Orthojoe .2 GT3 Thread
05-02-2018, 11:44 AM
#106
Rennlist Member
Actually, they don't. The highest that the right side (ccw track) jumps to is 36psi in the rear and 35psi in the front. As the day gets warmer, the pressures don't get any higher. I got a tip from a friend once and who taught me that the delta from cold to hot should be even and not the actual pressure. The more you drop the pressure during the day, the more you are putting heat into the tire and causing overheat. This leads to inconsistent and slower times as the day goes on. I've found my times to be more consistent throughout a session and throughout the day when I don't mess with the pressures.
It also depends on how much the ambient temp varies during the day. In my neck of the woods, that could be as much about 40 F, which adds about another 4 psi. I typically start the day cold at around 28 psi, bleed down to my target at the end of the first session, then check and bleed a little after subsequent sessions if needed. That sometimes means I need to add some air before the first session next morning if the ambient temp is cold. Generally, I avoid driving the car outside a range of about 26 to 40 psi to avoid tire damage or badly uneven wear.
I used to try to leave it alone, at track days in Europe where it was cold it kinda worked and I wasn't 10/10th.
Would be so nice.
But even when its relatively cool at Sebring (70F) they just shoot up, all the way to 40PSI for the second session if I would start at 25.
I've tried this when the outside tire was completely corded. Typical Sebring morning is say 70F and at noon its 90F
Start at 22 goes to 32 first session then 34-35 and so on. By mid day I am at 18-19PSI to keep them under 32.
Nitro expands less because its dryer, so I think the extreme humidity and sun on the asphalt here is what makes the difference VS the super dry air you guys run.
If I want to be 29F and 32R on Hoosiers, I need to start on 18-20 and 20-22 Roughly, they take the increase better then the MPSC2, I think.
05-02-2018, 11:49 AM
#107
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Good stuff to think about.
I used to try to leave it alone, at track days in Europe where it was cold it kinda worked and I wasn't 10/10th.
Would be so nice.
But even when its relatively cool at Sebring (70F) they just shoot up, all the way to 40PSI for the second session if I would start at 25.
I've tried this when the outside tire was completely corded. Typical Sebring morning is say 70F and at noon its 90F
Start at 22 goes to 32 first session then 34-35 and so on. By mid day I am at 18-19PSI to keep them under 32.
Nitro expands less because its dryer, so I think the extreme humidity and sun on the asphalt here is what makes the difference VS the super dry air you guys run.
I used to try to leave it alone, at track days in Europe where it was cold it kinda worked and I wasn't 10/10th.
Would be so nice.
But even when its relatively cool at Sebring (70F) they just shoot up, all the way to 40PSI for the second session if I would start at 25.
I've tried this when the outside tire was completely corded. Typical Sebring morning is say 70F and at noon its 90F
Start at 22 goes to 32 first session then 34-35 and so on. By mid day I am at 18-19PSI to keep them under 32.
Nitro expands less because its dryer, so I think the extreme humidity and sun on the asphalt here is what makes the difference VS the super dry air you guys run.
One possible explanation is that Joe and I are too slow to get the pressures to increase more than 10-11 psi.
05-02-2018, 11:49 AM
#108
Rennlist Member
Nope! Believe it! LOL!
Actually, the stock wheels I've run have worked out really well and you really can't notice any damage on them despite the usage.
Clutch is very light, but I'm ok with that. It'll be interesting to see what happens when I get back into a GT car after racing spec miata all of this year so far. I'll spend this month seeing what I can do with the GT3 at our 3 tracks. After that, it's back to racing. They sure do know how to keep you coming back. I'm currently in first for the seasonal championship in ITA, and in a respectable position in SMT. Do I go for it all, or just take a step back and stop burning money... ? LOL
Actually, the stock wheels I've run have worked out really well and you really can't notice any damage on them despite the usage.
Clutch is very light, but I'm ok with that. It'll be interesting to see what happens when I get back into a GT car after racing spec miata all of this year so far. I'll spend this month seeing what I can do with the GT3 at our 3 tracks. After that, it's back to racing. They sure do know how to keep you coming back. I'm currently in first for the seasonal championship in ITA, and in a respectable position in SMT. Do I go for it all, or just take a step back and stop burning money... ? LOL
05-02-2018, 12:44 PM
#109
Rennlist Member
Interesting, my hot pressures drop pretty slowly. If I let the car sit for hours after my last session, then add air before I go home to get say 33 psi, the next day the cold pressures are way too low, so they keep dropping for many hours.
One possible explanation is that Joe and I are too slow to get the pressures to increase more than 10-11 psi.
One possible explanation is that Joe and I are too slow to get the pressures to increase more than 10-11 psi.
Another good point, Its an issue after a 2-3 hours of lunch and I got in the car on a cold 40F morning and the PSI dropped to 14-15! So about 50% of where I was the day before in 75F end of the day.
05-02-2018, 01:03 PM
#110
Nordschleife Master
Thread Starter
Originally Posted by montoya
Hahaha- you should see my last three month stretch of banging around with my Spec Racer Ford- That will make you think racing is not for the faint of heart! But that just makes the success all the sweeter. Keep it up, I haven't seen any posts on your racing, would love to follow along on how you're doing. I have my blog here: https://rennlist.com/forums/racing-a...ur-blog-3.html. The link is also in my signature. Just an example of what you have to look forward to as you move up to the front- here's my (short) video of my start at the Button Willow super tour race on Sunday, LOL!:
Will you be at the majors event at Sonoma in June?
05-02-2018, 03:30 PM
#111
Nordschleife Master
Thread Starter
One nice thing is that Porsche improved the oil level measurement process. There is actually a timer now telling you that it is actively measuring rather than just sitting there and wondering if it is doing anything.
05-02-2018, 05:07 PM
#114
Rennlist Member
05-02-2018, 05:12 PM
#115
Addict
Rennlist Member
Rennlist Member
That's what I thought too, until I stumbled across this thread (the 996 GT3 guys want a digital gauge 
):
https://rennlist.com/forums/996-gt2-...-failures.html
):https://rennlist.com/forums/996-gt2-...-failures.html
05-02-2018, 05:35 PM
#117
Nordschleife Master
Thread Starter
Originally Posted by ms550
Would be nice if they put a shift light in those manuals. Ortho Joe, You look like Joerg Bergmeister flogging that thing around.
A shift light would be really nice. Do we know if those that got the sport chrono option have the shift light like in the GT4? I probably should have paid the $500 if that is the case.
05-02-2018, 05:48 PM
#118
Rennlist Member
Good stuff to think about.
I used to try to leave it alone, at track days in Europe where it was cold it kinda worked and I wasn't 10/10th.
Would be so nice.
But even when its relatively cool at Sebring (70F) they just shoot up, all the way to 40PSI for the second session if I would start at 25.
I've tried this when the outside tire was completely corded. Typical Sebring morning is say 70F and at noon its 90F
Start at 22 goes to 32 first session then 34-35 and so on. By mid day I am at 18-19PSI to keep them under 32.
Nitro expands less because its dryer, so I think the extreme humidity and sun on the asphalt here is what makes the difference VS the super dry air you guys run.
If I want to be 29F and 32R on Hoosiers, I need to start on 18-20 and 20-22 Roughly, they take the increase better then the MPSC2, I think.
I used to try to leave it alone, at track days in Europe where it was cold it kinda worked and I wasn't 10/10th.
Would be so nice.
But even when its relatively cool at Sebring (70F) they just shoot up, all the way to 40PSI for the second session if I would start at 25.
I've tried this when the outside tire was completely corded. Typical Sebring morning is say 70F and at noon its 90F
Start at 22 goes to 32 first session then 34-35 and so on. By mid day I am at 18-19PSI to keep them under 32.
Nitro expands less because its dryer, so I think the extreme humidity and sun on the asphalt here is what makes the difference VS the super dry air you guys run.
If I want to be 29F and 32R on Hoosiers, I need to start on 18-20 and 20-22 Roughly, they take the increase better then the MPSC2, I think.
Your starting pressure's are well below what Hoosier consider's safe for their tires (minimum 26psi)
05-02-2018, 07:41 PM
#119
If it's like the GT4, then the dealer can program the shift light thing to appear if they know what they're doing. But is it really that useful down in the dash?