Driving question

[erok]

I've heard that sometimes the shortest line around a turn is not always the fastest and some times it is. Can anyone generally comment on distinguishing the difference between a turn where the shortest line is faster and a turn where a longer line would be faster. Or does no generalization exist for this.

My guess is a turn that can be run tight to the inside without losing momentum warrants running the inside line over turning in later and closing in on the apex. Any comments are appreciated.

[NoCones]

I'd say it's all about what comes before and after the turn in question. One generalization:

If there's a long straight after the turn (not necessarily truly "straight," but a section where your accelerating non-stop), you probably want to late apex it to maximize the length of that straight. Kinda like you said with "turning in later and closing in on the apex"

If there's a long straight before the turn in question, you want to hang on to that high speed as long as possible with an early apex, letting the car swing out wider on exit.

Or there may be other course design elements that dictate wide/tight entry/exit--i.e. getting set up for a slalom or something.

If those situations don't apply, the factors would be personal preference and the radius of the turn. If the turn is so tight that it might bog the engine or require a downshift, it might be worth the wider line at the higher speed. My personal preference is to drive the shorter line when in doubt...a screw up on the long, fast line is probably more harmful, and harder to recover from.

My $.02.

[silver2001gts]

The proper line varies with each car and each driver to a degree. In low-powered or low-traction cars, the key is to maintain momentum. In general, the straightest line thru a turn is the fastest. I think experiementation is very important. Seat time is what we all need in order to go faster. There is no substitute for that.

If you want some real world examples, go to an autocross and walk around the course with an expert. I you see him/her go wide on a turn, ask why he/she did that.

[erok]

The turn I'm thinking of was a medium radius 180

[Raymund]

it usually boils down to compromises that must be weighed out in a case by case basis. sometimes there are exception to the rule and driving the smaller diameter path can yeild better results.

remember button willow? theres this section in between the "lost hills" and "dog leg" that i've run across the with same questions you have.

[clockwise]Coming out of the "dog leg" section the traditional racing line would be to apex "riverside" late and exit wide creating the widest arch possible and slowly crossing over the opposite side to prepare for the left kink followed by a short straight leading on to the "lost hills".

I've tried both "by the book-widest arch exit" and a "compromised- mid track exit".

Even though its a plain right angle sweeper connecting two straights, i've found coming off the apex and placing the car at mid track netted a faster result.

I chose to do this b/c I felt the trade of off a shorter line netted better results than going at a wider arch for the reasons the celica cant go fast enough to take advantage of a wider arch.
http://buttonwillowraceway.com/images/race_14_config.gif

maybe i can show you one day:)

[scapamouche]

Maybe you can show ME next weekend?

Or June 8? ;)

[Raymund]

I wish i could be there next weekend. Have fun and let us know how it went. June 8 is still on track. see you then:)

[erok]

scapamouche - what event are you talking about? April 20th school at Buttonwillow?

[scapamouche]

Buttonwillow is having an all day school next Saturday. Starts at 7.30 or 8 am and runs till 4.30pm. Assuming the Celica is back and ready to go, the wife and I will be attending. (If not, we'll call and change the dates.)

It's $165, and includes a shirt and lunch (I think lunch, anyway.)

Details at www.Buttonwillowraceway.com on the events page, I think.

[scapamouche]

BTW, for track time around here (CA, anyway,) that price is a BARGAIN!!

[erok]

I attended the driving clinic there last year. It was less money then I think. It might be worth going again. I wonder if it's full?

Edit: Just sent them an e-mail. If it's anything like before, there'll be plenty of driving time. That clinic killed my OE Yokohama tires. Maybe I'll go.

[scapamouche]

Good to hear. I was hoping it would be that way. I can't afford to kill the tires, though. The Falkens have to last at least till the Prosolo at Atwater in May.

[erok]

I reckon that the Buttonwillow driving clinic put the equivalent of 5,000 or more street miles wear on the tires in one day. Plus the tires were pretty ragged around the edges and caused a vibration over 80mph after that. $165 + expensive tire wear. I'm on a tight budget right now. Have you heard about the Lone Pine Time Trials? I think that might be fun and cost the same plus it has a competative element. http://www.solo2.com/Lonepine.pdf is the link to that event. I also want to concentrate on autox rather than road course events.

[scapamouche]

Well, it may be a moot point.

The dealer told me today that "I didn't realize it at first, but the shift gate mod requires major work in the tranny, including fork replacement. The parts aren't in, yet."

So much for getting it back today (yesterday, they said today.) All the goodwill I've had to this dealer over the last 2 weeks just got flushed. I now have doubts that I'll get it back in April.

I'm now hoping I can find a ride for the local Autox on Sunday, and I'll be trying to reschedule the school for later.