[jstefan]

Also remember that the "boost signal strength" that the wastegate actuator is sensing, doesn't necessarily have to match 1-to-1 to the peak boost you are seeing on a vacuum/boost gauge.

The wastegate actuator is usually set to much less psi, and the boost controller, or solenoid is going to be bleeding part of that 20psi boost you see on the gauge. In the end, the actuator would be sensing something like 7 lbs. These are example figures, I don't know the precise values for the EcoBoost.

That allows the ECU, for whatever reason, to fully open the wastegate without much "effort". It just has tell the solenoid to bleed 0% and let the full signal thru, and a relatively week 7 psi of boost would be enough to trigger the actuator. Different vehicles are going to have different spring rates, imagine a car with just 3 psi needed. From a stock (let's make this reliable) point of view, you can see how this is a good thing.

Also, if everything fails, let's say damaged solenoid, the spring rate is so low that it wouldn't take much exhaust back pressure to open the wastegate as a fallback.

 

[dgc333]

Also, is the PSI rating the 'cracking point'? Meaning: Once the pressure hits (assuming my answer is correct to my own question above) 7psi in the stock wastegate, that's when the "gate" valve is supposed to first "crack" open and begin to vent turbo boost to exhaust. Or does this not even matter? Does it basically go "full on open" once it hits 7psi??

The "7lb" rating of a waste gate actuator refers to the boost pressure from the intake manifold required to open the waste gate allowing exhaust gas to bypass the turbine section of the turbo. Since the ECU controls whether boost pressure ever gets routed to the waste gate the tune controls how the waste gate opens. This is why you can have 20 psi or more of boost pressure with only a 7 psi spring.

The other part of the equation is that there is pressure in the turbine housing that is trying to open the waste gate. The spring in the waste gate is what conteracts this. The stock waste gate spring allows the waste gate to leak at higher boost pressures resulting the boost pressure not being held. The aftermarket waste gates with higher spring rates prevent the boost leak. A tune is required for most waste gate actuators because the they do not react the way the tune is expecting them to.



Dave

 

[gatornek]

The other part of the equation is that there is pressure in the turbine housing that is trying to open the waste gate

I am trying to understand this 2nd force more. I found this video of the 2.3 turbo online from the Ford show a few years back. So, in the red area, as sthe exhaust side of the turbo is spooling up, that "exhaust pressure" (uhh words..) is "pulling" that wastegate open? Does that make sense? Again, I know its not the primary force (that's the push on the rod from the actuator on the top), but it is a force which can possibly bleed a bit of boost? View attachment 26933

 

[EcoVert17]

I believe your understanding is close but not quite spot on. The turbo ejects gases, which are routed to the engine and the wastegate actuator. The actuator has an arm or rod which is connected to the wastegate itself. When the actuator receives enough pressure to overcome the spring tension, the actuator uses that pressure to push on the rod, which opens the wastegate.

 

[gatornek]

I believe your understanding is close but not quite spot on. The turbo ejects gases, which are routed to the engine and the wastegate actuator. The actuator has an arm or rod which is connected to the wastegate itself. When the actuator receives enough pressure to overcome the spring tension, the actuator uses that pressure to push on the rod, which opens the wastegate.

The part about the boost controller sampling the psi at the turbo inlet and routing pressure to the "actuator" as the ECU deems fit...where, after enough pressure builds, it pushes down on the rod to open the wastegate. That is crystal clear.

Is this the only pressure there is? What I was referring to was @dgc333 2nd paragraph or "other part of the equation" and a few others have mentioned too about the spring holding the wastegate shut from, as Dave put it, "turbo housing Pressure".

 

[EcoVert17]

The part about the boost controller sampling the psi at the turbo inlet and routing pressure to the "actuator" as the ECU deems fit...where, after enough pressure builds, it pushes down on the rod to open the wastegate. That is crystal clear.

Is this the only pressure there is? What I was referring to was @dgc333 2nd paragraph or "other part of the equation" and a few others have mentioned too about the spring holding the wastegate shut from, as Dave put it, "turbo housing Pressure".

I will have to defer to those good folks to reply back on that subject as it's not entirely clear to me either.

 

[jstefan]

the Wastegate alone, without the actuator and corresponding arm attached to it, is just a free moving door. The only thing keeping it shut is the spring within the actuator.

It's main function is via the signal line going to the actuator. But if you were to force the arm with your hand, you'd eventually overcome the spring's force.

The exhaust gasses are also always pushing on the door, and are also putting pressure on the arm and thus the spring on the actuator.

Now about pull / push. Here I'm not 100% sure, but I've always seen diagrams where the door is oriented in such way that exhaust gasses push on it. And it certainly looks the same for external wastegates. I'd have re-check this, and get back to you.

EDIT:

OK, What you are seeing is the output part of the impeller, the gasses have already done it's job and or on their way out to the muffler. There's a channel you can't see that reaches the door, and that channel will have all the back pressure. The flow is coming towards the viewer.

Here's a good image:
How A Turbo Wastegate Works - Turbo Actuator - ECMOVO LTD

 

[gatornek]

the Wastegate alone, without the actuator and corresponding arm attached to it, is just a free moving door. The only thing keeping it shut is the spring within the actuator.

It's main function is via the signal line going to the actuator. But if you were to force the arm with your hand, you'd eventually overcome the spring's force.

The exhaust gasses are also always pushing on the door, and are also putting pressure on the arm and thus the spring on the actuator.

Now about pull / push. Here I'm not 100% sure, but I've always seen diagrams where the door is oriented in such way that exhaust gasses push on it. And it certainly looks the same for external wastegates. I'd have re-check this, and get back to you.

EDIT:

OK, What you are seeing is the output part of the impeller, the gasses have already done it's job and or on their way out to the muffler. There's a channel you can't see that reaches the door, and that channel will have all the back pressure. The flow is coming towards the viewer.

Here's a good image:
How A Turbo Wastegate Works - Turbo Actuator - ECMOVO LTD

That is a good image. So it is the exhaust pressure leaving the turbo that is "pulling" the wastegate open, even when the rod is not actuated.

 

[gatornek]

You guys forgot my other question on this thread.

Does anyone know of any other manufacturers that make plug and play wastegates for the ecoboost besides Turbosmart & Vargas?

 

[jstefan]

That is a good image. So it is the exhaust pressure leaving the turbo that is "pulling" the wastegate open, even when the rod is not actuated.

The push side of that door there is a small channel that is before the impeller. All the area before the impeller, including the channel, builds pressure. That pressure will always be pushing on the door until it can beat the spring.

Note that this pressure doesn't match the "boost" pressure you see on the intake manifold, because it's a totally different chamber.

 

[gatornek]

From everything I've read elsewhere, yes, the stock unit is supposed to be 7 pounds. I say that because it's also using cheap plastic parts and may not be completely accurate and reliable because of that.

So, if you simply swap out for a Turbosmart 7psi wastegate...theoretically, you wouldn't need a tune, right?

 

[EcoVert17]

So, if you simply swap out for a Turbosmart 7psi wastegate...theoretically, you wouldn't need a tune, right?

That's the way I understand it, yes. Or maybe more to the point is you wouldn't need a "custom" tune, which is one of the reasons I opted to go with the 7 lb instead of a 10 or 12.

 

[slojas]

Here is what stage 3 motorsports has to say about the 7psi wga for the ecoboost.

"Allows for Quicker and More Consistent Wastegate Performance
The stock wastegate actuator on your Mustang's turbocharger does a decent enough job when your aggressive 2015-2017 Mustang EcoBoost is running around with the factory tune at its stock power levels, but when you throw a tune and some bolt-ons at the thing, its inconsistencies start to show. To win you back the turbocharger and wastegate function that your mildly-modded Pony needs to run at its best, Turbosmart now offers their IWG75 Wastegate Actuator with a OEM 7psi spring. Rated at the stock boost pressure, Turbosmart's 7psi IWG75 Wastegate actuator keeps overall turbo functionality and boost curves near-stock, while providing more consistent wastegate opening and closing so that it doesn't feel like your Mustang is bleeding off boost pressure when you really punch the throttle. While rated at stock pressure, the 7psi spring in the IWG75 Wastegate Actuator has less preload than stock which allows for faster and crisper opening and closing of your turbo's wastegate, which can help improve overall drivability, especially in aggressive applications. "

Sent from my SM-G960W using Tapatalk

 

[EcoVert17]

Here is what stage 3 motorsports has to say about the 7psi wga for the ecoboost.

"Allows for Quicker and More Consistent Wastegate Performance
The stock wastegate actuator on your Mustang's turbocharger does a decent enough job when your aggressive 2015-2017 Mustang EcoBoost is running around with the factory tune at its stock power levels, but when you throw a tune and some bolt-ons at the thing, its inconsistencies start to show. To win you back the turbocharger and wastegate function that your mildly-modded Pony needs to run at its best, Turbosmart now offers their IWG75 Wastegate Actuator with a OEM 7psi spring. Rated at the stock boost pressure, Turbosmart's 7psi IWG75 Wastegate actuator keeps overall turbo functionality and boost curves near-stock, while providing more consistent wastegate opening and closing so that it doesn't feel like your Mustang is bleeding off boost pressure when you really punch the throttle. While rated at stock pressure, the 7psi spring in the IWG75 Wastegate Actuator has less preload than stock which allows for faster and crisper opening and closing of your turbo's wastegate, which can help improve overall drivability, especially in aggressive applications. "Sent from my SM-G960W using Tapatalk

Thanks @slojas. I think that answers at least a few of the lingering questions this thread has raised.

 

[Sarge]

I was reading about the different "slots" of the Cobb tunes, and IIRC they said that the slots primarily affect wastegate operation, changing it by different percentages, and in slot 5 (economy) the wastegate is deactivated. I'm trying to wrap my head around how that would make the engine more fuel efficient. Anybody have any thoughts on that? Or have I just totally misremembered what I read?

 

[EcoVert17]

I was reading about the different "slots" of the Cobb tunes, and IIRC they said that the slots primarily affect wastegate operation, changing it by different percentages, and in slot 5 (economy) the wastegate is deactivated. I'm trying to wrap my head around how that would make the engine more fuel efficient. Anybody have any thoughts on that? Or have I just totally misremembered what I read?

Interesting notation and conversation, but unfortunately I have no clue about how the different slots are effected or controlled.

 

[Bill_B]

I was reading about the different "slots" of the Cobb tunes, and IIRC they said that the slots primarily affect wastegate operation, changing it by different percentages, and in slot 5 (economy) the wastegate is deactivated. I'm trying to wrap my head around how that would make the engine more fuel efficient. Anybody have any thoughts on that? Or have I just totally misremembered what I read?

I found the info that might clear things up on cobbs slot # 5...

Map slot 5 = Economy - This mode disables the wastegate and adjusts WOT fueling and ignition timing for efficiency. This can be used to quickly lower power for times when performance is not needed.



Sent from my SM-G960U using Tapatalk

 

[Go Further]

I was reading about the different "slots" of the Cobb tunes, and IIRC they said that the slots primarily affect wastegate operation, changing it by different percentages, and in slot 5 (economy) the wastegate is deactivated. I'm trying to wrap my head around how that would make the engine more fuel efficient. Anybody have any thoughts on that? Or have I just totally misremembered what I read?

If the wastegate was completely deactivated in slot 5, would that not mean no boost would be produced by the turbo... Thus saving fuel?

 

[jstefan]

Some boost will always be produced. With traditional actuators, you need some boost on the intake side to serve as a signal for the actuator.

What the tune would do is change the duty cycle of the solenoid so that nothing is bled out. The full signal reaches the actuator. Thus it would only take the spring's strength worth of boost. which is just 7 psi.

But you still need 7 psi worth of boost to beat the spring, otherwise the wastegate door will stay shut.

You don't need a tune to save fuel. Some experts say you can save fuel by using a very advanced technique called controlling your foot!

 

[ZStang]

Some boost will always be produced. With traditional actuators, you need some boost on the intake side to serve as a signal for the actuator.

What the tune would do is change the duty cycle of the solenoid so that nothing is bled out. The full signal reaches the actuator. Thus it would only take the spring's strength worth of boost. which is just 7 psi.

But you still need 7 psi worth of boost to beat the spring, otherwise the wastegate door will stay shut.

You don't need a tune to save fuel. Some experts say you can save fuel by using a very advanced technique called controlling your foot!

Even with my custom tune, if I control my foot, I average around 31 mpg. I have achieved 33 mpg highway also. Driving style has a bunch to do with fuel economy.