Road America in GT2 RS & GT3 RS
04-30-2019, 12:19 PM
#136
Burning Brakes
Wow!
The part where I'm truly impressed is what Brian Sellers did on not the optimal setup and MPSC2-N2 tires. Sellers ran the car with the sway bars on the stock setting, which means rear bar at full stiff, stock alignment, and he still ran a 2:17 flat. On Cup2R Sellers would go so much quicker.
Dave Donohue is an awesome driver, but we are getting to the point of diminishing returns, and different Pro-drivers in same car can produce different lap times.
A few things on the GT3 RS lap:
- GT2RS on Magnesium wheels, GT3RS on brick wheels
- GT2RS with WP, GT3RS with heavy sway bars
- I timed a video I have from PBIR (on more humid conditions and a hot day, compared to Road America) from 72mph-149mph, my car did it in 12.6 seconds, Donohue's car took 13.2 seconds for the same speed range on a flat surface. My car runs at full aero. It doesn't make sense, except for the next observation.
- I'm suspect of the GT3RS running a little heavier than it should, just the WP and Mg wheels will give the GT3RS a 0.6s drop, add shifting at 9k rpm, and there are a few tenths there. It will easily land in low 2:17s, and it would be close to match what Sellers did on MPSC2-N2.
There was a test where the GT3RS on Cup2R lapped faster than the GT2RS on Cup2-N2.
King Kong is the King of course, but the true gap for these two cars equally equipped is smaller than what most people believe, and at most track days I attend, there is a much bigger gap on driving skills alone, so for the GT2RS to win a DE Cup Championship, it will still need a top driver.
The part where I'm truly impressed is what Brian Sellers did on not the optimal setup and MPSC2-N2 tires. Sellers ran the car with the sway bars on the stock setting, which means rear bar at full stiff, stock alignment, and he still ran a 2:17 flat. On Cup2R Sellers would go so much quicker.
Dave Donohue is an awesome driver, but we are getting to the point of diminishing returns, and different Pro-drivers in same car can produce different lap times.
A few things on the GT3 RS lap:
- GT2RS on Magnesium wheels, GT3RS on brick wheels
- GT2RS with WP, GT3RS with heavy sway bars
- I timed a video I have from PBIR (on more humid conditions and a hot day, compared to Road America) from 72mph-149mph, my car did it in 12.6 seconds, Donohue's car took 13.2 seconds for the same speed range on a flat surface. My car runs at full aero. It doesn't make sense, except for the next observation.
- I'm suspect of the GT3RS running a little heavier than it should, just the WP and Mg wheels will give the GT3RS a 0.6s drop, add shifting at 9k rpm, and there are a few tenths there. It will easily land in low 2:17s, and it would be close to match what Sellers did on MPSC2-N2.
There was a test where the GT3RS on Cup2R lapped faster than the GT2RS on Cup2-N2.
King Kong is the King of course, but the true gap for these two cars equally equipped is smaller than what most people believe, and at most track days I attend, there is a much bigger gap on driving skills alone, so for the GT2RS to win a DE Cup Championship, it will still need a top driver.
04-30-2019, 12:32 PM
#137
Rennlist Member
Wow!
The part where I'm truly impressed is what Brian Sellers did on not the optimal setup and MPSC2-N2 tires. Sellers ran the car with the sway bars on the stock setting, which means rear bar at full stiff, stock alignment, and he still ran a 2:17 flat. On Cup2R Sellers would go so much quicker.
Dave Donohue is an awesome driver, but we are getting to the point of diminishing returns, and different Pro-drivers in same car can produce different lap times.
A few things on the GT3 RS lap:
- GT2RS on Magnesium wheels, GT3RS on brick wheels
- GT2RS with WP, GT3RS with heavy sway bars
- I timed a video I have from PBIR (on more humid conditions and a hot day, compared to Road America) from 72mph-149mph, my car did it in 12.6 seconds, Donohue's car took 13.2 seconds for the same speed range on a flat surface. My car runs at full aero. It doesn't make sense, except for the next observation.
- I'm suspect of the GT3RS running a little heavier than it should, just the WP and Mg wheels will give the GT3RS a 0.6s drop, add shifting at 9k rpm, and there are a few tenths there. It will easily land in low 2:17s, and it would be close to match what Sellers did on MPSC2-N2.
There was a test where the GT3RS on Cup2R lapped faster than the GT2RS on Cup2-N2.
King Kong is the King of course, but the true gap for these two cars equally equipped is smaller than what most people believe, and at most track days I attend, there is a much bigger gap on driving skills alone, so for the GT2RS to win a DE Cup Championship, it will still need a top driver.
The part where I'm truly impressed is what Brian Sellers did on not the optimal setup and MPSC2-N2 tires. Sellers ran the car with the sway bars on the stock setting, which means rear bar at full stiff, stock alignment, and he still ran a 2:17 flat. On Cup2R Sellers would go so much quicker.
Dave Donohue is an awesome driver, but we are getting to the point of diminishing returns, and different Pro-drivers in same car can produce different lap times.
A few things on the GT3 RS lap:
- GT2RS on Magnesium wheels, GT3RS on brick wheels
- GT2RS with WP, GT3RS with heavy sway bars
- I timed a video I have from PBIR (on more humid conditions and a hot day, compared to Road America) from 72mph-149mph, my car did it in 12.6 seconds, Donohue's car took 13.2 seconds for the same speed range on a flat surface. My car runs at full aero. It doesn't make sense, except for the next observation.
- I'm suspect of the GT3RS running a little heavier than it should, just the WP and Mg wheels will give the GT3RS a 0.6s drop, add shifting at 9k rpm, and there are a few tenths there. It will easily land in low 2:17s, and it would be close to match what Sellers did on MPSC2-N2.
There was a test where the GT3RS on Cup2R lapped faster than the GT2RS on Cup2-N2.
King Kong is the King of course, but the true gap for these two cars equally equipped is smaller than what most people believe, and at most track days I attend, there is a much bigger gap on driving skills alone, so for the GT2RS to win a DE Cup Championship, it will still need a top driver.
You are quite correct about driver skills.
Last year when I ran the Sport Cup Deutschland, there is a street car class. There were a few GT2RS in the field but they are not even close to the top 5, which all are either of GT3, GT3RS. Some races a GT3 wins, others a GT3RS.
04-30-2019, 12:47 PM
#138
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Regardless, the 5-6mph min speed differentials at T1/T13/T14 suggests 2RS was leaving more time on the table than the 3RS. Aero and weight differences aren't enough to explain those speed differentials. I suspect a big challenge in the 2RS relative to the 3RS is judging braking given the higher terminal velocity headed into any given corner.
04-30-2019, 12:57 PM
#139
Do we know this or just assuming from the photos?
Regardless, the 5-6mph min speed differentials at T1/T13/T14 suggests 2RS was leaving more time on the table than the 3RS. Aero and weight differences aren't enough to explain those speed differentials. I suspect a big challenge in the 2RS relative to the 3RS is judging braking given the higher terminal velocity headed into any given corner.
Regardless, the 5-6mph min speed differentials at T1/T13/T14 suggests 2RS was leaving more time on the table than the 3RS. Aero and weight differences aren't enough to explain those speed differentials. I suspect a big challenge in the 2RS relative to the 3RS is judging braking given the higher terminal velocity headed into any given corner.
04-30-2019, 01:03 PM
#140
Race Director
- I timed a video I have from PBIR (on more humid conditions and a hot day, compared to Road America) from 72mph-149mph, my car did it in 12.6 seconds, Donohue's car took 13.2 seconds for the same speed range on a flat surface. My car runs at full aero. It doesn't make sense, except for the next observation.
.
04-30-2019, 01:03 PM
#141
Do we know this or just assuming from the photos?
Regardless, the 5-6mph min speed differentials at T1/T13/T14 suggests 2RS was leaving more time on the table than the 3RS. Aero and weight differences aren't enough to explain those speed differentials. I suspect a big challenge in the 2RS relative to the 3RS is judging braking given the higher terminal velocity headed into any given corner.
Regardless, the 5-6mph min speed differentials at T1/T13/T14 suggests 2RS was leaving more time on the table than the 3RS. Aero and weight differences aren't enough to explain those speed differentials. I suspect a big challenge in the 2RS relative to the 3RS is judging braking given the higher terminal velocity headed into any given corner.
I tend to agree re: the min cornering speed differences - does seem like there is probably more on the table from the 2RS. the carousel (T9 & T10) should eliminate the impact of the 2RS coming in so hot, and it looks like for that long turn, the 3RS had only a 1mph faster min cornering speed.
I do think the point about the Mag wheels on the 2RS is a good one though - at those speeds, I'm sure the differences in rotational weight shows up on the stop watch.
04-30-2019, 01:08 PM
#142
I thought both cars would carry more speed through the Kink with the aero help but understand there's a certain amount of self preservation that kicks in there. Watching the videos I started to wonder what a factory Porsche driver could have squeezed out for the laps.
04-30-2019, 02:09 PM
#144
Rennlist Member
Thread Starter
That has always been a Porsche hallmark. They never overheat. At Weissach they told me it's the first thing they do, to stop the car, everything else comes second. Brake cooling always is the priority, the one thing they won't compromise, unlike other manufacturers that do brakes that are only good enough.
As for the tech doing nothing. That's also their trademark too. They are also famous for bringing minimal crew. You heard the story before from David and Randy about that time when they brought a 918 to Laguna Seca doing the head to head with a P1.
As for the tech doing nothing. That's also their trademark too. They are also famous for bringing minimal crew. You heard the story before from David and Randy about that time when they brought a 918 to Laguna Seca doing the head to head with a P1.
2005~: 996 GT3 on standard brakes that faded a bit on a loop test for Excellence where the PCCBs on two 996 GT2s along for the trip did not; this happened to multiple drivers
2009~: Panamera at Road America, thanks to going four adults up with pad compounds designed to save your neighbor's cat in the morning at…Road America; this is an infamous press launch in PCNA lore
2016~: 991.2 Carrera in Tenerife on a closed ex-rally stage (downhill, brakes smelled but didn't go to fade; after subsequent talks with engineers, I wonder about pad bed-in for the press cars)
2018~: 991.2 Carrera T in the wilds of Northern California (brakes smelled but didn't go to fade; after subsequent talks with engineers, I wonder about pad bed-in for the press cars)
I have never experienced brake fade or a soft pedal in a GT-dept 911 since that 996 GT3 press car, and who knows how its pads were bedded or the condition of its brakes. It was, iirc, the last U.S. press loan for a 996 GT3 and a car pulled from the "Hollywood" fleet.
Haven't heard the story about the 918 H2H @ LS. Sounds like we have stories to swap, and we really need to get some dinners going…or better still, track days.
Wow!
The part where I'm truly impressed is what Brian Sellers did on not the optimal setup and MPSC2-N2 tires. Sellers ran the car with the sway bars on the stock setting, which means rear bar at full stiff, stock alignment, and he still ran a 2:17 flat. On Cup2R Sellers would go so much quicker.
Dave Donohue is an awesome driver, but we are getting to the point of diminishing returns, and different Pro-drivers in same car can produce different lap times.
A few things on the GT3 RS lap:
- GT2RS on Magnesium wheels, GT3RS on brick wheels
- GT2RS with WP, GT3RS with heavy sway bars
- I timed a video I have from PBIR (on more humid conditions and a hot day, compared to Road America) from 72mph-149mph, my car did it in 12.6 seconds, Donohue's car took 13.2 seconds for the same speed range on a flat surface. My car runs at full aero. It doesn't make sense, except for the next observation.
- I'm suspect of the GT3RS running a little heavier than it should, just the WP and Mg wheels will give the GT3RS a 0.6s drop, add shifting at 9k rpm, and there are a few tenths there. It will easily land in low 2:17s, and it would be close to match what Sellers did on MPSC2-N2.
There was a test where the GT3RS on Cup2R lapped faster than the GT2RS on Cup2-N2.
King Kong is the King of course, but the true gap for these two cars equally equipped is smaller than what most people believe, and at most track days I attend, there is a much bigger gap on driving skills alone, so for the GT2RS to win a DE Cup Championship, it will still need a top driver.
The part where I'm truly impressed is what Brian Sellers did on not the optimal setup and MPSC2-N2 tires. Sellers ran the car with the sway bars on the stock setting, which means rear bar at full stiff, stock alignment, and he still ran a 2:17 flat. On Cup2R Sellers would go so much quicker.
Dave Donohue is an awesome driver, but we are getting to the point of diminishing returns, and different Pro-drivers in same car can produce different lap times.
A few things on the GT3 RS lap:
- GT2RS on Magnesium wheels, GT3RS on brick wheels
- GT2RS with WP, GT3RS with heavy sway bars
- I timed a video I have from PBIR (on more humid conditions and a hot day, compared to Road America) from 72mph-149mph, my car did it in 12.6 seconds, Donohue's car took 13.2 seconds for the same speed range on a flat surface. My car runs at full aero. It doesn't make sense, except for the next observation.
- I'm suspect of the GT3RS running a little heavier than it should, just the WP and Mg wheels will give the GT3RS a 0.6s drop, add shifting at 9k rpm, and there are a few tenths there. It will easily land in low 2:17s, and it would be close to match what Sellers did on MPSC2-N2.
There was a test where the GT3RS on Cup2R lapped faster than the GT2RS on Cup2-N2.
King Kong is the King of course, but the true gap for these two cars equally equipped is smaller than what most people believe, and at most track days I attend, there is a much bigger gap on driving skills alone, so for the GT2RS to win a DE Cup Championship, it will still need a top driver.
Quick thoughts...
- Agree on Sellers, and Donohue; was thinking David set down a great target time for the real world, but a conversation we had was telling: Both of us are dads, and that changes things. I am sure he put down a very quick lap—but I am also sure he weighed out the risk-benefit ratio not only to himself (as any sensible driver would, regardless of age or employ) but also in terms of they had one GT2 RS and several members of the media showing up the next day. I suspect Donohue would be the first to say there's a little more there, and it would be interesting to see what "ultimate times" two freshly minted (or current) factory drivers might turn with a full-flight factory effort with two cars as we saw at the Ring. I think the reality is diminishing returns, as you say. Weather, track surface, and more quickly come into play—along with the difference between a fast lap for a veteran pro vs a young buck.
- I think elevation is at play with the NA car, and the metric applied while possibly imperfect sure looks reasonable.
- I can see some tracks/situations where even on the same tires one might be quicker in the GT3 RS; car is lighter, but also there are those times where a lot of power just turns into temptation to overdrive the car...another challenge to the GT2 RS to be dealt with—and I like cars that present challenges. This one's are like Mt. Everest when it comes to 911s...but it's so approachable. Hmm....
- Pobst noted a strong preference for the 2R, which I ended up agreeing with—and for the same reason. The "window" approaching/at the limit is nicer and more predictable. One thing I love about that guy, besides the fact he's quick in a variety of cars, is how human he is...how quick he is to note that a scary car is scary to him and won't get the most out of him. Just a very cool dude.
- Agree on GT3 RS, and Frank Wiesmann and I talked about this on pit lane. GT3 RS was shod in the heavy wheels because the focus was on a lap record with the GT2 RS and the idea of having half a dozen drivers pounding on a second set of those wheels all day wasn't appealing. Makes sense to me...
Indeed. HH mentioned that I was losing a lot of time in the carousel, and my thought was "who cares" as I didn't want to have an off on the way to the kink but more importantly wanted to plan my run into and through the kink down to Canada Corner. It was my first time back to this great American track in ten years, and the speeds through the concrete chute were nuts. I can only imagine how a seasoned pro felt going through there in a street car. Perhaps a European used to the Ring would feel right at home in there at such speeds....
Last edited by stout; 04-30-2019 at 02:55 PM.
04-30-2019, 02:42 PM
#145
Race Director
Sitting here at lunch somewhere in Mississippi... reading this and other threads.... makes me think
How blessed I am to own a Porsche, especially a GT3. Thinking how many people will never experience a Porsche let alone a GT car. I am reminded how great these cars really are. Porsche really gets it right.
Its true... Porsche..there is no substitute!
How blessed I am to own a Porsche, especially a GT3. Thinking how many people will never experience a Porsche let alone a GT car. I am reminded how great these cars really are. Porsche really gets it right.
Its true... Porsche..there is no substitute!
04-30-2019, 03:24 PM
#147
And now you see why, after driving the GT2 RS, I thought, Do I have to drive the GT3 RS again?
To me, the interesting thing with the GT2 RS is not only its insane speed on longer straights, but its ability—on relatively short straights—to get up to top terminal speeds seen on other tracks. The autobahn superiority of a turbo car paired with a modern GT3 RS-level chassis and calibration prowess from the 918 (without AWD or hybrid) is a potent, and fun, combination. Addictive, too.
I hope they made a lot of them, and I sure hope people will use them. At track days.
To me, the interesting thing with the GT2 RS is not only its insane speed on longer straights, but its ability—on relatively short straights—to get up to top terminal speeds seen on other tracks. The autobahn superiority of a turbo car paired with a modern GT3 RS-level chassis and calibration prowess from the 918 (without AWD or hybrid) is a potent, and fun, combination. Addictive, too.
I hope they made a lot of them, and I sure hope people will use them. At track days.
04-30-2019, 03:39 PM
#148
Rennlist Member
Min corner speeds explains how the 3RS managed to keep the delta so small given its power deficit.
25% power deficit and only a 2.5% time deficit.
2RS/3RS
T1/2: 74/79
T3: 64/66
T5: 48/48
T6: 58/59
T7: 85/87
T8: 56/54
T9/10: 86/87
T11: 110/112
T13: 87/93
T14: 59/64
Next up, GT2 RS Clubsport….
25% power deficit and only a 2.5% time deficit.
2RS/3RS
T1/2: 74/79
T3: 64/66
T5: 48/48
T6: 58/59
T7: 85/87
T8: 56/54
T9/10: 86/87
T11: 110/112
T13: 87/93
T14: 59/64
Next up, GT2 RS Clubsport….
Just looking at my best lap, some of it my driving, but not all corners..I am sure I can go 4-6 seconds faster in my new car on R tires.
It will be a long drive again, but it needs to get done...
04-30-2019, 03:52 PM
#149
Rennlist Member
Thread Starter
It would be very, very interesting to see what a 991.2 GT2 RS MR might pull at Road America (and other tracks) with a full factory effort including tire engineers, factory race techs, and current factory driver. The data points from the Sellers lap and Donohue laps are extremely positive.
Something to note with last week's test: It rained on Monday, washing the track, and then was windy/sunny on Tuesday. Temperatures were lovely on Wednesday...
04-30-2019, 03:56 PM
#150
Three Wheelin'
Downforce@v2 = Downforce@v1* (v2/v1)^2
*This won't work if the car has movable aero, or at very low speeds/high angle of attacks causing aero surfaces to stall below certain speeds, but not the case here.