The math doesn't have to be 'right' when you have an accepted WHP number. If you 'know' 115whp, it might come out to .32 or .27 or whatever.
Not saying this is the case here but the numbers don't always have to fit in a box to be 'correct' per the Process.
Andy,
I don't think anyone disagrees with that, or disputes it. I know I certainly don't.
However, per the ITAC Operations Manual, it's pretty well outlined what has to happen if you're going to use "Known Horsepower"
ITAC Ops Manual said:
Known Horsepower
In this method, the horsepower number published by the manufacturer is ignored, and instead, the expected horsepower comes from another source. These days it is pretty common to have dynamometer results, usually from a chassis dyno. For chassis dynos, the ITAC standard is that RWD cars have an 18% drivetrain loss (from crank to wheels) and FWD cars have a 15% loss. Thus, for example, if a RWD car is “known” to make 150 horsepower on a chassis dyno, then the “expected horsepower” for power-to-weight calculation should be 150/.82, which is 183. Care should be taken that the highest dyno numbers seen are used, and that cars classed by this method should be at the limit of the IT rules.
In order to use this method, an ITAC member should put together a set of documentation that proves what the maximum known horsepower is. Then each member should say how confident he/she is in the documentation, considering the source, how well-prepared the measured cars are, etc. If the average confidence is 75% or greater, then the “known horsepower” method may be used to derive the expected horsepower.
A 75% confidence level is a pretty high level. It is expected that the committee would bring with them a healthy amount of skepticism when it comes to reviewing dyno sheets. One should take into account the source of the info, the shop that ran the dyno, information about how well-prepared the car and the engine car, who did the build, and any hidden motives of anyone involved in providing the data. In the best of circumstances, dyno results are hard to trust as they can be extremely variable even when all conditions are the same. It is reasonable to look at on-track results of the cars in question to see if the perceived acceleration matches what the dyno sheets appear to say.
All dyno sheets should be posted to the thread on the letter-tracking site that is associated with the letter under discussion. That way all information associated with the decision is saved and findable. The letter number is known by the author and also published in Fastrack. Any CRB or ITAC member can then find that letter number in the system and find all dyno sheets associated with its weight decision.
If that's followed, the 'alternative' multiplier will be well documented, and supported by data and a confidence vote by the ITAC
Andy Bettencourt said:
On the ITB Hondas: I understand that when a reprocess request comes in they look at it. It SEEMS to me that just because they can't make the numbers make sense, they have to understand that they are based on a previous decision and data. Just because that info is not under their nose doesn't mean it doesn't exist. I hope that they are assuming the number is correct and looking at data to prove that it ISN'T instead of ignoring the weight, starting from scratch and saying, do we have anything other than this letter - and then changing it. To me, that would be very short-sighted.
And there's the rub. I'm sure that deviations from the process were based on data and prior discussions. However, if that information was not archived and preserved, you (the ITAC) have two choices, either re-compile it and follow through with the "Known Horsepower" process, or, lacking that, follow the "Published Horsepower" process (essentially starting from scratch).
If you see Jeff's earlier comment that I quoted and bolded, you'll see that he states
in the absence of an real data. Jeff's an ITAC member, and from what I can tell, a pretty thorough guy. I firmly believe that if the data and documentation used to determine the initial 2130# weight for the 3rd gen Civic/CRX Si were available, he (and the other ITAC members) would have used it.
So, I don't think anyone was short-sighted. I also don't think it's incumbent on the ITAC to disprove variations from the process that don't have supporting documentation. In fact, to not run a car through the "Published Horsepower" process, when the required "Known Horsepower" documentation and confidence vote is not in place, is subverting and 'going outside' the process.
This is why archiving prior decisions is so important. I believe Josh and the rest of the ITAC recognized this, which is why it was codified in the Ops manual.
As Jeff said, once you put something like The Process in place, you have to trust it and use it.