sirius9

Hope everyone's having a great weekend.

Having acquired a 2014 991.1 Turbo S recently, I have manage to read up on most of the threads in this forum. Great source of info.
I have completed my previous project in a Mercedes W204 C63 saloon/sedan which has been wide arched and supercharged.
Hence, Porsche and twin turbo platform is completely new to me.

Few question i would like to ask:

1) My medium term aim is to tune/remap and add CSF Premium Intercoolers. I feel this would help with the IATS. I am retaining stock cats and aim to install Speedtech 3' Muffler delete ONLY. I am still finding the in cabin noise very balanced and going 100 or 200 cel high flow cats may make it too loud in cabin.

2) Is CSF radiators necessary for the set up in (1)? I know upgraded intercoolers will help with IATS. Is the stock radiators adequate for tuned cars?

3) I been reading all about upgraded plenums and y pipe. Are these 2 parts only beneficial for big power upgrades such as hybrids turbos and Meth kit?

Thanks in advance.

Ttz06vette

If you have read the many threads on this forum then you know that Sam would be a good person to consult with in terms of fulfilling your goals.

I will tell you that from my perspective one of the largest power inhibitors is the stock cats. It's all about airflow on the inlet and outlet side. Even if you lower your IaT's with the CSF parts you will limit your gains due to the back pressure you will still have with the stock cats. Unless you are racing the car, I think you will be fine with the stock radiators. Although high coolant temps may cause the the ECU to pull some timing and reduce power, I doubt they will effect IAT's.

bigrpowr

@SamboTT@ByDesign will tell you what you need to know and help with the proper order of mods based on your goals.

cosmo1

what they said <

Pb Pedis

1 - For comparison, the first round of mods for me was a Kline exhaust and cat elimination pipes. I noticed no difference in cabin noise while cruising, and it sounds almost completely OEM to me when on the road at light load. WOT is a different story in a good way.

2 - I know many people running OEM radiators with heavy mods. I haven't heard or read of anyone having cooling issues with these cars.

3 - I think the Ypipe/Plenum upgrade is a good idea for anyone at any mod level, but my guess is the difference per the seat dyno is more pronounced as the accompanying mods improve which allow for more boost or airflow.

Overall, the best path forward with mods on this platform has been blazed by many others and I count myself lucky to have gleaned advice from them. One more plug for Sambo!!!

Beezupra

There are a great many cars with very restrictive stock cats for which this is true, so I think it becomes second nature to assume it is true for all cars. But on our cars retaining stock turbos, I am yet to see any dyno or ET evidence that the stock cats are a major limitation. Ttz, no disrespect at all, but if you can point me to evidence to support your statement, please do.

Of course a straight pipe flows higher CFM on a test bench than a pipe with our OEM cats, but that doesn't mean they are a restriction if they can handle the CFM of the upper end of efficient operation of our stock turbos and the other in line components.

FVD/Brombacher says their dyno testing shows that 100 cell cats don't offer a performance advantage over our OEM cats until the build is around 680 whp. Members have been told the same by APR. When I asked Soul about it, they reluctantly acknowledged that sounded about right.

I've made 600 whp with a JB4 tune and stock cats, and expect to be reporting back soon with 650 whp on the stock cats once my meth injection is dialed in.

So sirius, my .02 is no need to ditch your plans to retain your stock cats.

SamboTT@ByDesign

Hi sirius,

Congratulations and welcome! These cars are a lot of fun and you’ve got some good plans. Feel free to reach out anytime I can help you with any questions or guidance. Whatever you need it would be my pleasure to support more guys on the forum.

Thank you for the kind words guys. Remember the dynamics of performance and the factory exhaust on these cars is a lot more complicated then power to the wheels on a one gear run. Heat, back pressure and exhaust gas temperature play a big role

Cheers

cosmo1

Very true and I completely agree with you but also keep in mind the Catless dp’s help a lot with Egt’s (Exhaust Gas Temps) which help with cylinder temps..

NightBlueTTS

Welcome to the club..as I’m sure you already know, modding the car is a slippery slope..so it helps to have power and usage goals in mind before you start. That will dictate what mods will be worth it for you.

Now, my $0.02 on your questions:

1) a cat back system will provide a much “better” sound but not really provide much else. If you’re sticking with OEM cats, then you don’t really need the intercoolers as you’ll be capped by the flow through the cats. That said, you can pick up some great power with a custom tune (note: the OTS tunes from Cobb don’t come close to unleashing the potential of the car). Radiators are fine (I have tracked my TTS).

2) If you’re sticking with OEM cats, then you don’t really need the intercoolers as you’ll be capped by the flow through the cats. So think of things in balance with one another.. if you open up exhaust flow AND start running higher boost on a custom tune, then the intercoolers will make a big difference

3) These only seem to be choke points as you start getting into really big power, BUT….I HAD to replace my y-pipe because my OEM literally blew-up at the track (note: this was my running a Stage 3 car in summer heat with around 26-26.5psi). I didn’t replace the plenum as it wasn’t yet a choke point.

Honestly, I have been very happy with my Stage 3 setup: muffler delete + 200 cell sport cats, csf intercoolers, BMC filter, and tuning by Sam da man. However, as it goes, I’m starting to toy with the idea of adding meth since it cools things down and adds octane. It’s hard to just stop 🤣🤣🤣 🤷‍♂️

hope this helps

onfireTTS

Were you manual shifting when the y pipe failed ?

NightBlueTTS

No. I was in Sport Plus allowing the PDK to do its thing. It happened right as I was transitioning to braking (and so there was a small spike in boost). I was recording video/data, and so I was able to isolate the moment it happened.

Somewhat frustrating as it was towards the beginning of the day, but IPD was phenomenal in getting me the part ASAP. Can’t rave enough about their customer service.

Lofvis

Interesting thread, as i'm still on a bone stock .02 i'm gathering intel

Diverter valves also seems to be a thing to change out if you have everything off to install IC or Y-pipe as them seems **** to failure? it's not a power upgrade per say.

IPD claim a good amount of gains on their y-pipe (max 35whp and 40 lb-ft) and plenum (max 45whp and 55 lb-ft) on a stock car and together 55whp and 70 lb-ft,
If y-pipe is good to start with when is the plenum a good idea to swap out as again seems more beneficial to swap both if the skirt is off.

Big Swole

I popped my stock Y-pipe as well... I did happen to have it in manual and forgot so when I let off at the top of the rev range and it didn't shift, there was a boost spike and POP!!!

NightBlueTTS

I’m not an expert at all on airflow, but I’ve tried to think through how an upgraded y-pipe/plenum could aid in more power. To make it simple for myself, I try to envision the intake and exhaust as straws that the engine must “inhale” and “exhale” through. And that the power that the engine can make (ignoring the engine’s own limit based on its internals) will be limited by the “smaller straw’s” airflow capabilities.

My hypothesis is that by and large you don’t need more airflow (volumetric efficiency?) on the intake side while you’re still able to increase the boost that the turbos can generate. In other words, if the y pipe was a choke point, it wouldn’t be able to flow the increased air mass from the turbo.

That said, it would make sense to me that when the turbos are upgraded to larger compressors, you could reach the limit that the stock intake can flow, and could therefore benefit from this upgrade. And it follows that upgrading the exhaust side of the equation benefits the most initially, since it seems to be the “smaller straw” when looking at stock components.


Thoughts? Maybe someone who is an expert can weigh in? I’d love nothing more than to have some easy HP waiting for me by adding some fairly easy to install components 😁

NightBlueTTS

I remember when you posted! Thanks to your post, I was able to quickly diagnose what happened to my car. So thank you!!