The 997TT in stock form is a wonderful car. I have owned many turbos and Porsches in general and the old saying holds true, Porsche makes them better with every new model. Coming out of a 996TT making well over 690 Wheel HP makes anything other than a jet seem slow. I was impressed and disappointed at the same time upon receiving my car. The ergonomics and little touches were correct this time, the ride, suspension, handling were great, stopping power is unreal. Heck, my last car the upgrade I used for brakes is now a standard in the TT today. Porsche clearly with the program.
The one thing I felt lacking, power. All the hype of no lag and big HP left me with a few clear impressions. The car had lag plain and simple. Nothing as bad as a K24, but when they boast no lag you expect instant power like the no lag a Harrier Jet uses to hover off and launch! You could clearly feel the car utilize the sport chrono and that extra 10 seconds of boost, but some how my watch never showed 10 seconds of over boost in any band. A blip often left me wondering if my car was not correct. As you stay in the power and reach near redline the car would almost feel like it was being held back, almost a stutter of sorts in the power band. In the upper ranges the car seemed to launch hard then nose off and then come back in to finish big. It is like a switch being flipped on and off then when that last big surge the ride was over, redline was present.

I have learned to enjoy the car as is. And with each new mod brings character and more importantly drivability.
Recapping the prior test all the dynos were run in-house on our 500SE AWD Mustang Dyno. Latest SAE correction, self reporting weather station and latest calibration done 1 week prior to runs. The bumper is removed, independent fans run on each intercooler, engine bay, under the car on the exhaust and the front radiators. Car is run in Sport mode, 91 octane in the tank.

In the exhaust test we found that the exhaust was a big cork. Carrying large back pressure kept the turbos from breathing and robbed HP. Where we left off was our exhaust test yielding an increase to 450HP and 457TQ to the wheels. This was up from the initial 429HP and 440TQ.

Our latest round of testing and development has turned to ECU tuning. It seems that the whole market has been requesting, waiting for this modification. After all, this is the reason I bought my TT the first time, the second time, and now this third generation of turbo. All of our programming is done with Garrett from GIAC. We all spend hours upon hours of testing and development with Garrett and Todd. There have been two big priorities that have added time to this R&D process and the final release. First, exhaust gas temperatures (EGTs) are important and they needed to be monitored with the proper tool. These new turbos are incredibly sensitive to heat. Second, there are anti-tuning functions within the 997TT DME detectable by this factory scan tool. It has been a priority to make sure that the EGTs are happy and that the software is factory scan tool compatible to avoid factory service problems. One could modify only part of the DME program however it may raise red flags during a factory service. Not something we wanted. It was also imperative that the software be made to flash and we didn’t have to remove the physical chip like some tuners currently do. To add to this difficulty Garrett wrote proprietary software that is faster and more reliable than the factory PIWIS software. Along with this the few of us that were testing the software also received a propriety scan tool also written by Garrett. This allowed us to monitor EGTS, IATs and other critical data during testing.

The ECU must be flashed out of the car and done on a bench. We have been bench flashing for over a year and a half now so this is nothing new. Currently all flashes on the 997TT will have to be done out of the car and bench flashed. We use a partial harness with OBD2 port and simply plug into the ECU like it was in the car. Some tuners are soldering in chips like we did several years ago. We never open our the box, we do it all through software.
Now the good part. My car based 429/440. We removed the exhaust and placed the factory exhaust back on the car. Base line was established like the last runs, 8-10 runs until the numbers overlapped done another. Typically 5 minutes between runs to bring IAT and EGTs down to previous tested levels. Interesting enough our runs with the new software created less EGTs then the stock software. Something that is crtical in keeping the turbos alive. Our runs yields an increase to 480HP and 480TQ. Don’t let the numbers fool you. Yes, the gains are great. That is almost 50 HP to the wheels. But more importantly the car now does many different things. Running the car in sport mode, the 2-4K rpm range will blast 1.2 bar almost immediately. It does not flicker once, just solid until it settles in to 1.0-1.1 bar at redline. Additionally, the upper end dip that I felt is now gone. The boost is no longer all over the map and more linear. It is clear in the curve and drivability as well. The power under the curve as seen in the dyno is a huge improvement.


We then bolted the exhaust system back on the car and went for another round. Our results were a staggering 506RWHP and 516RWTQ!! Do what ever math you want to get crank HP. Looking at the dynos you will notice that the dip that is inherent in new TTs at 5200 is now gone. The new curve starts sooner, last longer, and makes more over all power--not only peak, but under the curve where it really matters. (Sounds like a Viagra commercial ) The best I can explain what the car feels like, is a stage 4 (in terms of power) but with the punch of the GT turbos used in the 700 package.

For comparison purposes I have attached a stage 4 car. Notice where full TQ occurs in comparison to the 997TT. It is at 5K compared to the 997TT at 4K. This is huge on the road.

The chip is offered in several configurations. 91 or 93 octane, stock rev limiter, 7000RPM rev limiter. Please email or call with questions.

 

Awesome write-up, amazing what you guys do over there!

 

Stephen, Congrats. Looks like the the VTG's turned out to be better than most thought. Kevin

 

Thank you. You know it isnot so much the HP I am impressed with. We know that HP can be made, but to get the full TQ at 1K RPM sooner is huge! On a stock turbo no less. I now offically love this car

 

Nice write-up. amazing numbers!
do you think that the VTG can be modified? some tuners just removed it to get more HP, don't know about the torque though.

 

Nice, but what kind of gas mileage am I gonna get when I run down the street to the grocery store, doc?




Wow, stunning work. I'm sure a lot of folks are going to be banging on your door!

 

Still 18MPG You think I didn't check that

I do think that there will be versions of the VTGs very soon The key here will be keeping the EGTs down. At this point everything we have done has given lower EGTs over stock. So while we are adding HP we are actually causing the EGTs to go down.

 

Thats the kind of writeup I like to see, backed up with dynos. Nice job.

 

Thank you.

 

Here is the dyno of our latest runs this evening. We added a set of triangular merge headers that are tuned specifically for the VTG technology. I literally smell like exhaust as I write this. Here are the results, 522AWHP/531AWTQ

 

The graphs alone speak for themselves. Your description gets the adrenaline flowing.

Congrats on these amazing results!

 

I kept telling people that those big hotsided laggy suckers could benefit from the headers. Better mid-range and top end along with a bit less lag Why'd Porsche have to slap on 996TT headers like that... I think we're going to be hanging 997TT DME's on the tree this Xmas.

 

Well really only a little bit. We of course have seen bigger numbers with bigger different TTs like the GT package. But to have that on a stock turbo wiht the driveablity the car has is unreal.

Yes, the headers work..I was not sure if they would or not. I haven't driven it with the headers as of yet because of the snow. I can tell you the thing lifts like nuts on the dyno!

 

Did you run it with better flowing headers, mufflers and cats ? Regardless, these numbers prove how great this car is with mild tuning in stock form. Really amazing results that I'm sure will have most new Turbo owners flocking. Nice work to you, Garrett and Todd.

 

Yes, the last Dyno on this page shows the combo of the three. I will also post the overlay of all the stages we tested here shortly.

Thank you. We are all very excited about the progress.