Gtb1756vk vacuum adjustment

xjjeeper

xjjeeper

Well-known member
Joined
Mar 20, 2016
Location
Chilliwack BC
TDI
99.5 golf, soon to be Tdi Xj
I am swapping to a vertical push vacuum actuator and am wondering what vacuum spec the actuator arm should contact the set screw at? The set screw has been set up by a turbo shop. I've heard multiple different answers (15 and 20inhg at the set screw )
 
A

adamss24

Veteran Member
Joined
Nov 2, 2005
Location
Great Britain
TDI
audi a4 2.5 tdi 98 quatrro 6speed
Them settings depend on a lot of factors, actuator arm welded position, stop screw protrusion, actuator type (push/pull), length of actuator arm, etc. best is to buy Vcds and drive the car taking lots of logs with the aid of a pyrometer to monitor EMP/EGT. Once you have a good understanding of the way turbo works and you happy of the mechanical adjustments then a PID control map adjustment will be necessary along with a n75 map massage...just remember to note position of before adjustments as small adjustment makes for big changes !
 
Digital Corpus

Digital Corpus

Top Post Dawg
Joined
Mar 14, 2008
Location
Ontario, California
TDI
'97 B4 w/ 236K mi body, 46K mi soul
I’m not sure, but it sounds like you’re asking 2 questions. Setting the set screw is technically tricky. Setting the actuator is easy and VW suggests 3-5 inHg for starting to move and 17-20 inHg for when it stops and the vanes are wide open. If the movement is opposite of this, then swap the numbers.

The simple and semi-crude way to set the stop screw is to do an a-to-b pressure differential check between idle and 1400 RPM. On a 2.7l, where this turbo came from, your volume of air is significantly greater than on a 1.9l at both of those test points. If test procedure matches each other between the two engines, then you technically need to bump it to 1275 RPM & 2000 RPM for a 1.9l running a 2.7l turbo. Pressure differential should be 140 mbar, iirc, idealy? There is a specified range.
 
xjjeeper

xjjeeper

Well-known member
Joined
Mar 20, 2016
Location
Chilliwack BC
TDI
99.5 golf, soon to be Tdi Xj
Digital Corpus said:
I’m not sure, but it sounds like you’re asking 2 questions. Setting the set screw is technically tricky. Setting the actuator is easy and VW suggests 3-5 inHg for starting to move and 17-20 inHg for when it stops and the vanes are wide open. If the movement is opposite of this, then swap the numbers.

The simple and semi-crude way to set the stop screw is to do an a-to-b pressure differential check between idle and 1400 RPM. On a 2.7l, where this turbo came from, your volume of air is significantly greater than on a 1.9l at both of those test points. If test procedure matches each other between the two engines, then you technically need to bump it to 1275 RPM & 2000 RPM for a 1.9l running a 2.7l turbo. Pressure differential should be 140 mbar, iirc, idealy? There is a specified range.
Click to expand...
The set screw is already set. I am swapping from a "pull" actuator to a "push" vacuum actuator and mounting it vertically. So vacuum vs vein movement is the same. Right now I have it start moving around 3 and stopping about 15-16. Sorry I read the original post again and it's a bit confusing
 
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