Looking at the time trial BRI

[kary]

I was looking at the results for the BRI and I came to the conclusion that I either need to learn how to drive a lot faster or we need to adjust the BRI index for my class to something more reasonable. Some of you might have this issue as well.

The past three years on the same track and roughly the same conditions I did the following:

2003 112.14 index 1.103 adjusted time 123.69
2004 109.87 index 1.097 adjusted time 120.62
2005 107.95 index 1.115 adjusted time 120.36

I improved just about 2 second in real time each year and while the index did change the adjusted time only slightly improved, about 3.5 seconds versus about a 4.2 second real increase in time. In order for me to have been somewhere near the top few in the BRI I needed the following:

106.00 index 1.115 adjusted time 118.19

which still would have put be behind Jack by 0.08 seconds in adjusted time. I don't know about some of you, but I do not think I can get another 2 seconds out the car (or myself). I could remove more weight but I cannot really remove enough weight to get the time down there.

Does that index seem fair (1.115) for MI? If so, can someone explain why?

[ttweed]

Does that index seem fair (1.115) for MI? If so, can someone explain why?

Kary- can you publish the BRI table you are using currently? The one on the website at http://www.pcasdr.org/autocross/bri.htm is out of date and should be revised to whatever new values you are using. It shows the MI index as 1.103, still, not 1.115.

[kary]

Does that index seem fair (1.115) for MI? If so, can someone explain why?

Kary- can you publish the BRI table you are using currently? The one on the website at http://www.pcasdr.org/autocross/bri.htm is out of date and should be revised to whatever new values you are using. It shows the MI index as 1.103, still, not 1.115.

Tom, here is a rough dump of all the BRI sets by date range. There are three of them in there now, the latest is ID number 3.

http://web2.pcasdr.org/pca/admin/admin_bri_listing.php

[ajackson]

Kary, you are saying that you don't think any MI car could be built to gain those extra two seconds?

The way I look at it, the BRI is an index assuming that a car in the class is built up as much as possible for the class.

[kary]

Kary, you are saying that you don't think any MI car could be built to gain those extra two seconds?

The way I look at it, the BRI is an index assuming that a car in the class is built up as much as possible for the class.

Yes, I have more points that can be taken, but I do not think there is another 2 to 3 seconds on that track with that car. Do you have another experienced opinion?

[ajackson]

Do you have another experienced opinion?

Nice little jab.

I was just saying that perhaps you don't have it in your car, but if a car can be built inside the class that can get the extra two seconds then the BRI is fine. I was just giving you something else to consider, not saying you are wrong or right.

The other point is that the BRI is a very generic tool. It is going to be off in lots of specific cases. The spread between cars is going to change depending on the track and conditions. One MI car can spend all the points on horsepower and do well on some tracks and another all on suspension and do well on totally different tracks.

Again, I am not saying that your suggestion is out of place. Just giving more points to consider.

[MikeD]

Kary, you made some improvements to your car at some point in the last 3 years. Was that between the '03 and '04 events? Or was in '04 and '05. I know it would not explain the BRI adjusted times. But it would help me understand why it's 2 seconds each year. I would expect you (and my) improvements to become incrementally smaller as our experience increases.

I went from MSS -> MS -> MP over the last 3 years so I am not a good data point, sorry.

FWIW, I am a bit confused by it also and am waiting to see the determination.

[Curt]

I don't want to get beat up here either, but I think Kary does some POC racing too. How far off the pace of the front runners in your class at POC are you?

The reason I ask is that Steve G has thrown Anthony DiLanzo's AM class times out at us in AM to show us how much faster an AM car is capable of going. It's just that when Anthony's fast as he11 PCA times at Willow are compared with his POC class in V3, he is 2-3 seconds slower than the frontrunners.

One of my very experienced POC racing good friends had just run his best ever time at Willow Springs at 1:33. Then he let Cort Wagner take his car for a spin. 4 laps later Cort brought the car in and had run two 1:28's in it. Cort said he probably could have run a low 1:27 if he didn't keep hitting traffic. The car is a 1970 RS clone and isn't even remotely similar to the modern race cars Cort is used to.

Since my buddy saw Cort do that in his car and has it all on in car video, he has not even considered doing a single mod to his car.

So Kary....... what would Cort Wagner or Craig Stanton or Patrick Long run in your car? Do you think even they could find that 2 seconds to make the BRI more favorable to MI cars?

[Carl Scragg]

The BRI was created from AX results and that it works at all for time trial results was a surprise to me. The Boxster S is arguably the best AX car Porsche makes and the 993 pays the penalty for being in the same class. I'd suggest that the best solution is to maintain two separate indices, one for AX and another for TT.

[Jad]

From what I can tell, if you win in the BRI, its a good, fair system, if you finish in the top 5 or 10, it is a fairly good system with some minor flaws, and if you finish worse, it is obviously a seriously flawed system good for nothing beyond the dolphin trophy

I think the middle group is correct, of course that is the group I am usually in

You are taking less than perfect classes, adding cars that are not perfect for the class, adding drivers that often have 1-2 seconds variation from lap to lap, add changing track conditions, track layouts, temperatures, tire wear and who knows what else, and expect a perfect BRI???? I personally am pretty amazed at how often it comes pretty close to matching how I would position people overall - except for me, which should always be higher

Also, the creators of the system where clearly biased toward the rear air cooled engine due to its vastly superior dry sump lubrication resulting in an indefinite trouble free life expectancy and the complete lack of passion of the newer Porsche owners and their smooth driving techniques!

[MikeD]

Also, the creators of the system where clearly biased toward the rear air cooled engine due to its vastly superior dry sump lubrication resulting in an indefinite trouble free life expectancy and the complete lack of passion of the newer Porsche owners and their smooth driving techniques!

[JHPGT3]

I hesitate adding my $.02 because I'm not as familiar with the BRI as most of you who have already commented. However, it seems clear, and all agree, that the BRI is flawed.
The BRI results make for interesting discussion and debate, but the only real bragging rights should go to Class winners, IMO.
If you want to talk about how seriously flawed the BRI system is, how could you possibly justify essentially the same index given to GT3s and AM Class cars?

[kary]

Ok, here goes....

Alan,
no jab intended. I am just looking for real world experience/examples to support an opinion one way or the other. I agree with you that I can take more points but as I said if I reduce weight and stay within the MI points, I do not think that will give me at least 2 secnds. And it does not explain some of the strange differences in BRI index numbers. More on that later.


Mike,
Yes, I have made improvements over the years but from last year to this year the only change was the roll cage and about 100 pounds lighter. I do not believe the weight reduction is solely the reason for the improved time at Pahrump, I believe I have learned more about this track which is quite technical. My belief is that I am learning along with others like Jack who also has been improving there but more so I went out with newbie's to the track and saw the mistakes in line that I made when I first went there. It just took three years for me to learn since we did not have anyone to teach us years ago. Now we do.

Curt,
you make some interesting points but here are few for you to think about.

1. Is this a professional BRI or a weekend warrior BRI? This was developed from auto-x data from weekend hacks such as ourselves. When did professional data enter into this equation? Furthermore, POC does not have a handicap system, they would laugh at such a prospect

2. I had a lesson from Cort Wagner three years ago, he drove my car at buttonwillow and turned laps that 1.5 seconds faster than me. That was three years ago and I beleive I am a better driver now since I have taken off 5 seconds from my lap times at buttonwillow. Those differences in time are also in line with the cars mods since then.

Carl,
Thanks for chiming in here and I want you to know I am not banging on the BRI, just trying to make it better if that is possible. Can we develop new numbers from the history we have from our time trail series?



Now for another fact.

If I were to take my car in MI and run against a GT3 with hoosiers on it which I believe would be in PP who do you think would win? Forget about drivers just look at the cars. They have the same BRI index 0f 1.1150. I believe that the GT3 would win quite easily even if they only did hoosiers and no other changes, don't you think that is a bit of a mismatch? After all, Evan and Chris were only just over a second off my time this past weekend and they were in PS not PP.

Thoughts ?

[ttweed]

The BRI was created from AX results and that it works at all for time trial results was a surprise to me.

I am with Carl on this, and a little bit with Alan as well. It has been discussed before on the forum, and I'm not convinced that the BRI works very well for time trials at all, but we still apply it for fun, and for lack of anything else. I wouldn't put much stock in the results, though. It is an autox index, and wasn't developed for big track events. It has enough potential flaws without applying it to something for which it was never intended.

Thanks very much for posting the link to the indexes over time, though, Kary. That was very helpful and interesting to see the changes over the years. I hadn't ever seen it all in one place before. I imported it into Excel and looked at all three iterations side by side. We definitely should update the BRI page on the website to reflect the latest data, though. I have sent an email to the "webmaster@pcasdr.org" address with the correct figures to replace the table at http://www.pcasdr.org/autocross/bri.htm, if that will help.

To address your particular concerns about the MI index, Kary, I believe you are a victim of the class changes that took place last year. With the elimination of the HM class in favor of KM, as well as the addition of O and P classes to cover the newer cars (GT2, GT3 and 997 Carrera S), the indexes for the MI class and everything above it had to be adjusted.

Interestingly enough, the second iteration of the BRI had a lower index for MI than the first one-- 1.097 as opposed to the original 1.103. The current index was raised to 1.115, to equal the new PP class index, while AM was raised to 1.095 from 1.074 (which everyone agreed was too low) and the new KM was placed at 1.12, while the AR class remained the highest at 1.13. I think that those changes look pretty logical to me, but will still need some tweaking as we see the newer cars developed fully. The BRI can never remain static, as new models and classes are added.

As Alan said, the BRI needs to account for the speed potential of the fastest, most fully developed cars in the class (keeping in mind that this is for autox courses.) The MI class includes the 964 3.3 Turbo cars as well as the 987S, both of which have greater speed potential than your 993, when developed fully within the 40 points available in the I classes. Look at what James Gunn-Wilkinson did with an '87 Turbo, much less a 964 variant, or with a PP class GT2. Do you think you could get those two seconds if you had 600 HP? It could easily be done in MI class with a widebody 964 Turbo with some engine and suspension tweaks, I think. It wouldn't be cheap, but it could be done.

Think of a lightened 987S with a 3.8 GT3RS engine in it and flared fenders to run wide slicks. That could be done within the MI class rules, and be an incredible autox machine. Even with as much development as you have done to your car, I don't think it is anywhere near what could be accomplished within your class by someone with the will and the $$$ to do it.

That's my semi-experienced $.02.

TT

[Curt]

Kary, what is your POC class?