Mac valve as fail safe boost dump?

[Tom86951]

I once saw a diagram showing how to use a typical 3 port Mac valve as the fail safe to dump boost with the aquamist system. Anyone know where to find that or have details on how to do it? I have an electronic boost controller, but want to trigger a Mac valve to revert to spring pressure on a dual port wastegate when the fail safe is triggered.

[Richard L]

Waht car do you have , I might be able to find a specific diagram for it.

[Tom86951]

It's a Porsche 944 turbo, but not stock. It has a Tial dual port wastegate controlled with an electronic boost controller. I'm looking to put the Mac valve in the control line to the top port of the Tial and have it bypass the EBC when fail safe is triggered, so that boost reverts to spring pressure when fail safe is triggered.