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So while crewing an Astin Martin GS class car at Sebring had this interesting experience.
AM did a software upgrade that was somehow flawed and we managed a total of only about 5 laps of practice out of a 2 hour,45 minute total practice time.
This of course causes me a lot of problems when you can't map pressures. Being a resourceful guy, I pulled up the information on nominal pressure increase, posted on these forums. Using that, and making an educated tweaking of the numbers, (those numbers are from a stick axle car, not one with an IRS unit) The car qualified 2nd.
Since you can't touch the car after the qually, I still didn't have any real numbers to work with. So again, I referenced the numbers for the race, and it all came out remarkably good, Overall I missed by about a PSI, but the numbers were all where they should be in relation the corners of the car, so the car was still balanced pretty well.
The car is instrumented, so you could graph some numbers, but you still need some type of baseline, and since we were dealing with rain squalls, lightning (red flagged) 97 degree heat, ten million percent humidity, they don't help you predict pressures say..an 20 minutes from now when it's skirting rain and you have a 15 degree pressure drop, or for that matter, if the driver is over/ under driving the car causing odd PSI , thirdly, if the car is not on the track, you're not getting ANY inputs, instrumented or not. The last issue, is that you never know if your pressures are correct until the car comes in and you check them after a pit stop, then it's too late to make a change on the sticker set.
Short story, we were close enough, the car finished in 2nd place.
So while the nominal pressure increase chart is a great reference, it doesn't get you EXACTLY where you need to be.
AM did a software upgrade that was somehow flawed and we managed a total of only about 5 laps of practice out of a 2 hour,45 minute total practice time.
This of course causes me a lot of problems when you can't map pressures. Being a resourceful guy, I pulled up the information on nominal pressure increase, posted on these forums. Using that, and making an educated tweaking of the numbers, (those numbers are from a stick axle car, not one with an IRS unit) The car qualified 2nd.
Since you can't touch the car after the qually, I still didn't have any real numbers to work with. So again, I referenced the numbers for the race, and it all came out remarkably good, Overall I missed by about a PSI, but the numbers were all where they should be in relation the corners of the car, so the car was still balanced pretty well.
The car is instrumented, so you could graph some numbers, but you still need some type of baseline, and since we were dealing with rain squalls, lightning (red flagged) 97 degree heat, ten million percent humidity, they don't help you predict pressures say..an 20 minutes from now when it's skirting rain and you have a 15 degree pressure drop, or for that matter, if the driver is over/ under driving the car causing odd PSI , thirdly, if the car is not on the track, you're not getting ANY inputs, instrumented or not. The last issue, is that you never know if your pressures are correct until the car comes in and you check them after a pit stop, then it's too late to make a change on the sticker set.
Short story, we were close enough, the car finished in 2nd place.
So while the nominal pressure increase chart is a great reference, it doesn't get you EXACTLY where you need to be.
nominal pressure increases
OK this is for you guys that do pressures incorrectly, as I have stated before, hot ALWAYS dictates cold, but for some bizarre reason people keep asking me about cold pressures..well I have no idea what cold pressures you should run, every tire, brand, type, size and application is different. I...
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