- GT25R Actuator comparison
- The actuators supplied with the GT25R's have a fixed length actuator arm, which will need
- modification because the actuator bodies will be placed in a different position.
- I have no idea what pressures the actuators are designed to operate to, so I thought best to
- directly compare how they react to simulated boost pressures. One of my aims is a very modest
- increase in standard boost pressure from 0.7bar to 0.8bar. I know the engine ecu can raise boost
- pressure by bleeding away pressure from the actuators, what it cannot do is reduce boost afaik.
- Using the same set up I used to reset the OE actuators on car, I compared how they both reacted
- to variable pressures from 8psi to 15psi
- The multimeter is measuring mv, 0.048 is about 8psi, ~0.094 is around 1bar, which should be the
- full normal range of boost the ecu would see.
- VIDEO of working actuator
- The video clip shows both actuators subjected to pressure starting from 8psi to just over 1bar and
- back to 8psi in short space of time. Both arms seem to extend by roughly the same amount, and
- also at the same speed.Also noted the range of movement in approx 0.5psi increments, apart from
- the gt25r actuator not actually moving until the pressure reached about 8psi, the range of movement
- v pressure for both remained the same from thereon.
- I think that the ecu block learn will be able to calibrate this slight difference in actuator performance...
- ...or at least that is what I hope ! ;-)
- Positioning and fitting waste gate actuators REAR TURBO
- Having changed the relative positions of the compressor and turbine housings about the spindle axis,
- the current bracket for the waste gate actuator needs modifying to suit.
- In addition, the bracket is secured to the inside flange of the compressor housing, I need to re-drill and
- thread new holes so that I can move the bracket, but, I have to remove the compressor housing first. It is
- held in place with a very large circlip, once removed the housing can be lifted off to reveal the
- compressor wheel.
- Notice the small machined cuts in the spindle nut and compressor end. These are made to balance the
- assembly.
- Basically I cut the bracket in half and re-welded the 2 pieces and added an extra rib for strength.
- The other problem was that in it's closed state the actuating arm should be normal to the waste gate
- pivot lever like this.
- But it was like this.
- This may have worked, but the forces and lever deflection would be all different, I wanted to try and
- maintain these to original spec as much as possible. So I needed to cut off the arm, and re-weld it in
- a new position.
- Something I still need to do is make the actuator rods adjustable.....I do have a feeling that these gt25r's
- were actually part of a batch made to fit a specific make and model of vehicle..............
......and I still have the front turbo to sort.
Next job was to modify the arms so that I can adjust them.
