981 Cayman GT4: 109dB, noise reduction needed

[Mark Harwood]

Hi

I have a 981 Cayman GT4, with Fabspeed headers, 200cel cats, PSE after the cats, IPD plenum, RPM low ratio crown wheel and pinion.

It is 109dB static with exhaust valves closed without clutch dipped and marginally lower with clutch dipped.

I understand that JCR are developing some noise reducing exhaust tips but they haven’t been released yet.

I’m keen to book some Club trackdays for 2023. Has anyone successfully reduced the dB on the GT4 (I appreciate that even completely standard they are pushing most trackday noise limits even the higher ones at 105dB).

With many thanks.
Mark

 

[ralphmusic]

I suspect the issue is the manifold/200 cell cats but 109 static is pretty loud, where was that tested?

I had Cargraphics 200 cell manifolds, OEM back boxes and IPD plenum on my 3.8L Cayman S which was generally 102/3 dB static and had drive by noise problems running at Goodwood even on 105dB static days.

I had some simple downturn tips fabricated by the exhaust company near Castle Combe. They made some difference to drive by noise but not a lot to static.

I then had some better ones with internal perforated mesh and a stub end made by Cargraphics’s UK manufacturing site in Devon but these were never made for sale.

I’ve run JCR tips on a 991.2 GT3 and had no issues at Brands. I now have their tips on a 718 GT4 (below) but the exhaust arrangement is different to the 981 GT4.

I presume the OEM tips are the “T” arrangement with a connector between the two boxes and the tips exiting from the connector? I don’t know of any good noise reducing tips for this arrangement.

You might reach out to “snowy999” of this parish who has fitted a GT3 rear box and JCR tips to his modified GT4 - not cheap but he can tell you to what extent it reduces noise.

Another solution is to copy this arrangement, specially fabricated by Edwards Motorsport, Wisbech.

Not particularly elegant but did the job

and finally, I found this image which I saw way back when looking for solutions for my 981, you might find these with a Google image search.

Good luck and if you find something that works it would be good if you could report back for others to try.

 

[snowy999]

As Ralph says, I fit the JCR GT3 turndown tips and they do the job. At hill climbs my dundon catted headers plus gt3rs box registers anywhere between loud but just ok to er no. The limit is 108dB so not surprised at your levels. I have tested MSA static anywhere from 98 to 103dB with them on. So the JCR design works. I think your solution will need to involve a specialist like Ralph did. fab a new x piece and have a set of attenuating turn downs fitted.

several people had problems with the 981 gt4 in standard form at Brands Goodwood etc. i only have gone to Silverstone and Spa and have never been asked to fit my turn downs! Not a good answer if you’re a track junkie.

 

[Mark Harwood]

Super helpful, thank you.

I’ve now heard that JCR are developing some noise reducing tips for the 981 GT4, hopefully being released in the first quarter of 2023.

 

[TDT]

Super helpful, thank you.

I’ve now heard that JCR are developing some noise reducing tips for the 981 GT4, hopefully being released in the first quarter of 2023.

I know the JCR team well…

Don’t hold out for this… we have been waiting for something to arrive for the last 3 years… and he is being pestered…but still no product and it will be pricey…

The only system that works as a bolt on to the OEM tips is the last one Ralph posted…

https://www.actproducts.co.uk/product/si06-porsche-gt3-sliencers-pr/

It says for GT3, but if you Call them they can make it 981 GT4 compatible, priced nicely also…