I know that boost controllers like the AVCR use a solenoid to control the pneumatic signal to the wastegate. What type of valve is it, does it vent the line to the wastegate to atmosphere when the solenoid is closed? does the valve port pressure to the back side of the wastegate to help spring pressure for higher boost levels. I would like to get away from running a large spring to keep boost low on the street.

I also understand that the lowest pressure I can go with the VBC is determined by the wastegate spring as well.

Reason I'm asking this is because on my last setup, with the wastegate line totally disconnected I would pull between 16 and 18 psi with only the exhaust manifold pressure opening the wastegate with a 9-13 psi spring. This was a Turbonetics Racegate on a turbo tech system. I know that the backpressure on that system was very high though due to the small size of the exhaust piping.

I am building a twin setup now and I don't want to run into the same issue, or do you you think that the manifold pressure will be low enough that this will not be an issue.

I'm looking to run twin Tial 38mm gates with 7 psi (.5bar) springs, and would like to be able to boost over 20 psi with these wastegate springs and a VBC. Will it work?

Bill

 

Bill thats how my car is setup. im running twin tial gates with a 8psi spring. My boost ranges anywhere from 8+psi. Im using a manual valve to controll boost right now. The only thing I dont like about it is when there is 15 degree ambient change i tend to notice a manifold pressure increase/decrease. This is not so bad in the summer, more of a problem in the fall. I may decide to get a electronic controller in the future because of this problem.

Your question regarding soleniods. The soleniod holds pressure from the wastegate until the desired boost level is achived. Then after you reach that level the soleniod is opened and the wastegate acknoledges pressure and works from there.

As for your racegate, if your still using the one I gave you there might be a shim or 2 in there, I cant remeber. I f'ed with that think so much trying to get it to hold boost. If you pull the top of the gate there should only be one pieace of metal between the spring and the diaphram.

 

The racegate went with the rest of my kit. I no longer own it

Thats odd that ambient temps effect the operation of the MBC, all it is is a small press regulator, right?

Your using the press regulator to send a pressure signal to the back side of the wastegate, correct? That is how I had mine hooked up way back when.

Bill

 

I'm running very similar to that.

Twin Tial 46mm gates, 0.2 BAR springs

Each gate gets the pressure feed from the turbo discharge directly. One turbo feed the pressure side of a standard pressure regulator, 0 to 30 psi (5 turn). The outlet of the regulator feed the top port of both gates.

Lowest i can get is about 5 psi, more than likely due to the surge limit of the turbos rather than the gates. But it's a quick adjustment to raise it.

I've found better response with a smaller srping rate and use the controller to raise.

If you think about it, a smaller spring will result it a finer range of pressure over which the gate open. So it should control better around that pressure range. You use the regulator to apply the added pressure.

Both sides of the diaphram will have the same pressure until you hit the set point of the regulator and not move. Then you only have to over come the spring rate on the pressure side to start controlling. Plus, a light spring will open much sooner if you do lose the pressure feed and have to rely on the exhaust pressure to open the valve.

 

The text book way to hook up a boost controller is getting a pressure source as close to the turbo as possible. However when a pressure drop exists across the intercooler you may experiance manifold pressure drop. I found the best way to hook up a controller is in series, and grab your pressure source at or close to the intake.

In essence you will only tap one hole. Then place 2 separate "T"s in line. The first "T" will go to the bottom of each gate. The second "T" will go to the boost controller. Then out of the controller another T will exist, route these lines to the top port of each gate.
Hopefully this makes sence, its easier to draw a picture. Bill if you need further assistance with this drop me an email. I recommend doing it this way because I ran into problems at 16psi doing it the "text book" way.