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WILSPEED's Avatar
 
Join Date: Apr 2009
Location: Los Angeles, CA
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Need help with Turn 3/4 and Turn 5 at Willow Springs (Southern California)

Hey guys. Just wanted some input on the ideal line for these corners at Willow Springs (big track) in Southern California. I'm running a 911SC with a 3.6 for reference.

With the turns 3 and 4 combo, I have been turning a bit earlier at T3 to try to carry as much speed up the hill as possible. Then I take a bit tighter line to get the car rotated around T4 as quick as possible since the car is light going over the crest anyway. The trade-off seems to be a bit less exit speed. I've been watching a myriad of POC videos on YouTube and it seems like this line is the one that is usually used. Those guys were in similar cars and were using this line even when no one was behind them.

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However, I've watched a "corner by corner" video guide on YouTube from a certain (and extremely fast) driver of a street legal 911, who turns in late at T3, stays a bit more to the left up the hill, then takes a much wider radius turn around T4. Seems like I lose a lot of momentum going up the hill after T3 when I tried this myself. The exit speed after T4 is a bit higher but there does not seem to be much gained because of the short distance to T5(?)

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Which one is faster? (ideal line, not racing **defensive** line)
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The other turn I wanted to ask you guys about is turn 5. I've been braking a bit earlier coming down the hill and try stay near the curbing on the right immediately after T5, before T6, then track out on the run to T8. Seems like I can carry more speed from the downhill from T5, into T6 this way. A bit more steering input is needed at the exit of T6 but doesn't seem to me much of a trade-off in speed doing this (I don't have telemetry data to be certain of this though).


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Again, referring to the same "corner by corner video," I noticed the driver turned sharper to the left after T5 so there seems to be a bit less steering input at the exit of T6 for the run to T8.


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Again, which one is faster (ideal line, not racing **defensive** line)

Please excuse the horrible drawings. I also tried to exaggerate the lines a bit in an effort to make it clearer to understand. Any input appreciated. Thanks.


Wil

Last edited by WILSPEED; 09-10-2019 at 02:44 AM..
Old 09-09-2019, 11:56 PM
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Old 09-10-2019, 09:35 AM
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I knew you would be the one to reply lol. Please help meeeeeee!!!!!!
Old 09-10-2019, 09:49 AM
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My car is an 80SC with suspension upgrades but a stock 3.0 the line you drew in red is faster for me, I've tried the other and my lap times were slower. I loose speed go up into 4 as well but getting that apex right and setting up 5 correct resulted in faster times for me. The red line through 5 gives you more straight line going into 7,8,9....having more confidence and a good line through 8 and 9 really result in better times for me.
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Old 09-11-2019, 08:43 AM
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I don't learn anything new from my own ideas about 3-4-5, so this thread is interesting to me.

But here's how I approach it.



I don't know that there's an ideal entry point for 3, other than not turning in too early or too late. You want to move to the right for your braking, but I don't think it has to be 'wheel-in-the-dirt right.' I don't even know that it's essential to clip the apex point on the left, although if you're too wide of it you're going to go off on the right side in a few hundred feet. Turn 3 is weird.

But it's also a sacrifice. I've driven a lot of cars at Willow and I've never driven one where it felt like the gearing was right for the uphill between 3 and 4. And the camber in that area is such that you're always going to be catching the car there. There isn't a no-drama line up the hill. And overcooking 3 or coming into 4 too hot doesn't really get you anything in terms of lap times, so I believe in treating it as a sacrifice to set yourself for turn 4 and the downhill.

So, you turn in for 3, get yourself up the hill. I don't think you should be anywhere near the rumble strip on the right, unless you're defending. And I think this is why people shoot themselves in the foot for 3-4-5: because the racing line is vulnerable here, other drivers tend to stay too far to the right on the uphill, defending against a non-existent opponent, which means the arc they have available for the turn 4 rotation is unnecessarily small. The farther to the left you enter, the larger the arc between you and the turn 4 exit apex point, and the more speed you'll be able to carry out of the corner.

And in my opinion, the only important thing about 3 and 4 is carrying speed out of 4. The sooner you're on the gas there, the more you can eat up your opponents on the downhill. And with a 911, you can rotate the car at the top of the hill by coming abruptly off the gas, turning, and letting the rear come around while you line yourself up and punch the gas for the apex on the right and the downhill section past that.

I bring the car back to full right and brake with the candy stripe on the right for 5, turn in early, and try to set up for 6 by getting to mid track. I think there's a temptation to underbrake for 5, which has guys trying to get their car under control on the uphill between 5 and 6, which blows their speed as they come to the crest of 6, which in turn kills their lap time because 5-6 is so important for the back end of the track.

Here's video from my quickest lap. I don't drive my cleanest line here and I'm not on the gas where I like to be. But it's what I've got.

https://youtu.be/jn1_h-7Y-q8

And here's another look, swiping some video from a Petrolicious short:

Old 09-11-2019, 10:47 AM
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Great info guys! Thanks!

Jack, based on the short video you just posted, it looks like you still use the red line for T3/T4 but now use the blue line for T5/T6?

The link below is your “corner by corner” video on YouTube that I was using as a reference.

https://youtu.be/fLCpHnA54cQ

In this video, you turn in much tighter to the left after T5 to set up for T6 (so you are using the red line method instead).

Then again, your, “corner by corner,” video was 7 years ago. Did you realize since then that the blue line is faster for you through T5/T6?

Last edited by WILSPEED; 09-11-2019 at 08:53 PM..
Old 09-11-2019, 08:37 PM
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Well, this gets complicated. In the low-speed footage in my how-to video, I definitely stay to the left on the way up the hill. Part of the reason for this is that I'm not carrying enough speed for the car to get thrown to the right.

I'm more mid-track in the higher-speed footage in the same clip, because inertia is throwing me in that direction. I try to teach a line that leads more or less to mid-track after exiting 5. Teaching people to go full right would mean a lot of them going off the right side of the track (been there, done that). In the newer (and quicker) clip, I do end up just about full right on the uphill. This compromises the entry to turn 6 -- but when you carry more speed through 5, you end up where the mass of the car decides, not the necessarily the driver.

I grabbed a frame from the low-speed footage, the higher-speed footage, and the more-recent lap. I switched data loggers and cameras in the interval, which makes it hard to judge much. But I'm farther to the right more recently.

Old 09-12-2019, 09:03 AM
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I’m about mid track as well after T5 and that’s actually what I (tried) to draw with the blue line in my picture.

However, I think I’ve been taking T3/T4 much differently than you. It seems like I can’t really get the power down going over the crest at T4 to really benefit from a wider arc. Maybe because I have to turn tighter. I suppose the choice of compromise seems to be more exit speed after T4 for the downhill (red line) versus more exit speed after T3 for the uphill (blue line). I wish I had telemetry to see the actual difference.

I am also running NT01’s. Slicks would give what? 2 seconds a lap or so difference?
Old 09-12-2019, 01:33 PM
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I’m in the middle of the track after T5 as well (blue line).





As for T3/T4, I think the blue line has been faster for me because I have quite a bit more understeer compared to you after watching those videos. I’m not sure if I can get my car rotated left that quick like you after T3 if I turn in late (red line) unless I scrub off a lot of speed (losing momentum for the uphill).

Last edited by WILSPEED; 09-12-2019 at 09:25 PM..
Old 09-12-2019, 08:58 PM
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