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I have been working an issue with my Hybrid S5 turbo with stock back end and a front A/R 70 . Searches on the forum are not very good and the subject lines of the ports people use are horrible.
My engine and fuel system are upgraded with Haltech E8 and I will be porting the wastegate.
I am finding the stock waste gate actuator starts to open about 4-5psi.
With a massive GReddy FMIC, I think I am getting pressure drop between the turbo outlet to the UIM. So the pressure leaving the turbo is higher , thus opening the waste gate sooner and by the time the pressure reaches the UIM. it has dropped like 1-2 psi. Thus the turbo is spinning faster and working more.
Most of the time I see about 5psi up to 5k rpm. beyond that It creeps like crazy all the way to my fuel cut @ 16psi in Haltech.
I would like it to start opening about 6-8psi.
I am about to put a boost control solenoid in place.
I would like to get an aftermarket wastegate actuator. Maybe dual port/spring replaceable to control the stock ported wastegate.
1. Has anybody used these?
2. If so what did you order?
3. What bracket did you use?
An electronic boost controller will allow you to keep the wastegate closed until your selected psi is reached. This will help you generate boost quicker and the car will feel more torquey.
I need to check my vacuum routing but I think I’m picking up vacuum signal from a different position (I think manifold pressure) than off of the turbo compressor and just have the boost controller in line from the compressor outlet to the wastegate.
as for boost creeping I’d recommend porting the wastegate. Look at examples from bnr super cars. There are other threads about porting the wastegate on this forum from years ago.
My hybrid runs out of steam due to the wastegate being open so I tune my boost controller to close the wastegate slightly at high load to increase boost pressure but i think my hybrid has a clipped turbine wheel and ported wastegate.
i think you’re on the right track with an aftermarket wastegate actuator and a boost controller, but also look into porting the wastegate and I think you got it.
Like DR_Knight said, you've got two things to work on. First, porting the wastegate. You know this one, and have plans. The second, putting in a boost solenoid, you know this and have plans as well. As far as hooking up the boost solenoid, you can try to model it after the stock S5 boost control as a bleed out system. The stock boost control takes pressure from the compressor housing nipple (no vacuum at idle, positive pressure under boost) goes through a restrictor pill to a T where it splits to the wastegate actuator, and control solenoid. The control solenoid is a simple normally-closed bleed solenoid that is actuated on a duty cycle by the ECU when it senses MANIFOLD pressure via MAP sensor below the maximum desired level. Once the MAP sensor reads what the ECU says is max boost, it keeps the control solenoid closed so that pressure can build up and shove out the actuator. From the solenoid, the bleed line is ran back to the turbo inlet duct, so there is a closed circuit behind the MAF sensor. However, with the haltech, you may not be running the MAF, so I would just put a port that is pre-turbo, post air filter.
By having an underrated wastegate, the system is a pull-up system. The ECU bleeds pressure away from the wastegate actuator to pull up to the desired level. However, in a failsafe way, if the solenoid stops actuating, the boost will be contained in the actuator and you won't over-boost as a result of control failure. This bleed requires the restriction at the compressor housing before the wastegate and solenoid, so that the solenoid can adequately handle the volume of air being pushed through the boost control vacuum circuit.
Note that with the control solenoid, the vacuum signal used to control the ECU is from your MAP sensor from manifold pressure. The Boost source for opening the wastegate has to come from the compressor housing. If you run a wastegate bleed control from your manifold, it will act like a vacuum leak.
I would try setting up the control solenoid first before replacing the stock actuator to see if you actually need to. Try using it in a similar manner to the stock control system and I think you will get the results you want. You will still probably need to port the wastegates.
Let us know if you have questions on this and I will try to get back to you as quick as I can.
When you have stock exhaust wheel and a larger compressor wheel for the exhaust wheel to power it is common that the increase in exhaust manifold pressure actually pushes the internal wastegate flapper open completely over riding any boost control scheme you have.
It is a common fix to put a wastegate actuator with a stronger spring in it to hold the wastegate closed.
As far as which wastegate actuator you should buy, I couldnt tell you. I wanted more throw from my wastegate actuator on my stock twins so I watched some product videos and chose a Kinugawa one that had lots of throw.
Adapting that to the stock turbo compressor housing was easy, just a strip of aluminum that mounted to where the stock actuator was with holes drilled in it for the new actuator.
There are a few different types of brackets to mount the actuator to the front housing. Which did you use? the one inline on a flat bracket or one with a bend moving the waste gate forward and away from exhaust side.
When you have stock exhaust wheel and a larger compressor wheel for the exhaust wheel to power it is common that the increase in exhaust manifold pressure actually pushes the internal wastegate flapper open completely over riding any boost control scheme you have.
It is a common fix to put a wastegate actuator with a stronger spring in it to hold the wastegate closed.
As far as which wastegate actuator you should buy, I couldnt tell you. I wanted more throw from my wastegate actuator on my stock twins so I watched some product videos and chose a Kinugawa one that had lots of throw.
Adapting that to the stock turbo compressor housing was easy, just a strip of aluminum that mounted to where the stock actuator was with holes drilled in it for the new actuator.
01-24-21, 12:06 PM
Stock/Hybrid S5 Turbo internal Wastegate actuator upgrade?
