N55: upgrading the Internal wastegate actuator ?

[katsooba]

Hi guys,

has anyone tried this mod on their N55?
i wonder if and what we can benefit from this, seems like a nice addition to the DV+ diverter valve upgrade

http://www.turbosmartdirect.com/Prod...ate-Actuators/

[Bmw doubles]

Originally Posted by katsooba

Hi guys,

has anyone tried this mod on their N55?
i wonder if and what we can benefit from this, seems like a nice addition to the DV+ diverter valve upgrade

http://www.turbosmartdirect.com/Prod...ate-Actuators/

Sub'd

[Gizmo135i]

Originally Posted by katsooba

Hi guys,

has anyone tried this mod on their N55?
i wonder if and what we can benefit from this, seems like a nice addition to the DV+ diverter valve upgrade

http://www.turbosmartdirect.com/Prod...ate-Actuators/

The wastegates on these cars dont work like that. It actually works opposit from how a traditional internal wastegate operates. It's normally open, and closes when the dme tells it to via vacuum supplied from the vacuum pump, where as a traditional wastegate is normally closed until boost pressure supplied from the intake manifold overcomes the spring pressure in the actuator and opens it.

[Bmw doubles]

Originally Posted by Gizmo135i

The wastegates on these cars dont work like that. It actually works opposit from how a traditional internal wastegate operates. It's normally open, and closes when the dme tells it to via vacuum supplied from the vacuum pump, where as a traditional wastegate is normally closed until boost pressure supplied from the intake manifold overcomes the spring pressure in the actuator and opens it.

What if your tuned, exhaust pressure is way above stock, wouldn't the exhaust pressure overcome regardless of electronic regulation?

[Gizmo135i]

Originally Posted by Bmw doubles

What if your tuned, exhaust pressure is way above stock, wouldn't the exhaust pressure overcome regardless of electronic regulation?

No that's not how a wastegate works

[Bmw doubles]

Originally Posted by Gizmo135i

No that's not how a wastegate works

You're saying that's not how the BMW wastegate works?

[The Wind Breezes]

Any modern turbo car uses a computer controlled wastegate like the N55. The actuation methods vary; N55 came with two different types, one vacuum actuated and one electronic actuated.

If you're forcing the wastegate open against the actuator you have a problem and your turbo isn't going to last very long. Or you have a broken / shitty actuator.

[Bmw doubles]

Originally Posted by The Wind Breezes

Any modern turbo car uses a computer controlled wastegate like the N55. The actuation methods vary; N55 came with two different types, one vacuum actuated and one electronic actuated.

If you're forcing the wastegate open against the actuator you have a problem and your turbo isn't going to last very long. Or you have a broken / shitty actuator.

I don't want to force it open. The goal is to keep it closed at above stock targets. If the stock pwg opens at anything above something like 10psi,then your tune is negated by escaping exhaust gases. Could the stock WG be adjusted so the actuator has less travel? Appreciate all the feedback guys, thanks.

[Gizmo135i]

Originally Posted by Bmw doubles

You're saying that's not how the BMW wastegate works?

No that's not how any wastegate works. The video shows how a basic one works, but I don't think you grasped what the video was saying.

The exhaust gasses don't open the valve, boost pressure from the intake, routed through a little hose to the wastegate pushes against a spring to open it when the desired boost is reached. Modern cars have a electronic valve in-line on that hose to control how much boost gets to the wastegate.... this way the valve stays closed until the computer opens the actuator and allows boost pressure to travel to the wastegate valve. This is the type of actuator the op attached a link to.

Bmw is different. On Bmw the actuator is normally holding the valve open, and is not connected to the intake, but rather an electronic valve which is connected to a vacuum pump, (the same one that provides vacuum to your brakes). When the computer targets boost it basically opens the electronic valve and sends vacuum to the wastegate actuator which closes the wastegate and allows the turbo to spool.

Also starting around 2013 BMW started in most models just have an electronic wastegate valve with no vacuum control.

[Bmw doubles]

Thanks Gizmo135i I think I understand it better now in that the PWG or EWG are both closed electronically. The difference being the PWG is an electronic signal to the feed pressure to the actuator and the EWG is pure electronic. Please feel free to correct if I'm off. If that's the case It seems the EWG guys have more accuracy in controlling the wastegate.

It could be that my wastegate actuator is not up to the task. I can hit 16 psi at 3400rpm and then it tapers off quickly. Would my stock wastegate perform the same on a upgraded turbo? I have the gfb DV and that seem to help hold boost a little better but not dramatically.

[all4bspinnin]

They have several tables in MHD/Cobb that allow control of the wastegate off throttle. It would be an interesting experiment to try reversing the logic in the DME. Maybe adjust WGDC to WGDC position and the inverse. As well as pre-control A maps.

In theory you could reverse the numbers in the DME to push instead of pull.

[Gizmo135i]

Originally Posted by Bmw doubles

Thanks Gizmo135i I think I understand it better now in that the PWG or EWG are both closed electronically. The difference being the PWG is an electronic signal to the feed pressure to the actuator and the EWG is pure electronic. Please feel free to correct if I'm off. If that's the case It seems the EWG guys have more accuracy in controlling the wastegate.

It could be that my wastegate actuator is not up to the task. I can hit 16 psi at 3400rpm and then it tapers off quickly. Would my stock wastegate perform the same on a upgraded turbo? I have the gfb DV and that seem to help hold boost a little better but not dramatically.

Well any turbo is going to taper off, especially when your pushing the limits of its efficiency. The stock n55 turbo is useless at higher rpm.

[Bmw doubles]

Thanks for the input guys.

[The Wind Breezes]

To answer your original question, you can keep the flap closed longer than stock via software. The stock tune doesn't run the turbo very hard so there is some room to make more top end power. The turbo will lose ability to push high pressures efficiently at high RPM since it's not designed to do that. If you want a lot more power you need a bigger turbo.

[Bmw doubles]

Originally Posted by The Wind Breezes

To answer your original question, you can keep the flap closed longer than stock via software. The stock tune doesn't run the turbo very hard so there is some room to make more top end power. The turbo will lose ability to push high pressures efficiently at high RPM since it's not designed to do that. If you want a lot more power you need a bigger turbo.

When you say bigger turbo are you saying compressor housing and wheels or just the turbine and compressor wheels?

[hardparker]

Just to revive this topic, for what it's worth, I've got one of these Mamba N55 vacuum wastegate actuators on the way for my PS2 PWG X3. http://shop.mambatek.com/product.sc?...0&categoryId=5

I'll update once I've got it installed and tuned for comparison to stock and overall results.

[hardparker]

The Mamba actuator, while not a total POS, is so poorly implemented as to be useless. First, the actuator arm is too short. Like an inch too short. Getting the lock nut fully threaded resulted in the wastegate nearly fully closed. Maybe 1/8" open. Backing it off to 3/8" open puts the nut half way off the end of the actuator rod.

The real problem, however, is the spring tension. Basically, they took their lightest, 5 psi spring and put it on the other side of the piston to act as normally open, pull style, rather than the usual normally closed traditional wastegate to accommodate the N55's operation. Fine, but that 5 psi spring is way too stiff. It took about 11 in. mg. instead of 6 to close it. The poor pressure solenoid has no chance of closing the damn thing, rendering it totally useless.

That said, I think there's hope for aftermarket actuators built from conventional actuator parts, which could be important, since you can't buy a new OEM N55 actuator without buying a complete turbo.

The two real tricks here are proper internal volume (same or slightly less than stock) and return spring pressure. I'll be playing with a Forge actuator and some spare parts to see if I can come up with an easily workable solution at some point.

[houtan]

Thanks for posting the update 👍🏽

Hopefully you figure out a viable upgrade. I believe the pwg cars loose a little boost compared to ewg because the wg doesn’t seal as good on pwg vs ewg.

[hardparker]

The EWG actuator is far more powerful and uses a positional feedback loop. It knows the exact position of the flapper at any given time and can change it in a split-second.

Looks like actuator volume doesn't really matter, but rather surface area, with a larger diaphragm applying more force.

[hardparker]

Here you go: Conventional pressure operated wastegates on the N55