aftermarket controller to control a VNT?

[foxracer1]

Found this haven't studied it yet but it is what they used for the Chrysler cars with the Vnt plus a way to raise boost. http://www.thedodgegarage.com/turbo_vnt_bleed.html

[jimfoo]

Well, it apparently has a turbo that can be controlled by both vacuum and boost. Not sure if that could be adapted to VWs or not, but it uses the vacuum from the intake, which definately couldn't be done on a Diesel. Looks like it uses boost in general to control boost, and vacuum from letting off the pedal to close the vanes and counteract the boost.

[foxracer1]

More on the mechanical control. http://www.thedodgegarage.com/turbo_vnt.html

[xud9te]

Hi,

I had a similar method on my VNT setup, using a twin port actuator. But I used vacuum from the brake servo controlled by a ball valve connected to throttle arm (see pic1).  Idea was to set throttle and ball valve relationship to allow vacuum to open vnt vanes when throttle is less than 1/4(ish).  In reality this produced moments of no boost, then a spike as the throttle was floored and the vanes moved from full open to full closed (i.e. no middle ground untill boost builds (no error feedback)).  It wasnt as mooth as I had liked!!

Lowering the point to about 1/8th throttle meant that the vaccum side was only used at idle and lift off during gear changes and braking, useless on the road for economy, but still a good thing for carbon build -up.  The happy medium seemed to be to set the vanes-closed maximum travel setting on the turbo itself to a boost level that was acceptable for 70mph cruising.  Once I had done this I realised that the vaccum system was doing amost nothing. I have removed the system and now use a ball spring valve in series with a normal bleed valve (pic2).  This gives control over max boost, and also boost curve.  Setting the ballspring valve to open at 12psi seems to be good when running 23psi max.  Prob with my current system is that some of the VNT function of being able to summon almost full boost very low down by closing the vanes completely is lost.  It still goes well though, and must still spool quicker than similar sized non-VNT?

That is not to say that the system below (in pic1) will not work with some more tweaking.  

In retrospect, I think the ball valve i used was too large and may also have leaked some vacuum at all times.  It was a hydraulic valve, not pneumatic.  To improve this design a simple on/off switch on the throttle arm (some VE pumps have one already to switch off glowplugs (try peugeot 405)), feeding a relay which sends 12v to open a Petrol Turbo car boost solenoid which allows vacuum to pass to the -ve post on the two port actuator would allow the vanes to be opened at a preset point.

PIC 1


PIC 2


Cheers!

(sorry for long post...)
  [/img]

[xud9te]

Actually, there is a post on the TDi section just now which shows the switch I mean that is on top of the pump that could be used to control vacuum to the actuator.

http://www.vwdiesel.net/phpBB/viewtopic.php?t=4447

pic:

http://www.home.earthlink.net/~rps1976/Images/Diesel/Smog/Smog105410470.jpg

Just like his diagram, but feed the vaccum to the -ve port on twinport actuator instaed of the BOV.  Switch is slightly adjustable for position, but holes can be ovalled to allow more movement, this gives you a method to open vanes fuly below a certain point, which is certainly easier to set-up than my ball valve one.

Basically it is the egr valve system, but take the end onto the -ve port instead of egr valve.

(Dont need the boost side of his setup).

EDIT:  Just reaslised that I forgot to mention that I had both systems running on my car at one time (e.g pic1 and pic2).  I think combining pic2 and using the instant switch method described here may give good control once the cruising boost has been set using bleed valves, and that we are out of the vanes completely open part of throttle travel when cruising (i.e. no vaccum applied).

Whaddaya reckon?

Cheers

[xud9te]

Well, i dont think Tintins idea is very simple, but is certainly effective!!  It is a very ingenious solution.  I am not sure how much MORE simpler or effective it is than the methods I have tried.  There are reasons that Tintins setup will not work on all applications.

Firstly, it may be too difficult for some to route the cables to the turbo location.  Tintins location is VERY handy for this setup.  Also I am sure things like the amount of travel that was needed on the actuator arm vs length of travel of throttle cable max/min and also dynamically how to know if the actuator was actually resting on the pin or not (i.e. doing anything)  took alot of trial and error.  

Also the two springs (one on actuator side, other on throttle side) need to be matched so that overall, the actuator does not have to try any harder then normal to push open the vanes.  

I wondered what happens when this system gets exposed to water and corrosion?  As the system relies on its mechanical properties of the materials used for calibration then surely this would change the charcteristics?  Do you not look at it and think "this is the kind of thing that gets sticky?"!! when it gets  a bit rusty and the cables get sticky it may need attention.  The longer the cables and the more joints there are, the more a system becomes prone to this effect.

With the bleed valve and switch system, adjustments could be easily made just by turning the knobs.  There is no complicated trial and error set-up procedure other than connecting everything up, setting to min and then going up from there until you are happy.  

So Simpler, i disagree.  More effective, i think as long as you get linear boost without spikes and have good cruising boost plus ability to make boost as quickly as possible then it cannot be more effective.

Do you agree?

[xud9te]

That would be the best option!  I would say a PIC or similar that has an onboard PWM module could be used to control the standard N75 valve.  Still need a map sensor and TPS module though.  They can be cheap out of the scrappies.  It also needs to be 'mapped' for each turbo though and even if you could buy a 'kit' the results would vary.  Plus there is no market for it!

I just think that it would be easier and alot less work to use the throttle switch and valves.  Time will tell. I reckon you could set up the switch/valves idea in an afternoon, plus all the parts are cheap.

Have you fabricated a version of tintins idea?  What are you currently using?

[Tintin]

No problem for the rust, my vnt control set-up is very cheap, and it have plays there everywhere, that takes much rust before sticky,  and the cable, it's a F150 throtle cable,  in a ford truck, never see a sticky throttle cable.

For the travel length, i made a slotted hole to adjust the good travel.

I absolutely nothing feels on the accelerator,  people drives my car, and they all are surprised not to feel the effects of the actuator on the accelerator, and the accelerator is quite tender, it is the spring in my linkage which does all this work,  and for the actuator, it is very powerful a actuator, it do not have any difficulty has to carry out its work.

I acknowledge that it is not carried of all to build this system, welding, grinding, etc.......

It have several way there to make a mechanical control, it do not need precision there.

I had already to look at to install a control by vacuum with these part, but that empties the reserve of vacuum.

[745 turbogreasel]

That looks like the transmission modulator control used by non electronic Ford and GM diesels.
Might not flow enough?
Wire a TH400 kickdown switch (mounts under the pedal) to open a larger bleed port at WOT, and off ya go.

Something in the backof my head keeps telling me to use engine oil pressure for RPM input, like the Nissan Vtec...That way boost will go down as your engine degrades.

[xud9te]

Tintin,

I agree that whenever you use the vaccum from the brakes, you will lose some pressure as the line needs a hole in it to stabilise the pressure (vent) once the vacuum side is closed, but then again, is this not how the tdi's work?

I have a question, with your mechanical system, when driving the car, is the actuator always engaged with the control lever?  It seems that when you push the throttle it departs company from the actuator and will not meet again until boost builds?  How does this affect part throttle and on/off situations?  I would guess that it will stabilise very quickly like in your video, but is there creep in the boost or spikes if you hit the throttle and then come of again?

Also may I ask, how do you set the maximum boost level?  Is it just with the travel of the actuator?  And how did you find the correct springs?  Are they both the same rate?

Je suis desole pour trop de question.

Cheers

[Tintin]

I already explained in other post, it is hard to explain it in my language, even more in English  :lol:

Pas de problème pour trop de questions.  :wink:

I will still explain, and i joined pic later if you wants, and with photoshop, I would make a better explanation.

Forget the actuator for the moment, when at idle, the turbo vanne are has off (No boost position), ¼ accélérator= ¼ torbo vanne close, ½ accelerator= ½ close, etc...........   full throtle = full close = max boost around 40-45psi and more with no actuator,  now, a actuator is added to control the pressure while pushing in opposite direction the last part of my linkage to open the vanne in order to slow down the turbine,  the spring in my linkage compresses and it's very soft,  just enough hard to close the vannes, and a actuator with 20-25psi of pressure, they is 20 times more powerful than my small spring, thus, the actuator do not have any problem to carry out its work in opposite direction.

To adjust the maximum boost level, I screw or unscrew the stem of the actuator.

The pleasure with this type of system, I make adjustement at some place in my linkage, I can thus have max boost at disired level of accelerator, that is to say, ¼, ½, ¾ or full throtle, too, I can place or I desire that the vannes starts to close, that is to say ¼, ½ etc..... and when a ¼ mile run or track session, I disconnect the cable and I put the vanne in full boost all the time, and the actuator does his work.

There is one can of spikes only when i floor quickly, because the turbo VNT reacted more quickly than the actuator,  if not, it do not have there.

All this applies is for a VNT20 with my experiment, I at all do not know the réaction with a VNT15 or a VNT17, probably similar, but more quickly.

And that to say whistle of this turbo..!!!  

[jimfoo]

Did fspGTD ever have any problems with controlling his with just the modded actuator being fed boost?

[lord_verminaard]

I believe Jake also had to use an external wastegate as the boost was a bit "hyperactive".  I have not heard from him in a long time so I do not know how the system is doing.

Brendan

[xud9te]

Tintin

merci pour le response. Et le question finale, what is the min opening pressure of your actautor?  And what pressure is it at fully open?  Can you tell me what application the actuator is from (what car)?

Cheers

[Tintin]

It's a garrett T2 actuator from AAZ engine 1993 in CDN.

It's a ''pushing'' actuator,  min opération is around 4-5psi, an the max operation  (full travel) is around 22-23psi.

Exist Garrett K03 actuator ''pulling'' actuator, min operation, around 2-3psi and max operation (full travel) around 15-16 psi, this type of actuator is less adapted, l would be necessary to harden the spring inside, and  to control the vanne in the opposite direction of my system.

I envisage to find a pushing actuator with a max operation of 30psi, for a better control with pressure of more than 25 psi.