Looking at the time trial BRI

[ttweed]

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?

Not sure I understand what you mean by this. The AM index and PS index are close, but when developed similarly, the GT3 would be in KM, with an index of 1.12.

An AM car is very much the equal of a PS class GT3 on an autox course. Just look at the results from this year of Steve and Denise compared to Clark Smith and Mark Kinninger in AM. Where's the beef? Do you think the GT3 index should be lower? AM higher? Each class has been faster than the other this year at times. It looks like parity to me.

TT

[kary]

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

You could be right about the $$$ for my car. I am not usre exactly what I would spend it on though which was the driver for my post here.

I am still wondering though if it is fair to say that a PP class car has the same index as a MI car as I know the PP car would easily beat the MI 993 based car, unless there is something I have missed for a modification on my car that would make the difference up. I currently have 13 points which is primarily in suspension and weight. What would I add to the car besides a turbo motor?

You are also correct as Alan also said, there are too many factors, but it would be nice to at least develop the BRI based upon time trial data versus auto-x data.

[JHPGT3]

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?

Not sure I understand what you mean by this. The AM index and PS index are close, but when developed similarly, the GT3 would be in KM, with an index of 1.12.

An AM car is very much the equal of a PS class GT3 on an autox course. Just look at the results from this year of Steve and Denise compared to Clark Smith and Mark Kinninger in AM. Where's the beef? Do you think the GT3 index should be lower? AM higher? Each class has been faster than the other this year at times. It looks like parity to me.

TT

Tom, my frame of reference is Time Trials and not AX. I can't/don't disagree with the index for AX. The facts pretty much speak for themselves. However, I've seen Jack Miller pretty effortlessly do a 1:30 in my GT3 at Willow with me in the car (and the a/c "on" as I recall). I have no doubt that in a Time Trial, by himself, he would do 1:28 in the GT3. I haven't seen any AM cars that could do this. If you look back at the Willow TTs, you see excellent drivers like Jim Copp doing 1:37 in his AM car. The best ever, I believe, was Anthony D doing a 1:30.
At Spring Mt. there were 4 AM cars incl. excellent drivers, Roland Schmidt and Dan Andrews who couldn't keep up with Chris B. and Evan B. in their GT3s. For TT purposes, IMO, the GT3 should get a higher value.

[kary]

Kary, what is your POC class?

I am in V2 because of the leading edge wing, otherwise I could get into LP prior to taking my interior out. Out of the events the past two yearsin POC I place 1st twice and 2nd twice in events at the Speedway, willow, and buttonwillow.

[ttweed]

For TT purposes, IMO, the GT3 should get a higher value.

I absolutely agree with that! At higher speed venues, the GT3 has an advantage. More so at WSIR and Ca. Speedway than at Pahrump, but an advantage nonetheless. I ran a 1:50 in my AM car the first time I went to Pahrump in 2003, and I was still learning the track. Evan and Chris only did a second or two better this time. That's not a huge spread. I think I could have run a 1:48 this year if I had gone and had some more practice on the course, a rear wing and a fresh set of slicks. Dan thought he might have done so, too. I don't think the classes are THAT far apart, especially on a short, technical course. It comes down to the level of car prep and the driver in a lot of cases. The best V3 cars in POC that would run in our AM class are turning 1:27-8s at WSIR. I have no doubt that Cort Wagner could get in my AM car and turn a 1:28 there in it, just like Curt's friend, but the best I have ever done in it is a 1:34.

As I suggested the last time this came up after Fontana, someone should develop a TT index separate from the autox BRI. We have a starting point (the current BRI) and some data (TT results in Kary's database), all it would take is a little tweaking to even things up and then constant maintenance and updating. I don't think Carl's up to it and neither am I, but someone should step up and try it. It's not rocket science, and it's all in fun, anyway. Nobody's career is hanging by a thread because they lost on the index. This is amateur racing, after all, for $2 trophies and $.50 ribbons.

I liked the explanation for the carnage in the Grand AM series that some driver gave on TV the other week. It went something like: "When you have a bunch of evenly matched cars and a whole lot of drivers with guns being held to their head to win, this kind of stuff is bound to happen." That's pro racing, and we don't want to go there...

TT

[JHPGT3]

For TT purposes, IMO, the GT3 should get a higher value.

I absolutely agree with that! At higher speed venues, the GT3 has an advantage. More so at WSIR and Ca. Speedway than at Pahrump, but an advantage nonetheless. I ran a 1:50 in my AM car the first time I went to Pahrump in 2003, and I was still learning the track. Evan and Chris only did a second or two better this time. That's not a huge spread. I think I could have run a 1:48 this year if I had gone and had some more practice on the course, a rear wing and a fresh set of slicks. Dan thought he might have done so, too. I don't think the classes are THAT far apart, especially on a short, technical course. It comes down to the level of car prep and the driver in a lot of cases. The best V3 cars in POC that would run in our AM class are turning 1:27-8s at WSIR. I have no doubt that Cort Wagner could get in my AM car and turn a 1:28 there in it, just like Curt's friend, but the best I have ever done in it is a 1:34.

As I suggested the last time this came up after Fontana, someone should develop a TT index separate from the autox BRI. We have a starting point (the current BRI) and some data (TT results in Kary's database), all it would take is a little tweaking to even things up and then constant maintenance and updating. I don't think Carl's up to it and neither am I, but someone should step up and try it. It's not rocket science, and it's all in fun, anyway. Nobody's career is hanging by a thread because they lost on the index. This is amateur racing, after all, for $2 trophies and $.50 ribbons.

I liked the explanation for the carnage in the Grand AM series that some driver gave on TV the other week. It went something like: "When you have a bunch of evenly matched cars and a whole lot of drivers with guns being held to their head to win, this kind of stuff is bound to happen." That's pro racing, and we don't want to go there...

TT

I think we have an agreement here.

[ttweed]

I am still wondering though if it is fair to say that a PP class car has the same index as a MI car as I know the PP car would easily beat the MI 993 based car, unless there is something I have missed for a modification on my car that would make the difference up. I currently have 13 points which is primarily in suspension and weight. What would I add to the car besides a turbo motor?

Kary- Am I missing something here?
If all you have is 13 points in improvements, you are 7 points shy of being at the top of MP-- not even close to being an MI car. I suspect the only reason you are running up in MI is so that you can use slicks, which are only allowed in Improved class and above, then? If that is the case, you have nothing to complain about. A seriously prepared MI car would have spent another 27 points on improvements, which could, in your case, include a complete 450HP+ Twin Turbo motor. You would still be in MI that way, as it would only add 24 pts under the current rules.

If you were serious about scoring well in the BRI, all you would have to do is optimize for the class. If you don't want to spend the $$$ to go up to 40 points, then all you have to do is lose the slicks and go to DOT Hoosiers or V710 Kumhos and run in MP. You could still take another 250 lbs. out of the car and be legal in MP by your accounting above. Why would you choose to run in MI with so few points? Just to use the slicks? You are far from being optimized for the class that way and can't really expect to be competitive in the BRI.

As far as comparing MI and PP indexes, look at every other Improved class in the BRI--they are ALL higher than the P class which is three letter classifications above (which is the relationship of MI to PP.) You are actually getting a break there, being the same:
MI = 1.115 while PP = 1.115
KI = 1.086 while MP = 1.08
HI = 1.066 while KP = 1.061
FI = 1.059 while IP =1.042
AI = 1.042 while GP = 1.04

It looks like IP is getting a big break and PP is getting hammered by this analysis, but the fact is the newer cars probably have more speed potential right out of the box. PP might even need to be higher.

TT

[kary]

I am still wondering though if it is fair to say that a PP class car has the same index as a MI car as I know the PP car would easily beat the MI 993 based car, unless there is something I have missed for a modification on my car that would make the difference up. I currently have 13 points which is primarily in suspension and weight. What would I add to the car besides a turbo motor?

Kary- Am I missing something here?
If all you have is 13 points in improvements, you are 7 points shy of being at the top of MP-- not even close to being an MI car. I suspect the only reason you are running up in MI is so that you can use slicks, which are only allowed in Improved class and above, then? If that is the case, you have nothing to complain about. A seriously prepared MI car would have spent another 27 points on improvements, which could, in your case, include a complete 450HP+ Twin Turbo motor. You would still be in MI that way, as it would only add 24 pts under the current rules.

If you were serious about scoring well in the BRI, all you would have to do is optimize for the class. If you don't want to spend the $$$ to go up to 40 points, then all you have to do is lose the slicks and go to DOT Hoosiers or V710 Kumhos and run in MP. You could still take another 250 lbs. out of the car and be legal in MP by your accounting above. Why would you choose to run in MI with so few points? Just to use the slicks? You are far from being optimized for the class that way and can't really expect to be competitive in the BRI.

As far as comparing MI and PP indexes, look at every other Improved class in the BRI--they are ALL higher than the P class which is three letter classifications above (which is the relationship of MI to PP.) You are actually getting a break there, being the same:
MI = 1.115 while PP = 1.115
KI = 1.086 while MP = 1.08
HI = 1.066 while KP = 1.061
FI = 1.059 while IP =1.042
AI = 1.042 while GP = 1.04

It looks like IP is getting a big break and PP is getting hammered by this analysis, but the fact is the newer cars probably have more speed potential right out of the box. PP might even need to be higher.

TT

Tom, thanks for the analysis on my questions. You make some very good points something that is difficult to find these days. I find the most interesting thing that as I have been so close to this car and this sport for so long I have not really been looking that closely to the rules, just what I like to do to the car and things that are fun. Slicks fall in that category as I have the suspension, alignment, and tires optimized. This alone has made my car competitive overall in real time even though the rest of the car still has a street motor, tranny, and air condition.

If I did add a turbo, stock 400 HP engine and upgraded the tranny and drive shafts, that car would easily add another two seconds at Pahrump. I could also flare out the fenders to RSR specs, wider tires, and would be hard to beat overall for both the overall time and BRI. That of course would cost some dollars but probably not as much as I would image. But then I still need to send the kids to college too

Edit/Addition: I forgot to mention this, what do you think 250 lb reduction would be worth in time on a track like Spring Mountain? The reason I ask is this might get another second or so, don't you think?

Also I actually have 21 points not 13. So it is not as bad as it looks


Thanks again for the great feedback on my question. I like your factual statements!

[ttweed]

Slicks fall in that category as I have the suspension, alignment, and tires optimized. This alone has made my car competitive overall in real time even though the rest of the car still has a street motor, tranny, and air condition.

That's what I thought, Kary. You have done the easier/semi-cheap mods that will lower your lap times and make your car competitive for TTOD. Unfortunately, those mods do NOT optimize you for the BRI competition, as they bump you up a class by including racing slicks.

If I did add a turbo, stock 400 HP engine and upgraded the tranny and drive shafts, that car would easily add another two seconds at Pahrump. I could also flare out the fenders to RSR specs, wider tires, and would be hard to beat overall for both the overall time and BRI.

That is probably exactly what you would need to do to compete for both TTOD and indexed time--optimize the car for the MI class. In our autox events, I can only think of two people who have done this- JGW with his Turbo in NS class last year, and Erik Kinninger at the last event with his Dad's AM car (which I must say may have been due to some key people missing the event, like Steve G. and myself. ) It is a very difficult thing to do, because the stock and Prepared classes have a better shot at the indexed time, I think, even though they may not be able to win TTOD.

That of course would cost some dollars but probably not as much as I would image. But then I still need to send the kids to college too

Oh yes, it would cost at LEAST one college education (at a public school anyway. ) The 993 TT engines that I have seen for sale are going for over $20K, plus installation, a chip, and the drivetrain improvements! The flares, bodywork and repaint could cost you $10K if you did it to the same standard as your factory finish is, and then the new wider wheels and tires would add another $3K minimum, if you got nice, light ones, and then of course you would need a spare set.

Edit/Addition: I forgot to mention this, what do you think 250 lb reduction would be worth in time on a track like Spring Mountain? The reason I ask is this might get another second or so, don't you think?

Yes, definitely another second or two at Pahrump w/ 250 lbs. less, I think. You would improve everything-- braking, cornering and acceleration with less weight. That is the only reason the AM cars can even come close to the GT3s there. At the bigger tracks, the GT3s heavier weight does not hurt it as much, and the better power, aero and suspension really helps.

Also I actually have 21 points not 13. So it is not as bad as it looks

Well then, if you took off the slicks and used V710s, you would lose two points and be almost perfect for MP class at 19. Your index would drop to 1.08 and you would do better in the BRI, even though you would lose a second or two from the tire change. Which do you want, TTOD or BRI? I think you made your choice already, and it's the right one for you.

TT

[Curt]

Tom, thanks for the analysis on my questions. You make some very good points something that is difficult to find these days.

I like your factual statements!

Hey Kary, you get what you pay for.

You really have a way with words. Very subtle.

You should run for office........... in Iran.

[kary]

Tom, thanks for the analysis on my questions. You make some very good points something that is difficult to find these days.

I like your factual statements!

Hey Kary, you get what you pay for.

You really have a way with words. Very subtle.

You should run for office........... in Iran.

Sorry Curt, let's talk about Cort Wagner and the BRI . Or maybe POC and their handicap system . Or maybe you could help me with a campaign plan for Iran? No that would not work because the campaign plan would be off topic and I would never win

Seriously though what is wrong with complimenting Tom on his thoughtful posts that answer the questions posed?

[Otto]

Tom wrote:

As I suggested the last time this came up after Fontana, someone should develop a TT index separate from the autox BRI. We have a starting point (the current BRI) and some data (TT results in Kary's database), all it would take is a little tweaking to even things up and then constant maintenance and updating.

Tom:

Since we are on the topic it might be interesting to elicit a discussion of what the members believe should be the criteria for this revised TT BRI. Most underlying principles should coincide with the AX BRI but there are differences in the way cars compare with each other when evaluating them from the TT standpoint vs the AX perspective. The question would be what are those differences which can then be used as basic criteria to "tweak" the existing BRI numbers.

For one, the basic principles should not change which are that the BRI factors apply to fully developed cars within a class; also higher classes should have higher factors regardless of whether there is a car or a driver in that class at the time that can perform to the highest class standards. What should matter most is the car and its potential which for any discussion would be assumed to be driven by a competent driver. The key when it comes to drivers is to compare apples and apples i.e. if your are going to bring Cort Wagner into the picture, assume he would be the driver in all classes compared so that the driver factor would be neutralized.

What makes TTs different than AXs? I throw into the discussion the higher importance of brakes and HP in TTs. The impact would be that cars with better brakes and high HP could outpace a lower class by a larger time differential than it would be possible in an AX setting, thus requiring a larger differential BRI factor than the current one.

We could develop a BRI Index for each track as track layouts favor certain cars but that would be too complicated. Further, you do not have a different BRI for each AX track that you design so same general principle should apply.

Does the above make any sense? Tom, you Carl and Chris have given this Index a lot of thought. Others? What factors / principles should we consider when revising the BRI for TT purposes? How should we proceed about doing it?

[ttweed]

Since we are on the topic it might be interesting to elicit a discussion of what the members believe should be the criteria for this revised TT BRI.

I think that would be an interesting discussion, Otto, and I feel you are on the right track with your initial comments. In general, I believe there would have to be an even greater spread between the stock cars and the race prepped cars for big track events vs. autox, because the greater distances and higher speeds allow more time to be gained by those cars that have increased their speed potential by modifications to engine, brakes, suspension, and especially aero aids. In general, the later stock cars have some of these advantages built in at the factory, now, so the spread between early and late stock cars would probably have to be adjusted wider as well. In my experience, the attributes which make for a quick autox car include a shorter wheelbase and narrow width, with a tendency towards oversteer in the handling balance, in order to manage the slow, tight turns, narrow gates, quick transitions and slaloms typical in AX. These same characteristics are a detriment to big track performance, where high speed stability is paramount. You really cannot have a car which is set up to perform well for both, there are too many compromises involved. That is indicative of why you cannot use the same index for both types of events, I think.

The magnitude of the changes to the index would have to be determined by some kind of analysis of "real world" results, trying to eliminate the "driver" factor, as you say. While there are certainly differences between short, technical tracks such as SOW and Pahrump vs. WSIR and Ca. Speedway, I think you are correct in assuming it would be too difficult to adjust for that. Some "happy medium" stance would have to be taken to average those differences and come up with a single index. Just as the current BRI is a "dull blade" for equalizing AX performance potential, you are never going to have a perfect TT index either. We just don't have a large enough sampling of results to average well, especially when a large percentage of the cars entering our TTs do not post a final time, as seems to be the case in many events, due to attrition or whatever. You would just have to take a stab at it with the data available and then adjust it over time when inequities are revealed by additional results.

I have not competed in the TT series this year for personal reasons, so I do not have a stake in the development of a TT index, but someone who has an interest should go ahead and try it. A discussion like this can point out the direction to be taken, and since it is an informal measure of performance which will never replace raw times, no one should get very seriously concerned about flaws in whatever system that is developed, just as we (hopefully) do with the current AX BRI.

It's all for fun, remember! The BRI is just there to give the underdog a chance to shine, and to enhance the trash-talking on the forum and at the bar after the event.

TT

[Otto]

Tom:

Your thorough reply is right on the money in my opinion and we should incorporate your suggestions in any BRI revision exercise. It would be now a question of quantifying those potential performance differentials between an autocross setting and a TT for the different car classes.

We would now like to hear the opinion and suggestions of others so that we can advance the discussion towards an acceptable compromise.

[Dan Chambers]

In general, I believe there would have to be an even greater spread between the stock cars and the race prepped cars for big track events vs. autox, because the greater distances and higher speeds allow more time to be gained by those cars that have increased their speed potential by modifications to engine, brakes, suspension, and especially aero aids.

It's all for fun, remember! The BRI is just there to give the underdog a chance to shine, and to enhance the trash-talking on the forum and at the bar after the event.

TT

My opinion: (Yea, yea, for what it's worth)

Tom, I think you're right on many points, the most poignant being the disparity between A-X and T-T, and the impact of mod's on cars. (I also included the quote about it being all for fun, since that's what the intent was for developing the BRI in the first place; IMHO.)

One of the things that has never really been addressed or discussed, at least in this thread, is the disparity within the modified classes themselves (*/P and above) in regard to points, mod's, and total performance influence of modifications. What I'm talking about is the amount of mod's any individual car has, assuming the range of mod's, from barely in the bottom of a class, to max'ed-out points car in a class. Take, for instance, the difference between a car in */P class with 7, or 9, or 10 points, vs. a car with 20 points. The car with a lower number of mod's/points will most likely not catch the car in the same class with maximum points, yet the BRI makes no adjusted equilization for these two cars. So, a car/driver that has minimum mod's will wind up much lower than a car with maximum mod's within the same BRI index.

Let's look at the points spread from a class perspective.

SS - S = 4 point difference at the top of S class from bottom of S
S - P = 13 point difference at the top of P from the bottom of P (ouch)
P - I = 19 point difference from Top of P to Top of I (Yeeee-ooouuuch!)
I - M = 13 point difference from top of I to top of M (ouch, again)
M - R = infinity.... your second, third, forth, mortgage (Real estate brokers/financiers should target that market)

So, the guys in */I class really take it on the chin in the BRI with a possible mod's/point spread of 19, or so points. With the cash outlay of up to 19 points to remain competitive with the top dogs in I class, someone could buy a fleet of 944's and start a racing company (Tim C., are ya listening?).

All this before I even get started with the whole concept of max speed/ potential at big tracks vs. A-X tracks. Tom's comments about a car being somewhat specifically built for a particular event type rings very true here. A-X cars are different to TT cars, although some mod's can facilitate both track types.

If you're going to take the BRI seriously, and build your car around it, you may want to consider buying the Brooklyn Bridge first. Afterall, the BRI is intended to give driver's something to banter about. It's all about the fun, and should be taken lightly.

Kary, I think your concerns about the BRI and it's application to TT's are significant, but what the heck, it's just the BRI. And, it wasn't really intended for TT's anyway.

Okay, back to work......