Boost controller/gate plumbing

[r34.rory]

What’s the best way to plumb the gate to my greddy profec b spec 2? before I changed to a sinco manifold I had this as shown in the pic. But never got to try it/dyno it as I changed up to a sinco twin scroll and different wastegate. Most pics/build I see have only two lines to controller and the third is vented to atmosphere. I’m not looking for anything crazy. 400-500bhp but prefer response.

should I just ask my tuner how I should plumb it? 

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RB25DET NEO

Holset HX32 twinscroll

sinco twinscroll mani

profec b spec 2

turbosmart ultragate 45mm 14psi spring 

[KiwiRS4T]

Why not follow the instructions? But have you got an aftermarket ECU? I would use that to control boost.

[Dose Pipe Sutututu]

2 hours ago, r34.rory said:

should I just ask my tuner how I should plumb it? 

Do this.

[r34.rory]

10 hours ago, KiwiRS4T said:

Why not follow the instructions? But have you got an aftermarket ECU? I would use that to control boost.

That’s the thing I was. I believe that’s a turbosmart diagram. But I see so many people just venting to atmosphere instead that’s what made me question it. Yeah but Nistune.

[Ben C34]

That pic is the least common option of all, how did you choose that one?

[GTSBoy]

It works out like this. External gate can have a weak spring, or it can have a stiff spring.

When it has a stiff spring, it will want to close quite well, so it doesn't need any help. So you leave the 3rd port of the solenoid vented to atmosphere and you plumb the 2nd port on the solenoid to the side of the wastegate actuator that will make it open.

When you have a weak spring on the wastegate, you will probably need to help it close, which is what the connection diagram you posted does. The boost signal that would go to vent instead gets applied to the closing side of the actuator. There is no venting, there is merely PWM sharing of the boost signal between the opening side and the closing side, giving actual servo control of the valve position.

[Ben C34]

2 hours ago, GTSBoy said:

It works out like this. External gate can have a weak spring, or it can have a stiff spring.

When it has a stiff spring, it will want to close quite well, so it doesn't need any help. So you leave the 3rd port of the solenoid vented to atmosphere and you plumb the 2nd port on the solenoid to the side of the wastegate actuator that will make it open.

When you have a weak spring on the wastegate, you will probably need to help it close, which is what the connection diagram you posted does. The boost signal that would go to vent instead gets applied to the closing side of the actuator. There is no venting, there is merely PWM sharing of the boost signal between the opening side and the closing side, giving actual servo control of the valve position.

But there has to be venting for it to actually work as intended, which is why typically a 4 port will be used 

in that method of plumbing a 3 port above, you would initially hold gate closed with pressure to build boost, then apply pressure under dome to control / lower boost, but there is still pressure trapped on the top so you are screwed  .it won't exhaust anywhere because there is no exhaust port!

even if you didn't hold gate closed initially, once you put pressure under the diapraghm it will stay there when you swap to the top port, fighting you.

unless I am missing something here, which has been known to happen, it really needs to be a 4 (or 5) port valve to work

 

But really turbo smart do list other connection methods which are more typical. Would love to know if people have done it like above and what happened.

[BK]

Yes you're right Ben, that 3 port setup is a bit WTF. It does say for obtaining max boost for 3 port, so I can only assume you'd use this method with a 3 port solenoid and a weak gate spring, but I still don't like the look of that method. I wouldn't do it and can't say I've seen that before.

Common method for above would use a 4 port like this:

 

More common method for 3 port is like this, he should just do it this way. At least it will work properly.. (I've always used this method for single turbo / external gate)

 

 

[GTSBoy]

I think on the 3 port double connection they rely on cross talk between the two downstream ports of the solenoid to bleed excess pressure across from the NC outlet to the NO outlet (or vice, versa, which the hell way around it is).

[Ben C34]

5 hours ago, GTSBoy said:

I think on the 3 port double connection they rely on cross talk between the two downstream ports of the solenoid to bleed excess pressure across from the NC outlet to the NO outlet (or vice, versa, which the hell way around it is).

True, but they will equalise pretty quickly then you can't do anything