Can someone explain to me in simple terms of what a wastegate actuator is and what are the benefits and cons of having one. Also why are there different psi actuators?
EcoNoob
A wastegate actuator controls the flow of exhaust gas to the turbine of the turbocharger. And we all have one. The problem with the stock one is that it doesn't open as quickly as we might like, causing a delay in the turbo spin-up (the time it takes the turbo to start producing extra airflow, which is sent into your engine, which we call boost). An aftermarket wastegate, such as a Turbosmart, does a much better job of controlling the flow of exhaust gas, which allows the turbo to spin-up faster, and also gives you less drop off at higher RPM's, meaning a more stable and constant flow to the turbo.
The spring pressure differences, 7lb, 10lb, 12lb is simply how much exhaust gas pressure the actuator will allow to be sent into the turbo. For small stock turbos like our EB's have, a 7lb spring is usually all you would need. Larger turbos however would likely warrant a 10lb or even a 12lb spring.
Here's a quick reference guide straight from Turbosmart showing the different spring pressures vs the desired boost pressure.
The spring pressure differences, 7lb, 10lb, 12lb is simply how much exhaust gas pressure the actuator will allow to be sent into the turbo. For small stock turbos like our EB's have, a 7lb spring is usually all you would need. Larger turbos however would likely warrant a 10lb or even a 12lb spring.
Here's a quick reference guide straight from Turbosmart showing the different spring pressures vs the desired boost pressure.
Correct me if I'm wrong, but isn't it the opposite, that it opens up too quickly ?? Thus, "venting" "excess" pressure out the exhaust? Open wastegate is bad for building boost, no?
Question, while we're on the topic...does anyone else make an aftermarket wastegate other than Turbosmart and Vargas?
The wastegate opens to stop the turbo from generating more boost, and to alleviate exhaust gas pressure from getting to high. The first typically more important than the 2nd. When it doesn't open all the exhaust goes to the turbo, and when it does open it bypasses and vents off all the exhaust gasses (wasting them).
There's 2 forces acting up the wastegate, and there's only one spring in the system holding them back. The spring is inside the wastegate actuator.
The actuator's main function is taking a vacuum/boost signal, and pushing the wastegate at a certain PSI. This is where you would intercept said signal and add a boost controller. A boost controller vents off part of the boost in that line, reducing it's strength. You can literally have no boost controller at all, and let the wastegate actuator be the only thing controlling max boost. Or have a boost controller with various settings like street/race/snow etc.
The 2nd function, is more like a safety, the exhaust back pressure on the wastegate is also acting upon the spring, if it's high enough the wastegate will open regardless if there is enough signal from the vacuum/boost line. Sometimes when the spring is too weak and you want to maximize the boost you are getting from a particular turbo, this safety will hinder your efforts.
So the problem is not that it doesn't open as quickly, the problem is that it opens too soon and doesn't allow enough pressure to build up for those looking to maximize what their turbine is doing. But the more pressure you build up, the more stress you are putting on the turbo and the engine. Usually a custom wastage is matched with a custom turbo. Factory turbos typically have an internal (built-in) wastegate, but bigger aftermarket turbos usually require an external wastegate. the actuator itself is always external.
Most cars today use the ECU as a boost controller. The actuator itself is set to a real safe, low boost value. And the ECU then will raise the max boost to "normal" performance levels. That's done by bleeding some of the boost signal going to the actuator, like any other boost controller. It has a solenoid boost controller connected to the ECU. But if the ECU considers that it need to give you less power for any reason, it just needs to stop bleeding the signal, and the actuator will get the full signal from the vacuum'boost line, thus opening it. That can happen if ECU considers the engine is too hot, or if you select some sort of less reduced power option like for driving in snow.
I'm speaking in general, not just for the EcoBooost.
There's 2 forces acting up the wastegate, and there's only one spring in the system holding them back. The spring is inside the wastegate actuator.
The actuator's main function is taking a vacuum/boost signal, and pushing the wastegate at a certain PSI. This is where you would intercept said signal and add a boost controller. A boost controller vents off part of the boost in that line, reducing it's strength. You can literally have no boost controller at all, and let the wastegate actuator be the only thing controlling max boost. Or have a boost controller with various settings like street/race/snow etc.
The 2nd function, is more like a safety, the exhaust back pressure on the wastegate is also acting upon the spring, if it's high enough the wastegate will open regardless if there is enough signal from the vacuum/boost line. Sometimes when the spring is too weak and you want to maximize the boost you are getting from a particular turbo, this safety will hinder your efforts.
So the problem is not that it doesn't open as quickly, the problem is that it opens too soon and doesn't allow enough pressure to build up for those looking to maximize what their turbine is doing. But the more pressure you build up, the more stress you are putting on the turbo and the engine. Usually a custom wastage is matched with a custom turbo. Factory turbos typically have an internal (built-in) wastegate, but bigger aftermarket turbos usually require an external wastegate. the actuator itself is always external.
Most cars today use the ECU as a boost controller. The actuator itself is set to a real safe, low boost value. And the ECU then will raise the max boost to "normal" performance levels. That's done by bleeding some of the boost signal going to the actuator, like any other boost controller. It has a solenoid boost controller connected to the ECU. But if the ECU considers that it need to give you less power for any reason, it just needs to stop bleeding the signal, and the actuator will get the full signal from the vacuum'boost line, thus opening it. That can happen if ECU considers the engine is too hot, or if you select some sort of less reduced power option like for driving in snow.
I'm speaking in general, not just for the EcoBooost.
Here's a very good article on wastegate actuators.
However, I would not go fitting an upgraded one without a tune, unless you want problems or a blown motor.
Blog : Adjusting and Upgrading your Wastegate Actuator : Stratified Automotive Controls
However, I would not go fitting an upgraded one without a tune, unless you want problems or a blown motor.
Blog : Adjusting and Upgrading your Wastegate Actuator : Stratified Automotive Controls
And for another reference... this is from American Muscle:
"While the tune is extremely crucial to the amount of boost, the physical components of the turbo system play a part as well. In all stock components, the general rule is 25 PSI is the max the EcoBoost can handle in stock form. Talk with your tuner about his or her preferences, as that is essential to the amount of PSI to be utilized."
"While the tune is extremely crucial to the amount of boost, the physical components of the turbo system play a part as well. In all stock components, the general rule is 25 PSI is the max the EcoBoost can handle in stock form. Talk with your tuner about his or her preferences, as that is essential to the amount of PSI to be utilized."
A brief point about boost pressure, we are very accustomed to seeing boost registered in psi or BAR, and these are indeed a measure of pressure, but has really no direct influence in assessing power production. The thing we are looking to improve with any power adder is air mass beyond what can be normally consumed by a (NA) engine during the intake cycle. It is completely possible to have a small power adder equipped engine generate X amount of torque at high psi, while the same engine can produce the same torque with a larger power adder at much lower psi.
The difference is flow and efficiency, and why no compressor map, turbo or supercharger, is labelled with plain psi. They refer to pressure ratio on the vertical axis, and show air mass on the horizontal (CFM typically) with impeller speeds and islands of efficiency in the middle.
In this example below from the internet we see it all laid out nicely:
![Image]()
Formulas for determining pressure ratio of a combination can be found online or in Corky Bell's books. But notice how we can increase pressure ratio and very quickly lose efficiency. The compressor in this example is most productive at 1.75 to 2.5 PR and can only properly support 22-27 lb/min airflow. If we move below 1.75 PR and 20 lb/min the compressor is too large and will be laggy and underperforming. If we crank it up to 3.5 PR and 40 lb/min we are building piles of wasteful heat, and the impeller is just "chopping air". Any boating guys will understand the same principle from over spinning a fixed blade prop.
Key take aways:
The difference is flow and efficiency, and why no compressor map, turbo or supercharger, is labelled with plain psi. They refer to pressure ratio on the vertical axis, and show air mass on the horizontal (CFM typically) with impeller speeds and islands of efficiency in the middle.
In this example below from the internet we see it all laid out nicely:
Formulas for determining pressure ratio of a combination can be found online or in Corky Bell's books. But notice how we can increase pressure ratio and very quickly lose efficiency. The compressor in this example is most productive at 1.75 to 2.5 PR and can only properly support 22-27 lb/min airflow. If we move below 1.75 PR and 20 lb/min the compressor is too large and will be laggy and underperforming. If we crank it up to 3.5 PR and 40 lb/min we are building piles of wasteful heat, and the impeller is just "chopping air". Any boating guys will understand the same principle from over spinning a fixed blade prop.
Key take aways:
- We want the most airmass possible with the coldest compressed aircharge (This is a balancing act)
- High Pressure is not high flow necessarily.
- Every compressor has a sweet spot of flow and pressure.
- High PSI is always a high heat aircharge, which must be managed.
- There is a point of diminishing returns when we are overboosting a compressor.
I woke the bear.
Thanks @GTC Darren Your input is always valuable here.
Didn't even know about 'compressor maps' until now. But this is the end-all as to why "overboosting" is inefficient.
Thanks @GTC Darren Your input is always valuable here.
Didn't even know about 'compressor maps' until now. But this is the end-all as to why "overboosting" is inefficient.
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.
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.
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 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
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
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?
Does anyone know of any other manufacturers that make plug and play wastegates for the ecoboost besides Turbosmart & Vargas?
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
"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
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.
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!
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!
I'm sure you noticed this, because you did this install yourself, but I found this video of the turbosmart wastegate actuator install. At the 20:15 mark he cranks on the wastegate with the actuator removed and you can see how 'flimsy' it is to open/close with no tension applied.I will have to defer to those good folks to reply back on that subject as it's not entirely clear to me either.
So in my mind, the two forces in the spring are:
1) The resistance of spring extension - so that the exhaust doesn't suck open the wastegate
2) The resistance of spring compression - so that the rod doesn't prematurely actuate the wastegate open
The strength of a spring or it's rate is expressed in lbs/inch. If you take a 10 lb/in spring and put 10lbs on it it will compress 1 inch, put 5 lbs it will compress 1/2 inch, 1 lb it will compress .1 inch. However, if you preload the spring 1 inch it will not start to compress until 10 lbs are applied then it will start to move at it's 10lb/in rate.
In the case of a wastegate you do not want it opening at all until the ECU commands it to by allowing boost pressure to act on the diaphragm. That is accomplished by preloading the spring. To little preload and pressure in the turbo housing will start to open the wastegate preventing the desired boost from being obtained. To much preload and you get over boost spikes or erratic operation do to the wastegate not operating as the ECU expects.
Dave
In the case of a wastegate you do not want it opening at all until the ECU commands it to by allowing boost pressure to act on the diaphragm. That is accomplished by preloading the spring. To little preload and pressure in the turbo housing will start to open the wastegate preventing the desired boost from being obtained. To much preload and you get over boost spikes or erratic operation do to the wastegate not operating as the ECU expects.
Dave
The spring in the wastegate actuator needs to be strong enough to conteract the pressure in the turbine housing of the turbo that is trying to open the wastegate.
A soft spring rate will require more preload than a stiffer spring to do the job. The ecoboost motor is tuned by Ford using torque targets. If the spring is to stiff and/or has to much preload there may not be enough boost pressure to open the wastegate at a particular target. That is why stiffer spring wastegate actuators need a tune to work right.
Dave
A soft spring rate will require more preload than a stiffer spring to do the job. The ecoboost motor is tuned by Ford using torque targets. If the spring is to stiff and/or has to much preload there may not be enough boost pressure to open the wastegate at a particular target. That is why stiffer spring wastegate actuators need a tune to work right.
Dave
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