ColorChange

OK, Here is the g-g plot. It looks funky and I felt a whole lot better when I saw Greg’s looked like mine. The red area is my cars superior acceleration so Greg can’t go there (literally). The green area is the trail braking area and you can see I fill it out a little better than Greg does. I had any advice to Greg, it would be that he could be a little faster by trail braking a more in some turns. I’ll talk more about this later. Our g-g plots are similar with me getting a slight nod in the trail braking area.




Here is a time comparison. The lap I used was 1:20.7 and Greg’s was 1:21.9. The yellow is my car out accelerating and requires little driver skill. The rare green areas are where I gained on Greg in the turns. The rampant red areas are where I got my lunch handed to me. Lap three may be acceleration influenced but 9 entry is a clear win for me (i.e. opportunity for Greg).




What is difficult to compare is on that day versus my day, with an old light car on race rubber versus a new heavy car on bigger street tires, how close should I be in the turns? It appears from the data that our lat g max’s are about the same. Therefore, I am at a 700 lb weight disadvantage and the 944 should be faster in the turns. How much faster I will try to have by tomorrow.


Here is a detailed look at the g-sum through the turns. I get killed through 1 and 2, and actually won turn 3.




I out drove Greg in turn 4. He gained time on me and that is either his weight advantage, or he had a superior line. I will try to determine which. I had a nice entry into 5 but got destroyed the rest of the way.




I won the entry with trail braking on 7 but Greg won the rest. Turn 8 is extremely close, but look at Greg’s superior smoothness, my g-sum’s all over the place.




I won the entry again with better trail braking again but got creamed the rest of the turn. Again, Greg is much smoother.

Jim Child

Sprint races are usually around 30 minutes.

Eric in Chicago

Greg's lap time in the graph above was 1.219. As stated, the car was going positive camber and started chewing up the drivers front tire. Again, it was practice and the first time Greg drove my car (ever). Pretty outstanding. Greg's best time in the enduro was 1.223 as at that point, I think we had about 1.5 degrees positive camber. Keep in mind, Greg was not going to "buy" the car should something happen and was going less than 10/10th.
Jim Child also drove my car that weekend to help out with DA baseline and was as fast as Greg. (Jim, I have you data as well if you want me to e mail it to you)
Greg drove the wheel off the car, we had a pit stop in the enduro where we changed the front, positive camber tire. A half hour latter,Greg came back in and the front was shredded and a lap away from failure (a special thanks to Gary Grisby who let us use the tire and rim for our pitstop tire change, that is what club racing is all about. Another F class racer letting a rivial (If you could call us that) have a tire to try and finish the race!)
A belated thanks to Greg, Jim and Gary for a great club race weekend!

Eric in Chicago

CC,
BTW, my race prepped car is not that light. Race weight of 2970, less driver and 207hp at the crank (est.)
It does have nice shocks but not a nice as the Motons your running. I have Ledas (single adj.) and monoballs all the way around. Standard brakes with stock 968 cooling fins.

ColorChange

Mark:
I agree, what I want is same car, same day, different driver. I wasn’t overly anxious to get data at Putnam because I’m not very good there yet (new track) and I wouldn’t be able to do good comparisons.

Line? No where do I say my lines are good or consistent. Anything but (and Greg will agree!). My comment on the graphs is that While I out g-summed Greg in turn 4, he gained time on me so either I chose a bad line or his lighter car made the difference.

Agreed, he is killing me on exit speeds! I sometimes win on entry speed. The problem is I often over brake. This contradicts nothing I have said. The fastest driver comes in hot and slows only to what he needs to. I’m not able to do it and Greg would be even faster if he did it more.

G-sum value
Turn 4 would indicate that by speed analysis, Greg was faster, implying better. This is not necessarily true. I “drove” the car better by keeping a higher g-sum, but either his line was superior or his lower weight car is that much faster in the corners that he was quicker. I will continue to analyze this.

On t9 I clearly won the entry but chickened out the rest of the turn. Greg could attack the entry harder and be faster.

ColorChange

Eric: What is your weight then? I'm a little over 3,600. I said in the beginning, this was not Greg's car and I think he is DAMN good so please infer nothing different from my comments. I don't rank anywhere near Greg. But I willkeep trying.

Greg Fishman

Tim,
Why don't you do a comparison of our best hypothetical times/segments? Or best rolling lap. Look at my other laps and see if this was an abnormally slow turn 9 entry, etc. I just think taking one single lap may not be the best as we may have had traffic to contend with even on our best actual laps.
I think my theoritical best or rolling best was in the 1:20 range.


Tim, Turn three will always be a better turn for your car if you are on line as it is essentially a short straight, your car should also be better through 6 as it shouldn't require anything but full throttle for almost any car.

Eric,
I wasn't able to download the analysis software but I may call David and see if he can help me. If I get that sorted I would love to see Jim's data in comparison to mine. Jim and I have both been doing DE's and racing for about the same amount of time and seem to have had comparable results in our respective classes.

ColorChange

Greg: OK, I'll try to look at other laps (but then again I''ll look at my other laps too)

You are probably right on turn 3 as I indicated, maybe I didn't win but if not, we sure tied.

Eric in Chicago

CC,
Weight less driver is 2970 lbs. Nothing infered, I was just listing the set up Greg was using to turn the laps.

Greg Fishman

Tim,
Absolutely, I personally think it means more (tell me if I am wrong) to look at your best segment in comparison vs. just the quickest lap. If you are really driving consistent the times should be close together. If not, either the driver is not consistent within the lap or had outside issues to contend with.

G-sum value
Turn 4 would indicate that by speed analysis, Greg was faster, implying better. This is not necessarily true. I “drove” the car better by keeping a higher g-sum, but either his line was superior or his lower weight car is that much faster in the corners that he was quicker. I will continue to analyze this.

Tim,
Help me understand this. What if the reason my g-sum was less because the car was limited by the relative lack of hp? Or does this imply that I was not using all the available grip and that you used more of your available grip?

Jim Child

Agreed, I would love to see that too. Our best times were roughly identical, but I bet we had slightly diferent ways of getting there. An analysis of those differences would be very interesting.

I agree with you about turn three. Its a full throttle no brainer in Eric's car, where you just keep your foot down and try not to scrub any speed. I'm sure its *much* different in Tim's car.

Regarding the turn 9 entry speed, Eric's car tach's out in 3rd gear at a most inopportune time between turns 8 and 9, and no matter how you choose to deal with that your entry speed into 9 is somewhat compromised.

Brian P

Tim,

Is it possible to come in too hot and it then compromises the speed that you can take out of a corner? If so, how do we know that Greg could really come in faster?

It seems to me that at some point, having the car well balanced is more important than carrying a tiny bit more speed.

SundayDriver

It is very possible and I have seen it many times. The faster guy is setting the car up by going slower in one place. Slower guy figures it out, slows down and goes faster. Sometimes it even changes on you. There was a decreasing radius corner I woule enter flat in the Radical, then brake really late and kill everyone else. Next time at the track, it didn't work that way. I had to gently brake going in to be fast.

Tim - you are refusing to even admit the POSSIBILITY that you are wrong about some things that those with experience say are wrong. What is your definition of Low Character and High Character again?

In theory, theory and practice are the same. In practice, they aren't.

RJay

Precisely what I was thinking. Doesn't this prove the slow-in fast out adage? I'm reminded of an article I read about a year ago I think in European Car in which one of the magazines journalists went to I believe Silverstone and drove an Elise with Jensen Button. So same car, same track, same day. The journalist was apparently an experienced track day driver. When they compared the data what they found was that the journalist was braking later and carrying more speed into the corner than Jensen. Exit speed, of course, was a different matter. I can't remember the exact times, but I think Button was over 4 seconds faster.

I also found the plots interesting, if a bit difficult to understand. It would seem that Greg's plots look smoother to me, but I'm not sure I'm reading things correctly. Anyhoo, good thread, very interesting stuff!

ColorChange

Guys, I agree that in turn 7, I did the classic come in too hot, blow the apex and slow to get to the throttle. Turn 9 is different. It's a long fairly constant radius turn initially and I could have come in as hot as I did and kept the g-sum up, I just lacked the ability on that lap (sadly, and most laps).

Greg
Regarding turn 4, if you were flat out, you would be right, but please lie if you have to and say that you weren't flat as you've got to leave me doing something better than you ... please.

On consistency, you would want to look at more laps and segments of course. you discard flukes and look for trends. The little analysis I am doing here is not very conclusive because of all the factors involved but it is still entertaining and major trends come out.

1 you are much smoother
2 you handle high speed turns much better (higher g-sum)
3 you select better lines
4 ... uggh ... you're just plain a lot better driver than me

Mark: Lighten up a little and be specific. What am I not considering that I could be wrong about?