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Discussion Starter · #1 ·
Hi Guys

Just a quick question to those of you that have fitted a Hybrid Turbo.

Does any other modification have to be done to the car?, the reason I ask is that I thought if the turbo over-boosts the fuel supply is regulated to bring the boost level down. If this is the case how does the car run with a Turbo kicking out a higher boost pressure.

Many thanks

Paul.
 

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Paul, depends on which engine management system. The 90 - 92 (I think) APC/DI system did not have overboost fuel shut down, hence a $35 Dawes device gives 18psi without any problems. Not sure about the later Trionic systems only jsut got one so not had time to play.
 

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Paul as Adrian said it depends on which year / model your talking about.

The older 2L B202 enginged 9000's had a fuel cut-off valve under the streering columb just behind the apc, This could be dialed in a bit to compensate.

The bigest prob with running a hybrid turbo on any car is that when you increase the pressure from the turbo output you also increase the air temp, and the intercooler can't necessarily cope with the extra air flow /temp.
This will cause pinking (pre ignition) and the saab APC or DI/APC will detect that pinking and turn down the boost.

Your then looking at 2 options : 1 get an uprated intercooler or 2 adjust the a APC so its less sensative. The second option not being the best!
You will also need to get a rising rate fuel pressure regulator fitted and set up correctly on a rolling road, so that when you do put your foot down the fuel rail has enough fuel pressure to supply the injectors.
If you don't do this your mixture will run lean at high revs and consequently actually get hotter and cause pinking again!

Basically you have to ballance the boost, fueling, air flow and exhaust to do it right.

BTW adrian you can also use the Dawes boost controller with Trionic.

Damian
 

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Damian tell me more about using the Dawes device with Trionic. I have a MY97 2.3T, has this got the Trionic T5? How will the Trionic respond to overboosting if a Dawes device is fitted?
 

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Discussion Starter · #6 ·
Thanks for all your replys,

Mine is a J reg (new shape) 9000 2.3 Turbo Auto, B234 Engine with the DI system.

The reason I ask is because I recently fitted a bleed valve on the waste gate, and as I was experimenting with the adjustment, the boost needle ran into the red, several times, and the engine would almost die for a split second and then pick up as the boost level dropped. Is this normal, or is this the fuel supply being interrupted?

Thanks again chaps.

Paul
 

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I have the same car as you by the sounds, the cutting out is the overboost protection working. If the boost goes too far into the red the engine will be cut for a fraction of a second to reduce the boost. I suspect my dump valve or wastegate is not working properly at the moment as in 2nd it will boost off the red without cutting, but cuts at about 2/3 red in 3rd gear.

HTH

Neil
 
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