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True Dual Exhaust: Good or Bad???

Discussion in 'Performance and Tuning' started by JK4, Jul 3, 2009.

  1. Jul 3, 2009 at 7:04 PM
    #1
    JK4

    JK4 [OP] Member

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    I am considering getting true dual exhaust for my 09 tacoma prerunner v6 4.0L.
    True Dual would be easy for me because i have 2 cats on each side so they would just have to cut off the y pipe and make it go straight back to my dual tips (that i will get) i will get straight pipes cat back no muffler

    I have been reading several posts about true dual and it looks pretty controversial. some people like it others dont.

    Is there anything i need to know before i get this exhaust done?

    Also if i do get true dual which should i get the H-Pipe or the X-Pipe?
    (to lessen the scavenging effect)
     
  2. Jul 3, 2009 at 7:16 PM
    #2
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine. Moderator

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    If your not going to supercharge your truck, you will loose power.
     
  3. Jul 3, 2009 at 7:33 PM
    #3
    jhodge83

    jhodge83 They all float down here... Moderator

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  4. Jul 3, 2009 at 9:04 PM
    #4
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine. Moderator

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    It may sound better, but it wont have any noticable affect on mpg.
     
  5. Jul 4, 2009 at 10:41 AM
    #5
    09WhiteTaco4x4

    09WhiteTaco4x4 Well-Known Member

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    The sound of an exhaust system is completely subjective. What may sound better to one person here may not sound better to another. I think this question is hard to answer. Personally, from what I've heard over the years, the more you open up the exhaust on a V6 engine, the more you realize that it's not a V8. There's simply no substitute for the exhaust note of a V8 engine with a free-flowing exhaust system. I would keep it simple, but that's just me. :)
     
  6. Jul 4, 2009 at 5:55 PM
    #6
    XrunnIT

    XrunnIT Well-Known Member

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    Not entirely true.

    Its all dependent on pipe sizing and mufflers/cats used. True duals with a crossover will always out perform a single exhaust with a y-pipe (better scavenging when both banks are balanced) when the two systems are designed properly. Like any system the exhaust should be tuned. :thumbsup:
     
  7. Jul 4, 2009 at 6:01 PM
    #7
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine. Moderator

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    I used to think the same way. We built a set up like what you are describing. Useing 2.5" pipes, on a Firebird WS6 (IIRC), and a single pipe set up, useing 3" pipe. The single made more power throughout the ROM range, and was lighter to boot. Funny thing about scavenging. Exhaust velocity plays a large roll in it. Too large a pipe, or to many pipes, and the exhaust cools down too fast, thus slowing down, and ruining scavenging. To small a pipe, and it goes too fast. There is very much a Goldie Locks affect when screwing with exhausts. And it veries engine to engine. Every "True Dual" I have seen on the Tacomas has shown a loss of power on the dyno. Unless, the engine was FI.
     
  8. Jul 4, 2009 at 6:48 PM
    #8
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine. Moderator

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    An X pipe, or H pipe aids in scavenging. On a daul set up, an X pipe is prefered.
     
  9. Jul 5, 2009 at 7:51 AM
    #9
    XrunnIT

    XrunnIT Well-Known Member

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    A dual 2.5" will flow more volume then a single 3". Depending on the displacement dual 2.5" could have been too much, hence the 3" outperformed the dual 2.5". Depending on the peak RPM, you may not have had enough exhaust to keep that velocity up.

    Velocity = torque
    Volume = peak HP

    IMO torque > peak HP any day of the week. I haven't seen any numbers for true duals for the tacoma. For those JBA dual exhausts and what not, I would imagine those killed a lot of the power through the full band.

    I would like to see somebody make a true dual setup using 2" pipe, and x-piped, with some straight through mufflers (for N/A with a CAI). On our 4.0L with a somewhat low peak RPM (5500 for most), I bet you would see more torque area (space below the torque line). But without being able to test it, that is just in theory.

    Exactly right. :thumbsup:

    X-pipe for performance, and I've read H-pipe for sound.
     
  10. Jul 5, 2009 at 8:15 AM
    #10
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine. Moderator

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    I agree with what your saying, But keep in mind that HP is a result of Torque. H.P. = Torque x RPM / 5250. All that happens whith different exhaust set ups, is the torque curve is moved around. An ideal curve is flat from idle to rpm cut off. That would give the most power, and acceleration. In the end, scavenging playes a huge role, more so than volume of exhaust gassses pushed out the pipe.....;)
     
  11. Dec 22, 2017 at 1:00 AM
    #11
    Blue2010

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    I plan on installing a flowmaster super 40” dual in dual out. The pipe diameter is going to be 2”. Will there be any hp and tq differences if I go with two mufflers instead of one? And also since I am using 2” tubing from the muffler and back should I use also 2” for the x-pipe? Thanks
     
  12. Dec 22, 2017 at 4:12 AM
    #12
    Clearwater Bill

    Clearwater Bill Retire from work, but not from life.

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    You posted in a thread that ended in 2009.

    What were you doing 8.5 years ago? :D
     
  13. Dec 22, 2017 at 10:20 AM
    #13
    Torspd

    Torspd Tor-nication

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    :laugh:
     
    SCH likes this.
  14. Dec 22, 2017 at 10:21 AM
    #14
    Torspd

    Torspd Tor-nication

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    Do not use 2" unless you want to choke your exhaust flow.
     
  15. Dec 26, 2017 at 9:03 PM
    #15
    Blue2010

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    Should I go with 2.25”? I see duals loosing low end with 2.5”. Thanks
     
  16. Dec 29, 2017 at 6:20 AM
    #16
    Torspd

    Torspd Tor-nication

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    Are you going duals, or staying single?
     
  17. Dec 29, 2017 at 3:53 PM
    #17
    Blue2010

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    For now I think I”ll just install a spec u headers and y pipe and just change the muffler. So single for now unless I go f/i later on.
     

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