Torque Cars

Exhaust

Discussion in '4x4 Owners club (off roaders)' started by duratrac, 7 February 2012.

  1. duratrac

    duratrac Newbie

    Messages:
    2
    From:
    canada
    Car:
    Fj Cruiser
    I have eh Y pipe on my ride ,, was thinking of having it removed this way I would have dual pipes all the way back, what would be the gain of doing this or down fall ? thanks for your input
     
  2. T9 man

    T9 man TC Pro Founder Moderator

    Messages:
    20,369
    From:
    London, UK
    Car:
    Saab 9-3SS T9
    Greetings and Welcome to our TorqueCars Forum my Friend! :)
    I am unable to help you with your question directly, but you are definitely in the right place for the answers! Somebody will be along in a little while who will be able to assist you with some answers or suggestions to your query!
    Good luck! :)
     
  3. turbonutter69

    turbonutter69 TC ModFather Moderator

    Messages:
    18,967
    From:
    Alone in the dark.
    Car:
    Insignia SRI.
    Hello and Welcome to TorqueCars.:bigsmile:
    Hope you enjoy your time with us.
     
  4. duratrac

    duratrac Newbie

    Messages:
    2
    From:
    canada
    Car:
    Fj Cruiser
    Thanks Guys ,, When talking with the muffler shops ,, all they want to do is sell u stuff, Your site looked like eh good place to ask, as you all have some really nice cars , and I bet they run really good to and u all know more about this then they do. Thanks again :)
     
  5. obi_waynne

    obi_waynne Administrator Staff Member Moderator

    Messages:
    41,345
    From:
    Deal, Kent UK
    Car:
    A3 1.4 TFSI 150 COD
    The way I understand it is that the fast flow of exhaust gases helps with evacuation as a suction is created behind the moving gases in the next cylinder along, if you go to a twin exhaust this effect will be reduced somewhat. (Although in reality it will make a minimal difference.)

    I would stick with a Y piece and go with a slightly larger bore size and then split it at the end again if you really wanted twin tail pipes.
     
  6. lexus8

    lexus8 Tuner

    Messages:
    97
    From:
    New Zealand
    Car:
    1991 Hilux Surf
    Hi and welcome , my 91 Hilux Surf is powered with a Lexus V8 , it has a 2 and a half inch pipe in a Y shape into a single pipe wouldnt have it any other way
     
  7. Charliep

    Charliep Torque Junkie

    Messages:
    125
    From:
    Thurrock, UK
    Car:
    Alfa GTV & 33
    On a V6, V8, V10 and V12 you can run separate pipes without a problem. However, the pipe sizes have to be corrected. And that's whereit gets a bit tricky and expensive if you don't want tolose low end torque.

    I rather would go for a Y-piece. Place the Y-Piece as far back as possible and make sure that the pipe reduce in size after the split.
     
    obi_waynne likes this.
  8. lexus8

    lexus8 Tuner

    Messages:
    97
    From:
    New Zealand
    Car:
    1991 Hilux Surf
    can i ask why you say reduce size after split mine is the same size through out , and it holds its own on the street
     
  9. Charliep

    Charliep Torque Junkie

    Messages:
    125
    From:
    Thurrock, UK
    Car:
    Alfa GTV & 33
    To keep gas speed up. It does help more than people think.

    Even if you do not have a Y-piece, every exhaust should reduce along the collector pipe. Best would be a tapered pipe. Unfortunately this is virtually impossible at acceptable cost.

    Next best option is a reduction, which is a soft step (no sharp edges).
     
    obi_waynne likes this.
  10. SLEEPER

    SLEEPER Pro Tuner

    Messages:
    2,783
    Reducing the pipe size may do many things but speeding the gas up certainly isnt one of them

    Try it with a hosepipe using a reducer
     
    Last edited: 9 February 2012
  11. obi_waynne

    obi_waynne Administrator Staff Member Moderator

    Messages:
    41,345
    From:
    Deal, Kent UK
    Car:
    A3 1.4 TFSI 150 COD
    Fitting a smaller exhaust than the OEM standard one will certainly not help at all.

    There are obviously optimums here but a really large exhaust bore slows up gasses so conversely a narrower on will cause the gases to flow faster than it would in a large bore exhaust.

    Using your analogy of the hosepipe for a high power jet that travels faster and further you use a setting with a small hole in it, a large hole and the water will just dribble out with no velocity at all. ;)
     
  12. SLEEPER

    SLEEPER Pro Tuner

    Messages:
    2,783
    I think we agree waynne ?

    I used the hosepipe because it is easier to explain/understand

    Specifically whatever size pipe you have if you enlarge it you may get more water out you may not it depends .
    If the pressure was restrictive before you probably will. If not you probably wont
    The water may appear to be coming out slower with a bigger bore but it isnt.
    Restricting the size may make the jet longer but the volume doesnt go up so in my eyes the speed does not either ( speed = how long in time a set volume of gas /water takes to travel a set distance)
    The pressure can and certainly does change which maybe was what was meant .

    High power exhaust system are very complicated. Back pressue and gas speed both count

    Lastly different engines demand different calculations epecially when a turbo is involved.
    So much so that they are worked out on a computer for best results and are way beyond most people ( inc moi :confused: )

    One thing I do know though - racing exhaust are larger than non racing ones
     
    Last edited: 9 February 2012
  13. Charliep

    Charliep Torque Junkie

    Messages:
    125
    From:
    Thurrock, UK
    Car:
    Alfa GTV & 33
    The Thiele-Small parameters are applicable in turbo as well as in N/a applications.

    The reason why race exhaust are bigger is because the aim is to set the peak power point as high as possible. Race cars usually operate in a very narrow band, which makes it necessary for professional racing to adapt more than the exhaust to make the best out of individual tracks.

    Rally cars usually have a smaller bore, which is calculated to a lower peak power point and a spread in torque.

    your hose pipe analogy does not work,because we are talking exhaust not watering your garden.

    Pulse tuning results in exhaust dimension that might not look logical to the onlooker but is correct.

    The reason why a reduction is advised is because gases contract on the way out. The temperature drop is several hundred degrees. Therefore it is advised to reduce along the collector pipe.

    hen splitting the collector pipe in 2 the gas speed is suddenly reduced, which costs power and has got a negative effect along the system in reverse. My partners and me are spending thousands of hours on the rolling road and track to get these things right. If it were this easy as you claim then we would have a much easier life.
     
  14. SLEEPER

    SLEEPER Pro Tuner

    Messages:
    2,783
    In fact I said the exact opposite and that it was very complicated.

    I will keep this polite as I very much am interested in any new information - the hose analagy was just about narrowing a pipe/speed . True gases are not liquids soi will happily make my comment irrellevant for this specific point

    However I am still persuaded otherwise as nobody in any performance car sphere that i know ( leaves out rallying) uses narrowing exhausts.
    Constant bore size is the considered the optimum almost everywhere

    Your claims to be this and that may well be true but if narrowing an exhaust is so wonderful why dont the rest of the tuning companies do this .(apart again from rallying)
    And some these tuners have larger R & D budgets than you possily can unless of course you own honda etc.

    last thing are you saying that exhaust tuning on turbo engines follows the same principles as on na ones ?
     
  15. Charliep

    Charliep Torque Junkie

    Messages:
    125
    From:
    Thurrock, UK
    Car:
    Alfa GTV & 33
    Supersprint exhausts are designed this way as being the biggest perofrmance exhaust manufacturer.

    Dave Vizard, the Mini guru of all times would disagree with you.

    I am a technical consultant to the automotive industrty other than having my own business and know that they do what I stated.

    We develop exhaust systems ourselves and come time and time again to the same conclusion.

    Most of the performance tuning specialists I know (and I know many personally) do it too.

    There is also a lot of info about it on the net by credible institutions.

    Force induced and n/a exhaust have several things in common. One thing they differ is that n/a engines rely on the scavenging helped by the exhaust design, which force induced engines do not need as the boost takes care of it resulting in a different lobe separation of the cam arrangement.
     
  16. T9 man

    T9 man TC Pro Founder Moderator

    Messages:
    20,369
    From:
    London, UK
    Car:
    Saab 9-3SS T9
    :confused: Sorry I don't quite understand, can you explain in laymans terms CP as to what the different lobe separation of the cam arrangement - means please? :embarrest: Thanks.
     
  17. Charliep

    Charliep Torque Junkie

    Messages:
    125
    From:
    Thurrock, UK
    Car:
    Alfa GTV & 33
    Sorry.

    When talking about lobe separation it refers to the angle between the exhaust lobe and the inlet lobe describing the overlap of valve opening between both the exhaust and inlet valve, which occurs at the end of the exhaust stroke leading into the intake stroke.
     
  18. boostnturbos

    boostnturbos Torque Junkie

    Messages:
    143
    From:
    Ireland, donegal
    Car:
    BMW 318ci SE
    what is scavaging for?
     

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