Orthojoe's track build journal
11-26-2015, 08:12 PM
#1546
Nordschleife Master
Thread Starter
Joe -
I ran Laguna on Monday with PCA. Got meatballed once for sound. Really had to coast up the hill to not blow sound. After 4 sessions the front right (Dunlops) center block was completely rounded on the outside edge. In addition, no matter what changes I made between sessions to lower that pressure it always came back higher than the inside and outside. Hot tire pressures were in the 34 front 36 rear range with slight variations above and below. Car has stock alignment and both sway bars are in the middle setting.
To say the least the GT3 on track was amazing. Yeah the Spyder is fun but the GT3 is just incredible. Really sharp turn-in. No under or oversteer but I am only at 7/10's. Rolling on the throttle at turn exit gives you all the HP you miss with the Spyder. Definitely felt good trail braking on Turn 2 which may have been a necessity given how much speed (120+) you can carry down the front straight. Corkscrew was fantastic. A little tire chirp on top and then a little wiggle if early on the throttle at the bottom.
I did not use sport plus or the paddles. Every time you get on it and the exhaust opens up is really a rush but you already that. Just an amazing car.
I ran Laguna on Monday with PCA. Got meatballed once for sound. Really had to coast up the hill to not blow sound. After 4 sessions the front right (Dunlops) center block was completely rounded on the outside edge. In addition, no matter what changes I made between sessions to lower that pressure it always came back higher than the inside and outside. Hot tire pressures were in the 34 front 36 rear range with slight variations above and below. Car has stock alignment and both sway bars are in the middle setting.
To say the least the GT3 on track was amazing. Yeah the Spyder is fun but the GT3 is just incredible. Really sharp turn-in. No under or oversteer but I am only at 7/10's. Rolling on the throttle at turn exit gives you all the HP you miss with the Spyder. Definitely felt good trail braking on Turn 2 which may have been a necessity given how much speed (120+) you can carry down the front straight. Corkscrew was fantastic. A little tire chirp on top and then a little wiggle if early on the throttle at the bottom.
I did not use sport plus or the paddles. Every time you get on it and the exhaust opens up is really a rush but you already that. Just an amazing car.
Another data point for Sport Cup2 outer tread block wear. I'm liking the theory discussed earlier that the outer tread blocks will wear sooner that center and inner just due to the varying tread compounds across the tire's surface. Granted, my car is a 991S and not a GT3, so suspension is different (PDCC, stock camber settings, no RWS), but overall chassis and weight distribution is basically the same.
Never ran the car on the stock PZeros.
First tires were AD08Rs, which wore the rears before the fronts (10 track days).
Second tires were Sport Cup2s, which also wore the rears before fronts (6 track days).
Third tires are current, replacement set of Sport Cup2s, which are actually wearing the L front much more than the R front or rears after two track days at Lime Rock (all right-hand turns except one). Maybe because the first set of Sport Cup 2s saw a mix of tracks (Watkins Glen, VIR and NJMP, in addition to Lime Rock), they wore more evenly?
In any case, wear pattern on outer tread blocks of that L front tire is pretty strange. The tread surface scallops in from outer edge to inner edge of the outer tread blocks, wearing more towards the inner edge and finally ending in a step-up lip or ridge on the innermost edge of the outer tread blocks, running circumferentially around the tire. Also, each outer tread block is "feathered," so that the wear is more toward the rear of each individual outer tread block, and becomes less as you move forward on that tread block. Input from the track section of the forum suggests issues with overinflation, not enough camber, and surface graining from sliding.
Never ran the car on the stock PZeros.
First tires were AD08Rs, which wore the rears before the fronts (10 track days).
Second tires were Sport Cup2s, which also wore the rears before fronts (6 track days).
Third tires are current, replacement set of Sport Cup2s, which are actually wearing the L front much more than the R front or rears after two track days at Lime Rock (all right-hand turns except one). Maybe because the first set of Sport Cup 2s saw a mix of tracks (Watkins Glen, VIR and NJMP, in addition to Lime Rock), they wore more evenly?
In any case, wear pattern on outer tread blocks of that L front tire is pretty strange. The tread surface scallops in from outer edge to inner edge of the outer tread blocks, wearing more towards the inner edge and finally ending in a step-up lip or ridge on the innermost edge of the outer tread blocks, running circumferentially around the tire. Also, each outer tread block is "feathered," so that the wear is more toward the rear of each individual outer tread block, and becomes less as you move forward on that tread block. Input from the track section of the forum suggests issues with overinflation, not enough camber, and surface graining from sliding.
11-29-2015, 12:13 AM
#1547
Nordschleife Master
Thread Starter
Update
Ran front cup2s with 3 days on them and rear dunlops with 2 days on them yesterday. Car felt fine with this setup, but grip had diminished.
The rear dunlops now have cord showing on the outer edge after the equivalent of 4 track days.
Ran front cup2s with 3 days on them and rear dunlops with 2 days on them yesterday. Car felt fine with this setup, but grip had diminished.
The rear dunlops now have cord showing on the outer edge after the equivalent of 4 track days.
11-29-2015, 12:39 AM
#1548
GT3 player par excellence
Lifetime Rennlist
Member
Lifetime Rennlist
Member
^ it's all ben's fault. if he did'nt try to escape and coax me into meatball sound violation, it would have lasted you another day.
11-29-2015, 12:54 AM
#1549
Nordschleife Master
Thread Starter
Originally Posted by mooty
^ it's all ben's fault. if he did'nt try to escape and coax me into meatball sound violation, it would have lasted you another day.
11-29-2015, 02:55 AM
#1550
Rennlist Member
I still like the 3 Dunlops + 1 Sport Cup 2 idea for lap time testing 
11-29-2015, 03:01 AM
#1551
GT3 player par excellence
Lifetime Rennlist
Member
Lifetime Rennlist
Member
its CW so he should have put 2 MPSC2 on left side and dunlops on right!!!
12-03-2015, 11:22 AM
#1552
Racer
Join Date: Aug 2010
Location: San Francisco
Posts: 396
Likes: 0
Received 0 Likes
on
0 Posts
12-03-2015, 01:54 PM
#1553
Intermediate
Join Date: Jun 2010
Location: Sarasota, Florida
Posts: 32
Likes: 0
Received 0 Likes
on
0 Posts
Haven't followed the whole thread since I just started to read it and there is lots of info. Have run 14 days in my 15 GT3, all at Sebring. Have GMG roll bar and 6 point harness on the 918 seats. Use 2.0 camber in the front and the rest is factory. Installed nanofusion instead of Expel in the same places that you do Joe. Very easy to clean. And, yes, the app does cut out on me, so I will go back to Harry's next outing. Had my car worked on by Autoquest in Ft. Myers, FL, who does many GT3s. He recommended 30 psi all around hot, and, at least at Sebring, it is the correct pressure on the PSC2. Finally broke 2:30 two weeks ago because I got an instructor in the car and asked him to get me 3 seconds. Being 73 and losing testosterone, I needed someone to make me keep my right foot to the floor. Made 4 seconds to 2:28. The car probably has another 8 seconds in it, but I am at my pucker point.
Last edited by JanStuart; 12-03-2015 at 01:55 PM. Reason: typo
12-13-2015, 01:41 PM
#1554
Rennlist Member
Joe -
The Dunlops were great yesterday at Thunderhill. We kept having to lower the pressures in order to get the temps right. Finally we got it all dialed-in. Surprisingly the fronts were best around 30.5 and the rears at 35.5. It was cool and cloudy all day. All the uneven wear in the front center blocks is gone and the tires are now wearing evenly across the entire tire. Rears are also showing even wear across the entire surface, nothing worth noting on the outside edges either. Kudos to Guy Gamba from OnEdge Performance. He is a master with anything tires. Attached is a PDF and changes made along the way.
Although I didn't time the laps, my videos shows lap times were in the 2:02-2:04 range. So pretty respectable given a stock setup.
The Dunlops were great yesterday at Thunderhill. We kept having to lower the pressures in order to get the temps right. Finally we got it all dialed-in. Surprisingly the fronts were best around 30.5 and the rears at 35.5. It was cool and cloudy all day. All the uneven wear in the front center blocks is gone and the tires are now wearing evenly across the entire tire. Rears are also showing even wear across the entire surface, nothing worth noting on the outside edges either. Kudos to Guy Gamba from OnEdge Performance. He is a master with anything tires. Attached is a PDF and changes made along the way.
Although I didn't time the laps, my videos shows lap times were in the 2:02-2:04 range. So pretty respectable given a stock setup.
12-13-2015, 02:30 PM
#1555
Nordschleife Master
Thread Starter
thanks for sharing, Phil. Tire pressure of 30.5 up front is significantly lower than what I was running (34psi) up front. Interesting as well that you have found a 5psi difference between front and rear to work on the dunlops. I'm going to let you experiment more. If you have continued success, I might try the dunlops one more time since I liked how they feel more than the cup2.
12-13-2015, 09:29 PM
#1556
Phil
I have a question, when you took the temperature readings was this done immediately once off the track. The temps seem low. I bet the Dunlops perform best around 185 deg.
I have a question, when you took the temperature readings was this done immediately once off the track. The temps seem low. I bet the Dunlops perform best around 185 deg.
12-14-2015, 10:55 AM
#1557
Rennlist Member
Yes, the temp readings were immediate. The reason that they are low is because it was cloudy, a bit windy and about 43 degrees. I don't think it ever got up to 50 degrees.
12-20-2015, 02:14 PM
#1558
Rennlist Member
Made it about 2/3 through this thread one evening and learned a lot. I know you are using the GPS unit to turn off bypass valves and I think you are using turn away pipes? Is your exhaust stock other than that (still have center muffler)?
I finally found a GT3 to buy and plan on taking it to MRLS next year so I'll need to address the sound issue for 90 db days. If I don't have the GPS unit what are your recommendations?
I finally found a GT3 to buy and plan on taking it to MRLS next year so I'll need to address the sound issue for 90 db days. If I don't have the GPS unit what are your recommendations?
Last edited by SamG; 12-20-2015 at 02:14 PM. Reason: correct spelling
12-21-2015, 11:29 AM
#1559
Nordschleife Master
Thread Starter
Originally Posted by SamG
Made it about 2/3 through this thread one evening and learned a lot. I know you are using the GPS unit to turn off bypass valves and I think you are using turn away pipes? Is your exhaust stock other than that (still have center muffler)?
I finally found a GT3 to buy and plan on taking it to MRLS next year so I'll need to address the sound issue for 90 db days. If I don't have the GPS unit what are your recommendations?
I finally found a GT3 to buy and plan on taking it to MRLS next year so I'll need to address the sound issue for 90 db days. If I don't have the GPS unit what are your recommendations?
If you don't do the GPS unit, you need to lift and short shift at the sound station.
12-21-2015, 02:18 PM
#1560
Rennlist Member
That's what I had to do on my 997.1 GT3 until I had a fairly simple mod done that kept the bypass valves closed while I was at the track.
Who would you recommend to make the turn away pipes?
Who would you recommend to make the turn away pipes?