I installed a mac solenoid in my fd. I'm having a problem with boost dropping after 6500 rpm. Any suggestions to cure that? Probably going to end up getting a boost controller but wanted opinions. No pills in the lines. It's set at 11 psi and wastegate is ported. Car is non sequential. Thanks.

 

boost dropping after 6500rpm ? Sounds like stock turbos to me.

 

Doesn't sound like a wastegate issue? Tired turbos?

 

It's possible, sure, but the engine made peak power at 6500 rpm stock anyway.

 

Oh yeah it does. I always thought the stock turbos held 10psi to redline. My boost is currently dropping to 7psi or below. Might try a turbosmart controller with their RPM boost correction factor and see if it helps.

 

I will be installing both Mac solenoids shortly to control my BNR Twins. Now that you all have clearly explained the vaccum routing how about a wiring diagram.
Thanks

 

Sorry for bringing up this old thread. I just replaced my WG solenoid with a MAC valve. The transition was quicker and the boost more stable.
Red and yellow in the graph are stock WG solenoid and green is the MAC valve.

I think I will replace the PC solenoid as well.

 

What size are the brass hose barbs that you guys are using?
Where did you source them?

 

Those brass barbs and end filters were available from the local Grainger industrial warehouse that had the MAC valves in stock. Some hardware stores may have them as well, usually in the plumbing or pneumatics area.

:-) neil