SundayDriver

But if you want to be faster, then you need to Out-DAS him. My analysis says you need a Motec, shock pots, 2 brake pressures, throttle, steering, airbox pressure, usual temps and pressures and g sensors. $12K should about cover it. Anything worth doing, is worth doing to excess.

Eric in Chicago

Mikey,
You better hurry, I am finding seconds like pennies on the sidewalk!!

Eric in Chicago

Stop that Mark,
He is already having his engine rebuilt now that he knows I got him by 3 seconds at one track and 4 at another. Mikes wife is small but strong, she will not like you pushing him over the edge like that!!!

SundayDriver

I met Mike's wife and my wife was there with the usual speech to her about keeping Mike away from me, if she knew what was good for their finances. Note the addition in the edit of what you quoted just to make things clearer.

Mike in Chi

Uhhh, Eric, three seconds at one track and four at the other will put you on pole at both.
You cheating?
(But don't worry, i won't mention a thing to Karl, Keith, Chris, Jim, Steve..).

Mark
12,000 is a lot, even for my persuasive powers. However, I may have a low cost alternative. A competent medicine man is only $400 or $500 a day. I could get him to do a rain dance for 25 or 30 race days. Some of my competitors do not relish the rain like the turtle does...

ColorChange

Mark:
G-sum is the proper and easy way in comparable cars. His and mine are anything but comparable.

If you looked at the speeds and concluded Greg’s lap was faster you would be wrong. My lap time was over a second faster than Greg’s and he out drove the pants off me! This is a perfect example of a big throttle covering up a multitude of sins. Times are irrelevant in mismatched cars. The only way to truly compare drivers would be to take turns in the same car and track that both drivers are equally familiar with. Since this is difficult, you could try to compare the percentage of the cars potential the driver extracted. This is doable but a little bit of work (and still doesn't account for set-up issues affecting driveability). My integral of g-sum is higher than Greg’s but that is because I have a superior car, even though a much inferior driver.

Lap times and segment times are not comparable in different cars if you are trying to asses the driver. G-sum is the correct way to do that. In highly comparable cars, you can use lap and segment times, but g-sum gives you much more insight. I think you can’t use either well in isolation and need to look at both (and more) to really understand what is going on.

Since our max g-sums are very similar, it makes direct comparisons in turns where I can’t use much throttle pretty applicable, as the data shows. Any time I can use throttle (accel g’s Greg can’t achieve, you have to stop comparing as it’s not fair to Greg). That is why the full 25 mph entry speed is overstated because I used my superior acceleration to achieve much of that.

Eric:
I agree, you guys were redlining coming into 9 but Greg could have held the throttle up there and not braked so hard and so early to increase his entry speed. In a very quick look, it looked like all of you did this. I am beginning to think it is because you guys were not using the entry apex of 9 and sweeping it instead of dbl apexing as Norm said, and I think, this is a slower line. My higher g-sum (and resulting faster speed early) is proof that the dbl apex approach is faster, at least in my car. You guys would need to drive it to see if it was faster in your car.

Eric in Chicago

Eric:
I agree, you guys were redlining coming into 9 but Greg could have held the throttle up there and not braked so hard and so early to increase his entry speed. In a very quick look, it looked like all of you did this. I am beginning to think it is because you guys were not using the entry apex of 9 and sweeping it instead of dbl apexing as Norm said, and I think, this is a slower line. My higher g-sum (and resulting faster speed early) is proof that the dbl apex approach is faster, at least in my car. You guys would need to drive it to see if it was faster in your car.

CC,
A rear engine car may be faster with the dbl apex, when I ran my 993 at Putnam that is the line I used as I could get the car to rotate, the 944 does not rotate as easy. I did try the dbl apex with the 944 last time out and found I could not feed in the power as much as if I used the big sweep single apex. Also, as others have mentioned. 9 has claimed more victims than any other turn at PP( that I have witnessed.)Upside down 944's, bent 911's and a 968 so far into the woods it left the property of Putnam. The outside of 9/10 is dirty and marble filled, not the place I want to expierment too much!

Brian P

I largely agree with this. My only small comment (and I mentioned it earlier) is how a novice/intermediate decides to go "fast in." I think most people decide the best way to do this is to brake later and brake harder. Maybe at the top levels, this is what should be done, but for most novices, they end up scaring themselves and brake even harder and longer. The might feel like they are going faster in, but in reality, they are going slower.

What would be better for most people attempting to go faster in, IMHO, is to achieve "fast in" by braking earlier, but lighter. This lets them easily modulate the speed because they aren't slowing down as much. They can then get accustomed to the sensation of going into a turn fast. After they are used to the new speed, they can then return back to a more forceful braking style.

SundayDriver

You are the one that set the parameters of the comparison as turn 4. Now why are you trying to put words in my mouth and assume I was taking about an entire lap when he was faster in ONE corner?

Jim Child

I've driven both lines extensively in my car (thousands of laps). The stopwatch says that the single apex line is faster for me. The double apex line causes me to scrub speed with the front tires turning in agressively enough to hit the first apex. I also find that the car gets really unsettled going over the bump on the inside of 9. On the single apex line in my car I can be flat on the throttle from the turn in to 9 to the exit curbing near the pit entrance. A quick breathe of the throttle is then all that's needed to initiate turn in for 10. I find that I catch *lots* of cars in 9 & 10.

ColorChange

Mark, the graphic is hysterical! My misinterpretation. My biggest point is turn 9 entry. Turn 4 may either be my bad line or Greg's lighter car, or some combination. I plan to look at this more.

Eric and Brian, I agree. Eric, I switched back and forth between the lines, and the dbl apex is much scarier/riskier, as you point out.

Jim: I yield again, especially if you have looked at it with data and can compare segment times with equal g-sums.

DJ

Tim,

Let me drove your car, and I guarantee that I'll beat Greg on every single corner entry. Of course, his lap times will beat mine because by going way too deep into every corner, I'll necessarily blow every corner, have poor mid-corner speed, and a slow exit speed. But by braking way too late, way too hard I'll be sacrificing exit speed, and mid-corner speed, but I'll spank his corner entry g-sum on every corner.

Sounds kinda stoopid, don't it?

mitch236

I thought about Tim's assertion that maximizing g-sum on the correct line is fastest and found the flaw. The correct statement should be "maximize velocity on the correct line". If you think about it, g-force (acceleration) during a turn has a vector pointed in a different direction than the direction of travel and therefore may hinder the overall velocity.

ColorChange

Mitch, You have found no flaw.

If you maximize velocity on the correct line (the better term would be maximize speed on the correct line as velocity is already a vector), you are in fact maximizing g's on the correct line. The two statements are equal. What gets confusing and is easier understood is that in braking, you want to brake as hard as possible, for a short of time as possible, as late as possible, (subject to not hurting g maxing capability later on) and while this is in fact maximizing speed on the correct line, it is easier to think about in terms of maximizing g's (lat and long). The driver has two primary tools, the steering wheel (lat g creator) and the bake/throttle (long g creator), and this is why it is usually beneficial to think in terms of g analysis.

FormulaOne10

This is true but...such an acceleration would actually put you "off" the correct line. So you actually wouldn't be on the line in the first place. The directions and relative proportions of your tangental and normal acceleration vectors together determine the path (or line) of the car (they are directly proportional to applied force on your tires). Maximization of these vectors gives the lower segment times.

In other words I could say that I can drive the same exact line...but at different speeds as long as the (g-sum) unit vector (or direction) were in the same direction throughout the turn. The faster you come into the turn...the more lateral g's you apply to stay on the same line (remember that your lateral force is a function of velocity in the tangental direction).