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Can anyone tell me what the correct turbo boost pressure should be on my 2.3 full tubo (Auto)?
I'm having a JT 3" exhaust system fitted on saturday and i believe that because the back pressure is decreased the turbo boost may need resetting. Is this the case, and if so what should the pressure be?

Thanks
 

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Surely an improvement exhaust in gas flow is fine regardless of ECU?
My Stage1 ECU ran beautifully on the JT3" full system - but its not part of the official stg1 spec.
I agree however, that you will cause damage running a stage 3 ECU with a std exhaust.
 

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Originally posted by Stoffe:
[qb]You should not change the exhaust without fitting suitable ECU-program at the same time. [/qb][/b]
Hmm, weren't you the man the 9-5 lpt stage 1 who fitted a Td04 turbo without changing the ECU program afterwards?
 

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Originally posted by /john:
[qb] QUOTE
Originally posted by Stoffe:
[qb] You should not change the exhaust without fitting suitable ECU-program at the same time. [/qb][/b]
Why not [/qb][/b][/quote]Because you will lower the exhaust temp and the back pressure will also be reduced with the risk of getting strange turbo pressure variations wich the ECU will have trouble in handling. Of course it will work but not optimal.
What's the point in having one of the best engine control systems in the world if you don't let it work like it should?

/Regards
Stoffe
 

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Originally posted by Marky:
[qb]   QUOTE
Originally posted by Stoffe:
[qb] You should not change the exhaust without fitting suitable ECU-program at the same time. [/qb][/b]
Hmm, weren't you the man the 9-5 lpt stage 1 who fitted a Td04 turbo without changing the ECU program afterwards? [/qb][/b][/quote]Yes that is correct. It was only for a short while when I waited for my new injectors to arrive. I was well aware of it not being an optimal sollution and drove with that in my mind. Nowadays my software is fine tuned for my hardware setup and the car runs like a charm.
How about 62-93 mph in 4.8 seconds on third gear, measured with an AP-22 performance meter?

/Regards
Stoffe
 

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One can change the exhaust on a T5 engine and not worry about the ECU. In fact, the same goes for a T7 engine. The only difference is that the T7 will adapt for variations in volumetric efficiency in order to maintain torque targets in the ECU matrices. With a T5, the increased volumetric efficiency should, theoretically, lead to higher torque and hp values. With the T7, the torque and hp values remain the same, but it will take less strain, stress, EGT's and intake temperatures, to do so. One of the most effective hardware changes one can do on a 9000 is to utilize a larger flow area on the downpipe and cat'. Not only will it increase VE, it also lowers EGT's, which lowers IT's. It's a win-win situation that will have no bearing on the stock ECU's ability to adapt the fuel, timing, and boost maps accordingly. One can easily make a good argument that the larger exhaust, providing much better 'living conditions' for any turbo engine, will lengthen the mortality span of a B234 engine.
 

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I put a 3" JT system on my 94.
strange turbo boost variations?
yeah I got them, quicker spool up and a little higher boost pressure. Is that a problem? eh.... No it is NOT a problem.

Granted I want a stage 4 ECU, but that's to take full advantage of the better breathing.
 

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robert lavergne >

That's not really true.

T5 and T7 works in different ways.

The T7 engine will " notice " that it can give more power.
Its because of the airflow measure.
I knows that its can take more air to the engine.

The T5 system works whit turbo pressure.

The problem you can get if you put a 3" down pipe is that the pressure is to high, and the engine don't know it.

But its normally not any big problem.


R/sasse
 

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Originally posted by aerosaaber:
[qb]I put a 3" JT system on my 94.
strange turbo boost variations?
yeah I got them, quicker spool up and a little higher boost pressure. Is that a problem? eh.... No it is NOT a problem.
[/qb][/b]
I may not be a problem in your world, but it still isn't the right thing to do. Why are you so keen on using half descent solutions instead of doing it the right way? Of course it's fun with extra power but isn't it more fun with a car that is tuned to take full advantage of the 3" downpipe completely without pressure variations and at the same time know that Trionic is working exacly as it should with all it's fine security functions?
I mean, how fun is it with pressure/torque variations? How proude can you be when your friend is testing your car and wonder why the strange torque curve?
Of course it's a money problem and I'm not saying someone's stupid just because he or she doesen't make the software upgrade but one should be aware of the consequences.

/Regards
Stoffe
 

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OK, before we all start ripping our teddies up
, let's put some reasonable heads on.

Firstly, regardless of theory, the fact in real life is that many people do simply fit a bigger downpipe and providing that an adjustment of base boost pressure is made, T5 & T7 systems work without any problems and with quicker spool up. People are happy with the upgrade, and why shouldn't they be? Furthermore, whilst adding a sports/performance exhaust will be acceptable to many insurers, ading a custom ECU may not be and is more likely to add a significant premium surcharge.

It is correct to say that to get the best out of any hardware change, you would need to match the software. However, in this case the difference would be small and probably not worth the cost.

Changing to a larger downpipe normally results in a lower base boost pressure due to a reduction in back pressure from the exhaust, which contributes to the force holding the wastegate shut.
 

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Originally posted by Bubbles:
[qb]It is correct to say that to get the best out of any hardware change, you would need to match the software. However, in this case the difference would be small and probably not worth the cost.[/qb][/b]
Many good points there.
But you can't be serious when you say it's not worth the cost (performance wise) changing the ECU software after mounting a 3" downpipe. The cost of a good software is lower than a 3" downpipe with a race katalyst and will produce way many more hp.
Anyway, do as you wish but I know what I'd do...


/Regards
Stoffe
 

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Stoffe,

The car in question is a 1994 9000 2.3T Auto. A 3" downpipe is under £200. A stock software upgrade is around twice that amount. A custom upgrade, mapped only for the exhaust, would be even more. The 9000 autoboxes are at their design torque limit in stock form on the full 2.3T. Getting more power out of them without significantly reducing the life of the box if you are going to exploit it fully is probably impossible.

In this case, simply fitting the downpipe alone is the most cost effective option.

So, I am both a) serious and B) correct.

You may know what you would do in your circumstances, but that is not necessarily appropriate or correct for everyone else's
 

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We all have differing budgets and a variety of other reasons why we may want to upgrade, ie parts fail and its cheaper to buy performance parts than to buy OE saab parts.

In this particular case I personally cannot see what harm a downpipe will do without upgrading the ECU. If it were the other way around then it may make more sense to me.
 

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I was under the impression that just upgrading the exhaust without a remap of the ECU would cause more damage than whats being claimed. Especially on the turbo charged engines.

Personally I do agree with what Stoffe has to say, when it comes to alteration to the car, it is certainly best to do it properly, best not to do a half baked pie.


ECU Upgrade + 3" pipes =
+
=


As for insurance... exhaust upgrades depending on companies may also attract a premium...best to check with each company before making broad claims.
 

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well guys, there would aonly be one certain way to resolve this......

anyone got a 3" downpipe + no ecu upgrage and anyone else got a 3" downpipe + ecu upgrade to compare on RR?
 
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