Formula SAE Intake for a Honda 600cc F4i Engine Matthew Labaza

Intake assembly and fuel injectors.

Intake as installed on vehicle.

Summary Formula SAE (FSAE) is an international engineering design competition where colleges design, fabricate, and race small formula-style cars. The Hope Formula SAE team will be competing at Michigan International Speedway May 12-15 2010. The 2010 Hope Formula SAE engine (2006 Honda CBR 600 F4i) requires a 20mm diameter restrictor mounted in the intake to comply with the competition rules. Because of the restriction that must be added to the system, a complete redesign of the Honda F4i intake system is required. The design will involve a new restrictor and a single throttle body assembly which will flow air into the intake plenum. The plenum is a large air cavity that stores air downstream of the restrictor. From the plenum, the air is distributed to four engine intake ports through four intake runners. One of the customers for this product, the Hope Formula SAE team, has many important requirements for this intake. They require that the intake must be free of air leaks, be located in a position so that the intake air is close to ambient temperature, lightweight, durable, and fairly simple. All this must be done while staying under the $500 budget that the FSAE team has proposed. The design process began by doing research and competitive analysis of other FSAE intake systems. The internet provided many pictures and information on the topic of designing a FSAE intake. The main sources of research were SAE White Papers, other FSAE team websites, the FSAE.com forums, and the book Internal Combustion Engine Fundamentals, written by John Heywood. A total of seven design concepts were considered. After many comparisons between each concept, a final design was decided. This design featured an air filter mounted right above the driver’s head, a plenum that equally distributed flow to each runner, and equal length runners. Once the concept was decided, it was necessary to optimize the dimensions of the system to achieve the most favorable airflow. Many SAE White Papers detail methods of theoretically calculating the plenum volume and intake runner size and length. These White Papers were used to theoretically fine tune the system so that the engine can achieve maximum air delivery to the combustion chamber, resulting in higher engine torque and horsepower outputs. The intake was constructed from a variety of materials. The Hope College Dimension 3-D ABS plastic printer was used for the construction of the air filter flange and the intake plenum. The plenum was designed so that it was able to split into two halves for maintenance, and both halves are sealed together by screws and an o-ring. Once each half of the 3-D plenum was printed, the outside was wrapped in carbon fiber to add structural reinforcement. Because of potential fuel vapors harming the bare plastic inside the plenum, 2-K Urethane paint was used on the inside for protection. The plenum was attached to the aluminum runners with rubber intake hoses and clamps, and the runners were welded directly to the original existing throttle body assembly (with the butterfly

throttles removed) in order to retain the stock fuel injector positions and mounts. The intake has currently met all customer requirements and is under the proposed budget. The final test will be using the intake for the FSAE competition in May of 2010.