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Discussion Starter · #1 ·
Ok guys . . . sorry if this thread repeats everything thats gone before . . . but my thoughts are focussed on LONGEVITY rather than PERFORMANCE.

So I want to take my 1995 2.0 LPT (Trionic T5) up to higher boosts (cheaply) and have read with interest all about ECU upgrades, Dawes Devices, Wastegate Bleed valves, manual boost controllers etc.

Is my understanding correct . . . . ?
A FPT with APC runs base-boost around 6psi and then adapts this up to around 14psi based on feedback from the knock sensor.
A LPT uses the same hardware (solenoid controlling the wastegate) but just limits max boost to a looooow value (about 6psi)

Then I come along and nobble the solenoid in some way so that it doesn't operate the wastegate until much higher pressures.
Over 6psi the Trionic is shouting 'Open the wastegate . . . OPEN THE WASTGATE!', but the turbo cant hear it!
Compared to a FPT I potentially have the same max pressure but no APC, no intercooler, unknown compression ratio and unknown fuel-map - welcome to Knock City
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My questions are . . . .
1) Will the Trionic continue the supply the correct fuelling up to the safety cut-off pressure?
2) Does the LPT engine run the same compression ratio as the FPT??
3) Does the LPT Trionic have APC???
4) Has anyone out there melted their pistons doing this????

Cheers
Gadgeteer

(oh yeah, and I plan to make a controllable gadget to nobble the signal into the solenoid )
 

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Yes, I think you have a basic understanding of how things work Still I'd make a refinement here:

FPT: basic boost set to 6 psi at wastegate, Trionic-controlled solenoid valve installed in intake-wastegate line holds pressure from wastegate until max boost (depending on version and engine rpm, say 14 psi as in your example) is reached as long as no knock is detected.

LPT: wastegate is set at 6 psi. Full stop. basic boost = max boost.

Apart from the solenoid valve, and the IC missing on some LPT models they are mechanically the same as their full pressure counterparts (although in the case of the 2.0 lpt in the 9k it's safe to say there isn't an exact FPT counterpart). Anyways, static compression ratio of the lpt engine is the same as on full turbo engines, as is the turbo itself.

As a result, the only proper and safe way to raise boost to the fpt level is retrofitting the solenoid valve, upgrade the Trionic brain to the fpt version and fit intercooler where applicable, making it effectively a full pressure turbo. OTOH fitment of an intercooler where you didn't have one before, will typically allow for a modest increase in boost pressure set at the wastegate, and still being on the safe side.

Happy Saabing,
Eric
www.turboteameurope.com
 

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Discussion Starter · #3 ·
Thanks Eric,

I'm pleased to say that my car definately does have the solenoid , I think it was added when going to Trionic ECU from LH. (See table below from Abbott Racing)

Model Years Engine Type Intercooler? Balancer Shafts? Engine Management Standard Boost
2.0 1992-1993 B202E No No Bosch LH/DI 0.45 Bar
2.0 1994-1995 B204E No Yes Trionic/DI 0.48 Bar
2.0 1996-1998 B204E Yes Yes Trionic/DI 0.35 Bar
2.3 1996-1998 B234E Yes Yes Trionic/DI 0.30 Bar
 

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Discussion Starter · #4 ·
I've just been out playing with my turbo.

I've tried disconnecting the compressor pipe to the wastegate solenoid, keeping the wastegate permanently closed to give max boost.

As standard, I saw a peak of 5.75psi (expected to see 6psi so pretty close)

With the wastegate bypassed I could get up to about 13psi before the fuel cut kicked in.

Smart!!!
Not quite the >15psi you FPT boys get to play with - but not a bad upgrade.

So Im off to make a boost controller to keep it below 12psi
 

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looking at my 2.3LPT, it does have an intercooler, it sits infront of the water cooling radiator!? is the 2.0 different?
how would an auto box cope with the possible extra power? or shall I get that thought out of my head
 

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Discussion Starter · #6 ·
Can't answer that cos my 2.0lpt doesn't have an intercooler (yet!)

I've just started to worry about how the autobox is gonna like the extra power.
I guess if Saab saw fit to limit the torque/power on the automatics there must be a good reason.
I notice that the Aero (225bhp) wasn't available as an auto - is that true?

Anyone out there putting more than 200bhp through an auto?
 

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Not only did the Aero auto get limited to 200bhp they are also limited to 294Nm torque (same engine spec as the standard 2.3T auto). The 2.3T manual meanwhile has 200bhp and 324Nm (approx- can not remember exact figure will need to get my anorak for that ).
Aero manual 1.08bar max boost
2.3T manual 1.0 bar max boost
2.3T/Aero auto 0.8 bar max boost

So I'm guessing that the ZH 4HP 18 box is torque limited to below 300Nm and power limited to 200bhp. Hoping to do some work with ZF people soon so will try to find out more. Like most thinks engineering wise the limits will be set according to a number of compromises - if we know these we can decide how far things can be pushed - alternatively just get someone to do some development work i.e. up the boost on their auto and see how long it lasts
 
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