the last time this came up, it was said that the FWD "adder/subtractor" was correct for ITA, but for ITS and ITR it wasn't enough. so i actually took some time to see just what would happen, if we used the same % weight break for ITS/R as we do for ITA FWD cars.
i took 18 popular ITA cars, and came up with an average % weight break of 2.08. going through the list of FWD cars in ITS/R, % weight breaks for FWD ranged from a low of 1.58% for the Mitsubishi 3000GT, and a high of 2.06 for the Celica GTS. applying the 2.08% to all of these cars didn't change much, with 16lbs more coming off the the aforementioned Mitsu. the cars everyone likes to complain about flowed through as follows;
Integra GSR; -5lbs
Civic Si; -2lbs
Prelude VTEC; -11lbs
GTi VR6; -7lbs
Acura RSX-S; -6lbs
Celica GTS; -1lb
it appears the former champions of that arguement have since moved on to a new approach in getting what they want for their specific car, instead this time based on hp/tq. if we're forced into determining a power multiplier based on *something else* then i like kirk's idea of coming up with a formula based on specific output of the stock motor. picking something out of the ITCS that is currently thought to hit the 25% factor right on the nose we can use it as a baseline. i don't know which vehicle that is, and i think it actually makes more power than 25%.....but just for funzies i'll use the ITA Integra
with minimal effort, i'm having a bit of a difficult time coming up with a formula that works for all cars. i took the specific output for a handful of different cars that challenge the current process like the BMW 325, Integra Type R, S2000, CRX Si, and a couple miatas and a neon thrown in for fun. if i take the % variance from "ideal" factory specific output, then devide that by 3, and apply that variance to the baseline 25% to get a new multiplier, it looks to be pretty close for the most part.
examples;
92 ITA Integra --- 140hp/1.8L = 77.8hp/L baseline specific output.
Integra GSR --- 170hp/1.8L = 94.4. ((77.8-94.4)/77.8)/3 = -7.13%. 25% - 7.13% = 17.87% multiplier
Type-R -- 195hp/1.8L = 108.3 ((77.8-108.3)/77.8)/3 = -13.08%. 25% - 13.08 = 11.92% multiplier
Honda S2000 -- 240hp/2.0 = 120. ((77.8-120)/77.8)/3 = -18.08. 25% - 18.08 = 6.92% multiplier
Honda S2000 -- 240hp/2.2 =109.1. ((77.8-109.1)/77.8)/3 = -13.41. 25 - 13.41 = 11.59 multiplier
Nissan SE-R -- 140hp/2.0 = 70. ((77.8-70)/77.8)/3 = 3.34. 25 + 3.34 = 28.34% multiplier
Miata -- 116hp/1.6 = 72.5. ((77.8-72.5)/77.8)/3 = 2.27. 25 + 2.27 = 27.27 multiplier.
CRX Si -- 108hp/1.6 = 67.5. ((77.8-67.5)/77.8)/3 = 4.41. 25 + 4.41 = 29.41 multiplier.
looks pretty decent, no? i'm not sure how this would flow all the way through to process weight though.
but here's where it fails....
BMW 325 -- 190hp/2.5 = 76. ((77.8/76)/77.8)/3 = 0.77. 25 + .77 = 25.77% adder. we all know that's no where near enough.
Last edited by tnord; 01-18-2009 at 12:44 PM.
Travis Nordwald
1996 ITA Miata
KC Region
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