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Here is the thing people dont get.
Sport mode turns on sound symposer, puts the exhaust in sport mode and usually gives a downshift to raise RPM.
People are thrilled by the instant gratification of all those collective increases of sporty sounds.
Turning off sport exhaust does not close the symposer.
Therefore the need to plug the symposer still exists.
People mistake the symposer sound for increased PSE sound.
PSE opens automatically above 4K (in any mode) so that is why people say it is louder than base exhaust.
Sport Exhaust off is actually very quiet and restrictive (but you only get it at low RPM).
Id bet that if it stayed off above 4K that it would be quieter than base exhaust.
You need the symposer disabled to realise all this.
Also, I found that when the Change Over Valve fails, PSE stays in sport mode.
So the bypas must be Normally Open, which is the opposite of what I would have expected.
Bumping this thread as I'm still confused on the symposer.
PSE is easily understood. Button on - on. Button offf - off below 3k-ish RPM, on above.
But what about the symposer? Is it only on in sport and sport plus? Does it come on with the PSE if I press the button in normal mode? Does it open at 3k rpm like the valves in normal mode, PSE off?
I had completely forgotten about the symposer until a recent thread brought it up.
The symposer is a tube that allows intake noise into the cabin all the time. There is no valve on it at all- just a one way filter that allows the noise but no fumes to pass. It has absolutely nothing to do with the sport exhaust. It makes a "noise" that matches the intake air flow- increasing with rising revs, and holding steady at constant revs. That makes it constant and a boring to many, and, to me, annoying at normal cruising speeds. I usually turn the PSE off when idling along at the 991's low rev cruising speeds, and on when driving where speed and gear varies.
The Porsche Sport Exhaust system opens a path from the headers that allows more noise to flow out of the tailpipes. When open it makes more noise. The electronics also adjust gas flow to produce "heroic" overtones deeper with pops, on overrun.
The 991.2 has two supposer tubes. I haven't had a chance to see if it also is "boring" at constant speeds, but it sure sounds good under acceleration and on overrun- not quite as good as the 991.1, but pleasantly sporty - as opposed to just "rorty", like jags and Mercs.
My buddies new M6 has the exhaust note coming through his stereo system to "add" electronically to what the tailpipies don't do enough of on their own.
The i8 does the same thing! However, it could be kind of fun if you had the sound pumping through a stereo with 2000 watts of power and some 15" subs
I had the symposer blocked on the engine side and then removed the back inside panel and blocked it from the inside too. It is behind your rear seats. It does not open and close with a valve it is just a tube that must be blocked.
I want to hear my exhaust naturally from the outside.
Actually, there is a vacuum valve for the symposer in a tube running from the intake to the port that is activated when Sport is pressed. You can see it in the parts diagrams.
Poking around, I see that Car&Driver also had a diagram showing it here. To kill it I guess you could hunt down the vacuum feed to that valve and cap it.
Originally Posted by chuckbdc
The symposer is a tube that allows intake noise into the cabin all the time. There is no valve on it at all- just a one way filter that allows the noise but no fumes to pass. It has absolutely nothing to do with the sport exhaust. It makes a "noise" that matches the intake air flow- increasing with rising revs, and holding steady at constant revs. That makes it constant and a boring to many, and, to me, annoying at normal cruising speeds. I usually turn the PSE off when idling along at the 991's low rev cruising speeds, and on when driving where speed and gear varies.
The Porsche Sport Exhaust system opens a path from the headers that allows more noise to flow out of the tailpipes. When open it makes more noise. The electronics also adjust gas flow to produce "heroic" overtones deeper with pops, on overrun.
The 991.2 has two supposer tubes. I haven't had a chance to see if it also is "boring" at constant speeds, but it sure sounds good under acceleration and on overrun- not quite as good as the 991.1, but pleasantly sporty - as opposed to just "rorty", like jags and Mercs.
Actually, there is a vacuum valve for the symposer in a tube running from the intake to the port that is activated when Sport is pressed. You can see it in the parts diagrams.
Poking around, I see that Car&Driver also had a diagram showing it here. To kill it I guess you could hunt down the vacuum feed to that valve and cap it.
Not sure where you found this, or what car it's supposed to be for, but it's Not for a 991.1. There is No valve
Not sure where you found this, or what car it's supposed to be for, but it's Not for a 991.1. There is No valve
I said it was an excerpt from Car&Driver, so I think your "Not sure where you found this..." is rather odd. Anyway, I'm have no idea how you can say "There is No valve" when the internet is full of reputable stories stating otherwise.
Beyond that, it's obvious to me just driving in the car ar a steady speed. If not in Sport and I press Sport, the intake noise noticeable increases. Close it again and the intake noise get significantly quieter. Outside that, just Google the key terms and see what you find.
Here is probably the most thorough article I see, and it has a pretty good photo of the valve including the typical vacuum valve fitting sitting in the middle of the hose to the symposer hookup. They also mention it in the text. Look at the eighth photo down and the text around that.
Achleitner said the new powerplant was so quiet that they had to add a second tube to the Symposer. "It was difficult from the engineering side to find the right location in the intake to hear the engine in the cabin so it sounds like a six cylinder," he said, "to optimize the membrane so it sounds like a flat-six, and so you don't just get the sound of air rushing by." He said the job proved so challenging that they only finished it six months ago.
from the Porsche Engineering page:
"What does that mean in practice? As soon as the driver hits the Sport button on the center console, sharpening the responsiveness of the transmission, engine, and suspension, the flaps in the sound symposer and the Helmholtz resonator open to allow unrestricted flow, intensifying the natural sound of the Porsche engine. If the intensity of the sound becomes too dominant, you can switch back to comfort mode and cruise along quietly."
I clearly had it wrong. Relecting on it, thats why it is quieter cruising with the Sport setting NOT pressed. What can I say? I know: D'OH!
So glad I plugged mine...annoyed the crap out of me...I want the real sound from the outside thank you not the drone inside...the car is already very high in ambient noise. There is a good post for the plug. Easy.
04-25-2014, 10:27 PM
However, it could be kind of fun if you had the sound pumping through a stereo with 2000 watts of power and some 15" subs 
