Tracking the Turbo
 

Anyone with experience tracking the TT, have you been able to dial out the under steer? How does it perform at the track?

Background for the question is last year I was in the market for a TTS or GT3 and visited Porsche experience in Atlanta for the comparison. After 90 minutes of thrashing each car around their "smallish" track and skid pad I was left with the impression that the turbo was fast but under steered and I could rotate the GT3 easier. Rightly or wrongly, I attributed that to the turbo's extra weight and AWD and figured it was inherent in the design. The instructor at Porsche Experience concurred, so I bought the GT3. I love the GT3. The car has great balance out of the box and has proven to be an excellent track partner. However in the never ending search for more speed I am considering upgrading the GT3 for faster lap times. This opens the door to other options. I've had and loved turbos and know my friend's TTS is faster in a straight line than my car, so I got to thinking about the new Turbo, could some tuning dial out that factory induced under steer and make it a fun track car? I only use the car to drive to and from the track and do DE events so that is the priority versus DD duty.

Looking any for real experience, thanks!

Hi,

So I tracked my TTS four days in the spring.

https://cimg8.ibsrv.net/gimg/rennlis...16b525c7a5.jpg

Now keep in mind that I am an intermediate level DE driver, so the validity of any input I have is limited by my skill and experience levels.

The car has an AWE exhaust but isn't tuned, so no real power gain compared to stock. It is lowered 30mm with techart springs but retains the stock neutral camber, so that may slightly affect its handling behavior compared to stock. The most meaningful upgrade was that I slapped a set of SC2s on her before hitting the track, which obviously makes a big difference and makes the comparison to a GT3 more even. I ran the car in Sport Plus without deactivating any nannies. One last note, I haven't tracked my RS yet so I can't compare the two.

I found the car to handle very well, especially for a car who's primary focus isn't the track. With new SC2s and temps in the mid 70s I didn't find the understeer to be a noticeable hinderance. With the tires wearing and with temps building during the day, by the afternoon of the second day and with tmps in the high 80s, understeer became increasingly worse. By the end of day four the tires were shot and the track was registering 140F, at that point I had to back way off on entry.

Where the car excels, due to its fantastic programming and AWD, is on corner exit (also excellent braking with ceramics). I was setting the same lap times as I did with my C7 Z06. Now the Z06 has tremendous cornering grip, much more than the TTS, but with so much HP and torque and without AWD putting the power down without losing the back is a challenge, and most of the driver's skill is focused on throttle modulation on exit so as to hook the rear tires without spinning the car. With the TTS you can basically get on the throttle a lot sooner and a lot harder than any other car I have driven on track. So much so that my best terminal speed at the end of the straight at Roebling Rd Raceway was 155mph with the TTS whereas it was 150mph with the much more powerful Z06.

Like I said, in the end my laps were comparable with the TTS and Z06, it was just a completely different type of driving. Now for some perspective, the Z06 is well known to be faster than the GT3 around most tracks that have a serious straight, so I would extrapolate that the TTS is also going to be faster than the GT3 with the same driver on equal tires. The issue is going to be for how long. From what I've heard anecdotally the TTS will eventually succumb to heat related HP loss whereas the GT3 will go all day. I didn't experience any HP loss in my four days at the track, but like I said I'm probably not good enough to be pushing the car to its limits so as to make those symptoms manifest. There are also upgraded intercoolers available if that becomes an issue.

Not sure any of that was helpful. :)

I track my 2014 TTS about 2 times a month. I have GIAC stage 2 + tune, 580 whp, 30 mm lowering springs. I got rid off most understeer by going with 265/325 MSC2. I now like chasing GT3 CUP cars

This-^

245 fronts are there to dial-in a little understeer. Remember: 911 Turbos are known for deadly oversteer and Porsches legal department hasn't forgotten the lawsuits from the original Turbo.

Soulsea, Karl and worf,

Thanks for the in depth explanation and the comparison to the Z06 is extremely helpful. A well driven Z06 is a beast on a track with long straights and fast corners. My home track is Sebring, so that comparison significant. One of the reasons I am considering the .2 is the more efficient intercoolers. It gets hot in Florida in the summer. I agree the driving style required is different. I learned to drive in an old Lotus Europa, no power but good balance, which shaped my driving style.

Trying to understand why you still experienced understeer, here are my thoughts. Going to SC2 in standard widths or uniform increases F/R with std geometry should up the limits but not change the F/R dynamics of the car. I am not sure about the lowering springs but if we assume they have uniform rate increase over stock at all 4 corners to offset the reduced travel; their affect should be to lower CG and increase stability through fast transitions. So these all increase the cars capability but not change the ultimate understeering character. This does prove there is huge potential in the platform that Porsche left on the table.


Guys,
A couple of questions:
After the 4 day track session were all the tires shot or just the fronts? Or put another way do you see significant wear difference front versus rear at the track?

Has anyone tried increasing negative front camber or using 265 front/305 rear tires to shift balance of traction to the front? My assertion is the nannies will keep the back end from coming around.

Also, I would love to read your comparison of the RS to the TTS on track.

Thanks!
CD

The 991 handles great, excellent suspension. The engine in the 991 was moved forward about 6cm, making a huge improvement in stability. I am not aware of change of intercoolers on 991.1 versus 991.2. On the Turbo S: Turbos, heads, awd clutches, fuel delivery, PDK, brakes, tires, and suspension have been changed though.

Read somewhere that the intercoolers were more efficient but can't find that in the official tech specs, so maybe that was miss information. Well that sucks. Was having a debate with a friend who has a 991.1 GTS who is also thinking of moving to a turbo. We were debating TT versus TTS. He was thinking turbo because of not wanting to track PCCBs. Searching for the intercoolers info, I found the S turbos are larger than on the TT, so need to factor that in. Thanks for making me look.

The 991.2 TTS runs a 7min 18 sec ring time on stock p-zeros, nearly 2 seconds faster the GT3 RS with cup tires, almost 10 seconds faster than 991.1 turbo. That is hauling ass, testament to how good the handling is on the turbos. The handling differences between the gt3 cars and turbos are shrinking.

The ring time used estimates for some of the top speed sections due to the ban on top speed that was imposed after the death at the ring. I believe that is lifted now, so will wait and see when they run it in the real world. No doubt it will be faster. I did find the openings in the rear fender inlet and exits are larger which should help intercoolers cooling.

I've learned that trailbraking is the most effective way to keep understeer away under all conditions. Feeling the rotation and getting on the throttle towards the apex is a magnificent feeling I must say :) d

My TTS has pads and SRF as its modifications

If you want more power, why not get an RS or an R?

Yes, 265/325, which the RS also runs, really helps the TTs handle much better.
also with the nannies on the 991s now its much harder to get the ass end to come around.

Not being a 918 owner, an R is out of the question and I have been on the RS list at my local dealer for about a year. Not willing to pay over MSRP and besides exploring options is a good thing. The turbo is a great platform, I just want to understand the differences and make an informed purchase.

I thought everyone knew R's were only available to a select few with few if any on the market and RS's are $50-100k over MSRP. Apparently this is not true or a bunch of us would love to know where this stocking dealer is and or his allocation schedule.

So what are the numbers for the standard 991.2 Turbo? Big improvement on the 2-S times over 991.1, and would assume a similar increase on the 991.2-non-S, albeit a bit below the S. Is the suspension of the S/non S the same? From what I can determine so far it seems that the only difference between S/non S is larger ceramic brakes and larger turbos that account for the 40+ hp. Easy to get reliable 40hp with quality aftermarket tune.