Alpine951

I am considering chucking my stock wastegate. I currently have a reliaboost running off the IC pipe going directly to the wastegate. If I get a dual port wastegate will the reliaboost work on a dual port? My understanding of a dual port WG is that pressure is applied to both sides of the diaphram. How is pressure applied to both sides.

jsonnen

I'm pretty sure to take full advantage of a dual port you need a EBC.

Jake951

You can run a dual-port WG in either single-port or dual-port mode. In single-port mode, you just leave the other port open to the atmosphere and apply pressure to the port that opens the WG. A MBC (Reliaboost or whatever) goes in series with that port and regulates the pressure to open the WG at a preset boost pressure.

There have been some good dual-port WG connection diagrams posted here in the past. Somebody probably has the link to those.

Alpine951

I understand how the single port mode of operation works. I have seen a diagram, a copy of which I am attaching. The picture shows a device which is referred to as a manual boost controller used in the dual port setup. What is it about the controller that it is used in the dual port setup that makes it different from the reliaboost which is in the first example? Aren't they both basically a pressure relife valve that has one inlet and one outlet that opens once a preset pressure is reached? Isn't it that MBC and reliaboost are just brand names but they both do the same thing in the same way? Why can't the reliaboost be used in a dual port setup and provide the same affect?

UK952

And what is that side port on the MBC? Is the tee needed in dual port mode?
Tony

awilson40

My big this is understanding the differences. I see how the 2 types work and understand the flow.
But whats the point??? Why is dual port better than single?? Or is it any better"
Mine is hooked up single with the AccuBoost.

Danno

There's no benefits in dual-port configuration because the most closing pressure you will ever have exerted on the valve is the spring-rate and that's it! The only time a dual-port configuration can generate higher than spring-rate clamping force is with an electronic controller with dual solenoids. Even then, if you have a stiff 1.0-bar+ spring in the wastegate, there won't be any difference between single- vs. dual-port anyway.

The differences between boost-controllers determine which way you hook it up. Only the pressure-regulator type of controller can be used to hook up in dual-port mode. The check-valve type of controllers like the LBE, Reliaboost and Accuboost can only be hooked up on single-port mode. That's because of the differences in how their input & output pressure functions-curves look.

The pressure-regulator type will always send pressure to the wastegate from the very beginning. Then it limits the outlet pressure. This difference in boost and outlet-pressure is what opens the wastegate. But until the desired max-boost is reached, it sends boost to both sides of the diaphragm.

The check-valve controller on the other hand, holds back all pressure from the wastegate until the desired boost is achieved. This gives much faster low-end response and less lag. Does generate a little bit of a boost-spike though, but that can be controlled by having a bleed hole between the controller and wastegate. This bleed-hole also allows faster closing of the wastegate as well, thus faster cycling action and flatter regulation of boost.

The input vs. output functions looks like the attached picture. You can then plug in the pressures on the previous hook-up diagram at various pressures and you can create a finite-state table of various conditions the wastegate can be in.

UK952

With an electronic Boost controller you can pressurise the close port until you want the wastegate to open. I dont think this is possible yet with a manual controller hence the suggestion to run in single port mode.
However a friend of mine runs an Lindsey MBC in dual port after running a reliaboost in single port mode and he says whilst it is slightly slower to spool he can hold boost later.

"it does hold 15 psi for about an
extra 1000 rpm. It now drops down to 14psi after
5500rpm whereas it used to drop down to 13 after about
4500. This must be the reason I now get 315bhp at 5400
rpm as opposed to 300bhp at 4500rpm."

Also

"It does seem to have tamed the onset of boost a little
compared to the Reliaboost, it is more gradual than
before, but only very very slightly."

I think the before and after rolling road runs were a couple of months apart.

Tony
(considering going dual port just to see - can I do this with reliaboost?)

I also have a bleed type controller but dont know how it works 3 ports 1 in 1 out and an adjustable 'blockage' on the third port - any ideas?

UK952

Seems we typed together (and I am a slower typist), OK, but in practice a Guru & Tial equipped car gave more power with an MBC in dual port operation than a reliaboost in single port. Admittedly with slightly slower spool and there isn't a lot in it. But the only change between the 2 runs was the controller - the same max boost was set both times (16PSI).
I guess it could be other variations (temp etc.) and there was very little difference at all in the real world so I should stick with my reliaboost until I can afford an EBC, (plus injectors as I am already boost limited by fuel).
Tony