997gt3north

- yes sport button was on, i did so as early in the sessions there were two corners #4 and #10 where i decided not to downshift into 2nd for #4 and 3rd for #10 but to leave the car in 3rd for #4 and 4th for #10 and the rpms were in that range where the engine felt dead (i.e. it need tq)
- in day 2 i eventually decided a downshift was required from 4th to 3rd to take the downhill #10 but I still took #4 in 3rd as i didn't want to be shifting into 3rd while taking the very twisty 5a, 6, 6a combo

- with my other car, a 500whp S4, i never had to think too much about gears other than when I had to shift up on the straights but the gearing in this car constantly comes into play at VIR

- examples:
1) you are coming into #1 on the rev limiter in 4th and maybe could shift into 5th but you would have to have short shifted on the straight likely just after the kink where it goes off camber?
2) the 4,5,5a twisty combo could all likely be taken in 2nd but a shift would have to be made somewhere while you are slighty turning
3) i was taking the uphill s'es at 105mph ( but you are entering much faster and you exit faster so 4th is a better gear but 3rd could have been used)
4) i did the racing line in the 14,14a complex that requires a sharp right hand turn at 45mph that I thought many times that 2nd gear would be faster but again would require a quick shift into 3rd while slightly turning left for #15 (but more tq on exit could have been useful)

Summary
- if the gears were a little shorter i don't think the sport button would be useful at all and especially on this track it would seem that CUP (4:1) rear end would be beneficial
- from a street practicality the stock rear gear ratio plus the sport botton for a little extra low end tq seems like a decent alternative (personally i think it would be a really neat idea if you could order from porsche as a no cost option what rearend gear ratio you wanted - personally i would give up the 196mph top end and make it 170mph in order to get slightly shorter gears that would bring 5th, never mind 6th gear into play)

frayed

Weird. I know that TC is a different system than PSM, which the GT3 doesn't have. However, in a power oversteer situation, TC should cut power and apply brakes to keep the rear end where it belongs. Perhaps in Sport mode it is so lenient that it does not intervene fast enough to prevent a spin.

trumperZ06

Nice write-up !!! Almost felt like I was in the car with you.

Very astute analysis on the cause of your spin... pinching the corner, Kudos !!!

mitch236

I have stated previously that the TC wouldn't cut in even when I was hanging the back out on a slow hairpin. I was testing when it would cut in and I had the rear drifting and even did a tank slapper and never did it intervene. Unlike PSM which is very intrusive, TC can't be relied on to save your bacon.

BobbyC

Mitch, how do you think the RS (with it's wider rear) will behave rleative to the 3? Thoughts?

Boxster Coupe GTS

...had an interesting demonstration of the impact of TC on a 997 GT3 at a test track: try a full launch from standstill as though you are exiting a T-junction at 90-degrees!

1) With TC-on you can achieve an entertaining launch with some fish-tailing!

2) With TC-off it requires some pretty quick opposite lock and a bit of throttle control to prevent a spin!

...it's worth a try!

(...not recommended for real T-junctions!)

mitch236

I think the slightly wider rear won't help much when the driver is overstepping the laws of physics. The real advantage to the RS's rear is the carrier. You have a better geometry, the change in width is a minor improvement.

frayed

Provided that the RS is demonstrably more planted in the rear over bumps than the 3 (as has been said by a few reviewers), I am in complete agreement with what you say Mitch.

I want the RS suspension components on my car if they work properly with the narrower rear track of the 3, i.e., the larger offset of the GT3 wheels is 17mm more inboard per side.

Anyone have more info on the RS components?

997gt3north

- Thank you for posting this information.

- This basically confirms what I thought happened - i.e. basically nothing - the TC allowed me to make 3 attempts at saving the rotation (counter left, then right, then left again) finally on the fourth attempt the car was coming around so fast we just 360'd off the track in a counter clockwise rotation.

- I am fine with the fact that this is the way TC works as this is one of the reasons I purchased the car - i.e. i want to learn how to drive not have the computer make you think you are driving well - BUT, hopefully this will be useful informaiton for everyone that TC is not going to save you like stability management does

- Maybe someone can try and confirm with Porsche if in fact Sport Mode does or does not alter TC - could be a reason for a lot of people not to engage sport mode

frayed

From Porsche's website:

Specifically configured for optimum sports performance, Traction Control reduces wheelspin under full acceleration which could destabilize the rear of the car. The standard trigger threshold for the system is purposely so high that it is rarely exceeded during normal road-driving in dry conditions. It is possible to raise the threshold higher still by pressing the Sport button on the center console. For maximum involvement, the system can be fully disabled by using the separate “TC OFF” switch.

997gt3north

frayed,

- nice find, now we know

- i think this line is useful: "Traction Control reduces wheelspin under full acceleration which could destabilize the rear of the car" - this is exactly when i have experienced TC kicking in - ie in the Uphill at Limerock under full acceleration when the rearend momentarily unweights, my foot is flat to the floor, hands are straight as I crest the hill and the rear wheels spin for the tiniest fraction of a second - the TC lights for an instant and then off

- i know this is just a verbal description in Porsche literature but this does not describe the situation that triggered my spin - ie: very slowly beginning to apply the throttle on trackout and then the rear just slowly slides out as i was not initially aware that i was pinching the exit and my tires did not have the grip that they had earlier in the session

stedge

Very open and good report, and much appreciated. I am only posting because I have memories of my first laps at VIR, with Bob Olthoff and Dennis Olthoff, and how different they were. Dennis was fast and aggressive, letting it hang out. Bob was smoother, keeping the car near its limits but always seeming in control, just making it seem easy and unhurried, and just so good. Sorry for OT post, just memories of VIR.

MRichmond

Hello to all. I ran the E60 M5 that 997gt3north referenced. We had a fantastic time together and, as I already told him, seeing his gorgeous car on the track made my GT3 obsession even more pronounced.

The video was taken during the second session on Day 2. At the end of the first session that day the car gave me the "your rear brake pads are fried" warning. (I was running Pagid RS19 pads on the front and stock pads on the rear, which I belatedly discovered is not a great idea.) So, after verifying that there was at least some pad left on the rears, I went out for the second session with the intention of not pushing the car as much as I had in an effort to ensure that I did not lose the brakes completely since I wanted to run the remaining sessions and still had a 150+ mile trip home. So, you will see the first lap or two being run conservatively, with especially early braking.

I then see that unmistakable white GT3 nose filling up my mirror through Turns 2, 3 and 4. Still intending to maintain my conservative approach, I waved him by coming out of Turn 6. But as he roared by, the game plan was left behind with our combined exhaust somewhere north of the bridge. I still tried to save the brakes as much as I could, but the priority became sticking to the Porsche's tail. The ensuing five or six laps were an absolute blast, and if you turn the volume up you will hear my displeasure twice when slower traffic got between me and my target. Thanks largely to other traffic getting in his way, I was able to catch up each time.

The video is long -- over 22 minutes and around 175 megs -- but I think you will find the wait for it worthwhile. (My special thanks to Chris K., who runs what has to be the meanest and lightest E46 M3 around, for hosting it.) I tried posting the link to the video, but apparently this forum's rules require a minimum number of posts to include links. So, I have e-mailed the link to 997gt3north so he can post it.

Once it is up, enjoy and I hope to see many of you at future VIR events.

NJ-GT

997 GT3 and 997 GT3 RS have the same front and rear carriers. When the PCCB option is selected, different front carriers are installed.

The key difference is the split rear control arm. I've that same control arm in my car. As you add shims, the wheelbase increases.

The additional track on the 997 GT3 RS is just the product of the wheels offeset (51mm vs 68mm-5mm). The RS wheels will have the same effects in the narrow body 997 GT3. Indeed the narrow body 997 GT3 Cup has even wider track than the 997 GT3 RS, as it uses offset 30mm although a narrower wheel.

Any feeling of a better planted car when comparing the 997 GT3 and 997 GT3 RS have to come from spring rates, shocks bump and rebound, as the extra track and geometry change on the split arm is negligible.

krC2S

i agree with this and if we assume that it feels more planted like some say then what will it be? i doubt diffrent spring rates since porsche didn't mention this and seems to advertise every extra bit in RS as expected..only thing i remember other than track/arms is "special" PASM tuning..just curious

maybe it felt more planted at higher speeds which could be due to the wing