K-A

Hey all. I've been wondering if my sound symposer works after I read about the changeover valves having a potential effect on it.

My car has an X Pipe, so perhaps it's the sheer volume from that, or because I don't pay close enough attention to the immediate noise differences between normal and Sport/Sport+ modes, but I feel like I don't notice a difference in cabin sound between the modes. The cabin is surprisingly quiet when driving docile in any mode (and appropriately screams at aggressive throttle).

Is there a simple way or test I can do, to ensure it's working properly?

Thanks.

Code

Check this thread out, it's one way to test it by blocking the sound tube: https://www.6speedonline.com/forums/...poser-mod.html

K-A

Thanks, maybe I'll try that. I assume it isn't as easy as switching to Sport at like a steady 4K RPM's and seeing if it gets louder?

asia

For a 991.2 with PSE try full throttle accelerations from 6,000 rpm to redline with the windows closed. Compare Normal and Sport modes. At these rpms PSE exhaust valves are open in both modes, so the sound difference will be primarily induction related to the opening of the second symposer. On my car the sound difference measures about 5 or 6 dB(A), definitely a noticeable increase in induction sound, but not a large amount.

Windows open, lower rpms, and partial throttle tend to mask the difference.

Here is what Porsche says:

"Sound symposers
In addition to the new exhaust systems, two sound symposers provide for a particularly emotional sound in the passenger compartment. They transfer the load-dependent pressure differences upstream of the throttle valve to a diaphragm causing this to vibrate and transmit the engine sound directly into the passenger compartment. In normal mode, one sound symposer opens above an engine speed of 1,800 rpm.

In SPORT or SPORT PLUS mode, the second sound symposer is additionally activated at all engine speeds. During deceleration, the first sound symposer is always closed and the second is closed between 3,500 and 1,800 rpm."

K-A

Interesting, did they add another symposer on 991.2's to make up for the quieter sound? I have a 991.1 and thought there was one. Thank you for the info!

asia

Even with two I think Porsche was a bit shy with the induction sound, at least on my base C2. But I admit I am spoiled by the 981 2.7L.

Don't know about the .1, maybe a similar WOT redline test would tell?

K-A

Yeah I hear ya. Even the 991.2 GTS with PSE isn't that loud. My .1 3.4 with Sherkwerks X Pipe scream like a banshee, yet is docile at low revs. Truly perfect imo.

So I figured out the best way to hear the symposer! Highway, windows up, and keep it in manual shifting mode so it doesn't shift. Keep at about 3K RPM's or so (could be any RPM over a low hum) and click Sport/Sport +, you'll hear an immediate more throaty tone. Like a pipe opened up. They do a good job of making it sound like it's coming from outside. With windows down, my car is loud enough to where you hear the exhaust over everything so the symposer isn't as easy to tell.

Mine sounds like it's working just fine!

asia

You may be hearing the exhaust valve opening at 3k rpm.

On my car in Normal mode the exhaust value opens automatically, no matter the mode, at about 3,300 rpm.

Do at test at 6,000 or above at WOT. You need to get some air flowing to hear the induction sound, and make sure that the exhaust values are always open. Windows down the exhaust should sound the same. Windows up you should hear an induction noise change by toggling the PSE button. I believe on .1 cars with PSE the PSE button controls the symposer, however on cars without PSE, the Sport button does so.

Needsdecaf

I can hear the change when my symposer opens immediately, at just about any revs over 2,000. You definitely don't need to wind anything out on a 991.1 to hear the difference. It's very apparent. Which is why it was easy for me to tell that mine is not working!

asia

OK. It is not so apparent on my .2.

wareaglescott

I gotta be the newbie that ask. What is a sound symposer?

K-A

Thank you. Yeah that's exactly what I did. I'm pretty sure I was above 3,500 RPM's (but like Needs said, I tested it all throughout the RPM range and it was noticeable every time, low or high) and the sound changed *only* when I pressed the sport button (no PSE), it would literally sound like I could hear the motors defined throaty noises as opposed to quietness at the click of the button. Since the RPM's stayed exactly the same and just the Sport button immediately changed the tone, that would mean it's the sound symposer, correct?

Also, does Sport button itself open up the exhaust valve, or is that controlled by RPM's?

asia

Probably. Not sure how your x-pipe affects buttons.

Porsche's way of piping more engine noise into the cabin on 991's. Some say it sounds too artificial/boomy, on my .2 I think it sounds good (but no where near as good as 981 2.7L Cayman).

R_Rated

Broken or you still have it plugged?

Needsdecaf

Broken. Suspect the turbo control valve is dead. Oh wait, wrong car.

https://rennlist.com/forums/991/1023...-symposer.html