The Great Mystery of BRI

[SuperCobraPilot]

Fellow Gearheads-

Being relatively new to all of this, I am thoroughly confused by BRI. I understand that it is supposed to be a handicapping system, that as the award is briefed, is supposed to remove the car from the equation. Makes sense (in theory). My early AXs showed the Reinhardts, Grosekempers, Kinningers, and Brennans of the group duking it out... Kathy Smalley said something that really has nagged at me since the event. "See.. you don't have to have a GT3 to win this!" Which got me thinking... you CAN'T win BRI with a GT3... Mike Avitt and Tom Tweed are EXTREMELY Fast, as is James Gunn-Wilkinson (whatever he shows up in)... No love for them in BRI. Not to pick on Kathy because she is an awesome driver but she said it so we'll use her car as an example. Her boxster is trailered to events, pit crewed (kind of), and is modified from CC02 in stock form to CC09. Without going through her points sheet, she is running 255s all around; probably race tires (Not sure what Tom and Mike's GT3s have but that's 20mm more up front than my tires). The prodigious amount of negative camber is pretty obvious to anyone who walks around the car. Tom and Mike are very fast but they'll never have a shot at BRI in their cars... Realizing there is no sympathy for GT3 owners, LOL, but I thought it was supposed to be about the driver?

It appears to me that grip incurs far less penalty for BRI than Horsepower. Amazing considering that in AX, it is difficult to get much above 75MPH. BRI tells me that it's not about the grip, it's about the horsepower (when it comes to handicapping), but look at the volumes of opinions on the RE-71R and the extra grip they provide... and it seems to be all about the grip...see why I am confused? BTW, I read the PDF on BRI and got a headache!!! LOL

Any help is greatly appreciated; See you guys at PDS.

Owen

[Jad]

The BRI is designed so any car, actually any driver, can win the BRI. That said, one of the base assumptions is that the car is optimized for the class. You will find the Boxsters and older cars are built to be optimized in the class versus the GT3's which tend to basically be run as delivered, which is not optimum. Also, it is a general classification, so as the track gets tighter, grip is more important, longer straights benefit HP. The BRI doesn't change per track, so it is not perfect, but a pretty good estimate of how you compare to other drivers. If you are always at the bottom of the BRI, look to your driving, and as you move of the ladder, you can be sure it is your driving, not changes to the car, tires etc that are resulting in the improvement.

That said, I have found it is MUCH easier to drive a slow car well, than to drive a fast car well. Lewis Hamilton may be able to get his F1 car around the track quite fast and would need to to win the BRI (if it existed). I would be lucky to even get it around the track. In a stock 944, I would be much closer to him as it is easier to drive the 944 near its capability than it is to drive an F1 car near its capability.

Make sense?

Also, Mike and Tom are both very good drivers, but I doubt either of them would say they were anywhere near as fast as Erik Kinnenger, and it is not because the GT3's are rated wrong in the BRI.

[SuperCobraPilot]

I see what you are saying, and I am not saying that GT3s are rated wrong..(I absolutely agree with you about Erik) as I read the pdf on BRI, there is a class-based factor that is applied to the TTOD standing. What I am getting at is that on points, you could have 2 CC09 cars, continuing to use the example of Kathy's car, one whose points are derived from suspension and tires, and one whose points are more horsepower based. I'll use Tom Sharp's C4S, which runs SS05 but would be CC09 based on points. Kathy's car has 616 points and Tom's car has 617. If "points-is-points", then Kathy should be able to turn almost identical times in Tom's car and vice versa. Isn't that the whole idea behind a points-based classification system? Both cars receive the BRI .962 correction factor for class... Bottom line is It would never happen. A full AX prepped and optimized boxster on race tires vs a stock AWD 911? No way Kathy is as fast in the C4S...but they have almost identical performance points and receive the same correction for BRI. I'm not trying to take away from Kathy's driving ability. My sole point is that I don't believe the car has been fully factored out of the equation... I'll close with another example: Last Event, Mike Avitt was #2 TTOD/#44 BRI in an SS09 2015 GT3. I was #19 TTOD / #29 BRI in my SS07 2004 GT3. In July he was #5 TTOD/#54 BRI and I was #12 TTOD/#23 BRI. No way I am a better driver than he is. I have only been at this half of last year and all of this year. By the way, I got new RE-71Rs before the July event and moved up around 10 BRI spots from the June event. I just think that for AX, cars receive too much "credit" for horsepower and not enough for grip...as you said, no one modifying a car for autocross success is going to throw money away on HP...I race Chumpcar/Lucky Dog in a Miata and just bought flyin'miata matched and tuned bilstein coil-overs for $800... we've spent about $80 on HP...wonder why lol!!

[jbrennen]

Note that BRI is just a secondary effect of the classing scheme. Since your class determines your BRI index, this is mostly about classing rules.

The classing rules are the same for AX and TT events. You don't need to be a math wizard to figure out that the grip/horsepower equation for AX is somewhere around 80% grip and 20% horsepower. For TT events, that equation is obviously more about horsepower and less about grip -- probably closer to 50/50. So the classing scheme which is shared between the two has to strike a bit of a balance.

High horsepower cars get a bit of a classing penalty for AX. Low horsepower cars get a bit of a classing penalty for TT. Because BRI is determined by class, high horsepower cars get a BRI penalty for AX, and low horsepower cars get a BRI penalty for TT events.


Here's how to use BRI... Look at your own results in BRI. Are you happy with it? If not, decide which of these you want to do to move up:

1) Drive better
2) Optimize the car for its class
3) Optimize the car for a different class
4) Change cars
5) Go run TT events


Also note that the BRI can't possibly take the car out of the equation if it doesn't give me a BRI boost for running RE-71Rs at their sixth AX event compared to running them at their first event.

There are some variables that you just can't account for. Doesn't matter if it's the RE-71R, the Hoosier R7, or the Goodyear tires that came on my car -- grip varies with tire age. (Now, when I ran Toyo Proxes RA-1 tires years ago, they seemed to get faster the more they wore away; are you going to penalize the RA-1 tire if it's seen more than 5 events??)

[LUCKY DAVE]

The BRI isn't perfect, or even close. That's just the way it is, folks. Get over it.
A few years ago I ran my car in KP. The BRI was "nice" to KP and I won the BRI repeatedly. Later I modded up to CC11, now I'm lucky to see the top ten. Same driver.
Watching Steve win the BRI over and over again with 100-ish horsepower illustrates how a low powered car optimized for the BRI (and very well driven) can win it.
Erik is a special case, he could probably win it in a Jeep.

[SuperCobraPilot]

That's BRILLIANT Dave! I can just see Erik bouncing around in a Jeep... too funny... but that would put him in X class, ha ha ha!!!!

Jack, I am much simpler than trying to use BRI to get better, LOL. I use His Grace (Keith). If I beat him, I drove well. If I keep close, I drove well. If he crushes me, I didn't drive very well. Not smart enough to apply any more complication to it. I'll be happy to keep picking up potential trophy additions to give the winners while I'm chalking cones...

[marcus981]

Jack's explanation is spot-on for your "points-is-points" hypothesis.

If you look at time-trial results, you'll see some GT3s closer to the top in BRI. For example, Rick Levenson has had a couple of top-10 BRIs in the past year in his non-optimized 991 GT3 (stock, except for safety gear and Hoosiers).

So, people that want to optimize a car for AX vs. TT BRI can make use of the fact that we have a single points system. Anyone optimizing for AX wouldn't want to take any aero points, for example. People that show up in unmodified or unoptimized cars are most likely going to be hurt in the BRI, as Jad pointed out.

[Erik K]

Owen, Jad, Jack, Dave, And Marcus are all spot on. Your GT3 and other GT3's are heavily "pointed" from HP figures. These are great handling cars, and would definitely be more competitive in the BRI at a big track (AAA speedway, where there HP and also there braking capabilities) will shine.

A light / well handling car won't need much HP to get around an autocross track quick, (older 911's, 914's and boxsters etc..)
I believe that is why you are seeing a lot of the top BRI positions at an autocross going to cars of this nature.

It's a fun system to base your personal achievements on from event to event, but it's not absolutely perfect...

Erik Kinninger
1981 911 SC

[mrondeau]

The BRI in a nutshell. All classes are assigned a numerical multiplier. This factor is based on any car in that class being optimized for it's class. As noted by others, the older a car is, the more likely it's been optimized for it's class. Keep in mind that optimized includes new tires and a dialed in suspension. Most GT3's, 997's and 987's have not been modified or optimized.

The BRI does not take into account track configuration at AX or TT. It's easier for a HP car to do well at Fontana than at Chuckwalla or Buttonwillow. We've also had HP AX tracks in the past. I've been on AX tracks where I've gone over 100 mph. Certain AX and TT track favor different types of cars. That will usually only allow for a slightly different group of names, but most of the top BRI finishers will still be the same.

A really good driver should always find him (or her) self near the top of the BRI. There's a reason you see the same names in the top 10 at almost every event. You'll also notice that the top of the TT BRI has a lot of the same names up there as well. The biggest difference is that some of those drivers don't do as much AX.

After about a year or two of TT events, I was certain that the BRI was off. I thought that since I was winning my class and setting new class records, I should be doing much better in the BRI. I was told that my car was not optimized and I just wasn't quite as good as I thought I was. Turned out, Otto was right. As I got faster and better, I moved up in the BRI.

The moral of the story is - The BRI is just for fun. Use it to gauge your driving against others, but don't expect it to be fair or perfect. If you do this long enough, and continue to improve, you will move up in the rankings. Remember, winning BRI pays the same as the driver who finishes last.

[Jad]

I would be very happy to race Steve G for top in the BRI with my 996 and him in his 914, AT A BIG TRACK like Fontana or Willow. I will not take that race at an AX. The term 'optimized' does not have one solution. A car 'optimized' for its class at AX, would not be 'optimized' for its class at TT.

A couple of concerns about your posts though, you state as basic fact that a prepared old car is better than a newer stock car (same BRI), this is not always as true as you may think. Also, Kathy may be able to drive her car very well, but not be good at all in a different car. She should not get the same BRI results when she switches cars. Her skills in one are not as good as her skills in another.

Summary, the BRI is a 'good' measure. If you are in the top ten, you are driving well, bottom ten, not so much, don't blame the car. But don't think the 16th driver clearly beat the 17th driver, it isn't that accurate and 'optimizing' the car is a moving target for each track and only one car model can actually be the optimized car for each class, but the others can be made pretty close.

[ttweed]

My sole point is that I don't believe the car has been fully factored out of the equation... I'll close with another example: Last Event, Mike Avitt was #2 TTOD/#44 BRI in an SS09 2015 GT3. I was #19 TTOD / #29 BRI in my SS07 2004 GT3. In July he was #5 TTOD/#54 BRI and I was #12 TTOD/#23 BRI. No way I am a better driver than he is. I have only been at this half of last year and all of this year.

Owen,
This example you chose of comparing Mike's result in the BRI to yours is not representative due to an anomaly in the classing system that is not widely known or understood. Mike is running in SS09 class, which is the highest-speed stock class we have (there is an SS10 class, but if you look at it, that is for the Cayenne, Macan, and Panamera, which are all slower). Take a look at the cars classified in SS09--it is a "catch-all" class for all the fastest Porsche supercars, and even the hypercars. It includes the 918, Carrera GT, GT2RS, and all the fastest Turbos and GT3RS cars. As others have said, the BRI is based on the most optimized car for the class. The index for the SS09 class has to allow for someone showing up and running in a 918 (highly unlikely, but possible), so it is set at 1.031, which is higher than every single class in our system except for CC16, which allows unlimited points!

In reality, Mike's GT3 is also a CC14 car in its current configuration. The index for CC14 is 1.014, which is considerably lower than the 1.031 index for SS09. If he really cared a hoot about his BRI result he would run in CC14, but he doesn't--he's running for TTOD and to beat the other SS09 cars. In the two events you cite in your example, you need to apply the CC14 index to his time to see where he really would have ended up, then compare your result to his. In the last event on 8/28, he would have had an indexed time of 1:28.19, which would have placed him 21st, not 44th. In July, he would have run a 1:29.57 indexed time, putting him in 27th place, not 54th.

Looking at it from this perspective, it appears that he had a better day in Aug. and you had a better day in July. Both the TTOD and BRI results seem to reflect the same thing. If you try to compare your BRI time to anyone in SS09, this anomaly pretty much renders that comparison useless.
HTH,
TT

[ttweed]

I would be very happy to race Steve G for top in the BRI with my 996 and him in his 914, AT A BIG TRACK like Fontana or Willow. I will not take that race at an AX.

This points out that to be fair, there really should be TWO indexes, one for AX and one for TT, just as there should be two classification systems with different points for particular cars and mods in each of those venues. No one really wants to deal with that kind of complexity for our level of amateur competition though, and we don't have the kind of data available to devise it accurately, so we settle for a duller blade of approximation, and should have expectations for the results that match the sharpness of our tools. The whole point is to have some fun and try your best to improve.

I have found it is MUCH easier to drive a slow car well, than to drive a fast car well.

SO true. I used to win the BRI all the time back in the days of my '67 911S w/160 HP. It was much easier to drive at its limits almost everywhere on a course. The limits of the 991 GT3 are so much higher they are difficult to approach consistently and constantly throughout a run. Of course, I never won TTOD in that car, but I got more of its performance out of it far easier, and on indexed time, it was a winner. In the GT3, I consider it a good day if I beat the Miatas on raw time at an AX.

Mike and Tom are both very good drivers, but I doubt either of them would say they were anywhere near as fast as Erik Kinninger...

Yes, if I dwelled too long on how fast Erik would be in my GT3, I would just quit driving....

TT

[Jad]

Tom,

The problem with two indexes, one for AX and one for TT, is that it is not enough. Fontana and Willow need different indexes than SOW or Chuckwalla. You can't win. The BRI just gives you a good idea how you did.

[mrondeau]

Tom,

The problem with two indexes, one for AX and one for TT, is that it is not enough. Fontana and Willow need different indexes than SOW or Chuckwalla. You can't win. The BRI just gives you a good idea how you did.

The only TT track that really seems to throw off the BRI is Fontana. Half the track is full throttle (or close to it) and HP makes all the difference there. The difference in AX tracks can be more severe than TT tracks and the track layouts can be harder for some drivers to learn which will obviously affect how well they finish. It's easier to dial in a track that doesn't change and that you get to perfect your line during session after session.

I think the BRI works pretty well at AX and TT as it is. I probably wouldn't change it, but if someone wanted to give me less points at an AX for aero that I don't need and the lack of ABS and electronic aids, I'll take it.

[Cajundaddy]

Fun discussion!

Remember that, even though Mike Avitt is not topping the BRI now in his bone stock 991 GT3, he has been TTOD and top 5 BRI many times in past AX events in his older, well-developed 2004 GT3. Getting the car just right for your class and being "at-one" with the car both play a role in moving up the BRI ranks.

In my own experience, I had a pretty well developed BSX Boxster for many years and would see top 10 BRI a few times a year if I drove well. My current 2009 Cayman is still in development and is not yet optimized for her class. She currently sits a full 200# over minimum weight for yr and model so I pay a "heavy penalty" for being overweight but, I sorta like the full leather interior, nav, and 18 way seats. In spite of this I still managed a top 10 BRI at WSIR in May with my plush-o-matic so it can be done if you got the juice and post a quick lap.

If I get more serious next year and put her on a diet, we might see a top 10 BRI at events more often. Until then, I am still having a blast just driving it like I stole it.