How does the PSE work and what is drone

[Ianbadams]

I've just replaced my 2001 Boxster S (3.2) original PSE with a custom made stainless steel exhaust. Needed cats replaced as well.

Just wondering if someone could explain how the original PSE operated in terms of the valves and bypass pipes to the super sound tips?

Id describe it as having a quiet rumble up to about 3000 rpm at which point it started to open up and get louder and sporty sounding. I guess that's the reason for the valves?

The new stainless steel (no valves) is much louder and feels constant. I do like it. But seems to be a lot louder at low rpms. And I wonder if people would describe it as having a drone between 2000/3000. It's like a constant ringing through your head and what you'd feel like on a plane when after a while youd want to swallow to depressurise your ears (Haha random example). Does that sound like what people would call resonance or drone? (is drone regarded as bad or is it just a given sometimes with an exhaust ?)

I guess I quite like it as it make the car sound really sporty now but is just different I suppose to the original where you could be cruising along not realising youre in a Porsche... Which I kind of don't see the point of.

[GTA_G20]

Yes you described drone quite well. From what I recall it the natural harmonic sync which occurs at a certain RPM range. I believe our cars 2500-3000. Usually highway cruising speeds. Annoying to some and tolerable to others.

PSE in 987and newer cars has the crossover valves electrically actuated via SPORT button on the lower center console.
PSE in our cars are vacuum actuated and always active unlike the 987 cars. I believe ours only operate under throttle which produces vacuum.

I could be wrong someone can correct me

[The Radium King]

vacuum-actuated valves tied to the vacuum system on the engine and activated by the same type switch that triggers the vacuum-actuated flap in the resonance tube in the intake. also uses the same electronic trigger signal from the dme, so the flaps open and bypass a portion of the muffler at 3000 or so rpm.

[rp17]

Yep dead on... Drone is soo perspective... riding around under 3k puts out drone but you shouldn't be there anyway... Some mufflers puts out some drone around there but it's what acceptable to your ears.. My Fabspeed was lovely loud over 3k... Didn't have to break the speed limits to enjoy the open valves.. Well too much over the speed limits top down that is .. 987

[Ianbadams]

Cheers guys. That's really helped me understand the valves on the PSE.

Gutted to have got rid of it off my 986 but am enjoying the much racier sounding custom box.

I've retained the PSE and it does need someone who knows what their doing to fix the leaks, may be restorable.

[Cunningr]

Maybe you mentioned already and I missed, but curious as to the exhaust you chose to install?

[Qmulus]

I just wanted to clarify how the PSE is controlled on our 986s. The PSE has two vacuum controlled flaps that are opened by an electrically controlled vacuum solenoid. The solenoid on the 986/996 implementation of the PSE is controlled solely by a relay located in the relay panel. It has no connection to the DME. The only inputs to the PSE control relay are vehicle speed, power, and the dash switch.

The relay defaults to "quiet mode" at startup, and when in "performance sound" mode it also closes the valves between 30 and 45mph. I believe this is to pass some European noise regulations, but you can disable it by disconnecting speed signal or pulling a resistor in the relay. Later Porsche PSE systems were controlled by the DME, but the system on the 986/996 was not.

I bought a late PSE ('03-'04 with bolt-on tip) from a list member and installed the complete system in my car following the factory PSE retrofit installation guide with all the right parts. Other than the valves, the late PSE muffler looks identical to the non-PSE exhaust, with the exception of the Eisenmann (exhaust manufacturer) stamp and part number.

Honestly, the difference between the valves open and valves closed is very subtle. I was expecting more, and have considered modifying my original muffler with a valve system that completely bypasses the muffler rather than just one of the chambers.

[BRAN]

Although the pre-FL PSE was dizzed A LOT...IMO it is one of the COOLEST looking exhausts ever!

Although the Eisenmann Tip, which I have installed looks super classic racer and I haven't seen a bigger single TIP yet, I would switch it for the pre-FL PSE.
On my to do list incl. working valves...Klappenauspuff
Soundwise not a big improvement (and tbh, I like the sound of my old untouched muffler)...but that look...drool

Really don't need more sound, especially when you have desnorkeled and a race filter installed...you won't hear the screams of your passenger anymore @ 5000rpm

[GTA_G20]

I've got it as they come standard on the 550SE I find it very noticeable when I step into the throttle

[The Radium King]

Originally Posted by Qmulus

I just wanted to clarify how the PSE is controlled on our 986s. The PSE has two vacuum controlled flaps that are opened by an electrically controlled vacuum solenoid. The solenoid on the 986/996 implementation of the PSE is controlled solely by a relay located in the relay panel. It has no connection to the DME. The only inputs to the PSE control relay are vehicle speed, power, and the dash switch.

The relay defaults to "quiet mode" at startup, and when in "performance sound" mode it also closes the valves between 30 and 45mph. I believe this is to pass some European noise regulations, but you can disable it by disconnecting speed signal or pulling a resistor in the relay. Later Porsche PSE systems were controlled by the DME, but the system on the 986/996 was not.

I bought a late PSE ('03-'04 with bolt-on tip) from a list member and installed the complete system in my car following the factory PSE retrofit installation guide with all the right parts. Other than the valves, the late PSE muffler looks identical to the non-PSE exhaust, with the exception of the Eisenmann (exhaust manufacturer) stamp and part number.

Honestly, the difference between the valves open and valves closed is very subtle. I was expecting more, and have considered modifying my original muffler with a valve system that completely bypasses the muffler rather than just one of the chambers.

here’s the tsb for the retrofit of the pse ...

https://rennlist.com/forums/attachments/996-forum/621157d1333401945-pse-porsche-sport-exhaust-996-pse2.pdf

it reflects what you have stated. however, it is dated 2002 and references an earlier version of the pse that is no longer supported. iirc this is what i was describing, most likely no longer supported due to being too loud at low speeds (ie, doesn’t have the speed input like the updated version).

[Qmulus]

There is a TSB floating around for the late 986, although I can't find it online now. I have a hard copy that I printed from a pdf that I found somewhere. It may be been on renntechDOTorg The nice thing is that it shows how to route the harnesses and vacuum lines, which is very different than on a 996 (obviously). I went to the trouble of getting the proper gauge and color Tefzel wire, and routed it all with the factory harnesses and through the correct connectors and terminals on the body and engine harnesses. I ran the oil pressure wire for the 996 cluster while I was at it. Kind of a PITA, but I like things to look like they were done at the factory.

The interesting thing is that you would think the cutout for excess noise would be more RPM based than speed if it was done because of potential drone (one popular theory, but there is no drone with the PSE, no matter what). I have driven mine with the speed cutout active and disabled and can't really tell the difference, probably because the PSE doesn't seem to do a lot anyway. From a driver's perspective the intake noise is most prevalent.

[professorman]

Originally Posted by Qmulus

I just wanted to clarify how the PSE is controlled on our 986s. The PSE has two vacuum controlled flaps that are opened by an electrically controlled vacuum solenoid. The solenoid on the 986/996 implementation of the PSE is controlled solely by a relay located in the relay panel. It has no connection to the DME. The only inputs to the PSE control relay are vehicle speed, power, and the dash switch.

The relay defaults to "quiet mode" at startup, and when in "performance sound" mode it also closes the valves between 30 and 45mph. I believe this is to pass some European noise regulations, but you can disable it by disconnecting speed signal or pulling a resistor in the relay. Later Porsche PSE systems were controlled by the DME, but the system on the 986/996 was not.

I bought a late PSE ('03-'04 with bolt-on tip) from a list member and installed the complete system in my car following the factory PSE retrofit installation guide with all the right parts. Other than the valves, the late PSE muffler looks identical to the non-PSE exhaust, with the exception of the Eisenmann (exhaust manufacturer) stamp and part number.

Honestly, the difference between the valves open and valves closed is very subtle. I was expecting more, and have considered modifying my original muffler with a valve system that completely bypasses the muffler rather than just one of the chambers.

California has a very specific noise test which is speed dependent. Porsche makes a lot of decisions to pass this specific test, so it make sense to be speed dependent.

SAE J1470 aims to measure "the highest noise level consistent with urban driving." The exact testing method varies based on vehicle size, power output, peak acceleration rate, and gearing, but generally, it involves a full-throttle run starting at 50 km/h (31 mph) and continuing until the engine reaches its peak-power rpm. Manual-transmission vehicles are tested in either second or third gear;

https://www.roadandtrack.com/news/a36741701/porsche-911-gt3-manual-fails-californias-noise-test/

[JFP in PA]

Originally Posted by professorman

California has a very specific noise test which is speed dependent. Porsche makes a lot of decisions to pass this specific test, so it make sense to be speed dependent.

Only problem is that the PSE was designed to pass the Swiss noise limits, which are the tightest in the world..................

[professorman]

Oh, so would I be disappointed with PSE? I like it slightly louder.

[BRAN]

If you want a head turner (oh...it's just a Boxster), then you will be disappointed.
Although I have an official "104db" notice in my car papers, which is way beyond nowadays regulated max db, it is not obnoxioulsy loud, has NO drone and thank god no backfire bangs.

Pre-FL PSE is the best looking exhaust ever, IMO. And guaranteed 100% pure Porsche sound.

[JFP in PA]

Originally Posted by professorman

Oh, so would I be disappointed with PSE? I like it slightly louder.

I would describe it as "mellow", but never loud.