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how much power will exhaust mods really make?

Discussion in 'Technical Q&A' started by joeyy, Jan 11, 2004.

  1. joeyy

    joeyy Karting

    Nov 11, 2003
    190
    long island
    Full Name:
    joe
    replacing a factory exhaust with an aftermarket like ANSA or TUBI makes the car sound good but how much more power do you really get. i have heard reports of 15 to 25hp. is this accurate or is is one of these things that look good on paper? When i was racing we dynoed motors for days making changes that people swore would make more power and actually went backwards. as any person who works with a dyno knows 15 or 25hp is a very hard thing to find.
     
  2. Dave

    Dave F1 Rookie

    Apr 15, 2001
    2,722
    Little Rock
    Full Name:
    David Jones
    It depends!
    I know you were not looking for that answer But it is true...

    By exhaust, were you referring to just the muffler,
    Or headers/collectors/pipes/mufflers.
    By just changing the muffler to a free flowing unit, can at times help gain a few HP.
    But the real performance gains come by flowing the entire intake/exhaust pathway to work in harmony so your engine works more efficiently.
    If you add a free flowing muffler like a Tubi,
    but then don't help the intake side to flow more air,
    Then you are not fully taking advantage of the benefits of a freer flowing exhaust.
     
  3. rexrcr

    rexrcr Formula 3

    Nov 27, 2002
    1,572
    Kalamazoo, MI
    Full Name:
    Rob Schermerhorn
    Your experience with other engines is similar to Ferraris.

    I suggest a search of the new board, as well as the old one here (search located from a link on the main page.) This topic is a hot one, many previous posts including data and opinion.

    Best regards,

    Rob Schermerhorn
     
  4. Dale

    Dale F1 Veteran

    Oct 7, 2003
    5,211
    uk
    Full Name:
    Dale Juan
    When the exhaust valve pops open what happens=the contents of that cylinder expanding go down your exhaust,ok piston now coming up to see the inlet valve pop open,hence weve come to that one called overlap,both valves now open and the new incoming charge(the piston hasent droped yet)is entering the cylinder and exhaust system due to a atmospheric pressure drop in that cylinder,15-25 bhp from an exhaust change,sorry can't comment on that one,there are so many factors that can give this 15-25 bhp gain,
    my question is can the exhaust manufactures give a new valve timing figure to suit there system,if it was stuck on a dyno and they saw what it did or didnt give i think they could give a new figure,
    Ferrari's have wide overlap periods so a new free flow exhaust will stop backflow=less exhaust gas in the inlet side so you get a little more power,depends on who did the timing belts and how they have set it up,
    Dale.
     
  5. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    6,334
    The Factory doe not leave this much HP to be found in the modern cars (355+).

    Figure 3-7 HP for a muffler
    Figure 3-7 HP for headers

    Figure you are going to have to spend $200-$300 in dyno time to really know if you gained or lost any power.
     
  6. zsnnf

    zsnnf Formula 3

    Sep 11, 2003
    1,877
    Well, when I dynoed my F40, I was very disappointed. After we upped the octane in the tank, removing the stock muffler and installing a Tubi was good for about 35rwhp. Removing the Cats was good for about another 15rwhp.

    Rick
     
  7. Wildwarrior

    Wildwarrior Formula Junior

    Mar 26, 2003
    280
    PA
    Full Name:
    Glen Winters
    My Tubi and test tubes sound great,however with over 400 hp stock ,you can't feel any more power.By adding my chip and exstending my red line from 7200 to 7600rpms she stays in her torque curve between shifts and does feel a bit faster.
     
  8. Verell

    Verell F1 Veteran
    Owner Consultant

    May 5, 2001
    6,951
    Groton, MA
    Full Name:
    Verell Boaen
    Why were you disappointed? Ferrari already put a lot of effort into the F40's air flow system. I'm surprised you did that well. The combination gave you 50rwhp! That's pretty good for an exhaust mod to an already highly tuned car!
     
  9. zsnnf

    zsnnf Formula 3

    Sep 11, 2003
    1,877
    Because it started out at ONLY 345rwhp!! 20% 100 octane brought the base up to 365rwhp. We ended up with a max of 420rwhp. I guess that would be about 480 at the flywheel. About right.

    Rick
     
  10. Brian C. Stradale

    Brian C. Stradale F1 Rookie
    Lifetime Rossa

    Mar 17, 2002
    3,603
    Dallas, TX, USA
    Making no other mods than a muffler change, generally you will achieve no gains on a modern Ferrari. Sometimes you'll gain a couple hp up high at the loss of a few ft-lbs of torque down low.

    If you make some intake and chip changes, then the muffler changes may have more impact.

    But on a modern Ferrari, there's very little to be gained by mere "flow" improvements. Ferrari is not going to leave easy stuff on the table.

    Full exhaust changes (elimination of emissions stuff) can net much more gains (10-15hp), but you'll need to deal with all those sensors or you may end up with a car in "limp mode".

    The biggest performance gain from an exhaust change is often just the reduced weight. The primary value of an exhaust change is improved sound.
     
  11. robertgarven

    robertgarven F1 Rookie
    Rossa Subscribed Owner

    Feb 24, 2002
    4,966
    Ventura, California
    Full Name:
    Robert Garven
    I noticed a marked increase in seat of the pants HP and response time when I switched to a tubi and K&N. The tubi was about 150lbs lighter than the stock muffler and I think the carb cars exhibit more gains with a freer flowing air filter. I know that there was a recent article in Forza where this was refuted on a dyno, but I know what my car was like before and after and it is like a different animal!
     
  12. joeyy

    joeyy Karting

    Nov 11, 2003
    190
    long island
    Full Name:
    joe
    thanks for the info guys. i had a feeling that was the case. finding every bit of hp is a difficult thing to do and this would be way too easy!!
     

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