03-26-2014, 03:10 PM | #1 |
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Circuit of the Americas-Track Guide/Video
Thought I'd try to write down what I learned at COTA this past weekend. COTA is a very special track, and there are lots of "correct" lines through it. Each classroom session we had we'd go over the various lines for this turn or that and generally they were somewhat vehicle specific.
For me in my car (F30 335i heavy, long, RWD, higher horse power) these lines seemed quick and more comfortable than some others we tried My car had the following modifications. At a minimum if doing COTA I would suggest racing brake fluid and better than stock brake pads as there are four triple digit sections that feed right into to sub 40 mph haripins and not a lot of brake cool down time. I'll list my modifications in order of their effect of increasing the safety and enjoyment of my time on the track
Here's a video of this lap before I comment turn by turn And a track map for overhead reference Turn 1 Turn 1 is coming off the 2nd longest straight by the grandstands/pits. Hard to tell here, but the straight ends into a BIG hill (I'm not sure I could walk up it without using my hands). I would get to 120 on the strait then start braking ~150 sign. Turn 1 crests onto a table top and is a very sharp hairpin. Wait to start turning after cresting the edge of the table, turn in late, clip the apex, and track out to a little past mid track to help setup for turn 2 Turn 2 Get all the way left to setup, turn in a little later than you would think and get on the gas early, late turn in, late apex 2 then track out only to about the half-way point then unwind but continue the turn to the right to place the car about 3/4 of the way to the right edge. Turn 3,4 There are a number of lines through the S's, this one felt best for me and I often caught cars under braking into 4. Try to cross under the bridge about 3/4 of the way to the right edge, then smoothly start your turn in to 3. This can be accomplished under power or with a slight lift depending on your car/confidence (I lifted corner 4 had eaten something like 60 cars on HPDE's last year - didn't want to be part of the total). The objective is to turn into the apex at 3, then straighten out the car pointed at the apex of 4, brake in a straight line (90 to about 60) apex 4 then head for the apex at 5 with a steady throttle. Track out after the late apex only part way to setup for 3 Start your turn to 3 about 3/4 toward the right edge under the bridge Straighten out to 4 and tap the brakes Turn 5,6 Clip the apex of 5 and track out, this will lead the car to an apex at the start of turn 6, a large double-apex. This turn can be driven as constant radius. Start the turn very gradually (not hugging the curbing), look far ahead and hold your steering lock. The car will drift out to a little past 1/2 track then come in to apex the back side of 6. Some people drifted out again here, but I found it just as easy to hold the line near the curbing and setup for 7 Clip the apex at 5, and track all the way out Start the turn in when you reach the curbing at the start of 6, keep your head up, this is constant radius Allow the car to drift out to mid-track then bring it back - this should require no steering inputs, just a slow roll on the throttle From here hold the curbing to setup for 7 Turn 7 7 looks like a 90 degree. I would tend to late turn in to apex here and try a smooth arc that would return me to the left side of the track to setup for turn 8. Lines through here were heavily debated My line mostly looked like this after clipping the apex at 7. Turn 8 Here late turn in to late apex from all the way left with two on the red worked best for me Turn 9 This is the benefit of that line - a straight line from the apex of 8 to the apex of 9. This leads into a triple digit section of track and exit speed around 9 pays big dividends Turn 10 This is a fast downhill blind sweeper - I'm coming from the curbing at the apex of 9, tracking all the way out then aiming for the apex of 10 that you can't see (literally, the apex becomes visible 1 second before you hit it). There is a bump on the track near the apex that would upset my car a bit, so I would lift just before the apex, bump, settle and throttle out of the corner. In a different car, maybe a better line would be wider missing the bump and full throttle the whole time. I had too much engine and not enough grip for that line. Some people might feel comfortable hammer down through the bump, some cars might deal with it better. Regardless finish by using the whole track. Turn 11 Turn 11 leads into the longest straight, and it's a hairpin. Line up all the way right, take a SUPER late turn in, throttle on way before the apex and track out. I'm lined up too far left at turn-in and don't use the whole track in this picture b/c we were warned about fluid on the track on line leading into this corner. As this is one of the 100+ to 30 corners, we were doing our braking off line out of the fluid mess. If you watch the video, you'll notice I V-max the car about 1/2 way down the next straight - thanks for that 130mph limiter BMW Turn 12 Yeah another hairpin! Not quite but much more than 90 degrees. I'd lift at about the 250, take a breath and brake starting slightly after the 200. All car dependent. I could have braked later but this wasn't a race - if you've got a 155 limiter, might wanna stretch it out a bit. Again late turn in here pays with higher exit speeds. Keeping you head up and focusing on track out makes it easier to judge Turn 13,14,15 Here take your time getting over to the left, and get the car slowed down - if you did 12 right (I didn't on this lap, apexed too early) you'll have a lot of speed to shed before 13. I would treat 13&14 as a double apex under a lot of power. Late apex 13, track all the way out, start unwinding the wheel and feeding in throttle toward the apex at 14 Here we apex 14 then make a straight line across the rumble strips on the left toward 15 - aim for the yellow padding all the way in the corner Approaching 15 aim at the yellow cushion, brake in a straight line then super late turn in (you'll feel like you're going the wrong way) then bring it round to clip the apex at 15 and track all the way out Turn 16,17,18 Carousel My absolute favorite part of the track. The three turns are one big constant radius turn - treat it like a triple apex (in out in out in out - seriously!) Bring the car back left, but not all the way, maybe a car width from the left side. Start your turn in early, go under the bridge about 3/4 of the way toward the inside, miss the apex at 16 shortly after the bridge by a half a car width - hold steering lock and roll on the throttle. After missing the first apex by 1/2 a car width you'll track to a little less than mid-track Back in to the curbing, manage the arc with your throttle Drift out to a little past mid track then back to the apex Then ride the curbing here - same radius then unwind and track out all the way left Turn 19 You should be booking coming out of carousel (I would enter 16 at about 60 and come out of 18 at 90). This turn is blind but wider than it looks. I would tell my self "this is not 20 this is not 20" (20 is a hairpin) every time to not over slow the car. Coming out of 18 unwind the car pointed at the turn-in point for 19 on the right side of the track - brake in a straight line (not too much, it's a fast turn) then turn in early, apex early and let it track all the way out. Turn 20 This always seemed harder than it looked - it's tighter than you expect, and important as hell because it leads to the second longest straight and the finish. Keep your head up, look down the track to the track-out. Late turn in and late apex. When I did it well, I was at 120 in the straight, poorly 105. This lap ended under caution so I had to let up half way down. You can watch other laps (I put up all the laps I videoed) on this playlist. https://www.youtube.com/playlist?lis...21QmCr9xbYBrQ1 Unfortunately my best session and best lap was in session 2 on Sunday and Dumb-ass me forgot to turn the GoPro on - I have telemetry and video out the back of the car, but nothing forward facing. Oh well - guess I'll need to go back next year Comments/observations welcome - I'm still learning
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Last edited by utenigma; 03-30-2014 at 02:20 PM.. |
03-26-2014, 05:28 PM | #3 |
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Thanks Bill - all done now
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03-26-2014, 10:03 PM | #4 |
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Great writeup and annotation One of the best I've seen...forum or otherwise.
I saw in another thread you had .15* toe out in front and .20* toe in rear. How did that work for you? I'm getting an alignment tomorrow for an event this weekend, so I'm very interested to hear how things went from that aspect. Also, how did the rear end do through 3,4? I've found the F30 rear to be a little 'floaty' at high speed (80+). Maybe it's just my inputs though. +1 on the BMS. I ended up removing/selling mine for this very reason. I'm curious what BMS comes back with, so keep us posted!
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03-27-2014, 10:53 AM | #5 |
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Dude this was a awesome write up. I have only been to MSR in Cresson in my car but I had a ton of fun. Hopefully I will be more experienced and able to run next time COTA opens to BMWCCA again.
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03-27-2014, 12:18 PM | #6 | |
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http://lscbmwcca.org/2014/02/25/spri...ation-weekend/ I'll be out there |
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03-27-2014, 12:23 PM | #7 | |
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But right now the car's really balanced on the square setup with that alignment - drifts nicely in sweepers, neither end seems to dominate the other. It is a touch darty on the freeway - but nothing crazy. We're not talking about extreme alignment settings here *EDIT* forgot to answer 3,4 - no issues with the rear - really stable through there. Actually the way I was driving the S's, because I was straight-lining 3 and braking to the apex of 4 the problem would appear at 4,5 if there was one - but again it was very stable through there - I never got worried in that corner. The S's were very autocross like though so I may be numb to the feeling as I'm very accustom to this car's weight shifting back and forth quickly (as in slaloms, or high speed offset gates)
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03-28-2014, 12:05 AM | #8 | |
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I will be in Tokyo for family and vacation for most of April. Don't think the wife will be too fond of me doing a track day that month lol. Which organization drivers edge?
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03-30-2014, 02:41 PM | #9 |
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Utenigma,
That is not the line through 7-8. I know many people teach it, but it just is not the line. Look at the rubber marks on track out of 7 and entry braking into 8. They tell the story. Start right at entry to 7, turn in to clip the apex of 7 at full throttle. If done right, it will push you out to the tire marks at track out. Ride the right side into 8 and brake hard to hug the inside edge over the apex. 8 is a throw away. Carry the speed thru 6-7. Then back on full gas thru 9 until 11. All that arcing for 8 is not the quickest line unless you are a miata.
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03-30-2014, 04:58 PM | #11 | |
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Remember I'm in a close to 4k lb sedan with McPherson front suspension, basically no front camber and an open rear diff with half the horsepower to weight and likely half the braking potential of your GT3. That being said, you are a 1/2 second faster from 7 to 9 than I was indexing the video - I'm by no means the an expert and next time I'm out there I'll likely give that line another shot. One that never felt right to me was 15. We always went straight along the left side then pointed into the corner and waited for a super late turn in, with the goal of having more speed in the next straight. Again my car doesn't turn on a dime, and I felt like we were wasting time driving in the wrong direction while creating what felt like a slower, tighter turn - all to have higher speed on straight that lasted all of 3 seconds. We didn't need any more speed in carousel, the car was on the limit of traction the whole way around feeding while feeding in throttle. I've seen some time trial guys just stay left around 15 and I might try that next time to see how it feels.
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03-30-2014, 07:18 PM | #12 |
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I am still not getting that set of turns how I want it. I need to drift out further in 6 to get a straighter shot to be on more gas into 7 before the quick uphill into 8 braking. I usually just never have the stones to do it. My wife was in an E92 M3 in your group, and she was about the only one running the line as was explained to me. Everyone was arcing 8, which freaks them out when it looks like she is about to t-bone you. She said she closed the gap on every car in that turn sequence. Of course her car is set up with brakes, camber, etc. Next time give it a try. Don't worry about how slow you have to go to hug 8. Carry all the speed from 6 into 8. Drop down to 2nd to power out of 9.
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03-30-2014, 07:21 PM | #13 |
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Definitely try to arc 15 more. Come in as planned but drift a little wider right, turn in a little earlier to clip the apex and track all the way out before setting up 16. You can go faster through the carousel if you keep it tighter. It falls away fast if you get too wide.
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