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Thread: Banked roval limits

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    Senior Member fatbillybob's Avatar
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    Default Banked roval limits

    How do you safely find the car's limit on the banked part of a roval?

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    BMW Master bawareca's Avatar
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    I am on a fear management yet. I dont think I have found the limit of any car I've driven there, but it is sure eye opening experience doing 105+mph with a 6000 lbs SUV

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    Chest hair required Olitho's Avatar
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    Only a couple of times have I started to get slip angle on the oval. I don't feel I have enough experience driving on an oval banked turn at the limits to feel I am willing to push in to the limits.
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    Senior Member robburgoon's Avatar
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    I've gotten the car to slither on the oval in the rain. Pretty much same as anywhere else you're in 5th in the rain and the car starts losing traction, that is to say; quite scary.

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    Senior Member fatbillybob's Avatar
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    Do you guys drive the banked section the same regardles of whether your tires are going away or not?

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    Senior Member robburgoon's Avatar
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    Quote Originally Posted by fatbillybob View Post
    Do you guys drive the banked section the same regardles of whether your tires are going away or not?
    If the tires are going away it's probably time to get off the apron.

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    Spec Backhoe Champion redtopz's Avatar
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    Quote Originally Posted by fatbillybob View Post
    Do you guys drive the banked section the same regardles of whether your tires are going away or not?
    Yes. Same technique but not necessarily the same speed. Taking fear out of the equation, it's a fairly simple process. Keep your foot matted on the throttle and try to keep the car on a steady line. You will pull more G's than you are used to so don't give up easily. Keep fighting to keep the car on that line looking up ahead for the exit. If you feel the car starting to slide outward even with a steady input on the steering wheel then you will have to ease off the throttle. In our ST2 cars, lifting is not necessary and we can take the ACS oval "flat out" with minimum speeds over 150 mph. This equates to sustained 2 lateral G's which you can imagine puts the oiling system to the test. Your T2 car would also likely be flat out or close to it, but without a dry sump your engine will eventually pay the price (including the LS6). Even though I know my car can take that turn full throttle, I still often breeze off the throttle simply out of fear or caution. I think I fear a tire or mechanical failure more than anything else.
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    Administrator ucfbrett's Avatar
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    I'm with Rob on this one. Obviously a Spec Miata line is different from that of an ST2 Corvette, but rain lowers the limits of all cars and I learned a lot in the rain at ACS from experiences in my car and from asking others around me. Let me put it into a few bullet points:

    1. Rob Burgoon gave me his secret for rain at ACS, which might work for more powerful cars in the dry: Don't go through the sharpest part of the turn flat. go through at three-quarter throttle. That way, if the car begins to step out, you have additional throttle and counter-steering available to you to correct it.

    2. I learned this from a Spec E30 driver who went out on dry tires, and then it started coming down in buckets halfway into the race. If your car begins to spin in Turns 1 and 2, the banking will contain it and your car will head to the inside, not the wall on the outside. A blown outside tire, on the other hand, will send you into the wall.

    3. With a Corvette, my best guess is you need to play with the line and throttle settings. Just like any other corner, you need to creep up on the limit slowly, so any errors are small and correctable, which is better than exceeding it by a large margin and making a big mistake you can't correct.

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    Old timer craZee's Avatar
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    I had a RR blowout in T1 in a Datsun 510 at about 120 mph there once. I was amazed that the car did not head towards the wall. Upon review, it appeared that the bead had been compromised during mounting, and the extra pressure from the banking caused it to fail. I had 2-3 track days on the tire.

    I now stand next to the person mounting any of my race tires, and observe what is being done. Funny how much longer it takes them when you are watching!

    craZee
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    I've seen cars at Daytona, going from yellow to green, on the banking, light up the rear tires, which loose traction, then the rear slides downhill until the car is pointed up, get grip, and drive up the banking into the wall. DNF

    Also, stay off the apron and marbles, and watch the transition from apron to banking.

    Start low, drift up.
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    Senior Member fatbillybob's Avatar
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    Quote Originally Posted by redtopz View Post
    Yes. Same technique but not necessarily the same speed. .
    If very close or at the same speed my pea brain says I'm no where near the roval limit if I'm steady on the roval yet drifting the corners on old tires.

    Quote Originally Posted by redtopz View Post
    Taking fear out of the equation, it's a fairly simple process. Keep your foot matted on the throttle and try to keep the car on a steady line. You will pull more G's than you are used to so don't give up easily. Keep fighting to keep the car on that line looking up ahead for the exit. .
    When you say steady line you mean the natural line your car wants to follow? At ACS if I'm middle to higher line the car feels good moving lower (sort of apexing) then drifting out on power to the wall before braking zone T3. You don't mean pick a lane and stay in it unless traffic is trying to pass you.

    Quote Originally Posted by redtopz View Post
    take the ACS oval "flat out" with minimum speeds over 150 mph. This equates to sustained 2 lateral G's..
    Our GPS based Aim SOLO might tell us 2G's but the solo does not know we are on banking? Is it really 2 g's or something else? I think if the data shows 2'g it is really less on the banking when taking into account the the angle of the banking.


    Quote Originally Posted by redtopz View Post
    I think I fear a tire or mechanical failure more than anything else.
    Me too! Before the Daytona Runoffs my calculations showed that we would overload the A7 Hoosier beyond spec. No one would verbally respond to me about that. Then I put those fears and calculations in writing to Hoosier and they still did not respond to me but before the Runoffs they told everyone running Hoosiers to add 4psi of air. Presumably, that supports the sidewall so it can take more load. At the pressures we run hot the tire was running at unsafe levels. I think they knew no one would sacrifice speed for safety and not follow Hoosier's directions. SCCA gave us 2 warm-up laps to warm up tires before the start of the race. I'm no engineer and my calc's could be wrong but Hoosier and SCCA must have thought about the issue based on their actions. I just ran new tires at low pressures figuring they would last the 40 min race.

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    Senior Member fatbillybob's Avatar
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    Quote Originally Posted by rikgray View Post
    I've seen cars at Daytona, going from yellow to green, on the banking, light up the rear tires, which loose traction, then the rear slides downhill until the car is pointed up, get grip, and drive up the banking into the wall. DNF

    Start low, drift up.
    I think this is unique to steep banks like daytona. IMO the Daytona road course is boring because in my T2 corvette, restrictor plated to about 350RWHP, I am floored everywhere that is not part of the road course. The only place to make up time is in the infield. SM must be really boring unless there are lots people around to race.

    I'm not so sure about "start low". The highest speeds are on the biggest circumference of the turn that is part of the reason for the later apexing of a turn to keep corner speeds high. So I think you need to find the lane that you can safely "mat" the throttle. If that is low because of low horsepower then that's the fastest line for your car. But I think the safest place to be might be high because your speed delta into the wall is low and glancing. If you are low and head to the wall your speeds will be higher and more damage and potential injury but being high will give you less room to correct for an error.

    If you could be in the middle and guarantee an oversteer and head down into the infield without rolling then sure being lower is good. But a street car tends to be designed to understeer. Under steer to me means you hit the wall. Oversteer means you dive into the infield. I could be wrong on that since I have done neither. Considering the number of idiots we all see at ACS perhaps the lack of crashes on the banking means that we as a group are way underdriving the banking.
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    Senior Member fatbillybob's Avatar
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    Quote Originally Posted by craZee View Post
    I had a RR blowout in T1 in a Datsun 510 at about 120 mph there once. I was amazed that the car did not head towards the wall.
    Quote Originally Posted by ucfbrett View Post
    If your car begins to spin in Turns 1 and 2, the banking will contain it and your car will head to the inside, not the wall on the outside. A blown outside tire, on the other hand, will send you into the wall.
    Crazee...this is because the RR blown will cause an oversteer which brings you down which jives with what Brett is saying. But brett I disagree with your statement about blowing an outside tire. If the tire is a RR then you gown down like Crazee says. If it is a RF tire you understeer into the wall. That's my guess.
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    Administrator ucfbrett's Avatar
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    Quote Originally Posted by fatbillybob View Post
    If the tire is a RR then you gown down like Crazee says. If it is a RF tire you understeer into the wall. That's my guess.

    Yeah, that sounds right. I should have clarified.

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    For the sake of info:
    At the Roval with Speedventures, I drive a 2014 Shelby GT500 with a Cortex Watts link, and carbotech front pads with cooling ducts, and nothing else. On OEM Goodyears. My best time there has been
    1:54.6 (Speedventures posts times online to verify, "P51D" is me) . I was there last in November 2016.

    One of the many reasons this time can happen with such a car (heavy) is because of the long straight section (156-162mph) and entering turn #1 at around 142mph, and holding on for dear life towards turn #2
    at around 115-120mph with this heavy beast. Full fuel tank, me, and car at around 4100 lbs. Of course this costs the front tires. Some days only 1 event, if I run all 4 runs at full push. The rears I can get around 4 events till the outer 1"
    tread flies off the tire.

    Not to mention it has very good power to fix my screw ups in the infield.

    Anyway, stay safe and have fun.
    Last edited by SCALECRAFT; 01-11-2017 at 08:56 AM.
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  16. #16
    Chest hair required Olitho's Avatar
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    This is not my fastest lap at ACS nor my fastest minimum speed on the Turns One and Two at 143 the car is too well planted. I have gone as fast as 148 MPH minimum and I am sure there is more speed, but the car does start pushing and twitching at that speed.

    Last edited by Olitho; 01-11-2017 at 07:45 PM.
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    BMW Master bawareca's Avatar
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    It is irrelevant, but I'll throw it just for fun. My ~5800lbs tow vehicle with full tank of diesel, spare tire, tools, etc. I could have gone a bit faster in most corners, but this thing has probably 20 gallons of fluids that will take hours to clean. Did not want to spoil other's day

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