Proposed alternative CDC index system, XLS linked

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hufflepuff
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Proposed alternative CDC index system, XLS linked

Post by hufflepuff » Fri Feb 27, 2015 9:27 am

https://docs.google.com/spreadsheets/d/ ... sp=sharing

All,

The above spreadsheet is a plug and play tool for calculating an index based on linear values between powers and weights, instead of discrete, step-wise index values. This is recommended because a car that weighs 2501 pounds and has 199 horsepower has a big (and unfair) advantage to a car that weighs 2499 pounds and has 201 horsepower. Even though their performance in reality should be quite similar, the traditional CDC index introduces a great disparity. Tire index is the exact same with discrete steps between tire types.

Values in GREEN are changeable and are what the competitor enter. The YELLOW value is their CDC index.

I did not invent new indexes; they are the values we've been using. It just makes it more fair if you are just over on power or just under on weight. Let me know your thoughts.

- Matt

PS, please don't break the tool. ;)
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v10climber
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Re: Proposed alternative CDC index system, XLS linked

Post by v10climber » Fri Feb 27, 2015 9:36 am

But this takes away my index advantage in the mini that weighs 2504lbs and makes 198whp :-P

It's a good idea but I'm not sure how realistic is is to implement. People aren't going to know exact whp or weight measurements for their car so what do you do for those?
--Nick D

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Re: Proposed alternative CDC index system, XLS linked

Post by Rock Star » Fri Feb 27, 2015 10:53 am

I like it but why stop at tire indexes? There are only so many tire types out there of any real benefit for AutoX. Why not have an agreed index for each tire model that is commonly seen.

Something along the lines of:

A6 - 1.00X
Z214 - 1.00X
V710 - 1.00x
R888 - 1.00X
RA1 - 1.00X
R1R - 1.00X
RS3 - 1.00X
Star Spec 1 - 1.00X
Star Spec 2 - 1.00X
BFG Rival - 1.00X
RE-11 - 1.00X
RE-71R - 1.00X
Ecsta XS - 1.00X
AD08 - 1.00X
Other - All-season (calculated through UTQG rating) .99X

If nothing else, it will give us something else to argue about :D


Regarding Nick's concern: since it is all Honor system anyway, just have them reasonably estimate the whp or weight. Even if they are only within +/-10hp or +/- 100 lbs it is a damn site better then the 50 hp or 500 lbs swing we got before.

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Re: Proposed alternative CDC index system, XLS linked

Post by hufflepuff » Fri Mar 13, 2015 3:16 pm

I think tire index changes would require some independent testing to get it accurate. We could start to gather data on it this season, or review last season's data, but there are so many variables (car, setup, driver, weather) it would be tough. I didn't propose any changes to the tire index mainly because I wanted to make the biggest improvements to the index with the least time and complexity.

I agree that some folks may not know their vehicle weight or horsepower exactly, but like Rocky said it's likely that with a little research (or their own independent measurements) they can get a LOT closer than with the current system. Truck scales / recycling centers are fairly common, and the internet bench racers often post horsepowers for common setups.
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Re: Proposed alternative CDC index system, XLS linked

Post by hufflepuff » Fri Mar 13, 2015 3:18 pm

I added a new feature that compares what your run time would be with the old index vs the new index.
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Re: Proposed alternative CDC index system, XLS linked

Post by Jim Harris » Mon Mar 16, 2015 8:46 am

For me in the S2000, the difference is over a second: 1.032 lower indexed time, using the new continuous formula compared to the current traditional formula, to be exact.

I'd be interested in how others come out using the continuous formula, and whether it results in a lower indexed time (like for me) or whether it would even out with the average for the entire field about the same. If it evens out for the field but some people are indexed 1 lower than on the current traditional system, then we have a problem. If everyone is a second lower, then we don't.

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Re: Proposed alternative CDC index system, XLS linked

Post by alex limparis » Wed Mar 18, 2015 10:43 am

well I can say I kinda like the new system but I will say the one problem I came across was finding the right weight specs to base my judgement off of.

IE: http://www.mustangspecs.com/years/03.shtml say that a 2003 GT coupe weighs in at 3,006 lbs curb weight but many other sites say the weight is around 3,250-3,350 lbs, which i believe to be closer to what it is.

so at ~3,000 lbs the old time was 46.800 new is 46.074
@ 3,275 the old time is still 46.800 but the new time is 45.827
@ 3,350 the new time would be 45.757

Now I'm not complaining, my old girl needs all the help she can get but it seems like an easy way to "game" the system a little bit by fudging the numbers a little bit, just my 2 cents, that said awesome work, I love being able to compare the times
"it's not about the times you get, it's about the experience you have"
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Re: Proposed alternative CDC index system, XLS linked

Post by Rock Star » Fri Mar 20, 2015 9:37 am

I see where you are getting at that people could "game the system" but that is how it is now anyway if you are close. For fun, lets take a 2012 Scion TC. This car is rated at 3060 lbs curb weight (manual) according to Wikipedia. That means that theoretically it would be in the same weight category as your mustang. But lets say the scion owner is an honest guy and knows that of his 14 gallon gas tank, he only runs about 2 gal during autocross. A gallon of gas is around 6 lbs so that means that he is actually 2988 lbs and therefore in the lower weight category. Now in the old system, this would be the difference between a 0.01 multiplier hit. With the new system, the index difference is .0014 (a lot less incentive to lie)

In my opinion, the old system breeds more dishonesty then the new one does. Even if you lie for an extra 200lbs, you are still closer to an accurate index then before.

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