4 Point 0

COBB figures state that GTS stock is 423 HP at the wheels. The Base Carrera with the COBB AP is 435 HP to the wheels. You think 12 HP is Significantly more?


When the GTS has the COBB it is 509 HP. That would be 74 HP more than the Base with COBB. Now that is significant.

GTS Stock 423 - C Stock 367 = 56 HP difference Stock to Stock.
GTS COBB 509 - C COBB 435 = 74 HP difference COBB to COBB.

4 Point 0

I would love to jump on this, but I don't like the idea of shipping ECU internationally. How long before local COBB dealers will be allowed to crack ECU - 6 months? And then how long before you won't need to crack it at all - A year ?

M4 went the same path. Had to crack the ECU in the beginning. Then took another couple of years before you never needed to crack it open at all. Hopefully COBB will follow suit.

groundhog

I have been looking at lots of dyno sheets in relation to the GT4 which in stock form makes about 320RWHP and whilst doing this I found all sorts of other Porsche related data. For example the GTS makes about 370RWHP in stock form. Having owned many turbocharged cars I would expect a reliable tune to add around 50HP to the base, (increasing the base crank to 420HP) so the base probably would make about 350RWHP. I did note somewhere the base pistons are not the same as those found in the S and GTS.

Had a look at the graphs and the Cobb base line runs are way off beam, the gains may be real (assuming internal ECU and dyno corrections haven't been piggybacked/doubled up) but the absolute values are no where near correct which means the peak power and torque numbers they are quoting are no where near correct.

I would also want to see AFR and boost profiles Vs RPM. There are some good reasons for this, for example the oft quoted 'peak' boost of 16psi and 18psi is incorrect - these numbers (for the S and GTS - quoted by Porsche) appear to be the modal value of boost in normally distributed data on acceleration from 4000rpm (SC sports plus mode if you like). In the case of the latter the real peak boost may be as high as 22psi - stock, with peak boost tapered from around 6500rpm.

For some perspective, numbers are around for the 992 series which will use this engine and those numbers (at the crank) look something like this 400HP for the base, 450P for the S and 475HP for the GTS.

I would expect the following to be close to the mark with the Cobb tune(s).

Base 370 at crank, 310RWHP - tuned, 420 at crank - 360RWHP (415BHP at crank)
S 420 at crank, 350RWHP - tuned, 470 at crank - 400RWHP (464BHP at crank)
GTS 450 at crank, 370RWHP - tuned 500 at crank - 420RWHP (493BHP at crank)

Other factors to consider:
Integration of systems - calibration in relation to other systems e.g. sports chrono, PDK-PTVE - even PSE etc
Change in drive - the Porsche torque curves were very flat to 5000rpm e.g. very linear power delivery - the Cobb curves decay from 2000rpm
Boost hold - the boost hold on the stock cars works very well because the actuators and wastegates are designed to operate in a specific way and hold a specific level of boost - this has now been changed
Im pretty sure there is a TD1 flagging system

Needsdecaf

Pretty sure that as the article states "Accessport Tuning" they mean they can tune with the handheld accessport tuner. No shipping ECU.

groundhog

Another tuner said the ECU had to be sent in and following that the Accessport would work

arter

Correct, you send the ECU in to open a backdoor, and then the Accessport can switch between stock and multiple alternate tunes.
(Plus data log, etc. if you leave it plugged into the ORD port).

Benedict14

4 Point 0

Can I ask, do you own a 911?

What country are you from? American dyno's read about 15% higher than Australian and German Dyno's.
So ignore the number and concentrate more on the delta.

It's obvious that people need to READ the threads. It has been confirmed in multiple threads, multiple times, "YOU HAVE TO SEND YOUR ECU IN." Just once. After it is unlocked, you can hand held tune all you want.

groundhog

yes

depends on type, calibration, corrections and how they're run - yes the germans are finicky (for good reason).

the number represents many factors - piggybacking correction factors is a problem for turbocharged Porsche sports cars - the Europeans know this.

thats correct, you can tune and tune till your heart content

stout

Open to it, so it's up to Cobb if they want outside validation and then finding the time to do it. But I am willing because I've been impressed with their work in the past, as well as the feedback I've seen from owners, and they've supported cars for a couple of colleagues/friends at Pikes Peak, further earning my respect.

Were we to do something, I'd want to drive a stock 991.2 Carrera 7MT (using my stock Carrera 7MT as a control) and then run their setup. As my car is a lease, I am not interested in unlocking its ECU—but I am happy to use it as part of the test for an unlocked "control" car. I'd be most curious about driveability, power band, character, etc. For an added dimension, we'd probably need to head over to the Wednesday night drags with someone who is actually good at that. Judging by my last reaction times, I am merely ok, which means probably terrible compared to someone who drag races regularly...it's a different toolbox. My toolbox is mainly road testing—how something works in the real world + dreamy back roads.

4 Point 0

People misunderstand drag racing. The only time reaction time is important, is when you are racing the car beside you. It has ZERO effect on your Trap Speed or your time. The timer does not start until you cross the line.
The second thing is your Trap speed. MPH does not lie. It cannot be faked or manipulated.
If you have two totally different cars, both run the same time...for example 11.5 Seconds and one has a trap speed of 118MPH and the other 122MPH. You know the 122MPH car is faster and with a better driver may improve its time.

The 122MPH may have spun the tyres more. Whereas the 118MPH may have launched hard. 60 ft times confirm these instances.

But I digress. The biggest thing with tunes is, MPH. Before the tune your best MPH was 1XXMPH and after the tune your MPH is now 1YYMPH. MPH takes the driver out of the equation.

Back to reaction time. If Car A has perfect reaction time and runs a 11.5 @ 118 MPH and car be runs an 11.0 at 128MPH But has a slow reaction of 1.3 seconds, Car A wins the race and crosses the line first. But his car is slower. Capiche?

stout

Yes, you are right, and this is coming back to me through a haze induced by the 5-6 years (or more?) since I last took a car to the drag strip.

What I should have noted, and actually meant by the "different toolbox" is the ability to launch a car (primarily) and then maximize use of each gear down the strip. My suspicion is that there is an art form and a science to both, just as there are in other disciplines. Then there are those who can do it well in their car, and those who can do it well in any car. And drag racing, while neat, has never been my passion. I respect those who are good at it, however...as drag racing has some very cool history and the current cars are insane. The amateur cars, just as with auto crossing or track days or club racing, can be very cool, as well.

In any event, if 0-60 or 1/4-mile times are involved, I'd rather have someone well versed and consistent handle them. Anything less will yield less than trustworthy results.

groundhog

I think this is a great idea - the drag strip trap times don't lie and a good road tester will pick the drivability aspects and describe them well.

"The Carrera GTS offers even larger turbochargers than the Carrera S, the compressor measurements come in at 55mm. With those turbochargers producing right around 18 psi of boost pressure we recorded baseline numbers of 423 HP and 409 TQ measured at the wheels. A simple Stage 1 calibration with 93 octane fuel in the tank took the GTS to an astonishing 506 HP and 488 TQ measured at the wheels, peak gains of over 19%!"https://www.cobbtuning.com/porsche-991-2-power-gains-with-accessport-tuning/

I look forward to the tuned GTS trap time given the "astonishing 506 HP and 488 TQ measured at the wheels" as claimed by Cobb.

Even better, get Motor Trend involved - Worlds greatest Porsche drag race 1 - the tuner edition. You could run the following cars - stock base, base with tune, stock S, S with tune, stock GTS, GTS with tune and for good measure stock 991 Series II Turbo and Turbo S as a bonus you could add the Series 2 GT3. Would get a lot of views.

Cheshi143

Just ask the folks over at RS1 if they think the calibrations from COBB Tuning makes a difference. https://www.facebook.com/RennsportOne

LavaGTS

I'll GLADLY be the guinea pig car with my GTS once the AP is released.