Crown

Board: Porsche - 911 - 997 - Turbo Language: English Region: Worldwide Share/Save/Bookmark Close

Forum - Thread


    ? for Expert: Could After-Mkt. Exhaust Hurt Power?

    While visiting an independent Porsche shop, I was told that in the case of a turbo engine, something like a bypass pipe could end up decreasing power delivery because it reduces back pressure too much. Could someone with technical expertise explain this please? Is this because too low of a back pressure is detrimental to the turbine's ability to compress air? What parameter is affected, horsepower, torque, or both?

    From one end of the spectrum--very low back pressure of bypass pipe, to the other--high back pressure of stock, I imagine there is a middle ground of Tubi/AWE/Cargraphic exhausts, with mid level back pressure? Is it possible for this middle ground to be worse than stock?

    Thanks in advance.

    Re: ? for Expert: Could After-Mkt. Exhaust Hurt Power?

    Because you lose alot of backpressure, HP will increase, TQ will drop up to a point. Probably much more significant with bypass pipes or a 70mm system.

    Re: ? for Expert: Could After-Mkt. Exhaust Hurt Power?

    I've read that w/ the 911 Turbo any back-pressure will hurt performance. Less back-pressure = more power. I know this isnt always true w/ N/A engines.

    Re: ? for Expert: Could After-Mkt. Exhaust Hurt Po

    No. The statement is incorrect. Where people lose power is if they use too large of a header on a turbo motor. The exhaust flow goes

    motor > header > turbo > exhaust

    for max spool up the pressure differential on either side of the turbo should be maximized. High pressure in the header and low pressure in the exhaust drives the turbine to spool very quickly. Some people will put a very large diameter tubing header on the car and expect gains. Unfortunately this will reduce the pressure and velocity of exhaust gas before it hits the turbine wheel, so the differential in pressure between the header and exhaust is less. The highest pressure differential achieved yields the fastest spool, period.

    Re: ? for Expert: Could After-Mkt. Exhaust Hurt Po

    At the very end of the Fabspeed video: "PRODUCT VIDEO: 997TT Exhaust Explanation Video"

    "No loss in reducing backpressure only power"
    http://www.fabspeed.com/997TT.html

    But like eclou mentioned this is true as long as it's after the Turbo, the muffler/cats, not prior to the turbo (the headers.)

    What shop said that Cann?

    Re: ? for Expert: Could After-Mkt. Exhaust Hurt Po

    I believe he said no loss in power, only reducing backpressure.

    Re: ? for Expert: Could After-Mkt. Exhaust Hurt Po

    Can: If you fool around with the headers and get the wrong cheap kind, it could happen. The 997TT stock headers are prett decent, so keep them as they are and you will be fine. Same concept applies to motorcycles. I know so many people that ended up getting a louder pipe assuming more performance is in the horizon. They found out the hard/wrong way. You need ample pressure to spin your turbins once that's compromised you performance is lost.

    Re: ? for Expert: Could After-Mkt. Exhaust Hurt Po

    Quote:
    TT Surgeon said:
    I believe he said no loss in power, only reducing backpressure.



    Nope. He said:
    "just like every other Turbo charged car reducing back-pressure is your objective and king. No loss in reducing backpressure only power"

    Re: ? for Expert: Could After-Mkt. Exhaust Hurt Po

    Thanks everyone for the helpful replies. So the conclusion is less back pressure is better, and bypass pipe would therefore be best as far as engine's horsepower & torque are concerned?

    Gregg, you are always ready with a URL and info from your careful research! Why do I have this feeling you are going to call Champion about this?
    Cheers.

    Quote:
    STRADALE said:
    At the very end of the Fabspeed video: "PRODUCT VIDEO: 997TT Exhaust Explanation Video"

    "No loss in reducing backpressure only power"
    http://www.fabspeed.com/997TT.html

    But like eclou mentioned this is true as long as it's after the Turbo, the muffler/cats, not prior to the turbo (the headers.)

    What shop said that Cann?


    Re: ? for Expert: Could After-Mkt. Exhaust Hurt Po

    Quote:
    cannga said:
    Thanks everyone for the helpful replies. So the conclusion is less back pressure is better, and bypass pipe would therefore be best as far as engine's horsepower & torque are concerned?

    Gregg, you are always ready with a URL and info from your careful research! Why do I have this feeling you are going to call Champion about this?
    Cheers.

    Quote:
    STRADALE said:
    At the very end of the Fabspeed video: "PRODUCT VIDEO: 997TT Exhaust Explanation Video"

    "No loss in reducing backpressure only power"
    http://www.fabspeed.com/997TT.html

    But like eclou mentioned this is true as long as it's after the Turbo, the muffler/cats, not prior to the turbo (the headers.)

    What shop said that Cann?






    LoL! I just remembered hearing that in the Fabspeed video when I listened to it a while back. So when you asked it seemed logical to post what I heard.

    Re: ? for Expert: Could After-Mkt. Exhaust Hurt Po

    That's pretty much why adding aftermarket headers don't benefit turbocharged engines much. You'd get more of a benefit from headers in a naturally aspirated engine.

    Re: ? for Expert: Could After-Mkt. Exhaust Hurt Po

    Quote:
    atomic80 said:
    That's pretty much why adding aftermarket headers don't benefit turbocharged engines much. You'd get more of a benefit from headers in a naturally aspirated engine.



    In general, it is true for stock turbos. I used to tell people to think of an engine as a highway system. It will only flow as good as the narrowest section of the road. If your turbos are flowing like a 4 lane highway, adding a 6 lane header won't improve it at all. Now if you increase your turbo size to a 5 laner, a 5 lane header will help.

    Re: ? for Expert: Could After-Mkt. Exhaust Hurt Po

    Before I changed to the Europipe system I asked the guys there about changing headers - here's their response:
    "We have built and tested headers for the 997 Turbo but we couldn't measure consistent performance gains on the dyno. Couldn't feel any gains while driving the car either. (that was with the sport muffler already fitted). I'm sure it will be great for big hp engines, we won't offer them though."

    Re: ? for Expert: Could After-Mkt. Exhaust Hurt Po

    so if i change the exhaust of my car, like tubi fabspeed europipe.... i will not have HP gain??

    thats the most important....

     
    Edit

    Forum

    Board Subject Last post Rating Views Replies
    Porsche Sticky SUN'S LAST RUN TO WILSON, WY - 991 C2S CAB LIFE, END OF AN ERA (Part II) 3/28/24 3:21 AM
    watt
    688998 1780
    Porsche Sticky Welcome to Rennteam: Cars and Coffee... (photos) 2/19/24 11:51 PM
    Wonderbar
    408922 564
    Porsche Sticky OFFICIAL: Cayman GT4 RS (2021) 5/12/23 12:11 PM
    W8MM
    255623 288
    Porsche Sticky OFFICIAL: Porsche 911 (992) GT3 RS - 2022 3/12/24 8:28 AM
    DJM48
    234882 323
    Porsche Sticky The new Macan: the first all-electric SUV from Porsche 1/30/24 9:18 AM
    RCA
    65461 45
    Porsche Sticky OFFICIAL: Taycan 2024 Facelift 3/15/24 1:23 PM
    CGX car nut
    4640 50
    Porsche The moment I've been waiting for... 2/1/24 7:01 PM
    Pilot
     
     
     
     
     
    857746 1364
    Porsche 992 GT3 7/23/23 7:01 PM
    Grant
    773706 3868
    Porsche OFFICIAL: New Porsche 911 Turbo S (2020) 4/6/23 7:43 AM
    crayphile
    447757 1276
    Porsche Welcome to the new Taycan Forum! 2/10/24 4:43 PM
    nberry
    378763 1526
    Porsche GT4RS 2/22/24 5:16 AM
    tso
    365502 1424
    Porsche Donor vehicle for Singer Vehicle Design 7/3/23 12:30 PM
    Porker
    360711 797
    Others Tesla 2 the new thread 12/13/23 2:48 PM
    CGX car nut
    354609 2401
    Lambo Aventador and SV 3/30/23 1:59 PM
    CGX car nut
    279024 724
    Ferrari Ferrari 812 Superfast 4/21/23 8:09 AM
    the-missile
    275406 550
    Porsche Red Nipples 991.2 GT3 Touring on tour 3/14/24 8:55 PM
    blueflame
    272432 658
    Porsche Collected my 997 GTS today 10/19/23 7:06 PM
    CGX car nut
     
     
     
     
     
    248187 812
    Lambo Huracán EVO STO 7/30/23 6:59 PM
    mcdelaug
    224999 346
    Others Corvette C8 10/16/23 3:24 PM
    Enmanuel
    217876 488
    Lotus Lotus Emira 6/25/23 2:53 PM
    Enmanuel
    196629 101
    Others Gordon Murray - T.50 11/22/23 10:27 AM
    mcdelaug
    155271 387
    Porsche Back to basics - 996 GT3 RS 6/11/23 5:13 PM
    CGX car nut
    126846 144
    Ferrari [2022] Ferrari Purosangue (SUV) 4/15/23 5:20 AM
    watt
    120430 141
    BMW M 2024 BMW M3 CS Official Now 12/29/23 9:04 AM
    RCA
    105927 303
    Motor Sp. 2023 Formula One 12/19/23 5:38 AM
    WhoopsyM
    102490 685
    Others Valkyrie final design? 4/28/23 2:45 AM
    Rossi
    97636 219
    Porsche 2022 992 Safari Model 3/7/24 4:22 PM
    WhoopsyM
    81031 239
    AMG Mercedes-Benz W124 500E aka Porsche typ 2758 2/23/24 10:03 PM
    blueflame
    74330 297
    Porsche 992 GT3 RS 3/3/24 7:22 PM
    WhoopsyM
    52109 314
    Motor Sp. Porsche 963 3/16/24 9:27 PM
    WhoopsyM
    23091 237
    133 items found, displaying 1 to 30.