Torque Cars

Exhaust system please read!!!

Discussion in '205/206/207/208 forums' started by Evanditchburn21, 13 March 2013.

  1. Evanditchburn21

    Evanditchburn21 Wrench Pro

    Messages:
    22
    From:
    Stockton-on-tees
    Car:
    Peugeot 206 1.1
    Where can I get a good stainless steel decat manifold for a 1.1 206 or even a cheap standard manifold and cat
     
  2. davalav

    davalav Moderator

    Messages:
    3,617
    From:
    Essex, England
    Car:
    Mini Cooper S R56
    Ebay... But you don't want to de-cat a 1.1. You'll loose so much back pressure. A decent high flow exhaust with a sports cat and 4-2-1 manifold. Actually... I think pugsport do exhausts for a 206....
     
  3. Evanditchburn21

    Evanditchburn21 Wrench Pro

    Messages:
    22
    From:
    Stockton-on-tees
    Car:
    Peugeot 206 1.1
    Do you have any idea on the price of the pugsport exhaust? And is that a full system?
     
  4. pgarner

    pgarner TC ModFather Moderator

    Messages:
    16,521
    From:
    Lockerbie, SW Scotland
    Car:
    Octy smoke machine
    quick google didnt turn anything up for a 206 but a 106 came back around £300 for cat back.
    watch if your buying cheap manifold as the quality on the weld might not be up to scratch and start cracking.

    tbh frank mate id say your wasting your money, put it in a pot for a better car/engine. the 1.1 isnt going to give you much for alot of money
     
  5. Evanditchburn21

    Evanditchburn21 Wrench Pro

    Messages:
    22
    From:
    Stockton-on-tees
    Car:
    Peugeot 206 1.1
    Thanks mate! Only wanted a new system as my cat has a couple of holes next to the bracket and sounds awful. Any cheap fix idea or would you just suggest on buying a new cat if there's no point In buying a full aftermarket system?
     
  6. davalav

    davalav Moderator

    Messages:
    3,617
    From:
    Essex, England
    Car:
    Mini Cooper S R56
    I was being a bit nice... :p

    Just replace with a bog standard exhaust system, and save for a newer car. Maybe even a 206 gti? :D
     
  7. Evanditchburn21

    Evanditchburn21 Wrench Pro

    Messages:
    22
    From:
    Stockton-on-tees
    Car:
    Peugeot 206 1.1
    Haha thanks anyway mate. I tried insurance for a 206 gti and insurance for me was 3000 so that's a no go. Think il be turning to a golf tdi 1.9. It's half the price for insurance which I don't understand lol
     
  8. pgarner

    pgarner TC ModFather Moderator

    Messages:
    16,521
    From:
    Lockerbie, SW Scotland
    Car:
    Octy smoke machine
    depending on how bad the holes are you might get away with welding them up. quick fix if your looking at getting rid of it.

    re 1.9 tdi make sure you go for the 130 ;)
     
  9. old-git

    old-git Moderator

    Messages:
    9,182
    From:
    Essex
    Car:
    Elan & Robin Hood
    Why do you want back pressure?
     
  10. davalav

    davalav Moderator

    Messages:
    3,617
    From:
    Essex, England
    Car:
    Mini Cooper S R56
    I have been lead to believe that a small amount of back pressure helps the flow of exhaust gases. If you remove the cat, especially on my car, you loose effiency from the exhaust resulting in the exhaust gases just piddling out. Hence loss of power. I just figured it would be the same, unless my understanding is completely wrong, in which case, please explain to me! :embarrest:
     
  11. old-git

    old-git Moderator

    Messages:
    9,182
    From:
    Essex
    Car:
    Elan & Robin Hood
    One of the most misunderstood concepts in exhaust theory is backpressure. People love to talk about backpressure on message boards with no real understanding of what it is and what it's consequences are.

    The exhaust system is designed to evacuate gases from the combustion chamber quickly and efficently. Exhaust gases are not produced in a smooth stream, they originate in pulses. A 4 cylinder motor will have 4 distinct pulses per complete engine cycle, a 6 cylinder has 6 pules and so on. The more pulses that are produced, the more continuous the exhaust flow. Backpressure can be loosely defined as the resistance to positive flow - in this case, the resistance to positive flow of the exhaust stream.

    Some people operate under the misguided notion that wider pipes are more effective at clearing the combustion chamber than narrower pipes. It's not hard to see how this misconception is appealing - wider pipes have the capability to flow more than narrower pipes. So if they have the ability to flow more, why isn't "wider is better" a good rule of thumb for exhaust upgrading? In a word - VELOCITY. A good analogy is the garden hose. If you let the water just run unrestricted out of the house it flows at a rather slow rate. However, if you take your finger and cover part of the opening, the water will flow out at a much much faster rate.

    The astute exhaust designer knows that you must balance flow capacity with velocity. You want the exhaust gases to exit the chamber and speed along at the highest velocity possible - you want a FAST exhaust stream. If you have two exhaust pulses of equal volume, one in a 2" pipe and one in a 3" pipe, the pulse in the 2" pipe will be traveling considerably FASTER than the pulse in the 3" pipe. While it is true that the narrower the pipe, the higher the velocity of the exiting gases, you want make sure the pipe is wide enough so that there is as little backpressure as possible while maintaining suitable exhaust gas velocity.

    Backpressure in it's most extreme form can lead to reversion of the exhaust stream - that is to say the exhaust flows backwards, which is not good. The trick is to have a pipe that that is as narrow as possible while having as close to zero backpressure as possible at the RPM range you want your power band to be located at. Exhaust pipe diameters are best suited to a particular RPM range. A smaller pipe diameter will produce higher exhaust velocities at a lower RPM but create unacceptably high amounts of backpressure at high rpm. Thus if your powerband is located 2-3000 RPM you'd want a narrower pipe than if your powerband is located at 8-9000RPM.

    I often wonder how the myth "Engines need backpressure" came to be. I believe it is a misunderstanding of what is going on with the exhaust stream as pipe diameters change. For instance, someone with a Civic decides he's going to uprade his exhaust with a 3" diameter piping. Once it's installed he notices that he seems to have lost a good bit of power throughout the powerband. He makes the connections in the following manner: "My wider exhaust eliminated all backpressure but I lost power, therefore the motor must need some backpressure in order to make power." What he did not realize is that he killed off all his flow velocity by using such a ridiculously wide pipe. It would have been possible for him to achieve close to zero backpressure with a much narrower pipe - in that way he would not have lost all his flow velocity.

    The faster an exhaust pulse moves, the better it can scavenge out all of the spent gasses during valve overlap. The general idea is a fast moving pulse creates a low pressure area behind it. This low pressure area acts as a vacuum and draws along the air behind it helping to evacuate the combustion chamber ready for the next charge.
     
    claymore and T9 man like this.
  12. adam1983

    adam1983 Road Burner

    Messages:
    339
    From:
    UK, Nottingham
    Car:
    Supra T67dbb 6Spd
    Excellent write up OG. Cleared up a lot of misconceptions people have with regards to the size of exhaust to go for.
    You see a lot of boy racers with big exhausts knocking about thinking its making the car faster when in fact it's either made no difference or had a negative affect.
    Is there a guide to what size pipe is most efficient to horsepower?
    Does having a turbo come into the equation as they run on exhaust gases?
    If my questions don't make any sense apologies in advance ;)
     
  13. T9 man

    T9 man TC Pro Founder Moderator

    Messages:
    20,369
    From:
    London, UK
    Car:
    Saab 9-3SS T9
    Thanks OG, I have just copied that write up and stuck it in my car notes for future reference ;)
     
  14. HugoBoss

    HugoBoss The Torque Meister

    Messages:
    1,488
    From:
    Australia NSW
    Car:
    r33 skyline gtst
    Almost every engine is different so there's no real calculation I'm aware of, it boils down to finding someone who has already tuned a exhaust system for your particular car, I've heard of gains between 15 and 25 kW by changing to a properly tuned system, unfortunately these are usually hard to find and very pricey. The real problem is to find someone that has tuned up a system for your car already, as this is usually done in a trial and error manner.
     
  15. davalav

    davalav Moderator

    Messages:
    3,617
    From:
    Essex, England
    Car:
    Mini Cooper S R56
    VELOCITY

    Thats what I got confused with! I am fully aware that a larger bore exhaust may reduce the flow, and a smaller exhaust will help with velocity.

    Anyway, thanks OG, nice write up. Maybe it can be a make a sticky?
     
  16. tecco

    tecco Wrench Pro

    Messages:
    31
    From:
    Danmark Horsens
    Car:
    Peugeot 206 GTI
    15-25kw gain on a 44kw car only from tampering with the exhaust system? :blink:
    Sounds like a fairy tale to me :lol:
     
  17. SLEEPER

    SLEEPER Pro Tuner

    Messages:
    2,783
    In a word yes - Turbo(s) completely change the exhaust charachteristics .

    This is because the exhaust gases are not constructively used to produce power on an NA engine whereas they are used to drive the vanes of the turbo(s). These "used " gases are then discharged sometimes back into the exhaust system and sometimes directly into the atmosphere through a seperate short unsilenced pipe. (usually called a screamer pipe for obvious reasons).
    So although the basic "rules" for exhaust gases remain the same this fundemental difference affects the workings of the exhaust and therefore the design.
    Also turbo engines usually rev higher and produce more power per litre than NA engines and higher revs mean more exhaust gases .
    So OGs excellent explanation explains why bigger bore exhausts will give good results on turbo cars
    As to size of pipe - I would say you need to be running serious power to need an exhaust much bigger than 3 inches
     
  18. HugoBoss

    HugoBoss The Torque Meister

    Messages:
    1,488
    From:
    Australia NSW
    Car:
    r33 skyline gtst
    You're right tecco those figures are obviously not for a 44kw car they are merely figures that have been obtained just by tinkering with the exhaust and will be different for each car and state of tune, what I tried to say was that done properly a tuned exhaust can give noticable gains, but some homework and lots of money will be required.
     
  19. old-git

    old-git Moderator

    Messages:
    9,182
    From:
    Essex
    Car:
    Elan & Robin Hood
    Being the pedant that I am, exhaust mods don't actually increase the engine's ability to generate horsepower, they just allow it to breathe better and so get closer to it's optimum output.

    To actually increase horsepower changes have to be made to increase the engine's capacity to suck in air. A properly designed exhaust then allows the spent gasses to escape.
     
  20. HugoBoss

    HugoBoss The Torque Meister

    Messages:
    1,488
    From:
    Australia NSW
    Car:
    r33 skyline gtst
    Yip, but you'd be surprised at how poorly some stock systems were designed,
     
  21. old-git

    old-git Moderator

    Messages:
    9,182
    From:
    Essex
    Car:
    Elan & Robin Hood
    No, I wouldn't. :) Production exhaust systems were designed to fit a space and a price. The extra few HP available from an optimum system wasn't worth the cost to 'normal' car manufacturers. You would struggle, however, to improve the exhaust system of a high priced super car.
     
  22. SLEEPER

    SLEEPER Pro Tuner

    Messages:
    2,783
    as og says its the reverse really a bad exhaust will restrict power a good one will merely lose the minimum amount.

    Just to clarify (pedants rule :bigsmile:) with a turbo set up the exhaust system doest power the turbos(s) the exhaust gases do which will be there anyway
     
  23. HugoBoss

    HugoBoss The Torque Meister

    Messages:
    1,488
    From:
    Australia NSW
    Car:
    r33 skyline gtst
    :cheesy:;):lol:
     
  24. tecco

    tecco Wrench Pro

    Messages:
    31
    From:
    Danmark Horsens
    Car:
    Peugeot 206 GTI
    Hardly worth the effort on a car this small, he would be better off selling and buying a 1.4 or 1.6
    Costing so close to the same as the one he have and it will be cheaper than adding any form of tunings part, and he will get a noticable performance boost.
     
  25. TCJBOLDIE

    TCJBOLDIE Torque King

    Messages:
    4,890
    From:
    Brisbane
    Car:
    JB Starion
    Top write up OG .NA exhaust systems are more difficult to get the best performing pipe size and header design and length whereas turbos require a much larger dump pipe than the turbine outlet to get the best out of them and a hi flow cat ( if one is needed by law) as well as a free flowing straight thru system.
     
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