718 Gt4 exhaust options

[TDT]

gtsralph said:

TDT said:

Electronically controlled now - not vacuum.

Sure? I thought they are vacuum - on start up low vacuum means flaps open initially until sufficient vacuum to close them. 992 electronic but 718 still vacuum.

I think in all cases the valves are vacuum actuated but electronics controls the behaviour.
As back pressure alone would mean that once you are up to certain revs/speed the valves stay open.… but we know they open and shut at various points in the rev/speed range.
Also you can open the valves for start up if you turn on ignition, press the button... you hear valves open if you listen out.… then start the car.

In older gen cars defo pre 9x1 (911 & Cayster)… the behaviour was different… open meant open all the time.
No dynamic opening and closing even though the button is pressed.
Been so long since I’ve driven my GT4… I can’t remember if it opens and closes or just stays open.

Edited by TDT on Saturday 18th April 18:42

[gtsralph]

TDT said:

I think in all cases the valves are vacuum actuated but electronics controls the behaviour. ....

Edited by TDT on Saturday 18th April 18:42

The 992 exhaust flaps are actuated by stepper motors as are the waste gates. Clearly whether stepper motor or vacuum actuation the instructions come from the ECU.

[oo7ml]

lagadmar said:

Hi, I have a 718 Spyder with nothing else to do these days I have decided to do the exhaust mod.

I am also going to fit a flap control unit as the flaps close at 2k rpm and don’t open until around 4 even in sport mode.

Does anyone know why Porsche does this? I am guessing either noise or maybe engine/torque control?

I would be interested if anyone knows.

Kind regards

Marc

Do keep us posted on what you go for.

There seems to be quite a few options for the exhaust now.

[TDT]

gtsralph said:

The 992 exhaust flaps are actuated by stepper motors as are the waste gates. Clearly whether stepper motor or vacuum actuation the instructions come from the ECU.

Ok right… i had read about the 992 valves somewhere but couldn’t remember the exact detail, and also thought it would apply to 718 4.0 as it’s a brand new exhaust system for this application.

[SWGT3]

I’ve gone with the JCR titanium option on my Spyder. Estimating 6 weeks delivery atm - no problem given I can’t drive the thing! Got 4-5 weeks to go, will update once it’s fitted.

[Cheib]

Twinfan said:

EU noise regs IMHO.

I was told by my OPC that there are more stringent EU noise regs coming which Porsche are apparently already compliant with.

[Gonzo0]

Another 718 GT4 owner here and what dissapoints me most if the complete lack of burbling on the overrun. I'm not after complete artillery fire just some nice burbling with the odd pop and bang. Maybe one for JCR but does replacing the back box system alone introduce more burbles on the overrun or are the OPFs just completely killing the fun?

[Twinfan]

They're caused by overfuelling via the ECU and emissions regs/GPFs have killed them off. You can't have exhausts chucking out unburnt fuel particles any more.

[TDT]

Twinfan said:

They're caused by overfuelling via the ECU and emissions regs/GPFs have killed them off. You can't have exhausts chucking out unburnt fuel particles any more.

765LT?... shoots flames and whip crack on the gear change via ignition cut. Porsche could have been more creative to retain some character

Edited by TDT on Monday 20th April 18:09

[Twinfan]

Maybe Germans are playing by the rules a bit more these days...

[arcamalpha]

All that burbling impacts economy too which might have been a driving factor for the 4.0 engine. Clearly economy is not the biggest deal for many of us but I was amazed to see the reduction in economy sport mode has on the 981 GT4. Much more so than any other car I’ve owned.

Correction: i meant exhaust button not sport mode. Thinking of the wrong car!

Edited by arcamalpha on Sunday 26th April 10:43

[Gonzo0]

Just seen that supersprint do a few exhaust parts now for GT4:

https://www.supersprint.com/ww-en/sport-exhaust-su...

Could be a good alternative to JCR at half the price

[oo7ml]

Gonzo0 said:

Just seen that supersprint do a few exhaust parts now for GT4:

https://www.supersprint.com/ww-en/sport-exhaust-su...

Could be a good alternative to JCR at half the price

Cool, have you seen / heard any clips of it?

[gtsralph]

oo7ml said:

Gonzo0 said:

Just seen that supersprint do a few exhaust parts now for GT4:

https://www.supersprint.com/ww-en/sport-exhaust-su...

Could be a good alternative to JCR at half the price

Cool, have you seen / heard any clips of it?

I wonder how they get round the GPF differential pressure sensors and how the rear box fits v the OEM saddle design.

[Evo9lution]

I've heard people with 991.3 GT3s say that if you drive the car quite hard, it doesn't take too long to blow the insides of the GPF out so you get back to a better sounding car quite quickly. JCR or similar a/m exhaust sounds like a good option but will the combination then mean that the car struggles to pass noise restrictions on track, even with the valves closed???

I have been considering the Sportec exhaust option but they did say that it may affect the warranty (and definitely isn't MFK - MoT equivalent here - compliant) so that puts me off a little. I need to speak to Porsche CH to see what they say about that ...

Should have my GT4 fully run-in this weekend (3k kms) so will be interesting to see what she sounds like at 8k revs! Unfortunately, I can no longer just pop over the border and use the derestricted German autobahn so I would only be able to test this in first gear! LOL

[gtsralph]

Evo9lution said:

I've heard people with 991.3 GT3s say that if you drive the car quite hard, it doesn't take too long to blow the insides of the GPF out so you get back to a better sounding car quite quickly. JCR or similar a/m exhaust sounds like a good option but will the combination then mean that the car struggles to pass noise restrictions on track, even with the valves closed???

I have been considering the Sportec exhaust option but they did say that it may affect the warranty (and definitely isn't MFK - MoT equivalent here - compliant) so that puts me off a little. I need to speak to Porsche CH to see what they say about that ...

Should have my GT4 fully run-in this weekend (3k kms) so will be interesting to see what she sounds like at 8k revs! Unfortunately, I can no longer just pop over the border and use the derestricted German autobahn so I would only be able to test this in first gear! LOL

Sportec distribute Akrapovic, do they have their own system? Blowing the insides of the GPF sounds a little unlikely.

[Cheib]

GPF thing sounds unlikely to me. Sports exhausts on pre GPF cars in my experience do release a bit more sound with miles.

[Evo9lution]

As I said, just what people with GT3s had said, but I suppose that it may not actually be the GPF that is releasing the extra sound. The Porsche dealer actually said a similar thing to me: "Due to the GPF there is now a smaller muffler set-up in the exhaust itself. You'll notice that the whole system get considerably louder through use as the flow starts to impact the system".

Maybe he was referring to blowing the packing out of the muffler (something I have done previously on the Evo so is eminently doable) but would also then worry about remaining track-friendly.

I guess I'll see over the coming months ...

[TDT]

Evo9lution said:

As I said, just what people with GT3s had said, but I suppose that it may not actually be the GPF that is releasing the extra sound. The Porsche dealer actually said a similar thing to me: "Due to the GPF there is now a smaller muffler set-up in the exhaust itself. You'll notice that the whole system get considerably louder through use as the flow starts to impact the system".

Maybe he was referring to blowing the packing out of the muffler (something I have done previously on the Evo so is eminently doable) but would also then worry about remaining track-friendly.

I guess I'll see over the coming months ...

That is true of the GT3 RS/ Speedster
718 GT4 is totally different system where they have not made the exhaust smaller… in fact it is much larger with the saddle shaped backbox.
So you have 2 muffling effects. From the GPF and then the back box.
Change out the backbox for a open pipe and the GPF is still there.
As mentioned before… over time… years and miles, it may turn out that the GPF material breaks down and let’s through more sound… but then in that case by definition it will be letting more gas particulates through also.

[Porsche911R]

Ice is over for fun new cars , buy a pre PPF car imo and keep it.
New cars will just get dire restrictions and any one messing will get fined and not pass MOT and righty so.