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Discussion Starter #1
Wastegate Springs

I read on an Import forum that a general rule for WG Springs is that you can double the Boost rating of the spring with a Manual or Electronic Controller.

So if I get 6 lbs Springs, I can get a max of 12 psi with a controller. True or not?
 

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That's what I understand too
 

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Yes and no...You need to understand how a wastegate works before you can start digging into boost controllers and expect your boost levels to be doubled.

A wastegate has open ports on top and below the valve. A waste gate valve is nothing more than pressure relief between the turbo and exhaust manifold. The greater your control here, means less back pressure on the engine, which makes more power.

So a waste gate has a spring installed, for your sake we will say its a 6lb spring. This means with the back pressure between the exhaust manifolds and the turbo reach 6psi, the spring will begin to open. From this point on the harder you push the more the valve will open and allow gas to escape before hitting the turbo.

Now if you ad a manual or electric boost controller here is where you can have fun. A boost controller takes the positive boost pressure being created by the turbo, and pushes it back into the waste gate. depending on which controller you have, this may be a manual turn of a dial, or it might be all at the push of a button. So the controller will pump positive air pressure into the top of the waste gate, this adds more tension n the top of the valve, the engine exhaust will need to overcome to open. So you 6psi spring has just increased in pressure to whatever you have it set at. You can also use a boost controller to lower the boost level by pump positive air pressure into the bottom side of the waste gate, this makes the valve open easier and you will by pass all your boost at very low levels if so desired.
 

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What you read is incorrect. You have to try it and see how your system behaves.

If you use an air-bleed type of controller that vents pressure off the sample line, the exhaust side pressure can push the gate open even without boost. With a single waste gate I can run a 10 psi spring and pull the boost sample line all the way off and not get more than 15 psi. At 15 it just pushes the gate open even without signal. A different system or different gate might make 30 or 40 psi. Who knows!

Boost can be all over the place with a bleed type controller, depending on how the gate responds to exhaust pressure trying to push it open.

A CO2 dome pressure adder, which is what I use now, lets me run a 5psi spring and get 30 psi boost via the controller. I normally run a 10 pound spring as the target lowest boost, and apply dome pressure to get the boost wanted. If I slap 18-20 pounds of CO2 on the dome with a 10 lb spring I get 25 psi boost. I can go up to 30 psi boost by applying 25 psi on the dome.

Can't do that even if I yank the compressor line totally off the waste gate because the exhaust just pushes it right open.
 

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the "double psi" thing is totally dependent upon the gate you use. you can have a 6psi spring and make 25lbs of boost if the gate valve is small or your hot-side/turbine setup allows. As the others stated, you're plumbing a boost line to the gate to open it up at the rated spring pressure or you add a boost controller that either decreases the boost reference (requiring more pressure from the compressor to open the gate), or adds pressure to the top of the gate (producing the same affect). without a boost reference pressurizing the gate diaphragm, you rely on the hot-side backpressure to crack the gate valve, which can be a tremendous amount of pressure (not the rated spring pressure).

On my specific setup, I had an 8lb spring and made 25psi when it had no boost reference.
 

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Discussion Starter #6
Thanks fellas. I think I'll be using the Turbocouple style solenoids for now because they're cheap.

I was thinking about a 6psi spring and then use the computer for 10-12 psi total depending on how it goes.

 

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A lot of OEM's utilize those pierberg units and they seem fine. My turbo volvo came with it and apparently porsche uses them too. I feel like it might induce a delay in boost response but I'm yet to try one on my car to see. maybe it has been tested by others before.
 

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Does it bleed the turbo boost side to the gate, rather than adding dome pressure??
 

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Does it bleed the turbo boost side to the gate, rather than adding dome pressure??
Operates by bleeding pressure from under the diaphragm to increase pressure in the manifold. When/if they fail, the cars see low boost so that makes me think the solenoid closes/turns off as a failure mode (for safety).

If something clogs the line somehow though...Yikes! Although I've never read of this happening to the OEM's.
 

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Discussion Starter #10
Seems like there's more than 1 way to do this.

Basic External Wastegate Set-up

For basic mechanical set-up you will need one vacuum line plumbed from the turbo compressor housing (pressure source) to the bottom port of the external wastegate. The top port is to be left open to atmosphere. This set-up uses no boost electronic boost control and will force the turbo to run on minimum, mechanical wastegate spring pressure.






3-Port EBCS External Wastegate Set-up Option 1

For the mechanical set-up you will need one vacuum line plumbed from the turbo compressor housing (pressure source) to a vacuum T. The opposite side of the vacuum T will be plumbed to port (1) of the 3-port wastegate solenoid valve. A 3rd vacuum line plumbs the middle of the T-fitting to the bottom port of the external wastegate. A 4th vacuum line will need to be plumbed from port (3) of the wastegate solenoid valve to the intake system, prior to the compressor inlet and after the air filter. The final and 5th vacuum line will need to be plumbed from port (2) of the 3-port wastegate solenoid valve to the top port on the external wastegate. This set-up uses a 3-port electronic boost control solenoid valve to manipulate the air pressure allowed to reach the top port of the external wastegate.






3-Port EBCS External Wastegate Set-up Option 2

For the mechanical set-up you will need one vacuum line plumbed from the turbo compressor housing (pressure source) to port 2 on the 3 port wastegate solenoid valve. A 2nd vacuum will need to be plumbed from port (1) to the top port on the external wastegate. A 3rd vacuum line plumbs port 3 to bottom port of the external wastegate. This set-up uses a 3-port electronic boost control solenoid valve to manipulate the air pressure going to the top port of the external wastegate. WARNING! This set-up will significantly increase the minimum boost pressure which is expected to run. We suggest you set all WGDC settings to zero so you can test your new minimum boost pressure achieved by this method of connection.

 

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The diagrams are correct but the port naming convention (port numbers) changed between EBC#1 and EBC#2. It also excludes the more basic 2 port boost controller setup, which i described above. The EBC#1 diagram you showed is good because if the controller fails to where no pressure gets through it (or clogs somehow), the gate diaphragm will still see a boost signal from the Tee and lift at spring pressure. this is a a safe configuration. the EBC#2 diagram doesn't have that simple safety, but the solenoid may default to allow boost to the bottom gate port during a failure, so it could still be safe. there are many ways to plumb a boost controller. lol another way is to go from turbo to port 1 of boost controller, then port 2 (opposite side) to bottom port and leave all else to vent. I believe this method produces a quicker response than the diagrams you posted. Similar to what you'd do with a 2 port manual controller without a Tee.

Anyway, if you get a MBC or EBC, there are like 6 signal routing schemes you can choose from so you'll get it going. lol
 

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None of the setups in the diagram below are ideal setups. A couple are notoriously unreliable, like the one that alternates pressure between spring and boost sides.

The best way by far is to use dual valves and a regulated pressure source like CO2.

Seems like there's more than 1 way to do this.

Basic External Wastegate Set-up

For basic mechanical set-up you will need one vacuum line plumbed from the turbo compressor housing (pressure source) to the bottom port of the external wastegate. The top port is to be left open to atmosphere. This set-up uses no boost electronic boost control and will force the turbo to run on minimum, mechanical wastegate spring pressure.






3-Port EBCS External Wastegate Set-up Option 1

For the mechanical set-up you will need one vacuum line plumbed from the turbo compressor housing (pressure source) to a vacuum T. The opposite side of the vacuum T will be plumbed to port (1) of the 3-port wastegate solenoid valve. A 3rd vacuum line plumbs the middle of the T-fitting to the bottom port of the external wastegate. A 4th vacuum line will need to be plumbed from port (3) of the wastegate solenoid valve to the intake system, prior to the compressor inlet and after the air filter. The final and 5th vacuum line will need to be plumbed from port (2) of the 3-port wastegate solenoid valve to the top port on the external wastegate. This set-up uses a 3-port electronic boost control solenoid valve to manipulate the air pressure allowed to reach the top port of the external wastegate.






3-Port EBCS External Wastegate Set-up Option 2

For the mechanical set-up you will need one vacuum line plumbed from the turbo compressor housing (pressure source) to port 2 on the 3 port wastegate solenoid valve. A 2nd vacuum will need to be plumbed from port (1) to the top port on the external wastegate. A 3rd vacuum line plumbs port 3 to bottom port of the external wastegate. This set-up uses a 3-port electronic boost control solenoid valve to manipulate the air pressure going to the top port of the external wastegate. WARNING! This set-up will significantly increase the minimum boost pressure which is expected to run. We suggest you set all WGDC settings to zero so you can test your new minimum boost pressure achieved by this method of connection.

 

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