Bleed valve/ boost controller

[Chesney84]

Hi chaps, been given a Forge UNOS boost controller for free, was wondering if I wanted to up the boost, just a few PSI, do I need to go the whole hog and do the cup mod to ge boost system? I have fitted a boost garage to the inlet manifold and reads just under 10psi, was thinking of upping to around 12.5psi, am I good to just go from the lobster to the forward port of the actuator? Thanks!

[Ian S]

You need fuel to go with that boost.

If you have a standard restrictive exhaust, then you might see a bit less boost at the higher load, as the job of all that piping is to raise the boost 1psi as the exhaust back pressure rises. With a free flowing exhaust, is has no effect.

The cup mod blocks off the carb top ports and take the pipe to the actuator from port in the middle of the carb. Not the clearest description but maybe enough?

Just doing the cup mod can provide more boost as it takes the feed to the actuator from below the venturi in the carb. That might be 2 psi, or more, extra boost. And more responsive.

But if the actuator spring is weak, you get the wastegate pushed open by the extra exhaust pressure.

[Chesney84]

Thanks for the explanation and response!