I will be installing the Apexi boost control solenoid with a Tial wastegate and wanted to confirm the proper connections. The Apexi site has a diagram for the twin turbos where the NC port is unused and another diagram for a wastegate type with the NO port not used. Based on the following threads I am assuming that the unused NO port is correct. (https://www.rx7club.com/showthread.p...light=com+port) (https://www.rx7club.com/showthread.p...light=com+port)
However, I would like to be more certain. Would someone verify, preferably by examining his or her setup, which is the correct connection?

Thanks in advance

 

manifold pressure to NC port
vented NO port
top of wastegate to COM

When the solenoid is active, boost pressure is delivered to the top of the wastegate, holding it shut. When the solenoid is off, the top of the wastegate is vented to atmosphere (to relieve any pressure in there).

^ That's what you want.

-Max

 

Thanks Max, I appreciate your help. I know you've answered this before and are probably tired of repeating it, I just want to be absolutely certain. I'm speculating that at a 50% duty cycle setting on the PFC and the NC and NO port connections switched that the same boost level would be maintained. Based on that assumption a lower duty cycle would increase boost and a higher setting would decrease boost.

 

I am not sure what duty cycle to start at. Just approach it conservatively. Start with a low duty cycle and see what happens. Keep increasing it until you get a spike or too much boost and then back it down a little.

Higher duty cycle = higher boost, since the solenoid will be maintaining a higher pressure in the top of the wastegate. Pressure in the top of the wastegate holds it shut, giving high boost pressure. At 0 duty cycle, there will be zero pressure in the top of the wastegate (it fails safe).

This relationship isn't always true -- some boost control systems give lower boost at higher duty cycles. But for your system, higher duty will give higher boost.

-Max