Boxster/Cayman GTS Exhaustvalve 6500 rpm PSE? - Page 2 - Boxster/Cayman - PistonHeads UK

Just bought myself a Boxster GTS and discovered that when your have the Sports exhaust activated it´s like it is opening its valves at 6500 rpm.. The exhaust just explodes. Sounds like when a GT3 opens up in sportmode. Is it anybody who knows more about how the PSE works?

Possibly the engine management altering the valve lift than anything on the PSE. Mine is still running in and trying very hard to keep the revs to 4,500 rpm. I notice the note hardens at just the time I have to change up - can't wait for the running in period to end! Love the fierce bark when changing down manually in sport or sport plus, even at comparatively modest revs!!

HosonAndersson said: Just bought myself a Boxster GTS and discovered that when your have the Sports exhaust activated it´s like it is opening its valves at 6500 rpm.. The exhaust just explodes. Sounds like when a GT3 opens up in sportmode. Is it anybody who knows more about how the PSE works? PSE (activated) works in two ways. There are valves in each half of the exhaust which change the exhaust silencing when activated (make it louder). The valves are "enabled" by the dashboard switch and actually open/close depending the engine vacuum. Secondly - in order to create the pops and bangs on lift off, Porsche cause unburnt fuel to enter the exhaust where it explodes in contact with the hot manifold. In days of old this used to occur because of poor carburation (either too rich or too weak mixture) but these days it does not, and need not, occur because fuel injection systems normally do a much better job - and on lift off fuel is normally cut off completely for economy reasons, so there isn't any unburnt fuel to get into the exhaust system. Some associate this second effect with what a sports car should sound like, others like myself think it odd that a deliberate malfunction should be viewed in that way. It has been a controversial subject on this forum which has aroused strong passions, so I'll leave it at that.

Oh dear... bcr chimes in with his BS about how PSE is so bad. Predictable.

koorby said: Oh dear... bcr chimes in with his BS about how PSE is so bad. Predictable. If this is BS explain what is technically incorrect or even unbalanced about what I ACTUALLY WROTE. Either CONTRIBUTE some information or shut up.

The pops and bangs are created rather than just there as in the past, but it sounds great and is a bit of fun. If I feel like being quiet I have the choice with a switch and if I were really worried about that little bit of fuel used to make the pops and bangs and fuel economy I wouldn't of spent 70K on what is a fun weekend toy.

bcr5784 said: If this is BS explain what is technically incorrect or even unbalanced about what I ACTUALLY WROTE. Either CONTRIBUTE some information or shut up. All you say is totally correct and I respect your dislike of this method. I really love the sound it creates end of. It's healthy we don't all agree :-))

Budweiser said: All you say is totally correct and I respect your dislike of this method. I really love the sound it creates end of. It's healthy we don't all agree :-)) Thank goodness we can sensibly disagree.

bcr5784 said: Thank goodness we can sensibly disagree. Oh jesus its the engineering god again out of interest engineering god, i have a 2007 cayman S, doesn't have any sports mode, no sport buttons etc, which means no pops, bangs, crackles etc, so on Saturday, local garage put on a aftermarket cat back exhaust system for me, and guess what Ive now got loads of pops, bangs and crackles, but hang on Porsche didn't program this stuff into the ecu on this model, so???

corvettedave said: Oh jesus its the engineering god again out of interest engineering god, i have a 2007 cayman S, doesn't have any sports mode, no sport buttons etc, which means no pops, bangs, crackles etc, so on Saturday, local garage put on a aftermarket cat back exhaust system for me, and guess what Ive now got loads of pops, bangs and crackles, but hang on Porsche didn't program this stuff into the ecu on this model, so??? The exhaust has cocked up the fuelling, as you might expect! It's really not rocket science. You need to get the ecu reprogrammed.

you are completely wrong my old fellow! i still have the factory headers with down pipe and cat on the car, and guess where the o2 sensors are, yep there's one on the down pipe for the ecu to monitor fueling and other is after the cat, which is before my new exhaust, that one is to monitor emissions s t so now what genius?

bcr5784 said: If this is BS explain what is technically incorrect or even unbalanced about what I ACTUALLY WROTE. Either CONTRIBUTE some information or shut up. The information I am contributing is conveying the message to you that everyone is sick of your anti-PSE bias and it's becoming quite tedious and annoying to see topics being hijacked by you these days. Given that PSE on the GTS is one of the major reasons people here have bought the car, can I ask that you please get off your soapbox and shut the hell up about the supposed engineering b disation in it.

koorby said: The information I am contributing is conveying the message to you that everyone is sick of your anti-PSE bias and it's becoming quite tedious and annoying to see topics being hijacked by you these days. Given that PSE on the GTS is one of the major reasons people here have bought the car, can I ask that you please get off your soapbox and shut the hell up about the supposed engineering b disation in it. Look at the original post - a guy asked a question, no-one replied for days so I answered it correctly and mildly in the hope that non of you lot would get abusive - some hope.

corvettedave said: you are completely wrong my old fellow! i still have the factory headers with down pipe and cat on the car, and guess where the o2 sensors are, yep there's one on the down pipe for the ecu to monitor fueling and other is after the cat, which is before my new exhaust, that one is to monitor emissions s t so now what genius? If you are getting neat fuel in your exhaust causing pops and bangs (which you didn't have before), then ergo your exhaust is the cause and has interfered with the fuelling. It's simple cause and effect. But I can't be bothered arguing further - if you like it that way then fine.

Maybe I am lacking the history of this emotional debate but I don't see anything bad in bcr's comments. I found them interesting as I was not aware that the pops and crackles were an "engineered malfunction" for aural pleasure. Whether you like it nor not is purely a matter of personal taste. To me it sounds good but feels a bit at odds with the highly engineered cars that generate it. I prefer the effect of the sport buttons in my GT3/RSs.

Dr S said: Maybe I am lacking the history of this emotional debate but I don't see anything bad in bcr's comments. I found them interesting as I was not aware that the pops and crackles were an "engineered malfunction" for aural pleasure. Whether you like it nor not is purely a matter of personal taste..... . Neither do I. I happen to disagree with him also and quite like the pops and backfires, it adds to the car's emotive character so often lacking in today's cars. All bcr said on this thread (even if maybe he went a bit OTT with his criticism on another thread which wound some up) was that the sound wasn't for him, to be greeted by all the keyboard warriors jumping down his throat. Seems there are some pretty short fused contributors on PH which to me detracts from the forum's quality.

On a side issue with PSE I believe the new EU noise regulations coming into force in 2016 will kill the sound of cars such as the Boxster / Cayman GTS - enjoy whilst you can. 981/2 Boxster / Cayman may well have turbo flat fours anyway, recent Porsche model history has seen new engines introduced in the model half life refresh.

We should revisit this thread when the pot4's arrive. Then we will be talk much more about synthesising of a PSE through speakers no doubt. So glad I bought a 981 GTS whilst I could. Last of a dying breed

Trotmant said: We should revisit this thread when the pot4's arrive. Then we will be talk much more about synthesising of a PSE through speakers no doubt. So glad I bought a 981 GTS whilst I could. Last of a dying breed Totally agree! The 2016 EU noise regulations, ever more demand on corporate CO2 emissions (which can only achieved by high efficiency turbo engines) all signals that the current generation of cars will be the last wonderful, evocative sports cars.

Trotmant said: We should revisit this thread when the pot4's arrive. Then we will be talk much more about synthesising of a PSE through speakers no doubt. I agree, but I think it but it will be all-but impossible to get a sensible discussion given the emotion on this issue.

bcr5784 said: If you are getting neat fuel in your exhaust causing pops and bangs (which you didn't have before), then ergo your exhaust is the cause and has interfered with the fuelling. It's simple cause and effect. But I can't be bothered arguing further - if you like it that way then fine. the point iam making is the 4 cats, factory exhaust system has hidden those noises, the reason you cant be bothered to explain your theory, is because you know iam right! lol

I think the higher back pressure of the OE setup prevents the bangs in the first place, rather than "masks" them? The slightly lower resistance of the new back box creates this situation of an incomplete burn, which then ignites in the manifold. I had the same on my Exige S, when I simply changed the heavy old stock backbox/outlet, for a Larini lightweight (read less passes/wadding/resistance). The overrun bangs and crackles were significant after making that mod and there were no valves involved. Similar to a PSE being in Sport mode?

corvettedave said: the point iam making is the 4 cats, factory exhaust system has hidden those noises, the reason you cant be bothered to explain your theory, is because you know iam right! lol See nsm posting. The reason I can't be bothered to explain it further, is because the effect and it's cause has been so well known for 40 years (to my knowledge) with both restrictive and unrestrictive exhausts. If you were right then the normal exhaust note would be far far quieter than it is, and the pops and bangs would be the ONLY thing you would hear.

nsm3 said: I think the higher back pressure of the OE setup prevents the bangs in the first place, rather than "masks" them? The slightly lower resistance of the new back box creates this situation of an incomplete burn, which then ignites in the manifold. I had the same on my Exige S, when I simply changed the heavy old stock backbox/outlet, for a Larini lightweight (read less passes/wadding/resistance). The overrun bangs and crackles were significant after making that mod and there were no valves involved. Similar to a PSE being in Sport mode? I suspect you are probably right in the case of fitting aftermarket exhausts with lower back pressure. Not sure whether that is how PSE "works" - but it's certainly possible.

I'm pretty sure that the PSE is no more complex than a by-pass valve(s) in the exhausts that permits a shorter route to the exit tips. Certainly has been on previous manifestations.

nsm3 said: I'm pretty sure that the PSE is no more complex than a by-pass valve(s) in the exhausts that permits a shorter route to the exit tips. Certainly has been on previous manifestations. If you're right, and it's a simple as that, then Porsche are NOT cutting off (all) fuel on the overrun. They could, of course, very simply, make fuel cut-off a function of PSE Sport mode. Do you know if they do? They have (on PDK) made Coast mode the default on the overrun, rather than fuel cut-off and staying in gear. That seems to yield excellent fuel economy for me, (despite my initial misgivings) on Motorway runs, but isn't an option on manual.

If you want to sample some major snap, crackle & pop this is worth a look for a laugh :- https://www.youtube.com/watch?v=t0uzHiNYnds Tell me that didn't make you smile just a little. It should be illegal to make this illegal...

GaryF said: If you want to sample some major snap, crackle & pop this is worth a look for a laugh :- https://www.youtube.com/watch?v=t0uzHiNYnds Tell me that didn't make you smile just a little. It should be illegal to make this illegal... WildWest!

Trotmant said: GaryF said: If you want to sample some major snap, crackle & pop this is worth a look for a laugh :- https://www.youtube.com/watch?v=t0uzHiNYnds Tell me that didn't make you smile just a little. It should be illegal to make this illegal... WildWest! Ha ha ha!

Brings back memories, mine only lasted a few days with the decats and minimal silencing it was just too loud and I never noticed the flames too busy seeing where it was heading to look for them. The inefficiencies of the speed six fueling system do provide great ammunition for those of us with a childish disposition though.