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Originally Posted by
Knestis
Cross-posted from the Sandbox...
K
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Step 1 - Research the manufacturer's quoted stock power and torque figures, determine the stock curb weight. Example - MkIII Golf = 115hp, 122 ft-lbs
Step 2 - Multiply the stock power by 1.25 (the "default power multiplier"). The product became the de facto "IT build power estimate," absent any evidence that a non-standard multiplier should be use. Example - 115 x 1.25 = 143.8
Step 3 - Run the initial math to rough the car in question into a class, using fixed weight multipliers, ranging from 11.25 in ITR to 18.8 for ITC. The product got called the "base weight." Example - 143.8 x 17 (ITB factor) = 2444#
Step 4 - Since it was possible (common actually) for a car to potentially be in one of two classes, we'd check to see if it was (1) plausible for it to reach the est. base weight in the faster class, and/or (2) if it were going to be a whale in the slower class. We generally tried to put it where it was the most natural fit but member input suggested to us that people would rather struggle with something that was tough to get to minimum, than drive a piggy (the ITC New Beetle theorem). Example - MkIII Golf 2 door plunks pretty well into ITB, albeit at a weight that's a little tough to get to without a minimal cage.
Step 5 (and this is VERY important) - At this point any committee member was empowered to propose a non-standard power multiplier be applied, if they believed 1.25 was not an accurate estimate of real-world IT gains. Evidence was collected, presented, and discussed - sometimes over a period of weeks or months - until an alternate multiplier was proposed.**
Step 6 (also VERY VERY important) - All committee members were polled INDIVIDUALLY, and asked for their "confidence" in the alternate multiplier, from 0% (no confidence at ALL in the evidence presented) to 100% - absolute confidence in the alternate option. All of this information was recorded internally, by member. This alternate multiplier only got used if it got essentially a mandate of confidence votes to move forward - we averaged them but I sure don't remember ever using an alternate number that had even ONE member voting way in the low numbers. (Note that I was NOT thrilled by this, being an orthodox adherent to the "pure formula" kind of approach, but we had heard from members that they wanted a safety valve, at which point the subjective [dare I say wisdom?] of the committee could be applied. This was a great compromise, in hindsight - allowing for adjustment but not manipulable by a few members.) Regardless, at this point, the real work was done... Example - it's not possible to fake this because it would require the committee working on it.
Step 7 - Apply the FWD "subtractor." Version 2 simplified and eliminated some previous adders/subtractors, on the logic that they had been - or could be - applied subjectively to diddle the outcome race weight. FWD cars got a break on a sliding scale (also a v.2 change) from 6% in ITR to ZERO in ITC. (Example - Golf in B would get a break of app. -49 pounds, at 2%)
Step 8 - Add/subtract the binary (yes/no) adders/subtractors - Mid engine (+50), live axle on a rear drive car (-50), DWB suspension (base was struts, +50). That's ALL. (Example - NA for the Golf III, lousy rear suspension was deemed to be a tiny issue on a FWD car.)
Step 9 - Judge the brakes and torque adders. We played with a lot of options between Sep 2008 and the spring of 2009, to try to get more sophisticated about these but member input suggested that added confusion without "discriminatory power," so we continued with chunks of weight added or subtracted (50 pounds) for particularly large or small (dimensionally) brakes, and for torque values substantially greater or less than other cars in the class. Torque adders/subtractors were different for each class (another v.2 change). Example - some suggest that the MkIII Golf should get a torque adder, so let's give it the ITB 50# chunk. It does pull like a mutha at places like the Climbing Esses at VIR...
DONE - at least as far as the ITAC's role went.
Our example Golf ends up at 2445 if I've done my math correctly - just about 100# heavier than the current ITCS weight.
K
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