ABSTRACT Manifold tuning has long been considered a critical facet of engine design and performance optimization. This paper details the design, analysis and preliminary testing of a continuously variable, carbon fiber intake manifold for a restricted 2003 Suzuki GSXR-600® engine. The device achieves a large dynamic runner length range of 216-325 mm through the use of a half-tube, sliding shell design that differs substantially from traditional variable intake approaches. A combination of Ricardo WAVE® and 2D/3D Ansys Fluent® simulations were used to aid in the design of the intake along with a custom software routine to optimize restrictor geometry through fully automated CFD simulations. The sliding mechanism was actuated via a cable linkage system and powered by a small servo motor. This motor was controlled by a Microchip dsPIC® microcontroller that was embedded in a custom power distribution PCB for the 2009 Cooper Union Formula SAE® entry. The controller communicates with the engine's MicroSquirt® ECU over CAN to read instantaneous engine speed and commands the servo based on an empirically tuned look-up table. Initial testing of the intake showed the expected torque and power variation, maintaining over 95% of the peak engine torque for an additional 60% of the usable engine speed range in addition to a peak power improvement of 5% relative to a baseline static intake configuration. A peak power improvement of over 22% was also achieved relative to the 2008 FSAE® intake. The variable intake system adds less than 1% to overall powertrain weight and is able to actuate the full dynamic range in less than 1.0 s. Additional gains are expected through optimized cam timing coupled with refinements to the initial engine calibration. INTRODUCTION As is characteristic in any rotary power-plant (electric, internal combustion, etc.), there exist various operating points where torque output reaches a local or global maximum [ 1]. Because torque affects the acceleratory performance of a vehicle, optimizing it is a critical factor for any vehicle designer. For engines, torque is strongly affected by Volumetric Efficiency (VE), which is a measure of the actual air inducted versus the swept volume of the piston [ 2]. VE, in turn, is closely coupled to the resonance conditions that develop in the engine's manifolds, the timing of the induction and exhaust processes, fluid flow losses and the average speed of fluid flow [ 1]. Many empirical and computational studies have shown a clear relationship between the geometry of manifold ducts and volumes to the resonance peaks favorable to high VE performance (see Figure 1) [ 1]. As a result, an engine manifold designer is able to “tune” an engine to achieve higher VE at certain engine speeds by carefully selecting appropriate geometry. However, drivability also remains a concern, and because highly “tuned” engines typically exhibit narrow operating bands of peak performance, it is the goal of this paper to explore dynamically varying manifold geometry in an effort to produce an engine that is “tuned” over a greater range of engine speeds. By taking this approach, a performance engine can be made more drivable (through a more constant, or “flatter” torque curve) without a corresponding increase in engine displacement to compensate for low torque regimes. A High Performance, Continuously Variable Engine Intake Manifold 2011-01-0420 Published 04/12/2011 Adam Vaughan and George J. Delagrammatikas Cooper Union Copyright © 2011 SAE International doi: 10.4271/2011-01-0420