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. 

[K.I.T.T.]

On the face of it, does sound like it could be drone you describe. If it sounds excessively load (ymmv) and 'boomy' at cruise.

Not a fan of that personally. Whilst I'm all up for a vocal exhaust when I'm having fun / pressing on, after a long day at work, sometimes you just want it to be restrained on cruise. The last thing I'd want is a boomy exhaust if I ended up stuck in a 2 hour traffic jam on the M6 on the way home. That's just me though. For a car that purely for fun, you may get away with it!

I'm a massive fan of TVRs, but wouldn't commute in one for the same reason above.

[ianbadams]

Yeah I know what you mean. 

I guess that's what was nice about the PSE (I was very reluctant to get rid), it sounded smooth until you started pushing it!

This exhaust sounds fairly aggressive most of the time. I've only driven it twice since getting it tho so it may calm down abit after being run in, I may get used to it more, etc.

It does make me smile so that's a positive, just very different at the moment. Wouldn't want to get tired of it tho. 

[james_ly]

Which exhaust is it, the ebay one?

[Greenman]

Drone is effectively a resonance in the cabin usually between 2000-3000 rpm, it’s not about how loud the exhaust is but it’s more that it is louder than you would expect at those revs ie louder at 2500 rpm than at 3500 rpm. It depends very much on the type of driving you do as to how much of an issue it is,  much Motorway/dual carriageway and it can be very annoying. 

[ianbadams]

6 hours ago, james_ly said:

Which exhaust is it, the ebay one?

James, I'm not sure to be honest. It's a custom made stainless steel exhaust by Stainless Creations in Falkirk. Don't know who their supplier of parts is.

[ianbadams]

5 hours ago, Greenman said:

Drone is effectively a resonance in the cabin usually between 2000-3000 rpm, it’s not about how loud the exhaust is but it’s more that it is louder than you would expect at those revs ie louder at 2500 rpm than at 3500 rpm. It depends very much on the type of driving you do as to how much of an issue it is,  much Motorway/dual carriageway and it can be very annoying. 

Yeah that is a good description, it does seem pretty loud 2000-3000 rpm then quietens a bit and the sound changes in general as you start to push it. To be honest, it's not the kind of car that I'd want a quiet exhaust. It does sound pretty sweet and racy tho. But do think from descriptions people have given than it suffers from drone. 

Very different to the original PSE 

[Greenman]

It’s subjective, one mans drone is another mans normal. All cars have natural frequencies that can be excited by the engine/exhaust or road noises. It’s where those peaks fall in the Rev range and audio spectrum that determines how much of an issue it may be. It does sound like this car may suffer from what some people might think is unacceptable drone, but what do you think, if it doesn’t affect your driving style then all is good.

[Toddie]

Does your missus ever go on about how much your Boxster costs? That is known as droning on about it!  hope that helps

[rowbos]

4 minutes ago, Toddie said:

Does your missus ever go on about how much your Boxster costs? That is known as droning on about it!  hope that helps

Don’t discuss Boxster outgoings.  Keeps droning to a minimum ?

[Toddie]

@rowbos same here!

[Patt]

If your custom exhaust doesn't have a "balance pipe" between the two silencers, then it is almost certain to drone - usually about 70-80 on the motorway is the most noticeable time.

The PSE on the 986 works off vacuum pressure, thus the more you build up your engine, the more the solenoid opens up the valve to bypass the silencer.  new versions have an electronic switch rather than the vacuum pressure.  Some aftermarket systems have a combination of the two.

I found the 986 PSE too quiet and thus welded the valves to constant "sporty".  This is the same effect as the aftermarket bypass solutions offered by others, except the PSE actually takes from the silencer , rather than the feed pipe.  The aftermarket bypass actually has a better tick over "grumble" than the PSE.

I've not looked under the a 981/982 yet, but can confirm both are electronic and there is a noticeable change in tone even on tick over. Plus the ECU enhances these new systems for more pops and gargles.

 

[ianbadams]

5 minutes ago, Patt said:

If your custom exhaust doesn't have a "balance pipe" between the two silencers, then it is almost certain to drone - usually about 70-80 on the motorway is the most noticeable time.

The PSE on the 986 works off vacuum pressure, thus the more you build up your engine, the more the solenoid opens up the valve to bypass the silencer.  new versions have an electronic switch rather than the vacuum pressure.  Some aftermarket systems have a combination of the two.

I found the 986 PSE too quiet and thus welded the valves to constant "sporty".  This is the same effect as the aftermarket bypass solutions offered by others, except the PSE actually takes from the silencer , rather than the feed pipe.  The aftermarket bypass actually has a better tick over "grumble" than the PSE.

I've not looked under the a 981/982 yet, but can confirm both are electronic and there is a noticeable change in tone even on tick over. Plus the ECU enhances these new systems for more pops and gargles.

 

Nice one Patt.  Great info!  Mine does have after a balance pipe I think. I'll try attaching a picture. 

I'm with you tho, having now changed to aftermarket custom exhaust I do much prefer the louder / racier sound. The original PSE is fairly quiet in comparison.

What is the Aftermarket bypass solution you mention? Do you have any links to this?

[ianbadams]

30 minutes ago, Toddie said:

Does your missus ever go on about how much your Boxster costs? That is known as droning on about it!  hope that helps

Brilliant!!  

Don't know why but my wife doesn't seem to bother to much. I just deal with it and she doesn't have to.

[Patt]

example of aftermarket bypass.

 

Any yes yours has the balance pipe so shouldn't drone, just bark ;-)

[Patt]

Yours also looks like sports cats ?

[ianbadams]

39 minutes ago, Toddie said:

Does your missus ever go on about how much your Boxster costs? That is known as droning on about it!  hope that helps

 

34 minutes ago, rowbos said:

 

 

4 minutes ago, Patt said:

also looks like sports cats 

4 minutes ago, Patt said:

example of aftermarket bypass.

 

Any yes yours has the balance pipe so shouldn't drone, just bark ;-)

On my mobile and having a mare with these quotes...Haha.

@Patt I've only driven it twice since getting the new exhaust and cats fitted so that's why I was asking what drone is like. It may have a bit of drone but I'm generally still to get used to the sound input and need to drive it more to get that. So it may not be too bad 

Yeah think they're sport cats. I'm not very technical tho so not sure what impact that has overall anyway.

Cheers for sharing the pic. Is that the dansk exhaust? What's it like for sound? Good aftermarket exhaust?

[Patt]

That picture is a standard 986 S exhaust with the aftermarket bypass pipes added.

I couldn't find a good picture of the 986 PSE that showed the pipes going from rear of silencer to tail pipes.

 

If I recall the (very rare) 987 PSE cuts a corner to avoid the silencer (but is mainly hidden behind a shield)

Your exhaust will take a few hundred miles to settle down - it will only get better!

Sports cats usually free up a couple more ponies, but seem to have a tendency to not last as long as full cats, and usually throw up errors on your rear (useless) lambda's being out of factory parameter.  They are only there to check the cat works and have no effect to engine management etc. so don't worry.

[ianbadams]

1 hour ago, Toddie said:

48 minutes ago, Patt said:

That picture is a standard 986 S exhaust with the aftermarket bypass pipes added.

I couldn't find a good picture of the 986 PSE that showed the pipes going from rear of silencer to tail pipes.

 

If I recall the (very rare) 987 PSE cuts a corner to avoid the silencer (but is mainly hidden behind a shield)

Your exhaust will take a few hundred miles to settle down - it will only get better!

Sports cats usually free up a couple more ponies, but seem to have a tendency to not last as long as full cats, and usually throw up errors on your rear (useless) lambda's being out of factory parameter.  They are only there to check the cat works and have no effect to engine management etc. so don't worry.

Cool. Thanks for the info on the sports cats. I phoned Porsche for a price on the original cats and they estimated £6.5K!! There were deductions that would come off it if you returned your old ones etc but that's mental.

The original PSE is £1300 from Porsche which isn't too bad in the grand scheme of things.

I have the original 986 PSE. I'll attach a picture. It has a few leaks in it and a poor weld job to try and fix them so I'm gonna try and sell it on, to someone who is willing to go through more effort to attempt to fix it properly and reuse it.