VNT turbo actuator

[lesharoturbo]

There seems to be a little interest in a device to control a VNT turbo's vane when attached to an IDI or other non electronic engine.  I have a few ideas for you to consider.

All you would really need is a pressure sensor, microcontroller, and a motor/solenoid.  Most sensors have an output that is too low to be usable as a drive signal to move the motor or solenoid.  This is where the microcontroller comes in.  It can detect the output of the sensor and drive a transistor to move a stepper motor or a solenoid to activate the vane linkage.  A single turn motor would be preferable since you could constantly adjust the vane whereas the solenoid would only operate at two extremes.  However the solenoid would be cheaper.  With a good controller you could also output the boost level to a small lcd display.  With a thermocouple, you could even show the EGT's on the same display.  A unit like this with everything could cost less than a boost/EGT gauge combo and still have the same responsiveness with the added benefit of a VNT controler.

If I had enough interest, I might be willing to build a few but qopuld need some specs on the VNT turbo acutator.

Bernie

[jtanguay]

I'm interested in programming the micro controller.  Would be nice to have some code that would actuate the vanes with inputs from egt, fuel pedal, rpm, etc...

Egt's go beyond a certain point, and the vanes would open completely as to not blow the motor, etc.   Idling could initiate a routine that would have the vanes completely open for less back pressure.  The vanes could be slowly closed as rpm's climb (mostly closed at around 1400rpm), as to not shock the turbo and 'lag' during accel.  At high speeds the vanes could be open unless the pedal hit the floor (better economy)

I found this cool site: http://www.hackaday.com/entry/1234000487032939/

I guess it wouldn't be too hard to program it... but those parts are expensive.

[fatmobile]

I've been thinking about this too.
 The original vane controller is vacuum controlled and vacuum switches are easy to find. No point hooking up a solenoid when the vacuum actuated vane controller is already hooked up and can be turned on and off using a vacuum switch, vacuum source and sensors.
  So vanes open means air bypasses the turbo, vanes closed means air has to go through the turbo impellor (expeller?).
 I think open, middle and closed would be better than wide open or wide closed.
 Using a vane controller postion sensor would probably work, a vacuum sensor might work better for determining the vane controller's position.
 
Inputs would be;
 idle switch to open vanes when idleing
 max boost setting, to adjust vanes when boost gets too high
 A turbo RPM sensor could open the vanes if the turbo gets spooling too fast. I've heard these VNTs can get going too fast and blow apart.
 If a boost hose pops off the turbo speed can spike.
 Probably could use the WOT switch for something too. Closes the vanes but other max boost sensors make sure boost doesn't get too high.
 I suppose at midrange, normal driving conditions it could hold the boost at a predetermined level.
 A manual override switch that will raise the boost independant of throttle postition sensors. I don't think 15 (example) psi of boost would hurt anything at idle. Click the switch and boost would jump to max setting before you take off.
 I think EGT and RPM should be monitored by the driver. I don't know of any boost contollers that use these inputs but maybe the VNT controller does. I could see it being used to raise the boost at low/middle RPMs but not to limit boost as RPM reaches it's peak.

[lesharoturbo]

I am glad to see some input on this idea.  I have used some of the items listed on the hackaday site.  In my opinion, the Basic Stamp is easy to program and already has serial I/O on all pins (16) plus 2 I/O ports for programming and control.  It is expensive, however you get a ready to use unit with all voltage regulation and memory on board.  It also has a lot of hobbyist add ons such as Serial LCD's, Motor controllers, and keypad controllers.  It is a very user friendly device and can be reprogrammed in system while running.

There are a lot of things that can be monitored easily with this setup.  The critical things are pressure sensing and VNT control.  The device for the pressure sensing has a maximum of 29 psi.  There are other devices that can sense higher, but at a higher cost.  I also thought the VNT would be out of its safe range above 29 psi anyhow.  Next would be sending pressure readings to the LCD and adding a thermcouple for EGT display.  Most of the sreial LCD devices are monochrome, but we could use a color device that turns red when we get to an unsafe operation area.  After these, I would suggest adding the turbo RPM protection as well as the other high end accessories.

The only reason I suggested a motor versus a vacuum device is the reliability of wires over tubes.  Either would work.  A stepper type one turn motor would have a finer control than a vacuum device. A vacuum device could have an auto return via a spring though.  I am sure we could find the best route if we weigh the pro's and cons of each.

Bernie

[OM617]

Just use a boost actuator from a traditional turbo. It's what I use.

No failsafe (If a boost line breaks, the vanes will be held closed) but it's simple, dirt cheap, provides instant response and fine tuning to the boost limit.

I don't think 15 (example) psi of boost would hurt anything at idle.

There is no way you can get significant boost at idle without any throttle input. I run with direct flow to the manifold, no intercooler, and always closed vanes. Even with that setup, I can barely get boost gauge needle off the 0psi peg at a 650rpm idle. That is in ideal conditions, the rest of the time I have ~2psi exhaust manifold pressure and no boost. However, revving the engine with no load to about 3000rpm can get the turbo to full boost pressure.

Follow the GT2256V VNT turbo link in my signature for pictures.

[DVST8R]

I would definatly buy one of these, but it would have to meet a few criteria:

-Electric servo driven, as vacuum or boost driven like on a stock TDI sucks it is way to slow to react.

-3.5 or 4 bar sensor, I need more then 29psi control...  :twisted:

- Needs to be able to control VNT / VGT / VVT ect...

-Infinite control, @ 3 settings I might as well just hook up a standered pressure contorller to the turbo, as was suggested.

-Egt control would be nice, but I would definatly need it to be able to override it, or at least set the limit at where it would kick (2000+ degree's)

-Full open at cruise a definate must, makes a big differnce in economy.

-Engine rpm and load, throttle position ect.. are all cool fetures that I would like to have, as long as they meet my final criteria

-Cost! I would pay upto $300usd for a contorler, after that I will just stick with wastegated turbo(s)

[wolfsburgnut]

Currently I am working on a VNT controller, however school is getting the way. :roll:   But for my boost controller, I am using a vacuum pump from a cruise control setup for a VW.  For the microprocessor, I am using a PIC18F2620 programmed with c.  I have tested this vacuum pump and pulls the vanes pretty quick, I am surprised, and so far the vacuum pump has cost me 5 dollars, if that gives you an idea of cost.  Adapting a electric servo would be easy from a programming standpoint, however it adds a lot of cost to the over all project.  

Peter