Eifeler

Agree with the exit positioning but if I'm not at full throttle well before that 2nd corner worker something has gone wrong.

ProCoach

The people that are quickest are those that anticipate WOT...

NJ-GT

I found very impressive that the time in between the two bridges (the car overpass, and the pedestrians bridge) is so similar, despite the vast difference of weight, power, car size and Aero.

With the exception of the SportCar (and those things weight nothing and run near 2:00 flat at Sebring), and the FIA-GT2 ALMS 996 RS, the variety of cars including the ultra-lighweigth Juan Lopez 911, the monstruous aero 997 3.8 GT3 Cup, the nimble and light 996 GT3 Cup, the cheater Aero/LW/TSB-Updated Trakcar 3.8RS, and my 0 downforce ultra-wide and ultra-stiff Fiat, we all spent in between 5.8 secs and 6.2 secs between bridges.

It would be nice to see the exit speeds when passing under the 2nd bridge.

analogmike

Peter,

T17 confounds me too, here is an enduro qualifying lap in my GTC4 car from a few years back, seems like 5.5 seconds between bridges (2nd time through, 1st time I was only interested in exit speed), any comments or hints appreciated!



https://www.youtube.com/watch?v=Ru-d2owIHKI

ProCoach

Not surprising to me at all, Rad. It's been reinforced more and more, the longer I have accumulated data.

It's the reason my business motto is "The Driver is the GREATEST Performance Variable"

People assume quicker cars go substantially quicker through challenging (slower) sections of all the various tracks. They do not.

They spend less time turning, though.

And often, I can help drivers spend less time in the challenging sections by giving them a very clear, VERY detailed idea of EXACTLY where to place the car, what external factors affect their trajectory and measuring them...

Mike, you and I should work together some time. You have leveragable skills!

ProCoach

Cory F 2006 996 GT3RS 2:08.7 6.9, 12.4
Sean Johnson 2011 ALMS Winter Test 997 GT3 Cup GTC, 2:10 6.8, 12.6
AnalogMike 997 Cup Enduro Qualy 7.8, 13.6
Clarke/Sly last week 996 Cup 2:16.9 7.6, 13.7
TRAKCAR 2011 Winterfest 2:19.9 7.9, 13.9
Juan Lopez-Santini 2-liter 901 2:25.5 8.1, 14.3
Rad 2011 Winterfest FIAT 2:21.7 9.3, 15.8
and 2-liter sports car 2:05.4 6.4, 11.5 (hey, it's thirty-five years old!)

85Gold

Mike

That is the old Sebing before they paved the track out from 17 to the wall. It allows a little more safety or speed to be carried through the exit. At least in my case not having the dirt there definently is a comfort factor.

Peter

Juan Lopez

In super simplified terms (and applicable at least in my "not so lightweight " car) must be WOT just before or at bridge and stay 1 car width away from the corner worker at the exit.

Car54

One thing that I haven't seen mentioned is to turn in early at 17a. Turning in before the 400' marker reallly gets you in deep to the turn and allows a good arc to brake and turn. This approach in also allows you to carry a lot of speed in.

I'm no expert on T17, but this is one of things I was shown that seems to work well.

MikeJim

This clearly shows what a difficult...and LONG... turn it is.

Veloce Raptor

Of course! The earlier you bend the car in = less steering angle = less of aturn & more of a slight bend in the road = longer on throttle & softer on brake = more entry speed

ProCoach

That's pretty early, for sure!

What I am seeing most is people NOT "carrying speed in" because:

A) They're not sure at what point (how deep, how wide) they should be when they "cut in" torwards going under the drive-over bridge and

B) They don't have a tangent (relatively straight angle) that they're trying to make work between the point they leave the left edge of the road and the point they're trying to reach in A)

There is SO MUCH distance BEYOND the 400 marker that it is well in excess of what is required to get the car slowed down to a speed that it will make that "cut in" under the bridge. Look at the great photo above. If anything, it looks like to do the optimal geometry, that you should turn in LATER than the 2 marker that the data suggests.

Nearly everyone I work with leaves far too much on the table and could afford to go faster, longer going in and slow more quickly to a slightly slower point than they think, so the car car turn (rotate) quickly when you ask it to.

So they lose going into the braking zone, through the braking zone and, if they aren't careful, AFTER the braking zone. Three places to improve and we're not even under the bridge yet.

My most preferred sources for this information are my colleagues who have studied this place for decades, every day. 12-Hour winner Jim Pace, Bruce MacInnes, Terry Earwood and Divina Galica, all from Skip Barber, have made those calculations and freely share. Of the tens of thousands they've seen, they know what works and what doesn't. From my terabytes of video and data, so do I!

The most recent video Skip Barber has put up at universityofspeed.com/videos (IIRC) shows a few Sebring laps narrated by Terry. It's very, VERY worthwhile. Pay attention to his T3-T5, T15-T16 and T17. It's good.

I think the answers are there, you just need to know where to look and then through data and video, make sure you're doing what you think you are.

MikeJim

While I am by no means an expert on Turn 17, I have found a few visual cues that help me negotiate this nasty turn. Under light braking, I look for the TWO cone (circled) and set a straight line as close to the wall as possible. I jab brake when I see the heavy black strip across the track and rotate the car and release the brake at the dark asphalt patch (circled). I try to have the car perpendicular to the cone on the drive-over bridge (circled) and try to be on full throttle right after I graze the bumps (circled). Full throttle then to the track-out jig in the outer wall (identified by all the paint from various cars before).

ProCoach

Nice geometry, MikeJim!

Leaving the left edge of the road where you do, you can almost draw a bead on the right side of the Skip Barber building (left of registration) and drive right to your black patch turn in! Beautiful!

I find a worse bump just right of the cone and before the bridge. By taking your entry and shortening the turning moment, it's possible to lessen it's effect.

Falcondrivr

Will either of you take a ride with me Feb 23 or24?