wanted 505 extractors
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  1. #1
    Tadpole
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    Apr 2001
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    melbourne,victoria,australia
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    25

    wanted 505 extractors

    need a set to suit 505 sli can any one help or do you know whre i can get them
    thanks
    john

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  2. #2
    Guru davemcbean's Avatar
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    Apr 2001
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    Camden NSW & Selwyn NZ
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    Ivan Washington, from the Peugeot Club of Victoria, used to make special tubular exhaust manifolds for 504s and 505s, as well as most other RWD Peugeots. I'm not sure if he still does. I'm not sure what cam timing their length was tuned for.

    Early model 505 2 litre manifolds were big bore and had a long secondary length. I've been told that after about 1983 they went back to the small bore short secondary length 504 type manifold, which is inferior.

    If you want the equation used to calculate the tuned length, etc, I can send it to you.

    It takes a bit of careful work to fit a nice tuned length extractor set up past the steering column on a right hand drive 505/504, but it can be done. There are some set-ups which go under the engine cross member and avoid the steering column entirely, but they are prone to damage due to low ground clearance.

    Regards,
    Dave McBean

    <font face="Verdana, Arial" size="2">Originally posted by John black:
    need a set to suit 505 sli can any one help or do you know whre i can get them
    thanks
    john
    NZ Fleet
    1976 504 Ti
    1984 205 GT twin carb
    1991 205 SI 1.6GTI motor
    1994 106 Xsi
    1996 Mondeo V6
    Aus Fleet
    1955 203C
    1997 Civic Cxi (great allrounder- revy, flexible, nimble, comfortable , economical, simple and durable )

  3. #3
    Fellow Frogger!
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    Mar 2001
    Location
    Brisbane, QLD, Australia
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    396
    I have heard that a set of extractors would be no better than the original manifold.

    I was told that you continue the twin pipes from the manifold down 750 mm to a collector and this gives the same extraction effect.

    Seems to be a pattern with the Pugs, as thats the same thing I was told about the 205 exhaust manifold, after I put on the extractors

    Seemed to make my engine feel happier to spin out to the higher revs, but didnt give any real increase in "power" as such...

    Sounds good tho...

    Chipper

  4. #4
    Guru davemcbean's Avatar
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    Apr 2001
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    Generally, the longer the cam timing, or the larger the cylinder capacity, the longer the pipes have to be before meeting at the collector.

    The standard 504 manifold and system can be a little restrictive when larger duration cams, etc are used. When I modified my 504 engine with 266 degree cam, slightly modified head and Weber carb, I found that the engine felt smoother than before up until 6800rpm when it felt like you were hitting a rev limiter, whereas in standard form 504s (the early ones with oil bath aircleaner) have no trouble reving up to 7000rpm and even beyond. Admittedly there is no gain in reving a 504 past 6000rpm, but it is an indication of breathing ability. Being very rigid motors with a good steel crank, they seem to be unbreakable unless they're low on oil or pinging.

    I replaced the exhaust manifold with a non-tuned length, but free flowing 4 into 1 manifold joining into a 2.25" mandrel bent system with a tri-flow front muffler and log-leg rear resonator. After this the mid range and peak power and torque felt exactly the same as before, however the engine felt much more tractable below 2000rpm (it was already excellent in this respect) and it reved out to 7000rpm quite easily (athough with pushrod engines those revs are always noisy).

    It sounds funny that the engine improved at both low and high rpm, but when you think about it it is not quite a silly as it sounds. When the manifold is tuned length, it is designed to give an advantages extraction effect (negative backpressure) at a certain rpm, but can have unfortunate shockwave effects at other rpm (increasing back pressure). When a manifold is just designed to be very free flowing but with no extraction effect at any rpm (like the old pre-WW2 racing cars) it tends not to have and negative effects at any rpm, but you don't have the advantage of an extraction effect at a particular rpm and so peak power and torque are not as high as a tuned manifold joined to the same exhaust system. The disadvantage of a system which just works on the free flow principal to reduce backpressure is that they can be very noisy.

    If I had my time again, I would probably just use an early 505 manifold (possibly with a longer down pipe and large collector), a good quality large diameter tri-flow front muffler, and I would leave the rest of the system as per standard. I think this would give the best compromise between free flow, quietness and cost.

    Dave


    <font face="Verdana, Arial" size="2">Originally posted by Chipper:
    I have heard that a set of extractors would be no better than the original manifold.

    I was told that you continue the twin pipes from the manifold down 750 mm to a collector and this gives the same extraction effect.

    Seems to be a pattern with the Pugs, as thats the same thing I was told about the 205 exhaust manifold, after I put on the extractors

    Seemed to make my engine feel happier to spin out to the higher revs, but didnt give any real increase in "power" as such...

    Sounds good tho...

    Chipper
    NZ Fleet
    1976 504 Ti
    1984 205 GT twin carb
    1991 205 SI 1.6GTI motor
    1994 106 Xsi
    1996 Mondeo V6
    Aus Fleet
    1955 203C
    1997 Civic Cxi (great allrounder- revy, flexible, nimble, comfortable , economical, simple and durable )

  5. #5
    Guru davemcbean's Avatar
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    Apr 2001
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    Camden NSW & Selwyn NZ
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    2,334
    On the subject of back pressure, a separate tuned length pipe for each cylinder emptying into the atmosphere with no measurable backpressure will always give higher power and torque figures than any other system. It has been proven in many engine labs and it completely agrees with the laws of fluid mechanics and thermodynamics. This is why Spitfires and other piston engine planes have separate pipes for each cylinder emptying into the atmosphere.

    An engine which produced more torque when more backpressure was present would disobey the laws of physics and belongs in fairy land. Torque is produced by gas pressure pushing on the pistons during the power stroke. A backpressure pushing on the pistons during the exhaust stroke can only subtract from the engine torque, this much is blatantly obvious.

    When people claim that an engine produced less torque because it didn't have enough back pressure, usually some of the following factors were at work:

    1. They never measured the backpressure (they just assumed it was lower) of the new system and unbeknown to them the backpressure was actually increased due to poor design.

    2. They destroyed all the advantages extraction effects designed into the original system.

    3. The new manifold had unfortunate effects which caused it to develop bad pressure waves at certain rpm which increased backpressure

    4. The fuel or ignition systems were not correct for the new lower backpressure and needed to be adjusted to suit.

    A properly designed tuned length exhaust manifold matched to the engine specification (cam timing etc), with a well designed exhaust system to reduce back-pressure will always produce better results than any other system. Sometimes however it is not worth the effort. On road cars producing less than 70hp per litre (like 8 valve engines), a really low backpressure system will not gain you much and will just make the car noisy. The biggest gains can be had in replacing the front muffler, which is typically the primary source of restriction. Tri-flow mufflers like the Walker super turbo are much better than the standard mufflers and are not noisy when used in conjuction with the standard tail pipe and rear muffler. This is also far cheaper than any other exhaust modifications. Don't expect to gain more than 5 percent more power and torque, unless the engine has a much wilder specification (wild cams or 16 valves). Typically you need atleast a 5% gain before you can feel the difference.

    Some cars with really bad standard exhaust manifolds (like alot of GM and Ford V8s) can gain 10 or even 20% more power and torque by using an after market exhaust manifold and system. Four cylinder engines of European and Japanese manufacture, typically have well designed exhaust manifolds and the gains from using an after market exhaust manifold and system on an otherwise standard engine are typically small to negligible.

    Dave

    <font face="Verdana, Arial" size="2">Originally posted by davemcbean:
    Generally, the longer the cam timing, or the larger the cylinder capacity, the longer the pipes have to be before meeting at the collector.

    The standard 504 manifold and system can be a little restrictive when larger duration cams, etc are used. When I modified my 504 engine with 266 degree cam, slightly modified head and Weber carb, I found that the engine felt smoother than before up until 6800rpm when it felt like you were hitting a rev limiter, whereas in standard form 504s (the early ones with oil bath aircleaner) have no trouble reving up to 7000rpm and even beyond. Admittedly there is no gain in reving a 504 past 6000rpm, but it is an indication of breathing ability. Being very rigid motors with a good steel crank, they seem to be unbreakable unless they're low on oil or pinging.

    I replaced the exhaust manifold with a non-tuned length, but free flowing 4 into 1 manifold joining into a 2.25" mandrel bent system with a tri-flow front muffler and log-leg rear resonator. After this the mid range and peak power and torque felt exactly the same as before, however the engine felt much more tractable below 2000rpm (it was already excellent in this respect) and it reved out to 7000rpm quite easily (athough with pushrod engines those revs are always noisy).

    It sounds funny that the engine improved at both low and high rpm, but when you think about it it is not quite a silly as it sounds. When the manifold is tuned length, it is designed to give an advantages extraction effect (negative backpressure) at a certain rpm, but can have unfortunate shockwave effects at other rpm (increasing back pressure). When a manifold is just designed to be very free flowing but with no extraction effect at any rpm (like the old pre-WW2 racing cars) it tends not to have and negative effects at any rpm, but you don't have the advantage of an extraction effect at a particular rpm and so peak power and torque are not as high as a tuned manifold joined to the same exhaust system. The disadvantage of a system which just works on the free flow principal to reduce backpressure is that they can be very noisy.

    If I had my time again, I would probably just use an early 505 manifold (possibly with a longer down pipe and large collector), a good quality large diameter tri-flow front muffler, and I would leave the rest of the system as per standard. I think this would give the best compromise between free flow, quietness and cost.

    Dave


    NZ Fleet
    1976 504 Ti
    1984 205 GT twin carb
    1991 205 SI 1.6GTI motor
    1994 106 Xsi
    1996 Mondeo V6
    Aus Fleet
    1955 203C
    1997 Civic Cxi (great allrounder- revy, flexible, nimble, comfortable , economical, simple and durable )

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