///M3THOD

A few words about the testing conditions and the intended takeaways here. I ran my car to determine the power over stock that the COBB Stg.1 tune offers. I did this to add to the community and provide some independent data. I did not do this to start an argument about max power (especially considering todays dyno conditions), dyno variance and other nonsensical topics. Lets try and keep this thread on topic and free of conjecture.

First, a big thanks to both Sam at ByDesign Auto and COBB for making this a seamless and pain free process!!

All runs were done on a Dyno Dynamics at Forged Performance in Marietta, GA. These guys are one of COBB’s authorized protuners and big in the GTR scene. Testing conditions were in Atlanta (1000ft above sea level) around +90 degrees and raining, so obviously humidity was very high, around 90%. All pulls were done in Sport (+) with 4th gear, which is slightly higher than the ideal 1:1, but the same gear all the tuners test in. The closest gear technically would be 5th, but a dyno pull with the wheel speeds of such a long gear isn’t really practical. The power pulls were done and then the car was let to cool down for about 15 mins.

Regarding 991.2 gear ratios, the base Carrera has a FDR of 3.44 in both 7MT & PDK. The remaining chassis variants have a 3.59 FDR in both 7MT & PDK.




My car is a 2017 991.2 GTS with PDK. I have a BMC filter on the car and AWE 200cell sport cats, otherwise the car is bone stock.

Now, down to my perceptions of the tune. Overall, I am very pleased with it. I have about 200 miles on it so far. The car runs solid as stock and retains the same powerband characteristics as the OEM tune. The power is very linear and pulls hard to the redline. One of my complaints with the OEM tune is the artificial feeling power plateau that would hit as the car reached around 6k rpms. That feeling is completely gone, the car just pulls hard to redline now. You can see this plateau shown on the OEM chart below in pink, it just stops climbing after 6.2k rpm. Its designed like that to limit the numbers the car makes. (What do you want to bet the 992 will have a linear chart with no plateau when Porsche modify's this tuning to give the car another 20-30rwhp?)

The powerband feels almost NA, there is no “surge-y” feeling like you encounter with large single turbo vehicles and there is ZERO lag. The turbos spool much quicker and the low rpm torque comes on like a train. I’ve found that PDK kicks up a gear early in Sport because the pedal position isn’t aggressive enough for it to hold it. I just don’t need to push the accelerator as hard as now to carry the same speed as with the stock tune. I’m assuming the COBB PDK software will help with this.

..DYNO DAY..





I had the car run 3 times with the Stg. 1 (93 oct) software loaded. The car needs time to allow the ECU to adjust to the Stg. 1 map, the only way I could practically do this would be dyno it with the COBB map loaded first and then drop to Map 0. The power pulls were within 5rwhp of each other. The highest being 470rwhp. If the weather was cooler and it wasn't as humid I think the numbers would have been a little better, but its a solid number either way.

Also playing into that number is the fact that my IAT's were 120-140F's on the power pulls, which means the car would have made considerably more power with a proper vent setup cooling the IC's and cooler ambient temps. From my logs on the hwy, I am seeing temperatures that are a good 20-30 degrees cooler on my IAT's in 4th gear.

The OEM runs, which I did 2 of, settled out at 383rwhp, but the IC’s were definitely heat soaked at that point considering they were the last runs. The first run the car was adjusting back down to the OEM tune and the numbers are off, so for simplicities sake I have excluded them. I have all the data logs for those interested. I believe that I’d probably be sitting right around the 400rwhp with a cold car, which is pretty much exactly as expected.

Overall, the car feels much more powerful. The car absolutely rips in 2nd and 3rd gear pulls starting from 3.5k. I think the Stg. 2 map should easily put the car over 500rwhp, which is a solid 100-120 rwhp over stock… not too bad! Next mod will be headers, with which I think I will probably see another 15-20rwhp consistently as well. Cat bypass pipes would also probably really help the turbos breath and prevent heat soak, but I DD the car and at the moment Im not really considering it at this moment.

Also for your reference, heres a 991.2 GT3 MT dyno, https://rennlist.com/forums/991-gt3-...pd-manual.html

To those of you who are considering tuning your car, I think COBB is hands down way to go. The support I’ve already received and the quality of their product speaks for itself.

Jaws1

Great results. I like the consistency of the delta between stock and tuned, which means that power delivery should feel similar to stock, albeit much stronger. Thanks for posting.

Valvefloat991

Impressive improvement and useful information. Thanks very much.

Just as an aside, the gearing chart you posed suggest that the manual and the PDK have different final drive ratios. That's not correct. the base 911 Carreras have the 3.44 final drive ratio with both the M7 and PDK transmissions. The S , GTS, and T have the 3.59 FDR with both transmissions.

///M3THOD

Nice catch, corrected. Thanks for point that out.

Churchill

I've never been a turbo guy, but damn, the power gains are just effortless. 470 at the wheels on a 991 is insane.

PTS-BRG

I have the same car, but a 2018 with the same tune. I have not yet had the opportunity to dyno test or really open it up.
To be honest, as much as I love the improvement from the chart and the removal of the artificial ceiling is fantastic,
I expected higher numbers from both stock and tuned.

I am coming from a 600hp Mercedes AMG and 380, 470hp.. It just seems so low compared to the HP numbers I see on other vehicles.
I know its not all about HP, but it would be nice to see 550-600hp with a tune and minor mods..

Steve Cole

I think a 470whp GTS will absolutely **** on a 550whp AMG C63. Just saying.

///M3THOD

You've got to keep in mind the car weighs ~3200lbs, so the hp/lb ratio is much better.

The numbers would be slightly higher with a better testing day. It was hot and pouring all day, I'm guessing another 15-20 hp would be easily duplicated on several runs.

The baseline was done at the very end, everything was heat soaked and the IAT's were way up, like 30 degrees. I have the data logs. I am assuming dynoing the car cool on the first run you would be around 400-410rwhp. I had a 991.2S and it pulled 387rwhp with bypass pipes when the car was cool. The numbers seem in line to me.

We're also only scratching the surface, the boost is only up 2-2.5lbs over the stock 18. I think target is 20.3 from what I am seeing as pre-boost target in my accessport display.

Another 2lbs should put it easily over 500rwhp and thats only with cats and a filter.

PTS-BRG

Steve: My AMG was 605hp and I have a 991.2 GTS. The GTS wouldn't **** on my AMG, I would be watching you in my rearview.

No question that drag and rolling weight are a big part of it. Also, AWD vs 2 WD helps the GTS. But once a car is in motion, nothing beats pure Horsepower.

M3thod: I also saw that the boost on my Cobb tune was only up slightly. I think that with the stage 2 maps we will see another 10%+
I also only have cats and a filter, but I am always curious if a plenum or different muffler or even headers would improve the HP significantly.
Can't wait to see what the ideal setup is going to be

SamboTT@ByDesign

tango131

///M3THOD

Thanks Sam. With the conditions being as they were, we can't get too hung up on max number, a different day could yield significantly increased numbers. As I think we all agree, the important thing here is the power picked up with a small increase in boost!

SamboTT@ByDesign

kennypowers

Valvefloat991

With a PDK, I'd expect high tens with trap speed in the high 120s.