Switching SC14 pulley - positive manifold pressure & brake booster vacuum questions?

[Futo_gt86]

Car - KE70 Wagon

motor / part in question - ST20V, GTIR intake, SC14 & Razorback ECU.

problems - Switching SC14 pulley with Razorback ECU, Positive manifold pressure and brake booster

occurs/started when (if applicable)-

personal situation (if applicable)

Hey all,
So my razorback ECU manual says that it has an output for VVTi/Supercharger.
I take it means 1 or the other, not both....and that is it set by RPM
My plan was to retain the stock VVTi, so I am wondering on how to switch the supercharger pulley......
Like I could just literally put it on a switch, meh don't really like that idea.
Or piggy back a relay off the VVTi rpm setting....meh kinda shit idea
I would like to trigger it with TPS%.
Is there a way of at say 75% Throttle to trigger the SC14 clutch?
I am thinking of calling Sam from Razorback and asking how to go about it, or if I can send him my ECU to add this option or something like it.....
The Stock GZE ECU triggers it off HG readings right? like 8HG
So could I hook up some kind of a pressure switch to the plenum or a vacuum line?

Also been looking at this pretty closely and wanted to ask a few questions
http://www.my-acoustic.com/Car/vacuum/4_throttles%27_vacuum/4_throttles%27_vacuum.htm
Just trying to wrap my head around this, if I 'T' together brake booster lines form 1&4 and run that with a 1 way valve to my brake booster I will still have brakes with positive manifold pressure?
Or do I use vacuum tank? How does a Vacuum tank go when positive manifold pressure enters the equation?
Everything i have read about vacuum tanks is for low vacuum with big cams, can't find a thing about boost applications....
Or do i go for an electric vacuum pump?

I think I think too much
Thanks,
Ali

[Hen may possibly be a nut]

(From what I have read on the internet) the stock 4AGZE clutch comes on at 8" vacuum (water) and switchs off at 10" of vacuum with a slight time delay too (so you don't get rapid off-on switching). I copied this and it switched smoothly and barely noticably.

Previously I had switched the clutch on at over 50% throttle. Not as nice a solution as you could often feel a surge as it came on, but still perfectly ok to daily drive. You had to be a little careful in the wet though.

As for the brake booster, the one-way valve ensures you never have positive pressure in the booster. Manifold vacuum sucks air out of the booster and the valve prevents the reverse. Plus you will always (well, unless you're doing something funny) have manifold vacuum when braking. Forget an electric pump, just connect your booster to the intake manifold with a standard one way valve.

[Futo_gt86]

Hen,
Did you use the stock GZE computer? If not how did you copy it?
How where you switching it with throttle %?

[Hen may possibly be a nut]

I was running a Wolf3D V4. I just used an aux output to swith a relay and programmed the output accordingly. I had to build an external circuit for the switch off delay though.

Throttle switching was as simple as:
AUX1 on over 55% TPS
AUX1 off under 50% TPS

More info here: http://forums.toymods.org.au/index.php?t=msg&th=83520&&pl_view=&start=0#msg_789530
About 10 posts down there's a link to the delay circuit.

[Futo_gt86]

Yep, vacuum and delay circuit is the way to go.
Thanks Hen!
I just need to work out if my ECU can work it that way....
I have txt Sam form Razorback, waiting to hear back.