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<H1>Turbocharger Description and Operation</H1>


<MAP name=1384618.map>
<TABLE>
<T>
<TR>
<TH align=left></TH></TR>
<TR>
<TD align=middle>(1)</TD>
<TD align=left>Turbocharger Vane Position Sensor</TD></TR>
<TR>
<TD align=middle>(2)</TD>
<TD align=left>Turbocharger Vane Position Control Solenoid Valve</TD></TR>
<TR>
<TD align=middle>(3)</TD>
<TD align=left>Turbocharger Vane Position Unison Ring</TD></TR>
<TR>
<TD align=middle>(4)</TD>
<TD align=left>Turbine</TD></TR>
<TR>
<TD align=middle>(5)</TD>
<TD align=left>Turbocharger Vanes</TD></TR>
<TR>
<TD align=middle>(6)</TD>
<TD align=left>Hydraulic Piston</TD></TR>
<TR>
<TD align=middle>(7)</TD>
<TD align=left>Cam</TD></TR></T></TABLE>


The turbocharger increases engine power by pumping compressed air into the combustion chambers, allowing a greater quantity of fuel to combust at the optimal air/fuel ratio. In a conventional turbo, the turbine (4) spins as exhaust gas flows out of the engine and over the turbine blades. This spins the compressor wheel at the other end of the turbine shaft, pumping more air into the intake system.


The turbocharger for this system has vane position control by the engine control module (ECM). The vanes (5) can be opened and closed to vary the amount of boost pressure. Thus, the boost pressure can be controlled independent of engine speed. There are 9 controllable vanes in this turbocharger. The vanes mount to a unison ring (3) that can be rotated to change the vane angle. When the engine is not under load, the vanes are open to minimize boost and exhaust back pressure. To increase boost when the engine load requires it, the vanes are commanded closed. The ECM will vary the boost dependent upon the load requirements of the engine.


The turbocharger vanes are normally open when the engine is not under load. However, the ECM will often close the turbocharger vanes to create back pressure to drive exhaust gas through the exhaust gas recirculation (EGR) valve as required. At extreme cold temperatures, the ECM may close the vanes at low load conditions in order to accelerate engine coolant heating. The ECM may also close the turbocharger vanes under exhaust braking conditions.


The turbocharger control system utilizes the following components:<A name=ss1-1394251><A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1394251&evc=sm&pubid=437&cellId=133229&mspsdsubkey=3243#ss1-1394251" target="_blank">
<H5>Turbocharger Vane Position Control Solenoid Valve</A></H5>


The vane position control solenoid valve (2) works in conjunction with oil pressure to control the turbocharger vanes. The solenoid valve uses two circuits; a control circuit and a low reference circuit. The ECM uses a pulse width modulation on the HI control circuit to control the solenoid valve. The ECM will control the solenoid valve to allow the engine oil pressure to move a piston (6). This piston rotates the unison ring, thus controlling the engine boost dependant upon engine load.<A name=ss2-1394251><A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1394251&evc=sm&pubid=437&cellId=133229&mspsdsubkey=3243#ss2-1394251" target="_blank">
<H5>Turbocharger Vane Position Sensor</A></H5>


The vane position sensor (1) uses three circuits; a 5-volt reference circuit, a low reference circuit, and a signal circuit. The ECM provides the sensor with 5 volts on the 5-volt reference circuit and a ground on the low reference circuit. Movement of the sensor from the open vane position to the closed vane position provides the ECM with a signal voltage through the position senso
 

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Nice! Thanks.
 

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Very interesting! Thanks!





Steve
 

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VERY
 

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GMCSID, did you notice also on SI2000 that there is also a description of the high idle system that will be ready out of the box on the LLY trucks? I don't know how to make it show up here but the document I.D. # is 1343526. See ya.
 

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Discussion Starter #7
Max Payne said:
GMCSID, did you notice also on SI2000 that there is also a description of the high idle system that will be ready out of the box on the LLY trucks? I don't know how to make it show up here but the document I.D. # is 1343526. See ya.

Found it. I'll post it.
 

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Wonder if this is a proven system and more reliable than the present Turbo. I'm from the old school and believe the more parts there are, the less reliable the system is and if moving parts are involved reliability could even be worse. Lets hope someone has done there homework.
 

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Look at the Ford 6.0L for all the proof you need!



Just kidding, I'm sure it will be fine.
 

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Yep, Ford opted for an electronic vane control. GM wanted to keep the electronics away from the high temps for reliability reasons. More efficient design, but more complexity and cost. Add to that it's so vane.
 

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So, for those of us that are ignorant when it comes to the "old" Duramax turbo, does it just have (4) and a fixed (5) with none of the other parts? I would really like to see a sketch of what I have in my truck.
 

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Bill Gisse said:
Wonder if this is a proven system and more reliable than the present Turbo. I'm from the old school and believe the more parts there are, the less reliable the system is and if moving parts are involved reliability could even be worse. Lets hope someone has done there homework.

Is there a problem with the old one? I thought it was pretty much bullet proof.
 

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34 psi and greater from what I understand can be detrimental to the stock one
thats my understanding too a64Edited by: sdaver
 

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So does the new turbo flow MORE air with less back pressure at WOT, or is there only an advantage at part throttle or spool up. I think I would rather have a larger ball bearing turbo than a variable vane turbo.
 
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