Variable Vane Turbo? How does it work ??
 

I have a turbo built in 2002 that has one plug connecting to the wiring harness.
The plug has 2 wires in it. Presumably positive and negative to control boost via opening/closing the vanes.
Open = low boost Closed = high boost

What voltage causes the switch from one to the other & or what voltage does a truck run at most of the time? What happens if I unplug the solonoid?

I remember that the 7.3 could be unplugged for more boost so what would happen if we changed the voltage to increase the boost across the whole rpm band of the motor. With the use of a "dimming switch" type control. That way the boost would still vary but at a selectable gain per out desired level.

Anyone got a handle on what I am trying to do? Low dollar + HP gain = big grin instead of broke pockets.

What do you say, can it be done and how?
Let all ye turbo prophets come forth to school us on Vanes and how they work for us?
Thanks, Eric

This sounds like a question for PSD(Matt)

If you're talking about the 6.0L variable vane turbo (and since you mentioned 2002 I'm not sure you are...) then as usual the 6.0 Bible has all the answers. This page is a good one:

http://www.backglass.org/duncan/ps60...l/ps60_036.jpg

More details available on nearby pages.

Duncan

Go here and read the "Air Management System":
http://dan.prxy.org/Truck/6L_bible_html/html/TOC.html

The PCM controls the VGT actuator. I'll have to go look at the pinout and see what the voltage is, I bet it is 1.5 to 5 volt.

thank you very much!
 

That is what I am talking about!!
Check on the voltage for me as well please.

Thanks again, Eric

I will. it is on my other computer.

The cheapest way to go is buy a Predator. Call MotorHaven. Best least expensive upgrade.

I don't know if I'de mess with that...the vains are designed to be closed at low R's thus producing "more with less"...and open up at high speeds to prevent over spinning...you close them up at high speeds and you run the risk of over spinning the turbo...and we all know what happens when things spin to fast...BOOM!...pieces everywhere...:-X10

Opening and/or closing the vanes does not have a DIRECT effect on controlling boost; it is rather an indirect effect by changing the effective size of the turbine housing outlet itself.

Leaving the vanes fully opened or closed will only change the point at where the turbo produces peak boost; it will in no way affect its mechanical capability to produce it.

On the 7.3, the wastegate could be disconnected to raise the peak boost. on the 6.0, there is no wastegate.

The opening of the VGT control valve controls the "curve" of boost as RPM's increase. Dropping the valve open too quickly will end up causing excessive lag, and then shortly following boost will peak early, causing the truck to drop its powerband far more quickly than if the boost is increased proportionately. If the vanes are left closed too long, the boost will peak TOO far into the powerband- causing overspeed, and the truck will shift before peak boost is ever developed.

The boost "curve" needs to be specifically tuned to work in conjunction with timing and fuel delivery to produce the highest peak power and longest powerband.

If you want to modify the curve, it needs to be done with actual tuning software. Simply using a rheostat/potentiometer will never make a constant, predicatable boost curve or powerband- IMO, all you will do is end up losing power and making alot of smoke, and quite possibly destroy the turbocharger from overspeed.

Simply keep in mind that the VGT controls DO NOT directly control the boost level, and it is fairly self-explaintory :-X22

Yea...Yea...Yea...:-blah ...wise guy... :-X24







Good stuff...:-X22

I do not want to start an argument. Just stating something. I agree w/ most of what you stated however If the vanes are closed exhaust is routed onto the turbine wheel making the turbo spin faster therefore creating more boost pressure. When the vanes are closed exhaust is baiscally bypassed and out the exhaust creating no boost pressure. My point is that you can leave the vanes closed 100% of the time and achieve full boost almost instantaneous and keep it there throughout the rpm band granted you have the injectors( and means to control them) to supply the fuel for it. The turbo will not create any boost w/ the vanes open or very minimal. I have logged several PSD's w/ aftermarket programmers w/ turbos creating over 50 psi of boost. The VGT duty cycles were 100% at WOT and injector duty cycles were dramatically increased as well to help w/ all the air being forced in. For all you guys and gals w/ programmers or dataloggers hook them up and see for yourself. The turbos start running out of steam at that duty cycle and RPM and boost pressure was falling off due that the turbo just couldnt force any more air in. So basically the VGT soleniod does control boost but you cant just simply lock it closed and have good things happen. With the vanes open it will take "all day" to achieve peak boost(if any) as it will probably come at a much higher rpm because you will be turning more rpms and have more exhaust flow. Vanes closed boost comes on much quicker and can sustain w/ engine rpm and open back under engine load conditions ( foot off pedal or just cruisin around and other things that come into play) Would sound neat to have the turbo "spooling" all the time though HEHEHEHE.

Where is the exhaust routed with the vanes closed? My understanding is the vanes are controlled by the VGT actuator by the PCM based on input from the EBP sensor among others. With low back pressure, the vanes are closed forcing exhaust onto the turbine blades. Use the analogy of the pistol type garden hose nozzle that as you move the grip, the stream of water gets stronger. As back pressure is increased, the vanes open. I don't see a valve or other mechanism that would bypass the exhaust. Maybe you are thinking of the 7.3 and its wastegate?

After rereading what I posted, I think I stated my thoughts backwards as you pointed out. I agree with your statement.

My initial point was that the vanes need to make a transition throughtout the RPM range to correctly maintain boost pressure at the points commanded by the computer. Just as you stated, with the vanes closed it will build boost quickly; however at the far other spectrum of the powerband range the boost would fade just as quickly, the vanes need to be opened to some extent DURING the process to drag the boost output all the way to the shift points.

Turbocharged cars work nearly the same way- take a Subaru WRX with a stock turbocharger- the stock turbo spools quite quickly (usually before 2500 rpms) but starts loosing boost at around 6500; install a larger turbo, and it will not start producing boost until around 3300 rpms, however will hold the output all the way to redline.

BTW, Wow- 50 psi on the stock turbo :-fire I'm sure those shaft bearings will last a loooong time :-X07

The vanes won't allow a direct bypass, but the housing cavity is HUGE in these things; the focus of the exhaust via the vanes has a pretty large effect on the turbine velocity.

I STILL haven't taken pictures of the one I have apart :mad:
I gotta go get my camera back...

I was referring to Int'l Techs post :

That sounds like wastegate system.

Im sorry that should say open.