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NASA Track Day in 991.2 GT3 on OEM Sized Hoosier R7 UPDATE
I'll plan to post a few more updates to this thread after tomorrows session, but wanted to give some updates on how the new Hoosier 20" R7 tires work on our GT3's!
I have a lot of laps at AMP (Arizona Motorsports Park) and prior to today, my best time in the GT3 on OEM Cup 2's and 1.8 Squared Camber, was a 1.42.18. AMP does have a DB limit of 96 DB, so I'm running turn downs, turning exhaust away from sound meter.
I've since swapped to the new OEM Size 245/35/20 Front Hoosier R7 and the 335/25/20 Rear Hoosier R7 (note the 335/25/20 is the same size as our Michelin 305/30/20).
I also increased the negative camber from 1.8 square to 2.6 Negative on the front and 2.4 negative to the rear. The Hoosier grip up front was MIND BLOWING! The 245's had just so much grip and you can see in these 2 laps... the rear frankly couldn't keep up! I've got to try to 'lead' the car better... it isn't easy jumping from our ST3 race car (91 Corvette) into the TT GT3, going from Front Engine to Rear Engine, but man is this GT3 FAST & FUN!
Lap 1 is the minute 40, lap to is a 42.0 and some fun slides.
The previous TTU (Time Trial Unlimited) class track record was a 1.41.8 by a 997 GT3 Cup car on slicks. I have a run a best time previously of a 1.42.18 in the GT3 on the Cup 2's as mentioned earlier. I started the pressures a bit higher than normal, starting with 28 front and 30 rear. I think the rear tire pressure is too high, as you'll see in the video, my fast lap was lap 1 and the rear got slick quickly. I lowered the rear down 2psi, and will try that for tomorrow morning.
And now for the good news... again, just could not be happier with the GT3, and the Hoosier Tires are a match made in Heaven! I reset the TTU record by a full second, running a 1.40.86! And this was in 90 degree heat/temps today! I know that there is a 1.39 in it... connecting all the dots... I only ran one session today, as the track was just getting too hot, and I still had to run our ST3 race car, which I also broke my previous best TT3 track record of a 1.42.8 by running a 1.42.4.
I think I'm going to try to stiffen the front bar to tighten up the rear a bit and see how that goes. I think the rear could also benefit from closer to 3 degrees negative camber, but I only track the car 3 or 4 times a year... so not going to go that crazy at this point.
Gotta thank the guys at Porsche Chandler, for selling and supporting such a great car! And of course Hoosier tires, who've I raced with for many years, and super excited to see them offer these tires for our cars in OUR SIZES! The 245's DO NOT RUB AT ALL!!! I'll post inner fender well pics tomorrow when I switch back to the street tires.
I did have a challenge with the Porsche Track App... which I blame user error... and should have setup as a 'new track' again, so unfortunately for today, I only have the GoPro helmet cam view, I'll hopefully have both views working properly tomorrow as we're running the track Counter Clockwise, which I have yet to run the GT3 in that direction so should be fun!
2018 991.2 GT3 6spd Hoosier 20" 245 Front 335 Rear
Awesome, great, video and driving! I'm gonna run the 19inch hoosiers next month at barber - as soon as these cup 2's wear out.
With that much grip in the front, I bet stiffening the front bar or loosening the rear (or both) will help tremendously. I have mine on full stiff up front and full soft in the rear and I have been pleased with balanced front and rear grip so far (running cup2's and re71r's)
Awesome, great, video and driving! I'm gonna run the 19inch hoosiers next month at barber - as soon as these cup 2's wear out.
With that much grip in the front, I bet stiffening the front bar or loosening the rear (or both) will help tremendously. I have mine on full stiff up front and full soft in the rear and I have been pleased with balanced front and rear grip so far (running cup2's and re71r's)
This is great to hear! If not too difficult I may try to make the front sway bar adjustment at the track, first thing in the morning.
I think 19" Hoosiers are the way to go for Non-PCCB cars, but for the PCCB, clearance is a bit too close for my preference.
Ok, Day 2 is now in the books (though I need to give her a good wash this evening still). The Hoosier 245/335 combination worked flawlessly. I probably should have done a few more laps, but also had my ST3/TT3 corvette at this event that I needed to get points in and it was just so hot this afternoon in AZ (about a 100 degrees!).
I adjusted the front Sway Bar to full stiff, and took 2 psi out of the rear and the car was considerably more predictable at the limit.
Below are the 2 laps I did, both Helmet Cam view and Porsche Precision Track App views.
The 245's up front didn't rub anywhere! (Lots of pics below to show the inner fender well). While I'm loving the GT3's 6spd manual, I successfully placed my order for the '19 GT3RS, currently at V200 with a November Build date!
Just a heads up. The 335/25/20 R7s have been delayed from the factory. I ordered these a month ago and delivery date to retailers has been pushed back a couple times already. Now looking like late July.
Nice laps! AMP looks like a super fun place to hoon around too. Was your rear bar on stiff? I agree that rear could use almost -3. I'm at -2.7 and Cup2 wear was pretty good (at 36-38 hot), but the car felt like it would like -3 even more. My turn-in on -3.5 front was amazing, but did pick up a bit of understeer off the corner, so rear bar stiff next time should help.
There was a .2 on 20" ho-ho's at the last PCA event at Putnam, and the car was FAST. He is pretty green to DE stuff, but even then, it took all I had to run him down or stay ahead on the Cup-2's. He was turning 1:12-13's, same as me. This tells me the car will be crazy fast on hoosiers. I would say about 1 second slower a lap than on Pirellis DH takeoffs, so probably 1:10-11's on Hoosiers.
Just a heads up. The 335/25/20 R7s have been delayed from the factory. I ordered these a month ago and delivery date to retailers has been pushed back a couple times already. Now looking like late July.
I was not aware of this, no. I'll reach out to my contact and see if I can get a firm date.
Originally Posted by Mvez
Nice laps! AMP looks like a super fun place to hoon around too. Was your rear bar on stiff? I agree that rear could use almost -3. I'm at -2.7 and Cup2 wear was pretty good (at 36-38 hot), but the car felt like it would like -3 even more. My turn-in on -3.5 front was amazing, but did pick up a bit of understeer off the corner, so rear bar stiff next time should help.
There was a .2 on 20" ho-ho's at the last PCA event at Putnam, and the car was FAST. He is pretty green to DE stuff, but even then, it took all I had to run him down or stay ahead on the Cup-2's. He was turning 1:12-13's, same as me. This tells me the car will be crazy fast on hoosiers. I would say about 1 second slower a lap than on Pirellis DH takeoffs, so probably 1:10-11's on Hoosiers.
I think the Hoosiers are a good 1 to 2 seconds quicker than the Cup 2's depending on the track.
05-19-2018, 10:14 PM
NASA Track Day in 991.2 GT3 on OEM Sized Hoosier R7 UPDATE
All cleaned and waxed up.
