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We got rain a lot of rain and I had the Trofeo Rs on and I don't think they're the right call for the standing water.
I did lose the PSM tho in the banking as expected.
thanks for the reply...bummer all the way around! Yeah not good rain tires. Seems like i'll stay away from Daytona since the banks still mess with psm.
A few of the 991 II threads have stirred the inquisitive juices, why? Couple of reasons - the usual magazine racing stuff and the general performance commentaries As we all know the performance of the car is really only dependent on the nut behind the wheel.
By the same token a mate, who is a very good driver has been getting a bit frustrated with his I RS. Basically it goes like this, we head off in a sprint, do the warm up (I'm in a GTS) and largely I stay on him, giving a bit up here and there over 5 laps or so.
Initially we thought it was set up (both on C2 N1), lots of tinkering largely the same result - more frustration. My view was he wasn't pushing hard enough around the corners and one corner in particular e.g. optimising both entry and exit speed - I know from my logging I'm maxed out in terms of lateral G and yaw, and the fact the tires are feathering like billy o .
At the end of the day I thought I'd just crunch the numbers (slow day I know).
The corner is an asymmetric parabola that runs into a straight just over 600m long. My speed as I approach the apex is around 100 kmh (60MPH) and I get close to 250kmh (160MPH) down the straight.
Given in that velocity range my GTS accelerates at around 2.79 m/s^2 and his RS accelerates at 2.894 m/s^2 - basically after 13.5s I'll have covered 616m and he'll have covered 626m - a difference of only 10m. Made up under brakes or gained through a slightly better line. I found this slightly surprising, but is consistent with my observations e.g. he barely pulls away from me.
I can now put his mind at rest - at least a little.
I also put the above graph together from the Car and Driver instrumented test sheets (all PDK). What is interesting is in the daily driving range, say up to 70mph there isn't that much difference. Above 70MPH its night and day - large difference in the common track speed range of 60MPH to 160MPH. Looks like Porsche planning in action.
Using this data, in the analogy above, the base would give up close to 60m - which is very significant on track (assuming RAS and C2 N1 tires).
Anyhow, I thought I'd share as a data point as it were.
Last edited by groundhog; 10-28-2018 at 09:22 PM.
Reason: typo
Nice graph, Bro... I wonder if Grantsfo and Copperhead37 among others will get the credit they deserve by stirring your creative juices flowing. Probably not, since you jumped threads on them. It's funny that you talk down "magazine racing" and the like, on this and some other posts, and then use similar stuff to support your argument. Your post is great, and makes sense, for a drag race not a road race. Just using your own example and data above... How long does it take you to cover that 600m from 60 to 160 MPH? Using your graph, and what you are trying to present, it should be @ 18 seconds... It's not, as you point out, it's actually less than 13 seconds. Less, as you have inertia and the rest of physics on your side at that point; you're already moving, etc. You started to go down the road with the acceleration rates, but stopped yourself, why? A 60m win sounds like a lot, but at those speeds, what are we really talking about in terms of time? At the slow end of your range, a couple seconds... maybe... at the pointy end, less than a second.
This is in no way trying to derail this thread or debate that a GTS or more powerful car is faster in most cases. Most but certainly not all. There are a number of examples and commentaries where we've seen a "lesser" vehicle keeping up just fine if not coming out in front, based on the reality that they are found in. Some realities work to a more powerful car's advantage. Some to the quicker attaining speed/lighter/most agile... You're a track guy, so you understand this. It's the nut behind the wheel...
Not sure how to respond to the above - the actual driver for this was something a friend of mine and I were trying to work out. He used to race in a touring car championship and the RS is his first Porsche GT car.
So I worked it out e.g. In sprint series events the two vehicles in question and the two drivers are surprisingly close and a good part of that can be explained on the basis of my post above. In fact at the next event which is a couple of weeks away I'll get him to log his car and I'll log mine. I suspect the differences will be quite small on a distance velocity plot and g sum plot.
The time btw is actually around 13.5s (as I pointed out) The differences on track between some of the models is quite stark - in the real world. I see this every two weeks or so. This is not a judgement merely an observation one that is consistent with the calculations . I put the data together as I found it interesting and as always surprisingly consistent with Porsche MO.
Not with standing this I am also involved in serious road rallying - so I do know the difference first hand between nimble and meat axe.
If you have some data or real experience add to the mix. Don't turn this into another T thread, its a track thread. Take yours out, smash it round a track for thirty lap bursts at full blat - tell us how it goes, log it and plot it. That's interesting and useful to the community.
See below for full table and matrix (all cars PDK except where stated).
Thanks for the charts. Too aid in further comprehension, what track was this, how many turns and average speed?
On a short, lower speed track, the difference between a GT3 & RS will be less vs a turbo charged car as the torque really helps on corner exit and mechanical grip is key vs aero. The GTS has an advantage of 100ft-lb of torque on the RS.
The GT3/RS cars can make more adjustment on camber, toe, sway bar etc than a GTS, S or T so a well set up GT3/RS car should be faster around a road course but the gap is not as big as it used to be 6-8 years ago.
As SS stated, driver and tires will make the biggest difference on a DE. GT cares comes with Sport Cup, non GT with Michelin 4S. My next set will be Sport Cup.
Thanks for the charts. Too aid in further comprehension, what track was this, how many turns and average speed?
track length ~ 2.5km (1.55 miles)
average speed ~ 145kmh (90mph)
elevation variation ~ 25m (80feet)
three sectors:
(1) start line through fast right hander into left right compound corner with undulating topography
(2) left hander uphill into blind right hander and fast down hill short straight
(3) right hander into straight into tight right hander onto finish line
seven corners:
(1) right hand parabola with double apex (no topo)
(2) right hander with fast transition into (undulating)
(3) left hander with transition on crest
(4) left hander off camber at start tightening up hill into
(5) blind right hander after crest followed by straight into
(6) asymmetric parabola with late apex into long back straight into
(7) 3 right then onto finish line.
The analysis pertains to turn 6 and the long straight. The whole Porsche line up is quick these days - on tight technical circuits with short straights and similar tires there would be no more than a couple of seconds across the whole line up of sports cars. Long open tracks are a very different matter, times will blow out in favour of the cars with the torque and HP to match.
The stock 450 Hp 991.2 GTS is amazingly fast compared to other modern 911 variants - https://www.stuttcars.com/about-porsche/nurburgring-lap-times/
On the Nordschleife, the 450 Hp 3.0 GTS 7:24 lap time is faster than the Carrera GT, 997 GT2, 991.1 TTS, and the 997 TTS, in that order, with the GT at 7:28 and the 997 TTS at 7:37. Amazingly fast!!
The factory test team was quoted that just the addition of RAS and PDCC dropped the GTS lap time 30 seconds! My recollection is the 991's are over 100 lbs lighter than the comparable 997's.
A C2S turned 7:33.67, faster than the 997 TS. Im assuming it had 420 Hp with the Sport Pkg RAS and PDCC.
I bought a new C2S in June with all the performance options, and added the X51 PowerKit. Some guys are going the software tune route, but I'm playing it safe on mine for a few years while under new warranty. In the meantime, I may upgrade my headers and cats...
thanks for the reply...bummer all the way around! Yeah not good rain tires. Seems like i'll stay away from Daytona since the banks still mess with psm.
It's honestly not that bad. I think that you still have the wheelspin control at corner exit (similar to a TC On / ESC Off setup in a GT3) - you just won't have the stability control for corner entry (ESC OFF). If you tip toe around the horseshoes and don't get too aggressive, you don't even notice it. Trust me, i'm not some purist who turns those things off because I think it's hurting my ultimate lap times - the PSM has probably saved over $400K in body damage during the 3 years I've raced the Clubsport. That computer loves me and I love it!
Originally Posted by tgavem
Nice photos.
Sorry about COTA and now Daytona. You need som sunshine so you can stretch the legs on that car.
I finally got some sunshine on Saturday & Sunday and had a chance to run it around. I did part of 1 session Saturday and I did 1 session on Sunday. The car is an absolute animal. I am uploading video now. It would have run sub 2:00 but I got held up by a Daytona Prototype...yes, I just said that.
On the Nordschleife, the 450 Hp 3.0 GTS 7:24 lap time is faster than the Carrera GT, 997 GT2, 991.1 TTS, and the 997 TTS, in that order, with the GT at 7:28 and the 997 TTS at 7:37. Amazingly fast!!
The factory test team was quoted that just the addition of RAS and PDCC dropped the GTS lap time 30 seconds! My recollection is the 991's are over 100 lbs lighter than the comparable 997's.
A C2S turned 7:33.67, faster than the 997 TS. Im assuming it had 420 Hp with the Sport Pkg RAS and PDCC.
I bought a new C2S in June with all the performance options, and added the X51 PowerKit. Some guys are going the software tune route, but I'm playing it safe on mine for a few years while under new warranty. In the meantime, I may upgrade my headers and cats...
Having been on track twice now with the car, my favorite part about it is the torque. I have enough brake pedal to keep up with the GT3s but when you're exiting the corners and unwinding the hands, at 4K RPM the turbos spool up and spit you out of the corner. It's not earth shattering torque like a 991.2 Turbo S but it's also far greater than any NA motor ever. It's like nothing I have ever experienced. I'm so used to racing these high revving cars that need to live in the power band north of 5.5K RPM whereas with this car, you unwind your hands at 3K RPM and roll into the gas and let the motor do all the work. I only drove 1 session at COTA and 1.5 sessions at Daytona because the car is listed for sale and I don't want to put the stress or miles on it. You will see what I mean in the video. It's uploading now. You should have it momentarily. It starts off with a drive-by through the trioval and then I cut up some highlight clips of the car on track. Given the long wide open throttle of Daytona I de-tuned the Cobb flash because I was worried the temps wouldn't cool off enough. The car is actually only running 70% throttle in these videos. I have the data on the Cobb to show you if you're skeptical. The video begins on the outlap of me following a friend in a 991.1 GT3 and then I try and make my way up to the front. I'm trying to catch the .1 RS that rolled off first on the grid but I then pit to log the car with the Cobb Accessport to make sure the motor was happy with the more conservative file. I now have a custom race track map for the Cobb for folks running on track that want to be more conservative. There was not a single hint of IGN knock during this run and I waited for the end of the session to log it so that it would be the hottest. Everything has come together according to plan with this car and everything is working as I had hoped.
Sorry for the video quality. I broke down and bought a Solo 2 DL and SmartyCam for the car for proper data/video but it's still in the box. I didn't install it once I decided to list the car for sale.
You guys that are following this thread have to have a colleague that is now interested in a 991.2. I'm a guy that wants to make a deal. Find a home for this car please and we will work on yours for free and if you come to a Florida track event in January I will coach you for free!
10-27-2018 | 12:23 PM
As we all know the performance of the car is really only dependent on the nut behind the wheel.
