THSCC Forums

I've been looking at the pax scale and I would like to know how it works, more of how it is figured into your raw time. also how come HS has dropped since last year and ss went up both only by .001 and how come it went from .794 a few years ago to .779 this year? who designates the changes?

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beware of EV powered Ford EXP's they are quiet and come for you when you least expect it... hide behind an aluminum light pole...... ya that will help

Your raw time is multiplied by your class's PAX factor to arrive at your PAXed time.
A guy by the name of Rick Ruth out of Chicago is the keeper of the PAX.
He analizes a number of national and div. events each year then does a statistical calculation to determine what is actually called the Racer's Theoretical Performance Index or something similar. It is a factor that "equalizes" all the classes so that if all the winners at an event ran to the same level of performance, after their raw times were multiplied by their PAX factor, they would all have equal times. It is used as a method of comparing different classes at a particular event. The factor itself is based on AM being the fastest class, thus always having a PAX factor of 1.000, and all other classes having a factor of less than 1.000. You cannot easily compare PAXes from year to year without knowing what happened in AM that year. This year AM's were quicker than last year, so all PAXes were adjusted down accordingly before being balanced against each other. Confused yet? If so, just do like most and not worry too much about it.
If you want to get an idea how you did at an event compared to everyone else, look at your PAXed position for the event. If you want to chart your progess, compare your PAXed position event to event by 10's% of the field, If you are consistantly moving up in %, you are improving, but don't get too anal as there are outside factors that enter in as well.
In Tarheel, the PAX factor s used to determine finishing position in the "special" classes: Novice, Street tire, and Pro so that the different classed cars can run against each other.

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SPIN or WIN!
there's no glory for going slow.

good explanation chuck, except you forgot the obligatory, "pax SUCKS!!!!" at the end..

- chris (who is quite happy with his sts pax)

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05 MCS

chris, who could be driving a DSP corrado

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www.ncvw.org
1993 VW Corrado VR6 - DSP15 (RIP)
1986 MB 190E 2.3L 16v - STX (SOLD)
1997 BMW M3 3.2L - BS for now

When trying to use PAX/RTI values to evaluate your performance, there are several things to keep in mind as to how those values relate to our local events. The PAX is generally assumed to be an evaluation of cars prepped to the limit of the rules, driven by the best drivers in the region/country, and on grippy concrete surfaces.

At local events, those three assumptions generally do not hold up well. With the exception of a very few, most local competitors are not the best drivers in the country, the cars aren't prepped to the limit of the rules, and only Laurinburg could begin to qualify as a grippy, concrete surface.

So, while it is easy to assume that PAX is an equalizing value for comparison, realize that it is an imperfect system. If we took the best drivers in the country and put them in our cars, on a gritty surface like Sanford, you would likely generate different indexes for each class than those currently published.

This is all speculation, but I would bet that:
- the spread between stock and mod cars would be much less
(in other words, a mod car would not be as much quicker than a stock car on a gritty surface)
- high horsepower rear wheel drive cars (like Mustangs, Camaros, Corvettes) lose some of their strengths on grittier surfaces
- AWD cars usually do quite well on on the grittier surfaces
- cars on slicks would not have as much of an advantage, if any, on grittier surfaces. Some folks speculate the best tire for Sanford is a full tread race tire like a Kumho Victoracer, or full tread street tire, like a Falken Azenis.
In fact, I believe there are times that slicks are not as fast as tires with tread- and the super gritty surface is an example. (Think of it like driving in the rain- the grit has to have somewhere to go).
- the mod cars need the grippy surface in order to take full advantage of the advantage offered by the modified suspensions

And finally, some cars are reportedly just easier to drive at 10/10ths than others. I'll let you figure out which those are.

Though imperfect, the PAX is the best we're willing to do, and we live with it for the purposes we use it for. Some people would say the above are just excuses for those that don't do well in the pax. Others would say that they are valid arguments.

There are also those drivers that are just so good, that they will prove the above wrong because they could drive anything to the limit under any conditions and make us all feel really slow. I don't know that they really disprove the above, they just make us mere mortals, go WoW- how'd he do that?

We've got a few guys in this club that seem to defy the laws of physics....
(Whitney, Whipple, GH, Rasmussen, etc....)

Just food for thought.. not trying to start another 10 page discussion on the validity of pax, but I wanted to give some of the other considerations to keep in mind when trying to use PAX to evaluate your performance.

One way that I try to track my progress using the pax is to evaluate my pax time against the winning pax time. I'll divide the winning pax time by my pax time and give myself a grade. Hopefully, as the year goes on, I'll see that grade improve.

Perhaps the best way to evaluate your performance, and take the car out of the equation, is to have a co-driver.

Miles

Dale, I don't think it is possible for someone to calculate a PAX to elminate the car/tire combination between the STX WRX and your HS Corolla.

If you want to worry about PAX, do a running comparison between yourself and the STS/STX cars in the club. That will give you a pretty good guage of your improvements through out the course of the year.

The most important thing is to have fun. I think the club's fixation on the PAX is very discouraging to new people. And the funny thing is, 90% of the drivers have no clue about it. If you want an eye-opener, attend the DC Tour and look at the HS cars running there that set your PAX

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Jim Pastorius
2008 Silverado VortecMax
1992 Camaro CMC#92
2002 BMW R1150R

2009 3rd Place CMC Mid-Atlantic Championship
2009 CMC Hyperfest Winner

Miles has a very good suggestion here! This is what I did long before there was a PAX in order to evaluate my performance relative to known top cars and drivers. First goal was to win my class. Second was to minimize the percentage I was behind faster classes with proven top level cars and drivers. The idea was to see if I as a driver and/or my car had gotten faster or slower. If there was a big change, then I would look for reasons such as course design, pavement conditions, etc. These days I do what Miles suggested and simply compare to the top PAX time at events with top drivers and Nationally competitive cars.

Another suggestion for folks who don't have a "competitive car" due to available car, prep level, tire budget, etc. Don't worry about PAX, etc. Just find other cars/drivers in similar circumstances and see how your relatve performance improves. Les Davis and I did that with our Mustangs at a couple of night events. Neither car was fully prepared or "Tired" for FS or STX but we both had OEM tires so our goals were simply to beat the other guy. Of course at the first event Mike Whitney jumped in Les's car and beat both of us. At that event both Mike and Les beat me so I spent some time "examining" my driving technique before the next event

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Dick Rasmussen

FS 50 2018 Mustang GT