Intro and autocross questions
06-11-2010, 01:00 AM
#1
Rennlist Member
Thread Starter
Intro and autocross questions
I'm a new GT3 owner (Cobalt '07) and am heading out to my first autocross with it this weekend (driver school and track days in the coming months if rain and work cooperate).
I'm going to run time only since I just want to get out there and see how the car behaves. From a recent thread it seems that the concensus for MPSC's to shoot for a hot pressure of 32fr/36rr. Any suggestions as to a good cold starting point?
One final question, my previous weekend/autocross toy ('94 Mazda RX7) had a well known fuel tank issue that essentially required you to run 3/4+ full tank or risk fuel starvation in the corners. My guess is that Porsche has that figured out so I could run lighter but thought I'd ask. Of course any other GT3 tips would be appreciated.
Keith
I'm going to run time only since I just want to get out there and see how the car behaves. From a recent thread it seems that the concensus for MPSC's to shoot for a hot pressure of 32fr/36rr. Any suggestions as to a good cold starting point?
One final question, my previous weekend/autocross toy ('94 Mazda RX7) had a well known fuel tank issue that essentially required you to run 3/4+ full tank or risk fuel starvation in the corners. My guess is that Porsche has that figured out so I could run lighter but thought I'd ask. Of course any other GT3 tips would be appreciated.
Keith
06-11-2010, 01:21 AM
#2
You get more info here:
https://rennlist.com/forums/racing-a...tion-forum-65/
or on the forums of various regional PCA club racing.
I've never noticed any starvation issues, but don't run much past having the low fuel light on.
I don't know about getting decent temps into the car for autocross ... take the car for a lot of high speed straight line stop starts just before lining up for your run? I remember liking the 911's (though never a GT3) in autocross to be very sticky and pointy, so low temps in the front and higher than normal temps in the rear. Just do your braking in a straight line and think about apex speeds.
I don't know if you're asking just for car tips, but I can say the car won't let you down. It's the other side of the steering wheel that needs preparation! If you're asking for driver technique tips, well, while some say autocross is "****** cross" because it doesn't compare to wheel-to-wheel racing (and I imagine it doesn't!) I think that put-down is in part a reflection of how frustrating it can be to develop the skills and feel for traction and weight control at lower speeds in a big, heavy, powerful car like the GT3.
From what I remember in a '94 RSA, I'd go for the stickiest, widest tire I could fit to the front, take the front bar to the softest setting ... maybe experiment with taking it off the drop links ... and put an extra notch in the rear sway bar to get the pendulum to free up a bit. Get the car in 2nd gear and leave it there for the GT3, any time and attention spent shifting to 1st will imperil the gearbox and any thought of getting into 3rd will imperil the driver, the audience and just waste precious tenths with the throttle closed and the clutch disengaged. Use "string theory" as a guideline for judging apex threshold speeds.
Find a wide open (debris and obstacle free) parking lot and go practice a friction circle and figure eight. If you have the luxury, have friends post as look-outs so you're not surprised by anyone arriving at your "practice field."
Be smooth and progressive with control inputs -- 911's punish "quick" hands and abrupt inputs (give the brakes a half a tenth of a second extra to bring the nose down before going to max ABS ... then eeeeease off the pedal to avoid the nose bobbing straight up in the air and unweighting the fronts (making the car feel like it's "pushing" ... in reality, the driver is making the car push.)
Transition the steering wheel with a light grip and sense of how much the tires are working -- no tire, not even an F1 slick under ideal conditions can transition as quickly as the driver can move the steering wheel ... keeping the front tires in contact and under load is the key to autocross or hill climb.
Lots of autocross techniques. I'd enjoy taking any 911 to autocross, but around the Bay Area, waiting in line for maybe three runs, each lasting two minutes ... for a whole day?
https://rennlist.com/forums/racing-a...tion-forum-65/
or on the forums of various regional PCA club racing.
I've never noticed any starvation issues, but don't run much past having the low fuel light on.
I don't know about getting decent temps into the car for autocross ... take the car for a lot of high speed straight line stop starts just before lining up for your run? I remember liking the 911's (though never a GT3) in autocross to be very sticky and pointy, so low temps in the front and higher than normal temps in the rear. Just do your braking in a straight line and think about apex speeds.
I don't know if you're asking just for car tips, but I can say the car won't let you down. It's the other side of the steering wheel that needs preparation! If you're asking for driver technique tips, well, while some say autocross is "****** cross" because it doesn't compare to wheel-to-wheel racing (and I imagine it doesn't!) I think that put-down is in part a reflection of how frustrating it can be to develop the skills and feel for traction and weight control at lower speeds in a big, heavy, powerful car like the GT3.
From what I remember in a '94 RSA, I'd go for the stickiest, widest tire I could fit to the front, take the front bar to the softest setting ... maybe experiment with taking it off the drop links ... and put an extra notch in the rear sway bar to get the pendulum to free up a bit. Get the car in 2nd gear and leave it there for the GT3, any time and attention spent shifting to 1st will imperil the gearbox and any thought of getting into 3rd will imperil the driver, the audience and just waste precious tenths with the throttle closed and the clutch disengaged. Use "string theory" as a guideline for judging apex threshold speeds.
Find a wide open (debris and obstacle free) parking lot and go practice a friction circle and figure eight. If you have the luxury, have friends post as look-outs so you're not surprised by anyone arriving at your "practice field."
Be smooth and progressive with control inputs -- 911's punish "quick" hands and abrupt inputs (give the brakes a half a tenth of a second extra to bring the nose down before going to max ABS ... then eeeeease off the pedal to avoid the nose bobbing straight up in the air and unweighting the fronts (making the car feel like it's "pushing" ... in reality, the driver is making the car push.)
Transition the steering wheel with a light grip and sense of how much the tires are working -- no tire, not even an F1 slick under ideal conditions can transition as quickly as the driver can move the steering wheel ... keeping the front tires in contact and under load is the key to autocross or hill climb.
Lots of autocross techniques. I'd enjoy taking any 911 to autocross, but around the Bay Area, waiting in line for maybe three runs, each lasting two minutes ... for a whole day?
06-11-2010, 02:06 AM
#3
Rennlist Member
Thread Starter
Thanks for the comments and suggestions, especially the stuff on the inputs. The RX7 was a very balanced platform and kind of spoiled me, the only thing I needed to watch out for was the transition when the second turbo came online, if that happened in a corner it could get interesting. I'm definately going to be on the steep end in learning 911 handling dynamics .
I'd like to go out and get the tires warm prior to starting a run but typically you line up in grid and are stuck there prior to your runs. The amount of time vs. reward for autocross is a head shaker, we've also lost all of our convenient sites around here which makes it even worse.... I just want to get out and have some fun with the car!
Keith
I'd like to go out and get the tires warm prior to starting a run but typically you line up in grid and are stuck there prior to your runs. The amount of time vs. reward for autocross is a head shaker, we've also lost all of our convenient sites around here which makes it even worse.... I just want to get out and have some fun with the car!
Keith
06-11-2010, 10:59 AM
#4
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The most common mistake I see in novices is NOT learning the course, thus getting lost during their runs. Walk the course several times, and do it alone and really learn the course. What tricks is the designer trying to play, typically there are traps if you are not looking ahead, offset gates are common. At each gate look ahead two, three, four gates/turns what is going on what will you see at that point.
On your first run make sure you have a clean run, if you DNF you will likely not know where you got off course. If you have a clean run you will know where you can go faster and can pick up the pace with each run.
Have fun!
On your first run make sure you have a clean run, if you DNF you will likely not know where you got off course. If you have a clean run you will know where you can go faster and can pick up the pace with each run.
Have fun!
06-11-2010, 01:36 PM
#5
Rennlist Member
+1.
Done my first and only autocross few weeks ago, total driving time was 8 minutes out of the own day. Fastest car was a stripped out Civic over all the Porsches and Corvettes on the lot.
Will not do it again, will only stay with track days.
Done my first and only autocross few weeks ago, total driving time was 8 minutes out of the own day. Fastest car was a stripped out Civic over all the Porsches and Corvettes on the lot.
Will not do it again, will only stay with track days.
06-11-2010, 02:51 PM
#6
Three Wheelin'
I'm not much of a fan of Autocrossing, however congrats on the Cobalt blue!! Awesome colour!!
06-11-2010, 04:16 PM
#7
Nordschleife Master
I'm a new GT3 owner (Cobalt '07) and am heading out to my first autocross with it this weekend (driver school and track days in the coming months if rain and work cooperate).
I'm going to run time only since I just want to get out there and see how the car behaves. From a recent thread it seems that the concensus for MPSC's to shoot for a hot pressure of 32fr/36rr. Any suggestions as to a good cold starting point?
One final question, my previous weekend/autocross toy ('94 Mazda RX7) had a well known fuel tank issue that essentially required you to run 3/4+ full tank or risk fuel starvation in the corners. My guess is that Porsche has that figured out so I could run lighter but thought I'd ask. Of course any other GT3 tips would be appreciated.
Keith
I'm going to run time only since I just want to get out there and see how the car behaves. From a recent thread it seems that the concensus for MPSC's to shoot for a hot pressure of 32fr/36rr. Any suggestions as to a good cold starting point?
One final question, my previous weekend/autocross toy ('94 Mazda RX7) had a well known fuel tank issue that essentially required you to run 3/4+ full tank or risk fuel starvation in the corners. My guess is that Porsche has that figured out so I could run lighter but thought I'd ask. Of course any other GT3 tips would be appreciated.
Keith
Have fun, Gordon
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06-11-2010, 04:28 PM
#9
Nordschleife Master
From Micheline PowerPoint----
Care and Feeding
! PRESSURES
! General Guidelines: ! Road Racing :
! 25-28 psi cold (front/rear)
! 32-36 psi hot (front/rear) is your typical target
! Autocross (slalom): Looking for same range (of hot pressures-- may need to start at higher cold inflation pressures because of the decreased pressure gain in autocrossing).
! Road: OE pressures
! Rain: For both autocross and road racing, you may have to increase tire pressure 6-10 psi from what you would normally run in dry conditions. Your car and driving style in the wet is important here, so some experimentation may be in order.
Care and Feeding
! PRESSURES
! General Guidelines: ! Road Racing :
! 25-28 psi cold (front/rear)
! 32-36 psi hot (front/rear) is your typical target
! Autocross (slalom): Looking for same range (of hot pressures-- may need to start at higher cold inflation pressures because of the decreased pressure gain in autocrossing).
! Road: OE pressures
! Rain: For both autocross and road racing, you may have to increase tire pressure 6-10 psi from what you would normally run in dry conditions. Your car and driving style in the wet is important here, so some experimentation may be in order.
06-11-2010, 06:06 PM
#10
Rennlist Member
Be careful with high speed starts and stops to warm the tires up. Exceeding 5mph in the pits or grid will get you booted from most events fairly quickly, likewise doing same in the street nearby. I don't know of any clubs that do not have "NO WARMING OF TIRES" somewhere in their rules.
It will handle very differently from your RX so pushing it hard at autox will give you a real feel for what it can do for you, and what it can do against you. Remember, if you don't spin, you are not trying hard enough.
It will handle very differently from your RX so pushing it hard at autox will give you a real feel for what it can do for you, and what it can do against you. Remember, if you don't spin, you are not trying hard enough.
06-14-2010, 02:00 PM
#11
Rennlist Member
Thread Starter
Hey Folks,
Just figured I'd give you a quick update on my first experiance running the GT3. The weather was perfect (for the Seattle area that means no rain), the course layout was great, the car performed far better than I could have even hoped and I met some great enthusiasts. I had a local GT3 expert ride with me on my first run (good call Gordon for recommending Jeff Barstow, he got me straightened out right away and I appreciated his guidance). It's been 6 years since I've autocrossed in anger and I was a bit rusty but thoroughly enjoyed it. I'm going to look into the alignment on the car and see where things are at (I haven't touched it since I bought it).
Just as an aside, while I was getting the car ready to run I realized the last time I drove a rear engine car with any sort of aggession was about 33 years ago ('68 VW Karman Ghia..... just a little bit of difference between the two cars). I figured I would have watch out for and deal with some understeer with the GT3 but I didn't run into any issues with that. I must not have been pushing hard enough..... Thanks again for all the suggestions and help.
Keith
Just figured I'd give you a quick update on my first experiance running the GT3. The weather was perfect (for the Seattle area that means no rain), the course layout was great, the car performed far better than I could have even hoped and I met some great enthusiasts. I had a local GT3 expert ride with me on my first run (good call Gordon for recommending Jeff Barstow, he got me straightened out right away and I appreciated his guidance). It's been 6 years since I've autocrossed in anger and I was a bit rusty but thoroughly enjoyed it. I'm going to look into the alignment on the car and see where things are at (I haven't touched it since I bought it).
Just as an aside, while I was getting the car ready to run I realized the last time I drove a rear engine car with any sort of aggession was about 33 years ago ('68 VW Karman Ghia..... just a little bit of difference between the two cars). I figured I would have watch out for and deal with some understeer with the GT3 but I didn't run into any issues with that. I must not have been pushing hard enough..... Thanks again for all the suggestions and help.
Keith
