8 valve T5.5 conversion

[s900t8v]

I hadn't committed to making a project thread anywhere yet so I thought maybe I would make one on Saabworld!

I recently converted my 8 valve c900 Turbo to Saab Trionic 5.5 engine management (originally in 94-98 NG900 and 9000 Turbos)



Here were the hurdles I had to overcome
- Direct Ignition Cassette wouldn't fit with the 8v plug layout (used spark plug leads to extend the cassette)
- Fuel rail from a 9000 wouldn't fit my 8v intake manifold (had to make my own)
- Fuel injectors wouldn't fit in the intake manifold (bored the ports out with a step drill and created a 2nd injector seal with 1/2 inch rubber grommets
- Crank position sensor needed to be mounted somewhere (I chose the crank pulley)
- Fuel lines needed to be made up (just used some general worm drive clamps and fuel hose bound to the original 12mm fuel line banjos present on 8v and 16vs
- Wiring loom (from a 98 9000) needed to be extended
- Coolant temp sensor needed to fit the intake manifold (engineer welded a new bung on)
- Needed an oxygen sensor bung installed in the exhaust
- Needed the air intake temp sensor installed into the intake piping
- Needed a different throttle body setup for the throttle position sensor (modified a 9000 TB to fit my 8v)

These were the major issues, of course the overall parts list for a T5 conversion was the same - mine were obtained from a 97/98 9000.
- AIC
- TPS
- DIC
- ECU
- Loom
- O2 sensor (I used a wideband with a simulated narrowband - wideband excellent for tuning)
- CTS
- injectors (red tops)
- 3 bar fuel pressure regulator
- MAP sensor
- AIT sensor
- Crank position sensor and Trigger wheel
- speedo and cruise ECU from 89+ c900 (for Trionic 5.5 speed signal) - you can run without speed signal, some features such as decel enleanment etc are a bit glitchy without a speed signal, otherwise it runs perfectly.

Tuning gear
- wideband O2 sensor
- Combiadapter from JohnC at ECU-Project (canusb+BDM adapter for the ECU)
- t5suite (program created by enthusiasts over at ECU project)

I think I'm the 3rd wacko to do this to an 8 valve (a number have adapted the system to other cars), the other 2 8v conversions being on track cars, I felt a little unsure not having much support to do this, it was a huge undertaking and well worth it! My hand was actually forced into doing this as I had considered it but when my car broke down 3 weeks ago, it was spend big $ getting K jet serviced or dumping the RUBBISH system and going to trionic 5.5

I'll explain some of the more involved issues I had to deal with.

Problem 1
- Direct ignition cassette wouldn't fit. I have used spark plug leads to extend the reach of the DIC (along with the stock BCPR7ES plugs) The important thing here is to use LOW resistance high quality leas (MSD 8.5 super conductor have 50 ohms per foot, and havent had any negative feedback I could find when compared with other brands (Mallory, Accel, Granidetti etc) The low resistance is vital to maintain the ion detection sensitivity of the DIC. The easiest way to attach the spark plug leads is to press the leads up into the plastic plug guides. Trim the lead inside the DIC and leave the center core exposed so it can fold over the coil tower contact. Make sure the plug leads protrudes a little into the inside so it is a press fit when you reinstall the plastic plug cover on the DIC.


NB: the leads shown are not MSD - they are cheap ones which affected the ion sensitivity)

Problem 2
Because the fuel rail wouldn't fit I made my own. I will mention that this was my first real go at silver brazing, and I was quite successful! I used Harris Safety Silv 56% silver braze (excellent capillary attraction) and Harris black flux I used a Bernzomatic Ts8000 torch with propylene gas. I cut the injector bungs off another fuel rail, and used some steel cut into the right sizes to make up what you see before you. Now the banjo fitting mounts on the rail are actually bright steel wheel lug nuts! At 12mm x 1.5mm thread pitch these are the perfect size for the 17mm hex head banjo bolts.




Problem 3
- Electronic fuel injectors wouldn't fit in the original intake manifold (mechanical injectors originally much longer) So to overcome this I step drilled the pots so the injector nozzles were right at the inside of the intake runner! You can see in the photo below how the injectors (old c900 ones I had laying around I used for the build up to avoid damaging the red tops) sit really deep in the manifold.



Problem 4
- Crank position sensor bracket and trigger wheel mount. To figure out how to mount the crank position sensor trigger wheel and bracket I removed the oil pump cover from the car and used it to mock up a bracket for the CPS. The CPS needs to be 0.3-1.3mm from the trigger wheel at all times. I used the A/C pulley to hug the T5 trigger wheel against the crank pulley.







Problem 5
- Fuel lines - This was really simple. I got some rated fuel hose and used worm drive clmps to secure the banjos to the hose. Cost me about 15 dollars. I used a double banjo bolt and a dome nut to secure the new fuel rail return line to the old K jetronic return line (tht runs to the tank)

Problem 6
- air intake temp sensor thread to be tapped into intake pipe, coolant temp sensor thread to be tapped into intake manifold (original CTS thread is larger than the T5 CTS thread) and exhaust bung required for oxygen sensor. These were things I didn't have the proper tools for, so I paid my local engineer to weld on a bung for the CTS, braze on a bung for the O2 sensor and tap a thread in the intake pipe for the air intake temp sensor (AIT)

Problem 7
- TPS - I just used a throttle body from a 9000, that believe it or not bolts directly up to an 8v intake manifold. I did need to modify the throttle cable apparatus (just pulled the stuff off my old TB) this allowed me to keep the TPS on the 9000 throttle body rather than trying to adapt the TPS to my throttle body


I'll update this thread with photos of the specifics when I have some more free time!

Wiring information
- Following the pinout in the trionic manual I found the wiring stuff to actually be quite easy. I had to extend the wiring loom to reach certain components and so I used the crimp/heat shrink glue butt connectors which provide an excellent connection.

TO get the tacho to work with T5 you need to disconnect the ignition amplifier and wire it in place of the original tacho input behind the instrument cluster
to wire in a T5 knock light and check engine light (my car never had a CEL light) I used LED's with in line resistors - the ECU grounds out both the knock light and CEL when there is an event.
Everything else was pretty much straight forward

[Crazyswede]

If you want to clean up your intake a bit or if you do another conversion in the future...the Djet manifold from a Saab 99 should still work on a 900 8v. You may have to block or add a port for a sensor or block off a coolant port. The Djet manifold ran early injectors that are very close in size to modern ones. We made a fuel rail from extruded aluminum rail stock and drilled the injector ports at the correct spacing. Looks good.

[Crazyswede]

you can sort of see the manifold in this photo:

[s900t8v]

hey thanks for the info, I'm pretty happy with my manifold. If at a later date I decide I want to do up my engine bay the aluminium intake manifold polishes up REALLY well so I'll stick with this one... I bored the ports so the injectors fit pretty well!

[s900t8v]

Just an update

Don't need a >89 cruise ECU to work with the 89+ speedo, the old cruise ECU still works with the square wave speed signal (as opposed to original sine wave)

car is out of action at the moment, rebuilding the turbo...

[s900t8v]

I also did the ECU mod so I can switch the T5 APC control valve to a T7 APC control valve. The t5 valves are prone to failure and over $300 new, the t7 valves are better and only $45 new.

To do this you have to modify the software and the ECU PCB to get the new valve to work. Details over at ecuproject



remove pin 5 from the component and then solder a bridge across 2 pads

heres my wiring almost completely tidied up (weeks ago) it's finished now





The fuel pump is fused, the main relay is fused, and the switched live is fused too (to the ECU)

The main and fuel pump relays only come on with switched live, the fuel pump relay safety feature (prime then stop unless engine turning over) is all connected. It's just as good as a stock wiring setup!

[Oldsaabguy]

Good job!!

[s900t8v]

I'll put it in here, if you have a wideband o2 sensor and you are using a simulated narrowband signal you need to change the symboltable in the ECU (using t5suite) sond_heat_tab! - set all values to -1 to prevent the ECU from tripping a CEL

Also the speed signal makes the car run ALOT better, The speed signal needs to be a square wave signal, any 89 or later speedo with cruise has the right signal (3 pin cruise plug instead of 2 pin). (you don't need to swap from the old style cruise to new style cruise though!)

If you want to put an 89 speedo in a car that was made before 86/87 then you may have to change the speedo drive gear in the transmission - the drive gear changed ratios around this time. you need the speedo drive gear that corresponds with the speedo ratio, so look at the bottom of your speedo there should be a W0.XX

If the W0.XX is different between the speedo you want to put in and your current speedo the speedo drive gear ratios are different and you'll need to get the right drive gear - it takes about 5 mins

You don't need to swap the speedo cables, the early style cable (86/87) will fit in the late style speedo, it's not perfect but it's an interference fit!

[TrollhattenSchatten]

This is brilliant! Amazing from a technological and engineering standpoint. Is this a common modification or was this figure it out as you go basically?

[s900t8v]

Hey thanks for your kind words. I know of 2 other cars it's been done to, one was a track car (speedparts 8vT5.5) and the other was a guy in norway on garaget.com which also looks majorly like a track car... they weren't much help cos they didn't really do a walkthrough, plenty of 16v walkthroughs I just adapted all the things to make it work on an 8v it was for the challenge, skill development and just plain fun! brazing is a great skill to have, now I'm onto arc welding practice so I can make up my new exhaust downpipe for my td04 15G turbo! .