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    997 Turbo S - just 0.9 bar max boost pressure?

    Hi all,

    I am following this forum for quite some time, in my mind one of the best Porsche forums to find.

    While I am sticking to Audi and BMW at the moment, my father recently bought a Porsche 997 Turbo S convertible.

    He is very pleased with the car, except for a lack of boost pressure. Up to now he never achieved a boost pressure above 0.9 bar, while the Turbo S should be capable of 1.2 bar max boost pressure.

    He had the air pathway checked, a software update was implemented, but nothing changed. The ambient temperatures where -5 degrees Celsius up to 14 degrees Celcius, no changes in max boost pressure.

    The dealer's argument is now, that the aftermarket exhaust, a 9ff systems with butterfly valves and new catalysts, might be the reason?!

    Has anyone of you an idea what the issue might be? The next step would be to go back to the stock exhaust system (my father never tried this, the car came with the 9ff system).

    Best regards

    Sebastian

     

     


    Re: 997 Turbo S - just 0.9 bar max boost pressure?

    highly possible the aftermarket exhaust is doing something to the maf sensors and therefore boost does not reach the max.

    iirc, max boost is only reached in Sport mode.....furthermore you would have to accelerate from low rpm (at higher Speeds) to reach Maximum boost pressure.

    one of the best ways is to accelerate from 80-140.....and read the boost indicator.


    --
    Speed has never killed anyone, suddenly becoming stationary... That's what gets you.

    Re: 997 Turbo S - just 0.9 bar max boost pressure?

    It is possible that the higher flowing cats and exhaust have caused this lower boost.

    Boost is back pressure in the inlet system, you have relieved back pressure in the exhaust system so the whole set up flows easier. The engine doesn't really see the boost, IIRC, the program adjusts the boost pressure to hit load targets so if it can hit the load targets with less boost then it will.

    I cold weather you will have lower boost than in hotter weather as the denser air can hit the load targets with less boost than in warmer air.

    530PS is achievable with 0.9 bar, my 3.8 litre 993 turbo engine manages 577PS on 0.99bar with two valve heads !

    Having said all the above I understood the principle of the expansion intake manifold was to force the air at higher (than "normal" boost pressure so it could expand and cool (and lose some of the boost) as it entered the combustion chambers....

    I guess the best way to check is to run an acceleration test using a performance box say 100-200kph and see if t matches the road tests ?

     

     


    --



     

    3.9  GT2 2011 make over


    Re: 997 Turbo S - just 0.9 bar max boost pressure?

    check VTG diverter valves, they tend to leak. Also while at it ask them to lubricate the VTG actuator mechanism (a factory recall actually).

    I would be surprised if problem is from the exhaust, especially since the car has ECU tuned if i understood correctly?

     


    Re: 997 Turbo S - just 0.9 bar max boost pressure?

    Since they apparently checked everything (hopefully), I too would blame the exhaust.

    Has your father never seen 1.0 or more bar and I mean not even for a short moment?

    Does the "arrow" (overboost) appear?


    --

    RC (Germany) - Rennteam Editor Porsche Panamera Turbo S, Cayenne GTS (958), BMW X3 35d (2012), Mini Cooper S Countryman All4


    Re: 997 Turbo S - just 0.9 bar max boost pressure?

    TB993tt:

    Having said all the above I understood the principle of the expansion intake manifold was to force the air at higher (than "normal" boost pressure so it could expand and cool (and lose some of the boost) as it entered the combustion chambers....

     

    Not quite; cause and effect are the other way around.
    The principle of the expansion inlet manifold is to dimension the tracts of the manifold in such a way that the inlet air expands as it enters the cylinders at higher engine speeds, thereby causing it to cool. The cooling effect allows the manifold boost pressure to be increased above the level which would otherwise be possible with a conventional resonance intake system without creating the conditions for pre-ignition or "knocking". The overall effect is that a greater volume of the air/fuel mixture can be forced into the cylinders at a given engine speed without it self-detonating, thus resulting in a higher torque and power output.

     


    --

    fritz


    Re: 997 Turbo S - just 0.9 bar max boost pressure?

    Hey Fritz, I thought you might comment in this thread and I'm glad you did kiss

    Your explanation above explains some of the things about the expansion manifold/VTG engine set up which had been alluding me.

    I never understood why the GT2 needed to run such high boost pressure, 1.4 bar for 530PS when as I mentioned before a well built 993 turbo can make 580PS on 1 bar......

    Taking your explanation above which makes complete sense and adding that it is the high advancement of the timing in these expansion manifold engines which contributes a lot to the high rev power (achievable thanks to the knock resistance attributes you describe) it is apparent that the VTG engines need to run the high boost since they work at very high exhaust manifold/VTG turbine side back pressure numbers and the only way to make the power is to run the high boost numbers to literally force the (super heated) air in and out of the turbos, hence the constant fight with the heat generated by the VTG set up.

    At 1.5 bar intake boost, RS measured 3.2 bar in the exhaust manifold in the 758PS engine.


    --

     


     

    3.9  GT2 2011 make over


    Re: 997 Turbo S - just 0.9 bar max boost pressure?

    My 558 hp (measured) 997 Turbo produced 1.2 bar maximum boost pressure with VTG chargers.


    --

    RC (Germany) - Rennteam Editor Porsche Panamera Turbo S, Cayenne GTS (958), BMW X3 35d (2012), Mini Cooper S Countryman All4


    Re: 997 Turbo S - just 0.9 bar max boost pressure?

    RC, was that stock?


    --

    Chris

    2007 997.1 TT (#3)

    1987 930 Slant 505


    Re: 997 Turbo S - just 0.9 bar max boost pressure?

    TT Surgeon:

    RC, was that stock?

    Of course not... Smiley


    --

    RC (Germany) - Rennteam Editor Porsche Panamera Turbo S, Cayenne GTS (958), BMW X3 35d (2012), Mini Cooper S Countryman All4


    Re: 997 Turbo S - just 0.9 bar max boost pressure?

    What mods did you have to make that power?

    c


    --

    Chris

    2007 997.1 TT (#3)

    1987 930 Slant 505


    Re: 997 Turbo S - just 0.9 bar max boost pressure?

    TT Surgeon:

    What mods did you have to make that power?

    c

    Not much. Sport exhaust system with high flow catalytic 200 cell converter, engine and Tiptronic software mods. Everything done by RUF, incl. a chassis setup adjustment done by H.P. Lieb (he loved my car, so he took care of the setup, perfect setup for semi-slicks). Car was very fast, considering the minimal mods.


    --

    RC (Germany) - Rennteam Editor Porsche Panamera Turbo S, Cayenne GTS (958), BMW X3 35d (2012), Mini Cooper S Countryman All4


    Re: 997 Turbo S - just 0.9 bar max boost pressure?

    Very cool RC.

    Re the op, doesn't the Siemens ecu sense the drop in back pressure from a em exhaust and pull timing  in A dfi turbo s engine with the gt2 style intake?

    c

     


    --

    Chris

    2007 997.1 TT (#3)

    1987 930 Slant 505


    Re: 997 Turbo S - just 0.9 bar max boost pressure?

    Hallo everyone,

    I am new at the forum and new Porsche owner.

    I had Audi S4 Bi-turbo, Audi S5 V8 and 3 months ago I bought brand new 997 Turbo S.

    The car was produced in August 2011 and have been unsold till I bought it in March this year.

    The car had 150 km,Porsche official dealer said they tested it with a few customers.

    Please help me with advice to know is performance of my car normal.

    When I sit for the first time I noticed I have to push gas pedal little more to awake the engine and to start moving.

    Gas pedal is slow and feels heavy.

    I can not feel 700NM and push in the back at lower and mid revs, and it is missing a bite until in very high revs.

    I feel very good power when I floor gas pedal.

    I have 1200 km until now, and I was not pushing over 5000 revs until 1000 km.

    Sometime I feel PDK slip and small vibration when I just start to go.

    Porsche diagnostics said only several low voltage problems -maybe battery was low as car was long time not driven.

    I will visit them again after they cleared it and I driven the car, if it is repeating.

    I was very happy with old S4 (I removed Cat, and put KW variable suspension,spacers-thats all)

    Audi was fast on gas pedal,had explosive power and much more midrange feeling.

    Maybe I have to break in the car, or there is some problem as it was not active for long time?

    Are there some unreadible problems like Mass air flow or anything else which diagnistics does not see?

    I do not feel excited when I drive the car.

    Other things are suspension-litlle nervous as front end is light, and the sound which is not inspiring.

    I wanted to see if this is normal, and the to start with Cat by pass pipes,exaust (maybe Akrapovich ) and some good street suspension with lift option (KW, Bilstein,...)

     

    Thanks in advance.

    Smith997 tts.JPG

     


    Re: 997 Turbo S - just 0.9 bar max boost pressure?

    smith68:

    Please help me with advice to know is performance of my car normal.

    When I sit for the first time I noticed I have to push gas pedal little more to awake the engine and to start moving.

    Gas pedal is slow and feels heavy.

    First, congratulations. Smiley

    Throttle response gets (much) better with Sport or Sport Plus active. Have you tried that?

    I can not feel 700NM and push in the back at lower and mid revs, and it is missing a bite until in very high revs.

    I feel very good power when I floor gas pedal.

    This is due to the 10 second Overboost, after which the car produces less torque. If you want to feel that again, you need to floor the gas pedal again.

    I have 1200 km until now, and I was not pushing over 5000 revs until 1000 km.

    No problem.

    Sometime I feel PDK slip and small vibration when I just start to go.

    PDK slip? Hmmm, are you sure it is PDK slip and not the PSM (ESP) jumping in?

    Porsche diagnostics said only several low voltage problems -maybe battery was low as car was long time not driven.

    After a couple of days of driving, this shouldn't be an issue anymore.

    I will visit them again after they cleared it and I driven the car, if it is repeating.

    I was very happy with old S4 (I removed Cat, and put KW variable suspension,spacers-thats all)

    Audi was fast on gas pedal,had explosive power and much more midrange feeling.

    Maybe I have to break in the car, or there is some problem as it was not active for long time?

    The Turbo S is a rocket. If it doesn't feel that way, there is something wrong. Have you looked at your boost pressure? Also keep in mind that the engine is HIGHLY fuel sensitive. Fuel quality is extremely important.

    Are there some unreadible problems like Mass air flow or anything else which diagnistics does not see?

    Not likely. What happens pretty often is that the air duct to the turbo chargers/intercoolers slips off and boost pressure is lost.

    I do not feel excited when I drive the car.

    This is weird.

    Other things are suspension-litlle nervous as front end is light, and the sound which is not inspiring.

    Tire pressure is essential (use the recommended one!!!), also maybe your car needs a proper chassis alignment (sometimes the cars came out of the factory with wrong alignment). 

    The sound is not inspiring, you're right and if you go for a sport exhaust system, go with Cargraphic or Akrapovic only.

    I wanted to see if this is normal, and the to start with Cat by pass pipes,exaust (maybe Akrapovich ) and some good street suspension with lift option (KW, Bilstein,...)

    I wouldn't touch the chassis but it is your money. A good alignment does wonders, RUF in Bavaria/Germany is very good with chassis alignments for the 911 Turbo (they are the closest to your location), so if you want a good setup...

    Good luck!


    --

    RC (Germany) - Rennteam Editor Porsche Panamera Turbo S, Cayenne GTS (958), 991 Turbo S (Oct. 5th), BMW X3 35d (2013)


    Re: 997 Turbo S - just 0.9 bar max boost pressure?

    Thanks a lot for answer and a support.

    I tried sport and sport plus, it is better, but still not old school.

    Turbo S does not have overboost for 10 sec, higher boost is always,that is what I found in Porsche specs.

    I saw boost is going up to 1.1 but shortly,all the time is changing.

    PDK is a little strange, like it have some pause and go when you start to drive.

    Esp should not react as I start slowly and notice that.

    The fuel is 98 and yesterday I put 100 Octanes.

    I will have to visit some tuner for inspection as they feel it better than official service here.

    As for exaust, I like Akrapovich (youtube) sound, but I have to find somebody who will do ECU and accept to match exhaust.

    Maybe some tuner will insist at their full package ???

     

    Best regards

     


    Re: 997 Turbo S - just 0.9 bar max boost pressure?

    smith68:

    Maybe some tuner will insist at their full package ???

    Very likely but if you pay, they (RUF) do "setups" and maintenance too. They are the only official Porsche repair shop (not dealer!) in Germany, just as a hint. 

    If you do not want to drive that far, I suggest you drive to a larger Porsche dealer in Austria (I assume this is closer to you than Germany) and let them check your car.

    I do not know what kind of expectations you have from a 997 Turbo S but everything you told me about it so far, doesn't match anything I or probably others have experienced with this car. So something is weird.

    The overboost needs to work (only full throttle and only 10 seconds), so I'm not sure what is wrong there.

    Did you buy the car from an official Porsche dealership?


    --

    RC (Germany) - Rennteam Editor Porsche Panamera Turbo S, Cayenne GTS (958), 991 Turbo S (Oct. 5th), BMW X3 35d (2013)


     
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