In essence, the V.I.S works as: at longer duct a negative wave, caused by the descending piston and the inertia of the gas in the longer duct, accelerates the air column in the duct. At resonance rpm the inertia causes the air to ram into the cylinder just before the inlet valve closes. This results in a considerable gain in volumetric efficiency and hence increased torque. Since the resonance Frequency change with engine RPM changing, the air duct must change its lenght. Clearly a complete variable induct system would be the optimum, but in a motorbyke there is not enought space. So, usually it can be implemented only a dual duct: short for high RPM and long for low RPM.
So, in figure it looks like:
For the electronic, I'll use Arduino since is a cheap and flexible hardware, the needed computation power is not so much anyhow...
The whole system is therefore:
Where:
* Arduino acquire the Aprilia's engine RPM and the trottle position
* when RPM > 6000 and trottle > 60% the servo has to move into the position where the duct is overall short (it is achieved by lifting up the top duct).
