Dual Manual Boost Controllers

Ok guys, tell me if this is crazy or not.

In a normal mbc setup, you've got uninterrupted manifold vac and pressure going to the lower port on the wastegate, and the mbc adds pressure to the top port of the wastegate I'm order to raise the boost. This effectively lets you run approx double the spring pressure of what's in the gate. Essentially the same thing as if you ran with nothing hooked up to the gate. The mbc allows you to set boost between the spring pressure and double.

Now, there's electronic gates that do two things. Add pressure top side, and remove pressure from the bottom side.

What I'm getting at is if you could use two manual controllers and emulate that. One plumbed to the top port, one plumbed to the lower port. Run until you max out with the top port controller, then start shutting the lower port controller.

Would this work?

Posted from my LG G2

Essentially I dont see why it wouldn't? But wouldn't it v e easier/cheaper to do an electronic? Unless you have two laying around and want to tryn...

Making you silky smooth...

I'm thinking out loud more than anything. Realistically I want to get the FAST controlling the boost, but I'm picking up a Hallman Pro for interim use, and if it works well, I may try the dual setup as it would be easy enough.

Posted from my LG G2

I think you are crazy.

Run it on WG spring only and then start messing with things.

Establish a solid baseline.

MBC plumbed to the top of the 'gate won't limit you to double the spring pressure... the limit is what ever pressure the regulator can supply the top port with + spring pressure.

They way mine is set up, the bottom port connects to the intake manifold (sees vacuum and boost) and the top port is connected to the MBC's outlet which is fed by the pressure port on the compressor cover (sees boost only).
That way the boost always pushes on top of the WG until pressure on the bottom is high enough to crack it open. Reduces lag vs a "pressure bleed" setup on the bottom port only.

FWIW my WG will do 5 psi on springs only and ran as much a 20 psi with a 0-25 psi regulator. :)

since we cannot run electronic boost controllers I am on the spring only, but with a 17lb spring i can only get 10lbs, I tried plumbing a MBC and it did nothing..

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Originally Posted by MoeHorsePower

since we cannot run electronic boost controllers I am on the spring only, but with a 17lb spring i can only get 10lbs, I tried plumbing a MBC and it did nothing..

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You probalby plumbed it incorrectly.

Mne is plumbed like this, except the bottom port goes to the intake manifold.

Attachment 28530

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Originally Posted by GuillaumeC

You probalby plumbed it incorrectly.

Mne is plumbed like this, except the bottom port goes to the intake manifold.

Attachment 28530

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Dont remember how I plumbed it, but I'll give this a try, Thanks

That's how I had mine plumbed but it only would get to double pressure. It's the same thing as running open. Once the pressures equalize across the gate, the exhaust will push it open. I may have run a little more than double, but not much.

I found a four port MAC valve that will bleed off bottom pressure and apply upper pressure. Going to just go straight for that with the XFI at this point it looks like. If I still have issues, there's a choke issue in the hot side and it's building up too much pressure. Either that or my MBC last time on the dyno was junk because I had it hooked up exactly like above myself and it wouldn't go past 14 lbs on a 7lb spring.

Yea, you have a large restriction... its called a T4 76mm turbo feeding a 383ci motor with very well flowing heads.

I do not see why you need/want to push it so hard, you just end up leaning heavy on meth and for what?

I have a specific power goal in mind. 14 PSI wasn't getting me there. Too many FI LTD cars in the 700 range......very few 800 and up. I want to be one of those few.

Found the four port Mac valve for $60, so going that route from the get go now.

Posted from my LG G2

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Originally Posted by Fastbird

That's how I had mine plumbed but it only would get to double pressure. It's the same thing as running open. Once the pressures equalize across the gate, the exhaust will push it open. I may have run a little more than double, but not much.

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Same thing happened to me, the problem was that I had reached the maximum pressure on the MBC (a 0-10 psi pneumatic regulator).
The 7 psi spring only got me to 5 psi running straight off the gate and 14-15 psi with the 0-10 psi regulator. Switched to a 0-25 regulator and it's fine now.

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Originally Posted by Fastbird

I have a specific power goal in mind. 14 PSI wasn't getting me there. Too many FI LTD cars in the 700 range......very few 800 and up. I want to be one of those few.

Found the four port Mac valve for $60, so going that route from the get go now.

Posted from my LG G2

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Well, easiest way to save time and money... pin gate shut and let her eat.

Idk why gate companies even advertise spring pressures saying "this one makes 14, this one 7", etc. So many factors contribute to how much boost a certain spring makes. Wastegate placement, backpressure, how much air is directed right at the valve, etc.

Sent from my SCH-I535 using Tapatalk

[QUOTE=GuillaumeC;395287]You probalby plumbed it incorrectly.

Mne is plumbed like this, except the bottom port goes to the intake manifold.

Attachment 28530[/QUwOTE]

Are you talking about the port that goes into the tee from the mbc, that is plumbed into the manifold?

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Originally Posted by MoeHorsePower

Are you talking about the port that goes into the tee from the mbc, that is plumbed into the manifold?

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Like this:

Attachment 28544

What does referencing the manifold give you? You build pressure under your valve that way no..?

You need the pressure under the valve to open the WG and control boost level...

I just use the turbo outlet for the top port and manifold for the bottom port because usually the turbo outlet sees pressure sooner and higher than the manifold. This is supposed to help spool a little quicker since the WG starts to open later. Just what I've read, works for me but I've never had it plumbed like the first drawing.

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Originally Posted by Ryan Stout

Idk why gate companies even advertise spring pressures saying "this one makes 14, this one 7", etc. So many factors contribute to how much boost a certain spring makes. Wastegate placement, backpressure, how much air is directed right at the valve, etc.

Sent from my SCH-I535 using Tapatalk

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Ryan I think they actually test them for an average using manifold pressure on the lower port of the gate. I'd be willing to bet that a 7# spring actually has a 6-9 lb boost range dependent upon application. I would bet that the advertised numbers are interpretable and approximate.

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Originally Posted by GuillaumeC

Like this:

Attachment 28544

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Ahh Gotya, That what I was talking about, Thanks again

That's still only going to let you make roughly double the spring pressure.

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Originally Posted by Fastbird

That's still only going to let you make roughly double the spring pressure.

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Like I said, you can run spring pressure + regulator pressure.
I get only 5-6 psi on the springs only and I've ran up to 20 psi with the regulator plumbed as illustrated. It does work very well.

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Originally Posted by Fastbird

That's still only going to let you make roughly double the spring pressure.

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Thats assuming you can make the t76gts push that much, I would pin it and run it on the dyno to see what it can actually do.