 [lb*ft] were observed. These “dyno-graph” results may be seen in the figure below. Project Description: The University of Utah Formula SAE Engine Team was tasked with providing an optimized engine/drivetrain system for the 2015 FSAE racecar. This included providing a powerful and reliable powertrain capable of propelling the racecar in the 2015 FSAE competition. To do this the team took a KTM 525 ATV engine and performed several modifications. Most notably, the engine was converted from carbureted to fuel injected, and from naturally aspirated to turbocharged. These modifications were performed to generate maximum power output given the limitations of a mandated intake airflow restrictor. The team was able to overcome many obstacles to provide an optimized engine package for the “Formula U” racecar. 1-D Gas Dynamic Engine Model The given results were achieved by increasing the engine’s displacement with a 570cc “big bore kit,” tuning the fuel and ignition systems using an AEM-EMS computer system, and employing a Garrett turbocharger to provide approximately 10 [psi] of intake boost pressure. This empirical data closely resembles the results of analysis obtained through Ricardo Wave, a 1-D Gas Dynamic Modeling Program. The model’s accuracy was validated using the dynamometer testing results. This complete engine system model was generated using the program Ricardo Wave. The results of this model were used to determine the optimal engine displacement and compression ratio when a rebuild of the combustion cylinder was necessary. This model was able to provide accurate horsepower and torque figures regarding several different available engine configurations. The results of this analysis directly led to the decision to use the 570cc “big bore kit” with a 12.5:1 compression ratio. This model also took into account the effect the FSAE mandated restrictor had on the intake air-flow. Engine Peripheral Optimization: Great importance was given to refining integral parts of the engine system through computer modeling and analysis. Two examples of this are provided below. ANSYS Fluent was utilized to aid in designing a “venturi-style” intake restrictor. The optimal geometry of the restrictor is an inlet and outlet taper of 16° and 6° respectively. A CFD model was used on the gas tank to ensure “fuel starvation” never occurred. The picture above shows a 1/8th full gas tank subjected to a 2g turn. Packaging Thanks to our Sponsors: KTM 525 Engine A very important consideration in vehicle design is how operational components are c o n fi g u r e d w i t h i n t h e c h a s s i s . M a n y considerations were taken when the engine system was implemented within the racecar. These considerations helped to determine the placement of all respective subsystems and their components.
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