Before we start with an explanation, let’s define a few terms:
Class – A grouping of vehicles that are thought of as similar based on their weight, engine displacement, modification level, etc.
Superclass – A grouping of classes that are “similar enough for our purposes”.
PAX Index – A list of numerical multipliers (handicaps) that correspond to each SCCA class, and are used to equalize the times run by multiple drivers that are in different classes.The Index list is updated annually based on national SCCA results. Drivers’ raw times are multiplied by the PAX index for their individual classes. These new “PAX times” are then compared.
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At Bridge City, we use a superclassed (grouped) form of SCCA classing . For those familiar with this, we group similar classes together into superclasses, and then PAX each time in that superclass based on the cars true class. The PAX times are then used for ranking.
If this does not make sense yet… Read on!
Below is an example of how scoring works. (For help finding your class, go here.)
Now – Lets say we have Jane Doe and Alex Smith. Alex Smith has a car classed into Street Modified Front-wheel-drive (SMF). Jane Doe has a car classed into Super Street Modified (SSM).
Based on our Superclass grid:
Superclass |
Class |
| Street 1 (S1) | SS, AS, BS, FS |
| Street 2 (S2) | CS, ES, SSC, HCS |
| Street 3 (S3) | DS, GS, HS |
| Non-Stock 1 (NS1) | SSP, ESP, SSR, EVX |
| Non-Stock 2 (NS2) | CSP, DSP, FSP, HCR, SST |
| Non-Stock 3 (NS3) | All Prepared, Modified, and Kart Classes and FSAE |
| Non-Stock 4 (NS4) | STS, STH, STR |
| Non-Stock 5 (NS5) | STX, STU |
| Non-Stock 6 (NS6) <——–> | SM, SSM, SMF |
| Non-Stock X (NSX) | CAM-T, CAM-C, CAM-S, XA, XB, XS |
| Junior | All Junior Karts |
They are both competing in the Non-Stock 6 (NS6) superclass.
For computing purposes, Alex is thought of as NS6–SMF, and Jane is NS6–SSM. But the trailing class postfix of SSM/SMF is simply an indicator for us to know which PAX time to use. They are both still competing in NS6.
How this works:
Janes best time today out on course was 56.358 seconds. Alex only had a 57.143. Those are raw times, and it looks like Janes winning. Her raw time was indeed faster, but the two cars are actually different enough that comparing raw times isn’t very realistic. So instead, we use PAX time.
Finding them in the PAX/RTP Index, we find that SSM has a PAX index of .882, and SMF is .861. (Those numbers are based off old PAX numbers).
Janes time was 56.358 (raw) x .882 (index) = 49.708 (PAX time)
Alexs time was 57.143 (raw) x .861 (index) = 49.200 (PAX time)
Notice that in raw times, Jane was ahead. But her car is theoretically faster, being in SSM, than Alexs car is, being SMF. So when PAXed, Jane is now just behind Alex in NS6.