Thoughts on the weight points in 2012 rules

[Mark Garriott]

Proposed new rule:
X. Weight of the car below the base car curb weight:
Penalty points are determined by calculating the difference in power to weight ratio achieved by the removal of weight according to the following formula:
[4000 / (ModifiedW/P)] - [4000 / (StockW/P)]

"StockW" is defined as the curb weight of the base car as listed in the chart in Section XVIII Appendix C. "P" equals the Horse Power for the base car as listed in the same chart. "ModifiedW" is the weight of the car as measured after modification. For weighing, the car should be ready to drive with all fluids (gas, oil, etc) full, tools, spare tire, jack, etc in the car but no driver. These items do not have to be in the car or fluids full while participating in the event. A discrepancy of 50 lbs. in total car weight is allowed to account for differences in scale weight calibration at varying locations.

Example:
165 lbs. have been removed from a 2010 Cayman S (determined by weighing the car per procedures above and comparing it to the listed Curb weight). The penalty points for this modification would be:
[4000 / (2811 / 320)] - [4000 / (2976 / 320)]
resolved as:
(4000 / 8.78) - (4000 / 9.3)
or
(455 - 430) = 25 point weight modification penalty

TT

Right, Tom!

Let's write out all that math to determine 'final' points: weight modification points (25) + base points (430) = 455:
[4000 / (2811 / 320)] - [4000 / (2976 / 320)] + [4000 / (2976 / 320)] = 455 points.
or
(4000 / 8.78) - (4000 / 9.3) + (4000 / 9.3) = 455 points.
or
455 - 430 + 430 = 455 points.

But this equation can be cleaned up, The 'stock' point values (430) wind up canceling each other out. The net effect is to simply plug the modified weight into the original formula.
(4000 / 8.78) - (4000 / 9.3) + (4000 / 9.3) = 455 points.
or
(4000 / 8.78) - 0 = 455 points.
or
(4000 / 8.78) = 455 points.

So, I can figure out the new 'base points' by doing just one PW calculation using the modified weight, and adding the model year and rim width adjustments back on.

The same thing can be done with Section J - Horsepower Increase. Plug the 'modified' (stock) motor horsepower into the equation.

[Mark Garriott]

Maybe we can avoid the term 'base points' because the it incorporates Power/Weight points, Model Year points and Rim Width points. The chart could list those things separately.
Cayman S:
Weight: 2976
Horsepower: 320
Power/Weight: 9.3 lbs/jp
Power/Weight points: 430 (4000 / (2976/320)
Front rim: 8.0
Rear rim: 9.0
Rim points: 5 (8 + 9 - 12)
Model year: 2011
Model year points: 0 (2011-2011)
Modification points, sections A-Z (minus X)
Just because points -- mid-engine +20, (or, targa/cab -10)

And, the full points equation could be listed out at the top of the 'determining points' section.

Total points = Power/Weight + Model Year points + Rim points + Mod Points 'A' + Mod Points 'B' + etc.
or
Total points = 4000/(weight/power) + (Model Year - 2011) + 5*(front rim + rear rim - 12) + Mod Points 'A' + Mod Points 'B' + etc.

[ttweed]

So, I can figure out the new 'base points' by doing just one PW calculation using the modified weight, and adding the model year and rim width adjustments back on.

Once the modified PW points have been tallied, the model year adjustment (MY-2010) and stock rim width adjustment, mid-engine adjustment, then the remaining A-Z modification points can be applied.

The same thing can be done with Section J - Horsepower Increase. Plug the 'modified' (stock) motor horsepower into the equation.

I'm not totally sure what you are driving at here, Mark. Are you saying we should do away with the mod point penalty and just let each owner calc their total basepoints directly, including the modifications in their calculation? I don't think that will work due to the provision in Appendix B, section 3:
Other "Adjustment Points"
Other adjustment points may added to or subtracted from each model’s basepoints as part of the annual rule revision process if deemed appropriate in order to consolidate models, account for the performance potential of specific models or to better balance competition.

Yes, you can recalculate the PW portion and add/subtract the model year adjustment, stock rim width adjustment, and mid-engine adjustment, but this "Other Adjustment Points" provision is opaque, as I noted in my last message, and the owner does not have access to it. It is determined by the Rules Committee and can change from year to year to adjust for demonstrated performance advantages of certain models.

For instance, taking that same 2010 Cayman S as an example. The base points are 475 in the chart, yet the 430 PW points, plus 5 rim size points, plus 25 mid-engine points only add up to 460. There are 15 more "performance potential" points (what you are calling "Just because points") in there that are not "visible." I could attribute this to the improved chassis rigidity and aero of the coupe body over the Boxster roadster, but I would be guessing. The owner does not have access to this info to do their own calc. I think that's OK, there has to be some provision for the Rules Committee to adjust for performance potential between models of similar PW ratios from year to year, but it means we need to depend on the chart and not calculate our own base points, keeping mod points as a separate add-on.

But maybe I'm missing your point entirely....it wouldn't be the first time...

TT

[Mark Garriott]

I'm not totally sure what you are driving at here, Mark. Are you saying we should do away with the mod point penalty and just let each owner calc their total basepoints directly, including the modifications in their calculation?

Tom,

That is what I am getting at, I suppose. Both of our proposals take 2 different paths to the same result. Your proposal is more correct because it fits within the verbal framework of the rules as currently written. If that makes sense.

Another way to go think about it is to pull the PW formula out of 'base points' -- but leave in the year, rim and 'other adjustment' points. So, a really old car could have negative base points, and then the PW points are added -- either determined by the chart for 'stock' cars (as it is currently, for people not wanting to do the math), or calculated using modified weight and power values.

I think the 'other adjustment' should be explicitly stated in the chart -- Cayman gets +25 points for mid-engine, and 15 "performance potential" points. That way the changes can be tracked, published, discussed and voted accordingly.