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Anatomy of an Ansa (cutting open a 308 exhaust)

Discussion in '308/328' started by Nuvolari, May 25, 2017.

  1. Nuvolari

    Nuvolari F1 Veteran
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    #1 Nuvolari, May 25, 2017
    Last edited by a moderator: Sep 7, 2017
    I'm in the process of doing a service to my carb 308 and decided that a new exhaust was long overdue. While not rotted it did have some internal cracks that were not practically repairable which affected the quality of the engine note. Before committing to a new unit I cut open the old one in the hopes that it could be repaired and to see inside.

    While often shrouded in mystery as to what is actually in an Ansa exhaust can, I took some photos to show what lurks beneath the skin. As you will see the front and rear banks of cylinders are treated totally separately. In fact there is a solid divider in the muffler casing that creates two chambers inside of the muffler (one for the 1-4 bank and one for the 5-8 bank).

    The path of the exhaust is as follows:

    1. The exhaust enters in via the inlet tube for the particular bank and is released into an empty expansion chamber located near the middle of the muffler body.

    2. The exhaust gasses pass past a divider wall that is maybe 40-50% covered in holes that are about 1 cm in diameter.

    3. The gasses then enter into two perforated tubes that are in a chamber that is filled with a fiberglass like packing.

    4. Each one of the perforated tubes exit the muffler case as a solid tube and feed the exhaust tips.

    I have totally no expertise in the field of exhaust design and will make no gut observations of what I think is right or wrong about this design. All I wanted to do from this post is report what is inside an Ansa exhaust can and show some photos to illustrate the above explanation. Here are the pics:
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  3. 308Dadoo

    308Dadoo Formula Junior
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    So based on what you have discovered what are your plans with the exhaust for your 308 now?
     
  4. mike32

    mike32 F1 Rookie

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    Scrap bin i would think as that going to leak a bit
     
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  5. wildcat326

    wildcat326 Formula 3

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    Hey, BIG favor request: While it's off the car, could you possibly weigh it (along with the panel you've cut off)? I'm trying to keep careful track of how I've altered my car's weight, and the only variable I forgot to check was the weight of the Ansa that I sourced, vs the stock muffler (stock on a 79 GTS is 45.6lbs!).
     
  6. guygowrie

    guygowrie Formula 3
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    I opened mine to repair a loose baffle, removed all the remnants of fibreglass packing and welded it back up. Sounds good.
     
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  8. Nuvolari

    Nuvolari F1 Veteran
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    No problem. 36.8 lbs including all of extra bits not visible in the photo.
     
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  9. Rifledriver

    Rifledriver Two Time F1 World Champ

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    Originally the open space was tightly packed with dense glass wool mat.
     
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  10. Martin308GTB

    Martin308GTB F1 Rookie

    Jan 22, 2003
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    what would you recommend after opening an old exhaust? Removal of all remaining glass wool? Or replacement with new stuff? Is this even practicable?

    My exhaust doesn't sound nice any more and I have to decide. A new exhaust or rebuilding my old one (ANSA four pipe Euro carb system)


    Best Regards
    Martin
     
  11. Nuvolari

    Nuvolari F1 Veteran
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    Maybe the wine got to the factory workers the day my exhaust was made but there was zero trace of packing in the empty areas. You never know with the Italians :)
     
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  13. Rifledriver

    Rifledriver Two Time F1 World Champ

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    It burned up and went out the tail pipe. It was just part of the Ansa life cycle. . The more it broke up, the more it was sucked through the perforations of the pipe.

    Timevalve is making some very correct reproductions.
     
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  14. Rifledriver

    Rifledriver Two Time F1 World Champ

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    If you can get very dense sheets of it. It makes it a little quieter and mellow sounding. If the metal is still in good shape I don't see why it cant be done.
     
  15. MNExotics

    MNExotics Formula 3

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    I was fully expecting to see a different design internally. Cool stuff
     
  16. Albert-LP

    Albert-LP F1 Veteran
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    that's a standard exhaust that had to pass the Italian noise test. It was full of glass wool, in the last chamber. It works much with expansion chambers rather then with passive race noise insulation (sorry I don't know the name in english). I think (never opened one) that the Tubi exhaust works with the direct exhaust (just a passive resonance chamber full of rock wool outside a just one perforated pipe), as the sound is completely different from this Ansa one, that just was an OEM sport exhaust that had to fulfil all the rules, while the Tubi (and others repro loud exhausts) hasn't
     
  17. Albert-LP

    Albert-LP F1 Veteran
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    install it just in the last chamber or it will burn: it doesn't allow more than 700 °C of peak temperature and the working point must be below 500 °C

    http://www.athenaparts.com/files/pdfs/S410000999001.pdf

    Pay attention and topuch it just with a very thick pair of leather gloves, better if with inside another protective plastic glove

    ciao
     
  18. vaccarella

    vaccarella Formula 3

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    Very interesting. I put some fresh Ansa stickers on the tail pipes a while back and noticed one of the inner ones has now almost burnt off, whilst one of the outer ones is almost like new. Could this be down to the difference in the amount of glass wool burnt out of the chambers?
     
  19. JCR

    JCR F1 Veteran
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    #16 JCR, May 26, 2017
    Last edited by a moderator: Sep 7, 2017
  20. RAMMER

    RAMMER Formula 3

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    I have no idea!!!!
     
  21. RAMMER

    RAMMER Formula 3

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  22. mike996

    mike996 F1 Veteran

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    I have never figured out where "back pressure" came from as some sort of "need" for an exhaust system. But people use that term all the time and claim the engine "needs" back pressure, which is absurd.

    The reversion wave, is a different thing and adjusting it - usually with collector length - can move the power band around. In my drag racing/engine building days, we carried several different lengths of collectors to the track. We would bolt whichever length we thought was optimum for the day/track conditions.

    FWIW, we did dyno tests that often showed that an aftermarket straight-through, "high performance" (loud) muffler made less power than new stock mufflers on some cars. I have no idea re the stock 3x8 muffler vs something like a Tubi on the dyno but I would not be surprised if there wasn't much difference. Often just because something looks restrictive to the eye doesn't mean it is to the engine. ;)

    To illustrate that - we dyno tested a set of well known, very loud straight through mufflers on a small block chevy and found that there was absolutely no gain from the aftermarkets. But it sounded faster! :)
     
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  23. Saabguy

    Saabguy Formula 3
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    For those of us with 2 stroke engines, the "back pressure" or resonance wave (?) is VERY important! No exhaust means melted pistons.


    I realize that most of you don't own 2 stroke cars... but just FYI.
     
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  24. JC Andruet

    JC Andruet Karting

    Jan 16, 2013
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    Having seen the guts of the Ansa system, we can sleep soundly at night, safe in the knowledge that "Ferrari tax" is alive and well.

    https://mrfiat.com/italian/ferrari/208-308-328-gtb-gts/exhaust/ferrari-308-gtbi-gtsi-2-valvole-ansa-rear-muffler-assembly.html

    And yes, I'm well aware some "development" would have been required 40 + years ago (though I think we all know that would have pretty much have been a case of "Does it sound louder ?" and little else) and the assembly jigs would have required fabrication. But 40 + years of production must have netted some very healthy profits for Ansa. Which would be fine if they wee producing a premium quality exhaust, but on the basis of the image posted earlier in this thread, they aren't.

    The TubiStyle is slightly more palatable at $2500

    https://www.eurospares.co.uk/tubi-exhausts/1?ModelName=308%202v.

    QuickSilver definitely applying Ferrari tax $2800

    https://quicksilverexhausts.store/products/308-gtbi-gtsi-stainless-steel-exhaust-1981-83

    No discount for the single pipe version (both systems are cleverly named and marketed under the "Heritage" banner) :

    https://quicksilverexhausts.store/collections/ferrari-309/products/308-gtb-gts-1-x-tail-pipe-stainless-steel-exhaust-1975-77
     
  25. dave80gtsi

    dave80gtsi Formula 3
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  26. AZDoug

    AZDoug Formula 3

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  27. RAMMER

    RAMMER Formula 3

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    Here are pictures of my original 1976 thermal muffler. I actually like the girthy tips (take your shots). This was removed because it had a loud rattle inside. I am saving it because I am an originality buff. Before you ask, I just weighed it and it weighs 71 pounds. It actually feels heavier than that!
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  28. nerofer

    nerofer F1 World Champ

    Mar 26, 2011
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    I have posted that one a few times already, but, For What It is Worth, here are the internals of the standard, Euro NON-CAT, factory exhaust of the four valve cars (Quattrovalvole and 328)

    Rgds
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