718 Cayman GT4 is here – at long last.!
- Thread starter Motorhead
- Start date
Yes, it must be a challenge being able to modify only part of the system. I suppose someone will eventually come up with a complete system incorporating freer-flowing cats and GPFs, but that’s going to take a lot of engineering effort and will be very expensive.Twinfan said:
Hope that 9M come good with their next attempt.
Jeff
Me too, although part of me is wondering if I should just stick with the standard exhaust given that I've decided to partake in track days in the future and the quieter exhaust could come in handy.
It's all down to how the car feels with just the flywheel mod, so I'll find out in about a week...
It's all down to how the car feels with just the flywheel mod, so I'll find out in about a week...
Nothing more annoying than getting sent home early from an expensive track day without a refund Dave!
I know that measuring pass-by noise out on track is a different kettle of fish but have 9M done any static measurements with the modified system to make sure that at least you get past the first hurdle?
Jeff
I know that measuring pass-by noise out on track is a different kettle of fish but have 9M done any static measurements with the modified system to make sure that at least you get past the first hurdle?
Jeff
They did do some simple static tests and it was under 105dB from memory, so loud days will be fine. It's the increasingly restrictive days that would be a problem, although at the moment I'm only looking at PCGB days which are all 105dB.
I suspect the "goes like a scalded cat" feeling the car currently has will be muted somewhat by refitting the standard exhaust, so I'll be keen to get the 9m silencer v2 on the car. It will be fine for 105dB days so maybe I'll be restricted to those which is probably not a problem shorter term if I stick to PCGB days a handful of times a year.
First world problems, eh?
I suspect the "goes like a scalded cat" feeling the car currently has will be muted somewhat by refitting the standard exhaust, so I'll be keen to get the 9m silencer v2 on the car. It will be fine for 105dB days so maybe I'll be restricted to those which is probably not a problem shorter term if I stick to PCGB days a handful of times a year.
First world problems, eh?
Managed to get the car out a few times this week for some good miles as the air temp was a few degrees above freezing. Michelin PS4S are really impressive even in the wet 
Does anyone think the drone around 3000 revs has anything to do with the engine closing down to half of its cylinders to save fuel ? Just a thought.
Does anyone think the drone around 3000 revs has anything to do with the engine closing down to half of its cylinders to save fuel ? Just a thought.
Peterh61 said:Managed to get the car out a few times this week for some good miles as the air temp was a few degrees above freezing. Michelin PS4S are really impressive even in the wet
Does anyone think the drone around 3000 revs has anything to do with the engine closing down to half of its cylinders to save fuel ? Just a thought.
There is the cylinder deactivation which has a particular sound on the 4.0. If you turn off auto start/stop... this will switch off the cylinder deactivation and bank switching and you wont hear this sound any more.
But exhaust drone from an aftermarket system or headers is very distinctive... and occurs under accelerative load usually right in cruising speed range as you start to roll onto the throttle. To get around it you usually have to give more throttle... and then you’ll be going too fast lol. Or back out of throttle and that’s no fun. Lol.
Totting-up the price of a full road-legal Cargraphic system (manifolds and cats, GPFs, silencer and tailpipes) gives an eye-watering price including German VAT at 19% of about €11,500 before fitting … ouch!TDT said:
I think that I’d have to be very unhappy either with the standard or a lightly modified system to take that route, especially since very likely it will invalidate any factory warranty.
Jeff
Full cargraphic system gives you sound and performance, but yep it’s an expensive game to do it without compromise and all factors taken into consideration.Motorhead said:
All of the other systems on the market have some kind of trade off, and you need to purchase based upon what you prioritise.... having your cake and eating it is gonna cost.
All in all for 718 4.0 from a sound perspective, I’d just leave it alone or get a valve controller to have full manual control, vs the cost of the various rear sections available. Valve controller is better/more useful bang for buck IMO.
Performance is separate topic as that will be targeted for a particular use case... and there you may end up back in position of needing to deal with a trade off.
Agreed T. Plus, by freeing-up exhaust gas flow you’d have to be thinking about improving the intake system and remapping the engine to get the full benefit, but that’s probably best kicked down the road until the car’s out of warranty and the tuners have had more time to work on the new engine.
It’s going to be interesting to see what Porsche have done on the GT4 RS, assuming that it’s going to have a small power hike.
Jeff
It’s going to be interesting to see what Porsche have done on the GT4 RS, assuming that it’s going to have a small power hike.
Jeff
Yep, I broadly agree with you both. Even the JCR system seems to be drone-prone so there is definitely no magic bullet with regards to sound. I'm not sure I agree with TDT on the valve controller as this only increases volume up to 4k when the valves open anyway with the PSE button pressed, unless you want more noise at lower revs only. It also risks adding some drone as it seems that's why Porsche have the "open valves" control set at 4k, along with for noise reduction reasons. But it's a cheap and simple way to get a bit more noise at lower speeds if that's what you're after.
I think the GT4RS will be going through extensive exhaust development at the moment, just as the GT4 appeared to do. It seems to be a real headache on the mid-engine platform, and I can see buyers being annoyed with the sound. Will the RS buying guys and gals kick off more or accept it?
I suspect my updated 9m exhaust will end being a little better in the drone department than it is now, but there will be some still present. Whether it's tolerable or not for me is going to be interesting to find out. My car is an all rounder, not a track-only rat, as are many other owners' I suspect.
I think the GT4RS will be going through extensive exhaust development at the moment, just as the GT4 appeared to do. It seems to be a real headache on the mid-engine platform, and I can see buyers being annoyed with the sound. Will the RS buying guys and gals kick off more or accept it?
I suspect my updated 9m exhaust will end being a little better in the drone department than it is now, but there will be some still present. Whether it's tolerable or not for me is going to be interesting to find out. My car is an all rounder, not a track-only rat, as are many other owners' I suspect.
MannyLon
Member
The valve controller is more than "a bit more" noise. It makes the car sound nicer with a few crackles IMO. Akra and Cargraphic use them as part of their exhaust setup. I'd bet their exhausts would be quieter without the valves being open.
I'll try and get a dB reader to measure the volume increase at some point.
It's all subjective when it comes to sound, but at least the valve controller keeps the standard engine sound with increased volume.
Having tuned many other cars, I can't bring myself to pay the silly money these Porsche tuners ask for a backbox.
I'll try and get a dB reader to measure the volume increase at some point.
It's all subjective when it comes to sound, but at least the valve controller keeps the standard engine sound with increased volume.
Having tuned many other cars, I can't bring myself to pay the silly money these Porsche tuners ask for a backbox.
Twinfan said:
The point of the valve controller is precisely to open the valves in low RPM where the OEM controller would have them closed,; addressing the primary complaint that the 718 4.0 is silent at low RPM - at high RPM everything is open and so makes no difference there.
Changing the exhaust without changing the valve control or removing valves entirely - is just amplification... and can reintroduce undesirable frequencies dependant on the design.... but is all about what trade-offs are being made if there is a design process.
Designs like Litchfield, Cargraphic, SuperSprint & Akrapovic, which include some kind of central silencer will be better at managing a wide range of frequencies... following the principles of the OEM system.
Race-pipe designs in the mould of the JCR such BCFabs, Fabspeed, Soul, & 9m - will have a narrower range for managing frequencies but their primary objectives may be different and may be more about overall volume with megaphone tips. But the clue is in the name!
You've never heard anyone talk about drone with 100% OEM systems on any of these cars.... even back to older generation GTx/RS cars which had more rudimentary valve control.
The OEM systems are designed and muffled enough to properly manage NVH and emissions, whilst being robust enough to manage a massive range of environmental condition (heat, cold, weather, water, salt etc),..... the compromise there is that some performance might be left on the table... but for Porsche it achieves their objectives as a baseline.
Porsche have had plenty of time to work on this Dave, so you’d have to hope that progress will have been made since the 718 GT4’s introduction. I don’t think there were any complaints about the sound of the 2019 991 Speedster’s exhaust which incorporated GPFs among other mods. I appreciate that it’s a different configuration … and a very kettle of fish! … but it shows what can be achieved given resources and funds. It’s going to be interesting to see how the 992 GT3 turns out in this respect.Twinfan said:
Jeff
TDT said:
I'm not sure it is the primary complaint T, people seem to be unhappy with the tone and lack of crackles etc not just lack of volume at low revs? When mine was standard I also felt it needed more with the valves open too.
It's all very subjective though and I'm looking forward to revisiting the stock system next week for a refresher!
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