Vaughan, A. and Delagrammatikas, G., "A High Performance, Continuously Variable Engine Intake Manifold," SAE Technical Paper 2011-01-0420, 2011, doi:10.4271/2011-01-0420.
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.