[scottysg]

So Im new to all this boost control stuff. But moral of the story is you want the waste gate to see no pressure until boost reaches the exact pressure you want the waste gate to open, then you release pressure to the waste gate allowing it to snap open fast. There are ball and spring type controllers (around 100$) that you adjust to hold pressure until it reaches your desired pressure, and there are electronic ones (300+). Im not running 40 psi so I dont need each gear to have a different pressure. I just want my wastegate to stay shut until its supposed to open, just to get spool a little bit faster. Take a look at the attached pieces and tell me this won't work for this purpose I'm describing.

Its a 2 part system: part one, an adjustable electronic pressure sensor that would tee into the the line going from your reference port of your choice (for me compressor bung) to the waste gate. Part 2, a normally open solenoid valve between the compressor and the wastegate that is kept shut by the pressure sensor until desired boost is reached. (N.O. so if the system fails it reverts to wg spring pressure)

https://cdn.automationdirect.com/static/specs/prosenseswitches.pdf

https://www.amazon.com/Cococart-2-W...?s=industrial&ie=UTF8&qid=1482168097&sr=1-1&keywords=n.o+solenoid+valve+12v+1/4

Thoughts appreciated, its the same price as a manual ball and spring boost controller but its adjustable from 7.5 to 145psi with 2.5 % accuracy. sounds a lot better than counting clicks or anything else.

Scott

 

[Beechkid]

IMHO, I do give the engineers a standing ovation for the engineering they have done on these engines, I will also say that considering the high boost levels (12 psi) as compared to typicalaftermarket systems (6-8 psi), this leaves a lot of reliance on the systems towork correctly…as this makes the engine much less forgiving especially withengine mis-fires, etc. which is very likely the basis for these "limitations'. When running this level of boost, let's face it, it either has to work right or if there is any ooop's there is very likely going to be catestrophic engine failure.

 

[scottysg]

agreed

IMHO, I do give the engineers a standing ovation for the engineering they have done on these engines, I will also say that considering the high boost levels (12 psi) as compared to typicalaftermarket systems (6-8 psi), this leaves a lot of reliance on the systems towork correctly…as this makes the engine much less forgiving especially withengine mis-fires, etc. which is very likely the basis for these "limitations'. When running this level of boost, let's face it, it either has to work right or if there is any ooop's there is very likely going to be catestrophic engine failure.

I completely agree on all fronts. The higher you push it, the more damage a small error will cause. I want the most accuracy possible. The system I described above allows someone like me whose running a 6lb spring in the waste gate to keep that spring and use a solenoid and sensor to block flow to wastegate until exactly 7.5lbs within 2.5% accuracy. The solenoid is normally open, meaning if any part of the circuit (sensor, power supply) failed, the solenoid would slam open allowing normal flow and reverting to the safe 6lb spring to regulate pressure. The main advantage of this I see is that it is accurate to 2.5%, and for someone like me who is running the stock engine and wants to get as close to 450 without going over, accuracy is completely important. I would prefer not to run a manual boost controller and turn it a few clicks and go WOT and hope I set it one 1 lb more than wastegate spring...that is too archaic. the grimmspeed unit has numbers but I can't see any reviews stating accuracy of boost in relation to the numbers on the boost control casing. on the same token, its not worth 3 or $400 to get a complicated multifeature EBC because I won't use those features. The hallman with the soft spring seems to only be able to add 5 lbs so that seems like the safest Mbc for someone with my goals, but still very inaccurate.

 

[blu13gt]

In reality you want a solenoid that cycles open and closed at a variable rate to controll boost. Holding all pressure off until boost is met makes it likely to see a boost spike followed by a dip in pressure due to too much boost being released which will probably cause the solenoid to close again causing another spike until the WG stabilizes mechanically (if it does). The boost spike COULD be problematic depending on the cababilities of the turbo and limitations of the fuel system. Even a manual controller actually starts cracking prior to the set boost level. The main advantage of electronic controllers is stability of the boost control, with proper tuning on one you get a very stable boost curve but the stable curve requires an electronic solenoid that rapidly cycles open and closed with the variable duty cycle to control boost.. Its your choice just some things to consider.

 

[blu13gt]

Most likely your boost will look like the blue line on the black chart. With maybe even more of the up down further through your rpm range.

Best case your boost will look like the left hand white chart.

The spike may or may not be the same extreme. But if your already running at the safe limit of your fuel system any boost spike could be catastrophic for your engine.

What you want is the right hand white chart.

 

[scottysg]

In reality you want a solenoid that cycles open and closed at a variable rate to controll boost. Holding all pressure off until boost is met makes it likely to see a boost spike followed by a dip in pressure due to too much boost being released which will probably cause the solenoid to close again causing another spike until the WG stabilizes mechanically (if it does). The boost spike COULD be problematic depending on the cababilities of the turbo and limitations of the fuel system. Even a manual controller actually starts cracking prior to the set boost level. The main advantage of electronic controllers is stability of the boost control, with proper tuning on one you get a very stable boost curve but the stable curve requires an electronic solenoid that rapidly cycles open and closed with the variable duty cycle to control boost.. Its your choice just some things to consider.

Thank you for these valuable points to consider and for the graphs to explain them. This concrete evidence is very helpful in understanding desirable boost control results compared to possible results from the system I proposed.

Do you think that since the 'sampling rate' of the pressure switch is 100hz the switch would accomplish the goal of rapidly opening and closing the solenoid based on instantaneous boost pressure thus preventing boost spike and low boost right after? (as long as the solenoid used with the switch was capable of that rate of opening/closing?) or are there other features of these electronic boost controllers Im still not understanding?

 

[blu13gt]

With the system your looking at you will get a boost spike because the wastegate will take time to open regardless of how fast the solenoid works. Your keeping all boost signal away from the wastegate until you hit the desired level. The turbo will be accelerating and there is no way around the spike unless the wastegate starts opening a little before it actually gets to the desired boost level. As far as the 100hz I'm not sure. I'm not extremely versed on exactly what parts you need to set up one of these properly. Will the switch only give an open and a closed signal when the boost hits the desired level and when it drops below the set boost level? Or will it cycle the signal appropriately to maintain the boat level desired? These are questions I'm not sure about with these components. I know how a proper electronic boost controller should work.

If you want an accurate boost controller, you would probably need to spend more than what your looking at here. You don't want an on off switch for boost sensing. You would want a map sensor or a pressure transducer that will send a signal no matter what the boost or vacuum is. Second you would need some sort of programmer to convert that signal to a usable signal for the actuator, which you can use to tell it to start opening at say 6 psi and be able to cycle the actuator more or less as needed to maintain the desired boost level of 7.5 psi(as example).
Effective electronic boost controllers are extremely variable through their operation. This is why they are expensive. Because it's not a simple open or closed switch.

I know how it should work. But I'm not sure how to explain it to someone else the best way. I'm trying here but if my explanation doesn't make sense I apologize.

 

[scottysg]

thank you

With the system your looking at you will get a boost spike because the wastegate will take time to open regardless of how fast the solenoid works. Your keeping all boost signal away from the wastegate until you hit the desired level. The turbo will be accelerating and there is no way around the spike unless the wastegate starts opening a little before it actually gets to the desired boost level. As far as the 100hz I'm not sure. I'm not extremely versed on exactly what parts you need to set up one of these properly. Will the switch only give an open and a closed signal when the boost hits the desired level and when it drops below the set boost level? Or will it cycle the signal appropriately to maintain the boat level desired? These are questions I'm not sure about with these components. I know how a proper electronic boost controller should work.

If you want an accurate boost controller, you would probably need to spend more than what your looking at here. You don't want an on off switch for boost sensing. You would want a map sensor or a pressure transducer that will send a signal no matter what the boost or vacuum is. Second you would need some sort of programmer to convert that signal to a usable signal for the actuator, which you can use to tell it to start opening at say 6 psi and be able to cycle the actuator more or less as needed to maintain the desired boost level of 7.5 psi(as example).
Effective electronic boost controllers are extremely variable through their operation. This is why they are expensive. Because it's not a simple open or closed switch.

I know how it should work. But I'm not sure how to explain it to someone else the best way. I'm trying here but if my explanation doesn't make sense I apologize.

That explanation makes total sense. Thank you for taking the time to write up that thorough explanation. Like you said, that switch would only trigger when pressure goes above or below the set threshold as opposed to starting early to prevent spike then regulating to maintain proper boost. That helps me understand why the cost of these controllers is so high. Looks like a no-go for a diy project sadly. Thanks for the clarification!