fun2k

Hmm the way my car is setup from factory it does not seem to understeer in the slow speed corners. Compared to my 997.2 gt3 there is a lot less understeer at low speed corners. And at high speed corners the 997.2 gt3 (factory setup) also understeers slightly. High speed corners in 991 gt3, the fronts dont give any hint of losing grip and so it actually feels like it will oversteer if i push too much.

Put quite simply the old car generated a lot of driver confidence while the new car at high speed corners only gave me palpitations.

Petevb

You guys talking about understeer/ oversteer. Are you playing with the swaybar settings at all, or did you leave it as delivered?

Dan39

You're not driving fast enough, Macca.

Dan39

As delivered.

Many posters who have put in significant track time have reported low speed understeer and most of these have addressed it with camber/sway bar adjustments.

Some posters have also reported high speed oversteer - one poster added a larger rear wing, which sounds like a great idea to me, but I'm going to try adjusting the existing wing first if I keep this car.

I only got 6 track days in before I had to park it for the winter and the first two were just getting tire pressures dialed in with my pyrometer...

GrantG

Low speed understeer and high speed oversteer is a tough combo. Low speed understeer is frustrating and high speed oversteer is scary. Dealing with the low speed understeer by changing swaybars could exaggerate the high speed oversteer (making the car dangerous).

I like the idea of adjusting the wing for more angle of attack, since this will provide a speed-sensitive solution (help with the high speed oversteer issue). If there is enough wing, might be able to solve the low-speed understeer issue with swaybar and alignment changes and then recoup all your high speed stability with more wing.

Driving technique (trail-braking) can help with the low-speed stuff too without loosening the rear at speed. This is a typical 911-centric issue. I wonder if the PTV can be tweeked for more low-speed turn-in by any aftermarket tuners? Maybe adding rear pads with higher friction could achieve the same end...

Manifold

Exactly, and my impression was that the 991, especially the GT3, has been made more neutral and predictable than the 997 via the longer wheelbase, wider front track, RWS, PTV, e-diff, etc.

I wonder if people struggling with the 991 GT3 don't have it set up right in terms of tire pressures and alignment. A problem with front and/or rear toe can wreak all kinds of havoc.

Personally, I like 911s set up to understeer a bit in general, since it's easier and safer to compensate for understeer as compared to oversteer (and I find that I'm slower with a loose setup too).

SamFromTX

The car couldn't be more balanced. I have the front sway bar set at the loosest setting and the rear at the firmest and even with that, no oversteer, even in the fast sweepers (although when I went to TWS, which has particularly fast sweepers, I put the rear at the middle setting to not get any surprises). When overly pushed, even with those settings, it will tend to understeer a bit. I think that is the reason all of us noted the front tires wearing faster than rears in this car, because they get pushed and ground (to go fast). Of course if one mashes the throttle, it'll oversteer and even spin.

Modena 1

My bet is kers and 4.0

Pdk only to start.

Then they will do manual later.

Macca

Thank you. I have data from at least a dozen or more European drivers pushing the car very hard that correlates with what Sam says here. Lane put the wing on as an experiment not because his car exhibited "significant over-steer at speed". The benefit of additional down force assumed balanced is always welcome on the track. I only have 4 track days on the car, and I may not be a semi pro driver but with 10,000 km on the car much of it fast road work I can honestly say "significant under and over steer" is not part of the package.

Dan. It might be an idea to have your geometry checked. I think your settings could be out. I have my geo sheets and those of others if it would benefit you to get some base settings and also some ideas on more aggressive negative camber settings etc. PM me and Ill send them to you.

Better let the 991 GT3RS speculation thing resume.

All I can add to the 991 GT3RS is that as time goes on the rumours here seem to get more interesting. From Turbos to KERs and totally new engine designs it must be fascinating for PAG to read our banter. All I can tell you is the car is the same as it was intended at the beginning - no real changes to talk of, front fender vents etc are all as originally envisaged. All factory GT resource was redirected to 991 GT3 engine issue for 3-4 months early to mid 2014 so no additional development was enjoyed by this car due to the delayed launch, however it has been thoroughly tested Im sure. The engine is the same as 991 GT3 - of that Im 100% satisfied. Any development since August 2014 has been in final settings for PDK-S, geo and tyres.

fun2k

I didnt change a thing on my car 100% stock with 28/33 cold tire pressures. I remember the time when i really struggled to resolve the slow speed understeer in 997.2 gt3, front bar to full soft and corver balance etc.

To me the new gt3 feels more like a mid engine car.

My car is 10,000kms old , like me

mjg

That's remarkably fast for the straight after T9 and the T10 sweeper at Hampton Downs... are those numbers from your AIM? Or did you mean kph?

GoHardGT3RS

Guys, what makes you think that the 991 GT3 RS will have KERS ?!?

Macca

236Kmph (147.5mph) registered at the speedo (231 kmph verified GPS via Vbox) braking end of front straight into T1 corner. Exit T1 at 142kmph (89mph) on the outside ripple strip - carrying speed through that corner is lower than T10 of course probably building from late 60s mph to 90 at exit. Happy to post screen shots and traces.

My experience is under brakes end of font straight HD you get a little shimmy from the rear as the diff and brakes do their job. Fractionally less than in the 993 but it is there and of course you are going greater speed. I think adjusting the rear spoiler blade angle could help a little here but its really no big issue. You are more than halving your speed in a few meters after all. Carrything speed through T1 & T10 the car seems to handle very neutral, no noticeable under or over steer very benign. You can get a little understeer pushing hard into T3 and tighter corners. car is very suseptable to tyre pressures and I believe prefers slightly higher than lower pressures.

GregJGT3

I would suggest that the PAG statement that the 991 GT3RS engine is "compleetley new" refers to the changing of the engine specification from the 997.2 GT3 RS generatation engine to the 991 GT3 RS generation engine. In this respect it is a "comletley new engine" but still an evolution of the 991 GT3 engine.

Regarding KERS, I don't thnik Porsche is going to incorporate that type of technology for the modest price increase indicated as the price range for the 991 GT3RS over the 991 GT3. They are after all in the business to make money. The spy photos already show a great deal of body aero change for the money spent in development realtive to the return.

mjg

OK, I wouldn't call T1 a sweeper as it's not a larg(er) radius steady state corner. Explains the confusion as I assumed you meant T10.

And now back on topic...