Explain the hate for the Sound Symposer

Discussion in 'Fiesta ST Chat and Discussion' started by BRGT350, Jan 12, 2015.

  1. Smokin

    Smokin Active Member

    interesting read fella's....

    I completely agree with you Bryan. Since I autocross a lot, here are my observations....Yes the sound symposer is authentic intake noise. Like a big old four-barrel....not in function but in noise output.
    No, it does not conflict with or cause drone of exhaust noise. And I have a 2jracing 3" exhaust that's got lots of drone....

    Just for shits and grins I took the foam part out and put a rubber stopper in the tubing. All it did was stop that whaaa sound on heavy acceleration. It doesn't make the turbo spool faster. It didn't make me go faster. (I'm kinda laughing about that one). it didn't affect the exhaust noise. And I put it back the way it was.

    In the midst of an autocross you can't look at the tach so engine noise is important. I doubt my exhaust provides much performance gain either but I do have auditory feedback while running with a big 'ole helmet on. And it's not just redline noise we look for. Since these are low powered cars I want to have all the sensory input I can have going through elements and for me sound is one of them. Intake and exhaust sounds are different. For instance in longer corners/sweepers I can tell if I'm managing engine power with light throttle or backing off, back on, and use the sound to control my driving especially since you can steer these cars with the throttle.

    And finally I really agree with you that the community (lemmings) you're addressing most likely knows nothing about the sound symposer. Kinda like questions I've seen like "when should I shift?"
    Last edited: Jan 16, 2015
    BRGT350, Firesail and marc89gti like this.
  2. Register or Sign in

    Advertisement Sponsor

  3. WestcoastST

    WestcoastST Active Member

    I put a rubber plug inside of mine to deaden the noise coming inside the cabin. The Symposer is a plastic part, and could, not necessarily would develop cracks over time. I personally plan on plugging my symposer inlet hose with a Turbosmart BOV plug ($10.40, including shipping at Summit Racing), primarily for peace of mind. I don't want to have to pull over at 4:00 A.M in 2019 with a boost leak, and have to call a tow truck and miss work. I know that most plastics release plastizer, become brittle, and fail over time. Because the FiST is so new, we haven't had any failures, but I'm sure Ford engineering knows the life of the symposer is not infinite. Remember, we are putting 20+ PSI into this closed, plastic box, with 10+ PSI average load. I'd rather have a plug in there. The fatigue strength of aluminum and silicone hose is greater than plastic.
  4. BRGT350

    BRGT350 Well-Known Member Staff Member

    As far as I can tell, nobody has actually proven that the sound symposer membrane's service life. There is a good chance that it is being loaded below the fatigue life curve and has infinite life. A low stress plastic part has a far better fatigue life than a highly stressed aluminum part. There isn't any actual proof that sound symposer is a weak link, just a lot of hypothetical claims. Looking online at Focus ST owners, it seems the internal parts of the engine are way more of a concern for failure. I see broken motor posts all the time, but haven't seen anything about a symposer failing.

    As for plastic standing up to a 20psi max load and average 10 psi load (which I bet the average is actually closer to low single digit amounts), I used to design valves that would operate for hundreds of thousands of miles at a max of 120 psi and continual load of 80psi. Many of those products where made from plastic. Chemicals attacking the seals were more of a problem than the plastic failing.
    marc89gti likes this.
  5. WestcoastST

    WestcoastST Active Member

    Most plastics do not have an endurance limit. This means that they cannot have an infinite life. A good example is a shower curtain that embrittles and falls apart, even though it is only supporting its own weight, and is subjected to mild water temperature extremes and soap. Another example is car headlights where the bulb holder cracks and fails due to embritlement brought out by the plastics' exposure to heat from the light bulb. Comparing plastic vs aluminum at two different stresses (low vs high) is comparing apples to oranges. Plastic loses its ductility as a function of age, due to plastizer release. Metals, in the underhood environment, external to the engine, do not suffer ductility losses.

    Concerning your comment on proving the membrane's service life, there are no MTBF results for any parts provided to the general public. Parts are typically designed with a safety margin to exceed the service life of the vehicle. Whether a plastic will withstand a given environment, depends on the chemical composition of the plastic. HDPE plastics are known to embrittle under fatigue loading, depending on the cyclic asymmetry (Polymer mechanics, Jan/Feb 1977, Vol. 13, issue 1, pp 31-36, endurance limit of polyethylene during cyclic loading under conditions of plane stressed state"). Granted there is no proof that this specific part fails, but in general terms, plastics have a higher failure rate than metals, in an underhood environment. New advances in composite chemistry have improved plastics, but the only real advantage plastics have over metals is their low density and weight, and in some cases, heat transfer. This fact drives car makers to use plastics in their effort to reduce weight and improve miles per gallon ratings. This is the same driver that results in aluminum hoods vs carbon steel hoods.

    FYI, I perform failure analyses on both composite and metallic components for Aerospace applications. My experience moves me to replace parts which serve no purpose, but may result in temporary failure of a pressurized system, based on FMEA principles. FYI, I don't hate the noise from the kazoo, but with an aftermarket exhaust, it is superfluous.
  6. BRGT350

    BRGT350 Well-Known Member Staff Member

    I buy into your analysis and all are good points. Probably some of the best points brought up for the removal of the sound symposer. As the Fiesta ST ages, it will be interesting to see any sound symposer failures. I plan on keeping my car for about 4-5 years, in which 3 of that are covered under warranty. If I get a failure in the first 3 years, assuming it fails in year 2, the replacement part will last the life of the car for me. Your analysis of the part and why to replace it is far better than the comments I get on YouTube and see on Facebook, which is "remove it because it is gay as f***". That is a horrible stance to take for replacing a part.

    Thanks for bringing the tech!
  7. reddog99

    reddog99 Active Member

    The "10+ PSI average load" is obviously just a WAG, as the boost in the real world is mostly in the negative range (with "real world" being the street, not the track). I watched my boost on my way home from work today, and I saw only 2-4 psi boost while traveling up a 6 deg. mountain grade, at 4000 ft, and cruising at 80 mph. The "average" boost (providing you can even define average) is mostly in the negative range for non-agressive steady-state driving.
  8. WestcoastST

    WestcoastST Active Member

    Non aggressive? How do you do that? It's an ST, not a prius. Today i raced a V6 mustang with exhaust, possibly more mods, got way over negative boost and beat him. Cobb Rev limiter and select a tune rules.
  9. razorlab

    razorlab Active Member

    Make sure you replace the plastic intercooler piping that see 20+ PSI too if you that is your stance on plastic parts.
    Smokin likes this.
  10. Soldjeepforst

    Soldjeepforst Member

    Was it the new v6 mustang non eco boost because when I was at stage 3, back seats out, ffs and it was 55 degrees out he pulled after 110. Huge difference from those older v6s. My friends 2013 v6 mustang hits 60 in 4.9 seconds and he only has a couple mods.
  11. WestcoastST

    WestcoastST Active Member

    2011 V6 Mustang. We didn't have enough room to get above #$. Boy the look on his eyes after the first stop was worth it.
    RZL, Good to see you haven't given up on us. Totally different plastic than the symposer.
    Last edited: Jan 20, 2015
  12. BRGT350

    BRGT350 Well-Known Member Staff Member

    If my turbocharger fell off in December, I probably wouldn't know it was missing until April. I very rarely get into boost in the winter because there is so little traction and it is rare I get to reach the speed limit on my commute. My ST spends way more time with more suck and less blow.

    Just a friendly FYI, no posting about exceeding the speed limits or street racing on the forum.
  13. Soldjeepforst

    Soldjeepforst Member

    Because of your stupid ass comment im going to make a 120 wot pull and edit it nice. Hope your liberal ass enjoys it. Ill post what ever I feel like it.
  14. BRGT350

    BRGT350 Well-Known Member Staff Member

    actually, as a moderator on the site, I am required to enforce the rules. I could probably ban you for your comments, but you will get off with a warning. I don't take kindly to your comments. By the way, I would suggest an apology for your actions.
    Turboduck01, marc89gti and reddog99 like this.
  15. Smokin

    Smokin Active Member

    hey genius... "FYI, I perform failure analyses on both composite and metallic components for Aerospace applications. My experience moves me to replace parts which serve no purpose, but may result in temporary failure of a pressurized system, based on FMEA principles. FYI, I don't hate the noise from the kazoo, but with an aftermarket exhaust, it is superfluous."

    There's a difference between intake and exhaust sounds.....

    And oh yeah, Zippy the Chimp can go fast in a straight line....
  16. WestcoastST

    WestcoastST Active Member

    Obviously there is a difference between intake and exhaust sounds. At no point did I confuse the two. My point is, with an aftermarket exhaust, the sound from the symposer is drowned out by the exhaust. I think you are reading more into my post than I intended. Thanks for the genius complement, though.
    timboslice and RodMoe like this.
  17. XR650R

    XR650R Member

    You want to race the car.
    You have a louder exhaust, so you don't need it.
    You're an audiophile.
    You don't need it to know when to shift.
  18. ZREXER

    ZREXER Member

    Sound like someone needs a hug. When you do your 120 WOT pull, just don't run over my kids as I will be kind of pissed. If we are lucky you will get pulled over by the police and you can sit and think about driving for a year while you are banned from driving, but I am sure someone with your mentality would drive without insurance or the legal right to do so anyway.
    marc89gti and reddog99 like this.
  19. BlackBird

    BlackBird Active Member Staff Member

    Bringing terms like 'liberal" into a car discussion. So on-topic. Tsk, tsk. Let's keep it civil. Don;t make myself or BRGT350 have to do our jobs. I for one prefer to be lazy.
  20. jfdana

    jfdana Member

  21. BRGT350

    BRGT350 Well-Known Member Staff Member

    Firesail and LuvfiestaST like this.

Share This Page