Hey guys! Couple questions for you about the 991's boost.

What is the max peak midrange boost for a 991.1 S? Also what is the max boost at redline?

When the car is tuned what is the max boost in the midrange and at redline?

Do the tuners run 100% wastegate tunes on the car?

Is there any reason to keep the torque low such as weak rods or is the DCT trans the bottleneck?

Does Cobb offer software so we can tune our own cars?

Thanks!

 

Hi there. Lots of great questions you have that will be hard to answer in detail through a post. But if you search you will find plenty of info. Even easier I would be glad to take your call and answer any questions in detail anytime. The Cobb AP system does allow you to install he tune yourself as well as many other features. You can log and see exactly what it is doing in factory as well as upgraded form for yourself. We can get you plenty of tire churning tq safely!

Cheers,
Sam
310-600-1850

 

Sam, thanks for the quick reply. I will start searching the forums tonight.

Cobb offers what they call "ATR" Access Tuner Race for some of the other platforms they work with. It lets people tune their own cars.

I will take a look at Cobb's site and see what they offer for the P cars.

Thanks again.

 

Here is a Stage 3 AP run. Peak boost is about 21lb (MAP-14.7) at gearshift points.

 

Here is some info I found about the GIAC stage 2 tune.

I think I will have to go with Cobb because I want to be able to datalog. Can Cobb also due a gear relearn for the DCT?

Also does Cobb disable some of the TQ management like GIAC does?

Answers below:

1. Boost pressure #'s2. Fuel/air ratio info?3. Timing ?4. Rpm redline increase?5. PDK changes?6. Also. Does this make exhaust louder again if dealer performed WE64 campaign?7. Anything else important I missed you know about?

 

1)On the 991 Turbo S we were seeing aproximatly 17psi at boost onset at 3000RPM followed by a slight decline in pressure to 13psi at 4000RPM then a climb and steady hold of 18psi from 5000RPM to redline. All our 991 testing was done at our facility in Southern California near sea level.

2) The Max boost on our OTS maps start at 20.5psi(Stage1), 21psi (Stage2), and 21.5psi (Stage3). On stock turbos these boost pressure will all fall to roughly 18.5-20psi by redline.

3) We do not run max VTG duty cylce. Below is a log with typical VTG DC.
During spool it is obviously going to be higher(70% falling to 40%) to try and increase the velocity of the exhaust over the exhaust turbine but as target boost is reached it starts to hold steady between 35%-40%. This is from a Stage 2 Tune on ACN91 Fuel.


4) If you tried to run all the boost the car would make you would likely bend rods with the stock turbos since they spool so quickly and have the potential to make 800+ ft/lbs of tq to the wheels at such low RPM. But honestly we have not heard of a car bending a rod as of yet.

We actually bought a set of rods and had them tested. We were the first to step into uncharted torque territories with the 991 Turbo. We were curious what the rods would hold and did not want to find out the hard way.

Here is a link to that discussion about the rods:

http://www.cobbtuning.com/porsche-99...g-rod-testing/

https://www.6speedonline.com/forums/...cting-rod.html

5) We have in the past supplied AccessTuner Race for other Porsche platforms but the 991 Turbo platform hasn't really had a demand for that product. However, we are currently revamping our AccessTuner Race platform on all vehicles (Subaru, GTR, Ford, etc..). This is being done in a better effort protect our customers and deter unauthorized tuners from abusing the system. AccessTuner Pro is still available to vetted businesses who are certified COBB ProTuners.


To add onto a few things:

- Our approach in tuning these cars has never been to defeat safeties, limits, or control strategies. Torque control, intake air temp limits, airflow limits, etc.. all remain intact. However they are tuned along with other aspects when it comes to raising the power output. The limits are set just above the levels we deem safe on our maps, so if something does fail mechanically the ecu can still utilize the factory strategies and take action to save itself, be it putting itself into limp mode, closing the throttle, or simply lowering VTG duty cycle. Porsche puts the limits in there for a reason and we manipulate them to retain their proper function, only at a higher power output.

- There is actually a fairly simple target boost table in the ecu which dictates what boost pressure to run. If you are encroaching on a load/torque/airflow limit it will lower boost or close the throttles however. With these limits properly adjusted, as discussed above, boost should remain relatively consistent. There are compensations for intake air temp, turbospeed, etc.. that also play a part in boost pressures.

Here is an intake air temp compensation table for example:



Factory data has been altered for this display purpose but the the principle remains the same. As IAT increases, the scalar that impacts allowable airflow decreases.

- Rev Limits are stock in our OTS maps but ProTuners have the ability to alter them if requested.

- It excites me to know that you already see the benefits of datalogging. Many of the guys here, like William (wrs) who posted above, love going over the data they are able to retrieve from a log to help improve lap times or look for inconsistencies. Not only that, but in the rare case you were to ever encounter any issues it will expedite the troubleshooting process immensely. You can simple take a datalog and send it to the ProTuner of your choice, look over it yourself, or send it to us. We are always willing help! The parameters you can log with the AccessPort are the same ones we use with our in-house tools.

Having a tuned car without the ability to datalog or pull trouble codes is like having an investment broker who won't allow your input or let you know what stocks you are invested in. Sure everything could be doing great, but wouldn't you want the ability to provide proper feedback or know if something is drastically wrong so you can take action?

Please, if you have any questions don't hesitate to post. There are many forum members well versed on what it takes to go fast, safely on the Accessport. They are generally always willing to share their stories!

Also feel free to email us anytime at Porsche.Experts@Cobbtuning.com or myself personally at Jon.Hebbeln@Cobbtuning.com.

I hope we were able to answer your questions!

-Jon

 

You Geek Jon! Okay COOL Geeks Jon and Mitch are! This is why I love this team!

Let me know if I can help in any way sir and as Cobb's strongest Porsche rep will gladly lay out the red carpet for you as we have for so many!