Variable Runner Length Intake Manifold Design: An Interim Progress Report

Manifold tuning has long been a critical facet of engine design and performance optimization. This paper details the design, analysis, and initial fabrication of a variable runner length intake manifold for a restricted 2003 Suzuki GSXR 600 engine. A series of analytical Helmholtz resonance calculations were first performed to assess the feasibility of such a system. A comprehensive CFD study was then performed using a combination of Ricardo WAVE® and Fluent® simulations. Custom software was developed to optimize restrictor geometry through fully automated CFD simulations whose results were investigated to determine the optimal transition for the intended flow characteristics. This resulting candidate geometry was then used with a variable intake design in a Ricardo WAVE® manifold dynamics model and was varied iteratively to yield an optimum final geometry. This step-wise design method was intended to minimize the computational expense necessary to produce an acceptable design slated for production.

A series of manufacturing processes was then developed to fabricate the various intake components out of lightweight carbon fiber or aluminum. Sliding mechanisms were actuated via a linkage system powered by a small servo motor. This motor was controlled by a Microchip dsPIC® microcontroller that was embedded into the 2009 Cooper Union FSAE® car's power distribution PCB. The controller communicates with the engine's MicroSquirt® ECU over CAN to read instantaneous engine speed and commands the servo based off a empirically tuned lookup table. The system can be monitored wirelessly over 802.11b.