macnewma

Hey CC, have you read this: http://www.putnampark.com/profellows.htm

It is Ron Fellows take on the track.

Max

SundayDriver

I'm still curious about my questions to Tim in regards to G data vs. speed. What can be learned from the G-Sum vs. time that the Speed vs. time does not show (and show better from what I see).

mitch236

This is where I disagree. It may be more fun and feel cool to be at your limit off line but the reality is that you (and everyone else) should learn the line first. As your speed increases the line will change somewhat but slightly. When I instruct, I have the student show me the line at lower speeds during the cool down lap to prove he knows it. The line is more important than the ability to maximize g-forces along the wrong line.

Robert Henriksen

This is so obvious I'm completely at a loss as to how 'splain it to somebody who just insists to pee into the wind.

Brian P

I was thinking about this... I don't think it's too wrong to point out that somebody could enter a corner faster and they are losing time because of it. Hell, I know there's tons of corners (all of them?) where I know I could enter faster and also exit faster because of it.

The difference in my mind is how you enter the croner. I'm not quite sure that what Greg should be doing (if he really is entering the corner too slow) is to be lifting later. Perhaps he should be lifting at the same time that he is, but just not as much.

In the end, lifting later or lifting not as much might get him down to the same overall speed. However, the difference between the two will be a measure of how well the car is balanced. Lifiting at the same time but not as much will have the car more evenly balanced than lifting later. Now, there may be corners where you want more weight up front and you want to be less evenly balanced, and that will dictate the kind of approach you want to take to the corner. There's just more to it than raw speed.

I know that I'm still at the stage of the game where the answer for me is to be gentler on the brakes if I want to enter a turn faster.

ColorChange

Max:
I still think 9-10 complex is critical as it so strongly influences the big straight, has such risk, and has widely disputed optimal lines. This was Greg’s fastest through 9 and was consistent with his other laps so it is representative. The speed difference resulted in me gaining about 0.2 seconds on the entry. I lost about 0.7 seconds through the rest of the turns. This is not a case of slow in fast out. Greg could have gone faster in, and I didn’t overcook the turn, I just lacked the skill and chickened out to maintain the high g-sum. Now, Greg could not get the full 0.2 seconds or the full 25 mph difference because a large portion of that was due to my 600 hp. The only point is that he could have gone a little faster on entry here.

Bob:
Thanks for the compliments. I agree with everything you said, as long as you aren’t implying turn 9 is an example of slow in fast out being better as discussed above.

Mark:
I thought the comments about turn 4 are an ideal example of speed not telling what is happening. I held a higher g-sum but was still slower. That indicates either I was on the wrong line (probable) and/or his car is lighter and therefore faster through the turns (haven’t calculated the magnitude of this yet). Normally you would tell the driver to go faster by just looking at the slower speed. This would be wrong for me. I need to find a better line and/or accept his car is faster in the corners.

Mitch:
The data clearly shows Greg’s and my car’s limits. These are the car limits, not driver as I was often past the limit … again, ask Greg. He drives the limit extremely well, I often exceed it (by mistake of course). I’m not sure we are so far off on the line issue. I agree it’s important and I worked on that a lot. It’s just that I didn’t want to take my car there when I was not comfortable with a new car and how it handled at the limit. Remember, I was in a new car at a new track. If comfortable with the car, I agree, line, line, line.

Thanks Brian.

Jim Child

When I drove Eric's car I too had to lift a little early for 9 because I was out of revs in 3rd gear. 9 and 10 need to be taken in 3rd gear, and in my judgement there wasn't room enough for an upshift to 4th, followed by an immediate downshift back to 3rd. My solution was to lift at redline in 3rd and brake a little bit early then get back heavy on the throttle well before the apex of 9. Greg, how did you deal with this?

JackOlsen

What's interesting about ColorChange is that he allows himself to crumble, rationalize and backslide on just about every point he initially advocates. Oddly, the end result of this might be that he becomes a competent driver -- although it's very clear that he'll take a lot longer to get there than if he didn't try to re-invent the wheel in his own peculiar fashion.

Learning to 'drive at the limit' without knowing what line to be driving is, of course, ludicrous. It simply doesn't mean anything. But what ColorChange says and what he does (and then what he says in the wake of having done something) are all subject to frequent re-definition and revision. He's clearly learning something about the line every time he goes out. He's just committing -- and then wrong-headedly defending -- a host of typical rookie mistakes as he does so.

A little bit of knowledge can be a dangerous -- or at the very least, annoying -- thing. In spite of having no doubt that ColorChange has no idea what he's talking about, most of the time, I keep coming back to the discussions he initiates.

Greg Fishman

Jim,
Your memory is better than mine. I do recall hitting the rev limiter a time or two at that point but not sure how I handled it. It would be interesting for us to do a comparison to see if we were both doing the same thing, or maybe your exit out of 8 was better than mine and were on the rev limiter sooner.

Glen

CC if an excellent skier will also be an excellent driver at the limit. Same issues involved in both with momentum being key in both. Chris Cervelli and I once again this weekend worked on this and feel that we passed many slow in fast out proponents throughout the weekend. Our data is limited to just low laptimes but Chris did have AIM setup in his car so he may share some actual in car data here with us.

ColorChange

Thanks Glen, I am an excellent skier but I'm sure not an excellent driver yet, I have a long, long way to go!

Chris, please share!

SundayDriver

I have to admit a great deal of confusion on this. I thought that your assertion was that G-Sum was the proper way to evaluate a lap. The person with the highest G-Sum would be the fastest. That bit of data shows it to not be the case.

Then you modified it to be the highest G-Sum with no unnecessary G creation and then all of the above while on the right line.

So from the G-Sum trace ONLY, what can you learn? Your theory, if I understand what it was, would say that you are faster because you created a higher G-Sum. That is a bad conclusion that is only corrected when you look at speed data and/or segment times.

My assertion is that the Speed trace tells you far more. By ONLY looking at speed, my conclusion is that Fishman was faster. But, I don't yet know why or what happened from just that data. I will give you this in G data. If I were to then look at Lateral G data, I would see (I assume) that you were genreating higher g's while going slower, therefore you were on a poor line.

The summary, as I see it, is that speed will give me the right answer but not all the details. G-Sum can give me the wrong answer and only by looking at additional data can I correct that answer. So maybe I am being dense but from where I stand, I would rather use speed data, get the right indication from the start, then look at other data to understand the nature of what happened. I ask again, what can I learn from G-Sum that I can not learn (better) from Speed?

In fact, even that is somewhat academic because I don't care about speed any more than I care about G's. I care about lap time. Why aren't you comparing lap and segment times? Then go to speed to see where the differences are, and only then drop to Lat G's for more details?

Eric in Chicago

Greg, Jim,
I just sent you each others data from the Putnam race. I looked at everyone's data including my blazing 1.22 lap and we all were bumping off the rev limiter going into T9. Knowing that it was going to happen, I would feather the throttle just under 6200 RPM, brake and back on the gas. Interesting, my fast lap had me shifting only 2 times in the lap, I ran 3rd from T2 (downshift from 4th in T1) to T10. If I had got T7 right in 2nd I might have picked up another .5 sec but I kept smacking the rev limiter mid apex and wanted to try something different.
This time was in the sprint race and I was desperate to catch the car in front

SundayDriver

I happen to hate the Slow In - Fast Out concept unless you are in a car with someone. It can mean far too many different things to different people.

Too many use it to support the idea of crawling through the corners, jump on the throttle and shoot down the straights, thinking they are driving the fast way. BS!

I beleive in Fast In, Faster Out. If you want exit speed, then you may sacrifice a TINY bit of speed on entry so you can take a later apex and gain exit speed.

It is also a good mental image if you have the tendency to overcharge the corners.

It is a great tool with a novice to get them to gain exit speed so they can later work on entry and mid-corner speed.

But, the flip side is that it is unfair to label anyone who uses the phrase to mean Fast In, Faster Out in with someone who uses it as an excuse to be a wimp in the corners.

Mike in Chi

" I care about lap time. Why aren't you comparing lap and segment times? Then go to speed to see where the differences are, and only then drop to Lat G's for more details?"

That seems like a good evaluation sequence to me, Mark.

And good point on how to analyze segments.
This discussion may do wonders for the sale of DAS equipment. I know of one racer who was helped considerably by DAS segment tuning two weekends ago. I fear I've lost my .005 second advantage over him, and will have to comparably arm myself.