Questions about boost management and vacuum tubing

Okay so I noticed the ST205 IC core has a hose connector on the back of it which appears roughly the same size as the one on the back of the manifold on my ST185 (not visible in the picture). Is the functionality meant to be the same or is it there for some other purpose? Could I use it to send pressure to my EBC sensor and boost gauge? or should I just cap it and stick to using the one on the back of the manifold? Or, is there another use entirely that this was intended for?



Also, is it detrimental to have many feet of vacuum tubing in the boost controller circuit? I have the EBC stashed behind the rear intercooler bracket, so hoses run from the turbo to the back of the engine, through the boost controller solenoid, and back to the wastegate actuator in front. I'm wondering if I should be concerned about a delay in wastegate actuation causing pressures to spike and exceed safe levels.

The rate that pressurized air fills the small volume inside of the vacuum line would overcome any extra length.

Would be a fun experiment though

hoys":itxu3bbg said:

The rate that pressurized air fills the small volume inside of the vacuum line would overcome any extra length.

Would be a fun experiment though

Click to expand...

More length means more volume as well.

regarding the other question, does it matter if I get my pressure reading from the intercooler vs the manifold? I've heard the manifold is the place to get it, but considering this IC core has the connector right there....

Certainly more length means more volume, but it is such a small amount even with a few feet of hose. Think of how big the diaphragm area of the wastegate actuator is.

It's always best to get boost pressure as close to the cylinder as possible as this is where it really matters. By the time you've gotten to the part you've shown, most of the drop has occurred. I used a spare port on my manifold.

hoys":dwd67ip6 said:

Certainly more length means more volume, but it is such a small amount even with a few feet of hose. Think of how big the diaphragm area of the wastegate actuator is.

It's always best to get boost pressure as close to the cylinder as possible as this is where it really matters. By the time you've gotten to the part you've shown, most of the drop has occurred. I used a spare port on my manifold.

Click to expand...

Should I just plug the port on the ST205 IC core then? or what is it supposed to be used for?

The small tube in the WTA Intercooler is for AC idle up. Somewhere in the inlet manifold is a port where the AC idle up valve
screws into it (mine was at the r/h end of the manifold)Then a vacuum tube in between. The intended idea is when the AC is on and
your engine is at idling speed is to open (ECU or AC Amp. controlled) and allow a little more air from Intercooler into the inlet manifold thus
allowing the revs to increase and prevent stalling.

freddie":fkanu1sn said:

The small tube in the WTA Intercooler is for AC idle up. Somewhere in the inlet manifold is a port where the AC idle up valve
screws into it (mine was at the r/h end of the manifold)Then a vacuum tube in between. The intended idea is when the AC is on and
your engine is at idling speed is to open (ECU or AC Amp. controlled) and allow a little more air from Intercooler into the inlet manifold thus
allowing the revs to increase and prevent stalling.

Click to expand...

That's both fascinating and oddly terrifying. It's no wonder this motor is a nightmare of vacuum tube complication to work on.

Ha ha Yeah. I have a AM ECU installed. It controls everything including my AC. The AC idle up valve - gone. The ISC valve - gone
factory boost control - gone. cooling fan controller - gone. IC pump controller - gone IC water level controller - gone.

I still have about 6 vacuum lines but lol.

EvilStig":3rc2ggr5 said:

regarding the other question, does it matter if I get my pressure reading from the intercooler vs the manifold? I've heard the manifold is the place to get it, but considering this IC core has the connector right there....

Click to expand...

Between the intercooler and the intake manifold is your throttle body/plate. So there is a significant different in absolute air pressure between the intercooler and the intake manifold (less so if you have a wide open throttle, which of course is not possible 100% of the time the engine is running).