vdi activation
 

Ok when i posted my s5 manifold swap thread it was mentioned to have the vdi operated by and rpm switch. How does it activate? I assume its through the airpump. And at what rpms does it usually activate? I need to knwo so I know if I can use one rpm/pump to activate it alogn with my 5/6 ports or i need a seperate setup.

It kicks in around 5500 RPM and is quite a noticeable punch of power. As far as the rest goes, I have no idea. :)

Operate it just like the stock set-up. The air pump supplies pressure to two solenoids, with one solenoid output connected to the VDI actuator and one solenoid output tee'd to the two 6PI actuators. The solenoids are each operated by an rpm switch. Look at the S5 NA vac routing diagram to see how it's all arranged.

The stock activation points are 3850rpm for the 6PI and 5200rpm for the VDI, but these points may not be ideal for a modded engine. The only way to tell for sure is to do two dyno runs; one with the auxiliary ports closed and one with them open. Where the two power curves cross is the ideal activation point. Then you repeat this process for the VDI.