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[kgx]

i am a cheap bastard, and as such i have no intention of bothering with an external WG anytime soon. so in the interest of fattening my own head, i thought i'd bring this up for discussion.

so i was trying to work out a simple EBC setup that would be cheap and effective. this is what's on the car right now:

(red trace is simulated MAP voltage, green is output of amplifier to pressure switch/comparator)

the idea is to use an amp on the MAP sensor line and an RC filter on the output, so that it amplifies the MAP signal with respect to how quickly pressure is changing. the faster pressure rises, the higher it pulls the map signal. the faster it falls, the lower it pulls the signal. the intent was to allow the solenoid controlling the wastegate pressure to be able to anticipate the WG's position to avoid spiking.

it works, but it's meh. it definitely works better than the grainger valve MBC i was using before.

so now i've got this on the drawing board:


this one should work better. the MAP signal is input to a differential amplifier. the output of the amplifier is inverse to where the MAP voltage is with respect to the reference (boost level) set point. the more OVER the boost set point, the lower the amp drives the output.

the bottom of the circuit is a 12Hz triangle wave oscillator. the output of this is sent to one comparator input, with the amp output sent to the other input. so essentially, when the MAP goes over the set point, the output of the circuit results in more duty cycle to the drive solenoid (normally closed, used as a bleed. more DC= higher boost). like the other circuit, this also is a closed-loop system, but with finer control. the nature of the amplifier in the first part of the circuit will drive the solenoid with whatever duty cycle it takes to get the MAP to equal the reference voltage. it's like a closed-loop bleed type MBC, really.

there are two other parts i need to add to the circuit:
1. an initial level for the controller to start pulsing the solenoid. it would just be a pressure switch that holds the solenoid at 100% duty while the turbo is spooling, and at, say, 3 or 4 psi before the desired boost level, lets the controller take over the solenoid.

2. mostly just an optional thing, but another pressure switch that holds the solenoid closed (boost at wastegate pressure) until the coolant temp is above a specified level. kind of an "i'm a cold engine, don't beat on me yet" failsafe. i probably won't bother with this one.

my concerns are also for once i want to go above 22psi or so and the WG starts to blow open. i've thought of using the same controller as the second one above, but change how it runs the wastegate.

instead of manifold pressure being fed to the WG actuator, use a lightweight, noncorrosive fluid (coolant, maybe) and a small windshield washer pump capable of 40+psi. bump the frequency of the oscillator up to about 2kHz and use the controller to drive the pump to control wastegate position. that way, i can use a WG with an extremely stiff spring, and still retain control of any boost pressure i want.

i had looked at similar methods using PS fluid or even engine oil pressure to actuate the WG, with something like toyota's VVT oil control valve to control WG position.


anyone have any other ideas?

[dvst8r]

...anyone have any other ideas?

External gate... 

[snm95ls]

anyone have any other ideas?

At that point wouldn't it be easier and more effective to just come up with an electric linear actuator and complementary drive and logic circuit to preform the tasks at hand?

I guess what I am wondering is; is there a particular reason why you want to keep the pneumatic actuator?

[92CXyD]

Would it make a difference if you are using a 2-bar, 3-bar, or 4-bar map sensor?

How would it be different than the  AVC-R or other E-boost controllers?

If I send my electronic bypass valve off of my SC14 supercharger, could figure out a way to open and close it based on boost levels and throttle position?

My bypass has this 6 wire plug, with the center two wires are hot and the four out wires are grounds. Each ground is operated by the original ecu from a Previa. Basically it grounds the circuit in a CW to get the valve open and CCW to close the valve.

I can send a section from the OEM repair manual explaining it if it helps.

[kgx]

anyone have any other ideas?

At that point wouldn't it be easier and more effective to just come up with an electric linear actuator and complementary drive and logic circuit to preform the tasks at hand?

I guess what I am wondering is; is there a particular reason why you want to keep the pneumatic actuator?

because it's alerady on the car.

i had looked into electronic linear actuators as well, but the cost tends to make it cheaper to start looking at an external gate. the idea with keeping the pneumatic actuator is to find a way to effectively control it with components available at radio shack for <$10. it's more of an "i know it can be done that way, but here are the limitations, now solve the problem within those limitations" kind of thing.

Would it make a difference if you are using a 2-bar, 3-bar, or 4-bar map sensor?

How would it be different than the  AVC-R or other E-boost controllers?

If I send my electronic bypass valve off of my SC14 supercharger, could figure out a way to open and close it based on boost levels and throttle position?

My bypass has this 6 wire plug, with the center two wires are hot and the four out wires are grounds. Each ground is operated by the original ecu from a Previa. Basically it grounds the circuit in a CW to get the valve open and CCW to close the valve.

I can send a section from the OEM repair manual explaining it if it helps.

1. MAP sensor doesn't matter. you just change the bottom end resistance on the potentiometer to adjust the desired boost level.

2. the difference between this and a typical EBC would be that this should be able to be built for $10 with parts from the shack.

3. sounds like a stepper motor setup. would likely need a microcontroller to run it properly. there are stepper motor drivers available that might be able to use analog input for position commands though. i'll look into it.

External gate...

fuck you and your non-RHMT suggestion. and also your mom. and any female siblings, half-siblings or step siblings. ok, that about covers it.

[92CXyD]

3. sounds like a stepper motor setup. would likely need a microcontroller to run it properly. there are stepper motor drivers available that might be able to use analog input for position commands though. i'll look into it.

LMK if you come up with an idea for this. ;D

[dvst8r]

External gate...

fuck you and your non-RHMT suggestion. and also your mom. and any female siblings, half-siblings or step siblings. ok, that about covers it.

Fuck you, you want a more RHMT answer, build a: Squarefold or fencefold or handrailfold and a used CDM external gate, should be ~$10-20 for the used cdm gate and some valve lapping compound to clean it up, and if you are truley RHMT you should be able to build the manifold from shit you find. 

[kgx]

 fuck you more harder and with bigger letters.

it wouldn't even take that to put an external gate on- it would take grinding a hole in the adapter and welding on an el with a flange. squarefold/fencefold/railfold would be a step backward compared to the stock manifold, which is actually pretty good for what it is. hell, i'll probably even do that someday.

that's not the point though. it's supposed to be a challenge: these are the limitations, solve the problem within them.

[dvst8r]

... these are the limitations, solve the problem within them.

LOL at your big letters...

I really fail at here is a coloring book, stay in the lines, it's why I make a lousy employee.

[kgx]

haha. i make a lousy employee because i make it a point to take a 10 minute dump every day, thus accumulating 43 hours of "paid to poop" time by year's end. it's like a vacation in itself.

[turbob16hatch]

I didn't read all your nerdy shit in the first post but.... why can't you run any form of ebc with a 2 port wastegate actuator?

http://www.horsepowerfreaks.com/partdetails/Turbonetics/Wastegates/Wastegate_Actuators/Internal/2989

[kgx]

because $10 < $138 + cost of EBC. it would probably be cheaper to fab the external gate on.

i certainly could. i just don't like dumping money into my car when i believe a problem can be solved another way. basically, i'm trying to come up with a closed-loop electronic boost controller on the cheap. referencing the boost control to absolute pressure would eliminate changes in boost that occur with the ambient pressure, temp, altitude, etc.

[That Guy]

New quote material lol. I like where this thread goes, this sounds like a very over engineered simple concept, nice work  ;D

[92CXyD]

because $10 < $138 + cost of EBC. it would probably be cheaper to fab the external gate on.

i certainly could. i just don't like dumping money into my car when i believe a problem can be solved another way. basically, i'm trying to come up with a closed-loop electronic boost controller on the cheap. referencing the boost control to absolute pressure would eliminate changes in boost that occur with the ambient pressure, temp, altitude, etc.

Works for me.  ;D

[kgx]

i could also add an SMT ICL7107 (digital voltmeter LED driver) chip to the mix for another $5 or so and work the whole thing to fit into a 52mm gauge housing with an LED display. mount a pair of knobs for controls in the gauge pod, with an SPDT pushbutton to toggle between current boost/desired boost (for setting boost level) and you'd have a crazy cheap digital boost gauge/controller.

[dvst8r]

To me the inherent problem with the internal gate is lack of flow. It seems to me that most if not all internal gates use too small of port, coupled with a design that most only release from one volute, combined with lousy flow placement. This just makes them all but useless.

While it is cool that you are trying to design a cheap functional controller, that I am sure could be implemented on an external gate setup as well, doing anything with an internal gate is just polishing a turd. You could make the best internal gate controller ever conceived but at the end of the day it is still connected to shit.

I'm sorry that I don't have any input on your design, but it is well over my head. So instead I will just keep shiting on internal gates. 

[snm95ls]

kgx, i would love to see some results on this.  Unfortunately I am not knowledgeable enough in the pertinent  areas to contribute much.

 

I didn't read all your nerdy shit in the first post but.... why can't you run any form of ebc with a 2 port wastegate actuator?

http://www.horsepowerfreaks.com/partdetails/Turbonetics/Wastegates/Wastegate_Actuators/Internal/2989

That seems exceptionally high for a dual port or any internal wastegate actuator.  Does the Turbonetics stamp/sticker make it worth that much?

[turbob16hatch]

That seems exceptionally high for a dual port or any internal wastegate actuator.  Does the Turbonetics stamp/sticker make it worth that much?

I assume so, i just posted the first one i found in my google search. You could easily get one for less, or find a used one from an oem setup i would assume.

I'm all for cheapness, so i'm interested to see how this turns out.  :yes:

[Joseph Davis]

High boost + internal gate = lol

What you are experiencing is not boost spike... it's what you've set the boost to.  Where it falls off up top is the inherent design of an internal gate fucking you on the deal.

Variable duty PWM to a solenoid controlling an external gate, done.  Yes it sucks and is expensive but I've yet to see a TiAL/Turbonetics Evo/Turbosmart gate go bad, and with how the Precision gates ship in TiAL boxes I get the funny feeling they won't, either.  As such, cost to own over the years is negligible.

And, yeah, I don't like saying that as much as you don't like hearing it, but short of a thousand year old Audi gate I don't see any alternatives. 

[kgx]

What you are experiencing is not boost spike... it's what you've set the boost to.  Where it falls off up top is the inherent design of an internal gate fucking you on the deal.

And, yeah, I don't like saying that as much as you don't like hearing it, but short of a thousand year old Audi gate I don't see any alternatives. 

my dreams.... are dead.

i'm pretty sure it is actually spiking. it'll spool, hit 24psi or so at about 3500rpm, then immediately drop back down to 20 and more or less stay there til redline.

so you don't think a controller that's closed-loop and referenced to manifold pressure would stabilize things any more than it already is? i would think if it's actively monitoring boost and varying the duty cycle at the WG, it would be able to compensate when the IWG wants to taper off.. the first circuit i posted does keep trying to hit the target boost, and doesn't spike then taper nearly as bad as an MBC, but i think it's due more to the coarse nature of control (it's a glorified pressure switch). i'm really only targeting about 22-25psi of boost, which isn't all that much compared to what some guys try to run on internally gated MHI turbos. see below for reasons for the insanity of pursuing this..

I'm sorry that I don't have any input on your design, but it is well over my head. So instead I will just keep shiting on internal gates.  Tongue

i did realize last night that it's not so much that i want to keep the internal gate, it's that i want to keep the internal gate for the rest of the summer/fall until i put the car away for the winter. i have serious issues getting shit done on the car once it's on the road because it's just too much damn fun to drive that i don't want to take it apart. i will more than likely go external gate over the winter, but this is just an exercise in trying to come up with a short term, cheap means of keeping the car out of the garage until there's snow on the ground.

[snm95ls]

High boost + internal gate = lol

What you are experiencing is not boost spike... it's what you've set the boost to.  Where it falls off up top is the inherent design of an internal gate fucking you on the deal...

Maybe I haven't thought about it on a deep enough level, but I have never really understood this statement.

[Robb]

High boost + internal gate = lol

What you are experiencing is not boost spike... it's what you've set the boost to.  Where it falls off up top is the inherent design of an internal gate fucking you on the deal.

+1

I remember all too well trying to keep the gate shut on the integra. It would never hold more than 17psi regardless of what we did. I think we even wired it shut at one point?

[Joseph Davis]

so you don't think a controller that's closed-loop and referenced to manifold pressure would stabilize things any more than it already is? i would think if it's actively monitoring boost and varying the duty cycle at the WG, it would be able to compensate when the IWG wants to taper off

100% duty aka no signal sent to the gate on the S13 in the parking lot results in 20 psi at 4500 rpms tapering to 13 psi.  It's the inherent nature of an internal gate to taper off.  Closed loop, or a simple rpm based compensation, would do a good job controlling spiking and taper from stock 7 psi up to ~13 psi on said car.

There is a reason why external gates are sold and everyone runs them.  I'd offer you my Audi one but in about a year I plan on building a car out of recycled crap and therefore it is needed.

[turbob16hatch]

so you don't think a controller that's closed-loop and referenced to manifold pressure would stabilize things any more than it already is? i would think if it's actively monitoring boost and varying the duty cycle at the WG, it would be able to compensate when the IWG wants to taper off

100% duty aka no signal sent to the gate on the S13 in the parking lot results in 20 psi at 4500 rpms tapering to 13 psi.  It's the inherent nature of an internal gate to taper off.  Closed loop, or a simple rpm based compensation, would do a good job controlling spiking and taper from stock 7 psi up to ~13 psi on said car.

There is a reason why external gates are sold and everyone runs them.  I'd offer you my Audi one but in about a year I plan on building a car out of recycled crap and therefore it is needed.

what spring pressure is the gate? if it's 7 psi liek stated then how is it the internal gates fault? You can't expect a spring that soft to hold the flapper shut at those pressures. I think the larger issue is the inherently modest turbine side that the internal gate is attached to rather then the fact it's a smallish hole with an actuator attached to it.

[kgx]

so you don't think a controller that's closed-loop and referenced to manifold pressure would stabilize things any more than it already is? i would think if it's actively monitoring boost and varying the duty cycle at the WG, it would be able to compensate when the IWG wants to taper off

100% duty aka no signal sent to the gate on the S13 in the parking lot results in 20 psi at 4500 rpms tapering to 13 psi.  It's the inherent nature of an internal gate to taper off.  Closed loop, or a simple rpm based compensation, would do a good job controlling spiking and taper from stock 7 psi up to ~13 psi on said car.

There is a reason why external gates are sold and everyone runs them.  I'd offer you my Audi one but in about a year I plan on building a car out of recycled crap and therefore it is needed.

wastegate pressure on this one is 14psi. it's a TD06 8cm turbine housing and the WG hole/shelf is ported quite a bit. the gate does a great job of controlling boost under 18psi, and it can easily hold 14 to redline without creep despite a full 3" exhaust that is all of 5 feet long. it's not so much that it can't hold higher boost- with the WG line disconnected it will hold well over 20psi. it seems for right now, it's just a matter of getting better control over what position the WG is in at any given time.

it really seems to me that the spiking is just the actuator not opening far enough, fast enough once max boost is hit. being able to start opening it 4 or 5psi early, then modulating the solenoid based on MAP input after that seems like it would work pretty well.

if anything too, this controller should work pretty well for an external gate. run dual solenoids and invert the signal to one of them so it can control the other port.

[Joseph Davis]

so you don't think a controller that's closed-loop and referenced to manifold pressure would stabilize things any more than it already is? i would think if it's actively monitoring boost and varying the duty cycle at the WG, it would be able to compensate when the IWG wants to taper off

100% duty aka no signal sent to the gate on the S13 in the parking lot results in 20 psi at 4500 rpms tapering to 13 psi.  It's the inherent nature of an internal gate to taper off.  Closed loop, or a simple rpm based compensation, would do a good job controlling spiking and taper from stock 7 psi up to ~13 psi on said car.

There is a reason why external gates are sold and everyone runs them.  I'd offer you my Audi one but in about a year I plan on building a car out of recycled crap and therefore it is needed.

what spring pressure is the gate? if it's 7 psi liek stated then how is it the internal gates fault?

The general rule of thumb is external gates are good for 20 over spring, 20% of the time they fall short of that but a 7 psi external wastegate will still hold 20-22 psi rock solid, guaranteed.  But you are still correct - this is not the fault of internal wastegates.  Obama understands they can't do any better yet deserve to own high end shit like everyone else.  In the very near future internal gate fans will be cut monthly checks so they can buy crack rocks and Tupac albums.

[turbob16hatch]

nice edit bald man, now quote the whole thing and respond with what you should have said. ie: it;s the tiny turbine wheel that can't flow for shit combined with low spring pressures that make it hard for the thing to stay shut.

tisk tisk

[Joseph Davis]

Matt, I've gone from internal to external gate on several turbos.  I'm not leaving anything out.  Taper, and failure to maintain a decent boost level, is inherent in the internal gate design.  OEMs use this design because they don't care about performance, and it's cheap.  I don't see where this is confusing, or why you think I'm trying to twist things.  :/

[Bree]

How would it be different than the  AVC-R or other E-boost controllers?



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