The Topic:
LPT to FPT conversion.

The Problem:
You got a LPT (low pressure turbo) and you want more power. The first thing you can do is to do a conversion to a FPT (full pressure turbo).

The Solution:
I. Get the parts 
 (try and get closest to the year of your car)

Inside the car

  1. Remove the centre console (only the part in front of the gear lever)

  2. Remove the lower dash fascia

  3. Locate the pressure transducer and overpressure switch bracket

  4. Remove the bracket and remove the old LPT overpressure switch (this is not the same as the one found on a full pressure turbo)

  5. Install the full pressure turbo overpressure switch and the pressure transducer

  6. Plug the overpressure switch in the same way as the old one was

  7. Prepare 2 wires for the pressure transducer

  8. Plug the vacuum/pressure pipe that was on the old overpressure switch into a Y junction to feed air to the pressure transducer and to the new overpressure switch (longer nozzle) 

  9. Take a length of pipe from the shorter nozzle on the overpressure switch this shall feed the pressure gauge so adjust the length according to where you will place the gauge (I placed mine in the top section of the centre console) 

  10. Now take the wiring from the pressure transducer through the bulkhead (I went through one of the rubber grommets just near the brake master cylinder) – make sure it is watertight 

  11. Do the same with a length of wire from the spare plug from the brake switch (this is located just above the brake pedal and is a red wire – be careful as the switch is somewhat fragile)

In the engine bay

This is the head scratching part!

  1. Remove the top of the fuse box

  2. Unscrew the to retaining bolts either end of the fuse box

  3. Next very carefully peel off the insulating tape of all the wires from the ignition amplifier cable junction to the fuse box (take great care not to cut anything)

  4. Cut the original ties on the rubber grommet at the entry of the fuse box (take great care not to damage it)

  5. Now you can lift the top half of the fuse box up to access all the wires – if necessary cut any plastic ties so you can manipulate the wires more comfortably 

  6. First of all bring the wires you previously prepared for the pressure transducer through under the fuse box compartment

  7. Take the wires from the APC socket connector and connect the various wires as follows (for 1992 model, older models have different colour codes):
        1. Grey/red => connect to APC fuse (10A)
        2. Black (thinner) and yellow/red to the wires prepared from the pressure transducer (use cable connectors with insulation)
        3. Blue/red to the blue wire under the TSI socket (funny round 6 pin socket at the front of the fuse box)
        4. White to the cable prepared from the brake switch (use cable connectors with insulation)

  8. You should now be left with the thick grey wire with the green and the brown wires inside to the knock sensor, a yellow/white to the APC solenoid and the thick black APC ground wire.

  9. Now fix the APC box into its location on the inside of the front LH wing and plug the connector in 

  10. This allows you to position and check the wire lengths so there is no strain on any of them

  11. Connect the thick black APC earth wire to the earthing point just opposite the APC box

  12. You may also connect the black wire from the solenoid valve at the same place

  13. Run the knock sensor wires and the solenoid wires through to their locations to check position and length

  14. Now use insulating tape (preferable the textile type as used originally by SAAB) and wrap up all the wiring from the fuse box to the APC box 


    The next thing is to fit the hardware

  15. Remove the air filter housing to give you access to the bottom of the engine compartment and fit the bottom intercooler bracket (the holes are already in the chassis all you need to do is screw the plate on) 

  16. As you have taken out the air filter housing you can now remove the old plastic pipe between the air box and the turbo and replace with the new one (the new one has the small outlet that is then linked to the APC solenoid - R) 

  17. Now refit the air filter housing and plug the crankcase vent pipes back to the new piping just fitted previously
    Next remove the aluminium pipe from the turbo to the inlet manifold be sure to preserve all the clips and fittings as they might be useful later

  18. While the turbo is exposed use a very clean rag and plug the outlet to prevent ingress of dirt
    Now comes a little creative part; trial fit the intercooler and using a length of stainless steel make a small bracket to link the top of the intercooler with the front left radiator mount.

  19. You can use a spirit level to get the intercooler straight or just guess (don’t forget that the pipes will have to fit on without fouling with other parts of the car). 

  20. Once you are satisfied with your bracket, fit the intercooler.

  21. Now you can fit the new aluminium pipes from the turbo to the intercooler and the one from the intercooler to the inlet manifold.

  22. The next to fit is the solenoid valve; you will find two holes in the front crossmember just right of the coil. Fit it here (on mine the holes didn’t line up so I drilled the solenoid valve little bracket rather than the painted body).
    Plug the solenoid valve in and connect the vacuum pipes .
        1. W – to the wastegate actuator
        2. C – to the turbo (compressor side)
        3. R – to the plastic pipe with connector (Air box to turbo)

    Note on this photo I placed a piece of rubber piping on the aluminium pipe (turbo to IC) to protect it from being damaged by the upper radiator hose and clips where the sensor is.

  23. Now last but not least the knock sensor! This is a bugger! Unless you have the engine in bits or the inlet manifold off you will need to place the sensor in its location with your hand either from above or slide you hand under the manifold to the rear of the oil filler cap/pipe then get the bolt and screw it in finger tight then tighten it with a tool but keep the sensor plug in the correct direction (it took me approx. 2 hours to do it with a sore hand at the end)!

  24. Plug the sensor in 

  25. As the final touch fit the plastic air duct to the top of the intercooler

II. Finishing touches
Now back inside the car tidy up and refit the lower dash fascia and centre console taking care to leave the lighting wire to the ash tray and the vacuum pipe to the boost gauge free and not squashed
The location of the boost gauge is personal so I leave it up to you to fit it where you like but here are the pics of how I did mine 



III. Test run
This section is what I did and is my personal method and not necessarily a reference.

  1. Start of with turning the ignition on without starting the car this will allow you to find out rapidly if you have bodged the wiring (at your own risk)

  2. Now start the car with the solenoid unplugged this will allow you to assess your pipe work and find any leaks in the inlet system

  3. Now arm yourself with the adequate spanner to adjust your wastegate actuator

  4. Drive off and first check you still have the 0.4 bar max boost of the LPT setting

  5. You will have to adjust this to 0.3-0.4 bar (dependent on model year etc.) refer to the Haynes or other manuals for details of how to adjust. This is your base boost

  6. Once you have the base boost you can plug in the solenoid valve and fly off you should be now boosting at a healthy 0.7-0.8 bar (dependent on model year etc.)

  7. Then there will be no holding you; you will be trying APC tuning and more; have fun!