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12-09-2007, 11:57 PM | #199 | |
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The point I am trying to make is when you know what you don't know. Its often best to not attempt to simulate those variable but rather just estimate them from real world data. The what often happens is you simplify the whole thing to the following. Look at the dyno, notice the M3 makes ~93% of its power in the range the engine operates in within each gear. Then a very good estimation of all 2nd and higher gear acceleration simply becomes A ~= HP * 0.94 * (derived drivetrain losses) / (weight * speed) * (unit conversion factor) In first gear you just use the max G force you think the rear tires can put to the ground. Thats probably 95%+ as accurate as us trying to factor in information about other components when we don't yet have access to the cars to get such information. If you have a rear wheel dyno graph for the car then you can probably do much better since drivetrain loss is mostly coverd at that point. Differences will still exist for gears other than the one tested. Also no simulation (we have) covers the ram air effect on engine output. |
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12-10-2007, 12:13 AM | #200 |
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Getting back OT. Just read the new in print article about the IS-F in C&D. The online verision of the article is here, but is not identical to the print version with the print version being longer, more thorough, better pics, etc.
Highlights:
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12-10-2007, 12:18 AM | #201 |
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12-11-2007, 11:00 AM | #202 | |||||||
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You've got balls, I'll give you that. As far as traction, goes, we did the obvious and only thing that anyone could and would do when addressing such an issue: We adjusted frictional coefficients based on a simple numeric input, best to worst. I don't think I'm giving away anything Eric (the gentleman who wrote all of the code) would consider to be proprietary in that context. since the devil is in the details of varying coefficients based on slip rates and type of tire used. Quote:
We did that by using models from SAE papers, Gillespie's "Fundamentals of Vehicle Dynamics" and other such tomes, and allowing user intervention. We addressed everything you've mentioned and of course much more. However, the ONE thing you've mentioned in this paragraph that we considered to be a significant issue and possible shortfall was friction as a function of temperature. We did the best we could with simple things like reading SAE papers from various tire manufacturers, dragging tires around at various temperatures whilst measuring the force it took, pulling various cars over the same surface at varying temperatures and measuring the results (trying to get somewhere on temperature-variable rolling resistance), etc., but neither of us was fully confident that we had universally applicable reults. Quote:
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However, having said that, I admit it makes sense at this point. Here's where I am: I don't have any current software at the moment, but the one thing I did find in this old electronic box was output from a tool done by Racing Systems Analysis called "Quarter, Jr.". It's not the good one (called "Quarter"), but when I opened it up, lo and behold I had an E46 M3 model from probably around 2001 or 2002, done before we had one in our garage in an effort to see what such a car could do. I hadn't realized that I had done anything in this regard since around 10 years ago at least, but there it was. Here are the results: 60' 2.03 330' 5.55 660' 8.48 MPH 84.1 1000' 10.98 1320' 13.10 MPH 106.2 I know it was done as a straight model before 2004, because it shows the ambient weather conditions as an SAE (gross) Standard Day. This model was a little off my actual times from around 2005. I was a couple-three hundredths higher if memory serves, but more importantly, I'm quite sure my actual trap speed was at just over 107. However, if I understand Car & Driver's techniques, it's spot on with that previous note submitted to you earlier in this string! If someone will give me a clue as to how to do it, I'll be glad to post the input sheet and results. Now here's the semi embarrassing part. I've downloaded ShiftMaster from the net, but can't in fact run it. I think it has to do with DOS vs windows, but can anybody give me a clue about that, as well? Thanks. Quote:
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12-11-2007, 12:56 PM | #203 | |||
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Sure you are not, but I think anyone would agree at some point it is time to put up or shut up. Quote:
Although I definitely appreciate your humor about being a pain in the ass, I'd also say resorting to insulting someone parents and genes (sarcastic or not) is stooping pretty low and grasping at straws. |
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12-11-2007, 03:28 PM | #206 | |
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12-11-2007, 04:16 PM | #207 | |
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Dude, once again you have TOTALLY missed the point (what a surprise) in a long multi-page, multi-faceted argument between me and Bruce. Kindly butt out of this one. If Bruce wants your "help" lets let him decide that. |
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12-11-2007, 05:00 PM | #208 |
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Hopefully BMW will price the car lower than 59K. Who would buy an IS-F if it cost more than the M3- only a few dozen i'd guess. Blocking another competitor from gaining market share will be crucial in maintaining the M3 as the leader in the category. That said, I think the IS-F will need to be at least 5-10K less than a similarly equipped M3 to sell.
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12-11-2007, 05:12 PM | #209 |
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Why is everyone under the impression that the IS-F isn't really much of a threat to this disillusioned belief of BMW's all conquering supremacy. Guys the day that you could always count on the M3 winning are long gone, the others, Mercedes, Audi, Lexus etc are all up there with BMW.
I wouldn't count my chickens on the Lexus being a walk over on either out-right performance or handling. |
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12-11-2007, 06:22 PM | #210 | ||
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We all really know the story it has been covered by the mags already. The IS-F is a bit faster in a straight line but still drives and feels like "a Lexus". That is not bad until you realize that and IS-F when competing against an M3 should feel more like an M3. Want to place any bets about track time performance rankings between the M3 and IS-F (or any other handling metrics)? |
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12-11-2007, 06:50 PM | #211 | |
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I don't doubt the M3 will out-sell the Lexus, the same was true on the RS4 yet it was regarded the better car. That was not my point, people here just assume that BMW will continue to beat all comers and that is a very silly belief to have, especially against a company the size of Toyota. If the IS-F isn't quite as good as the M3 at everything they won't just pack their bags and go home, they will fine-tune it until it is as good if not better and by this I don't mean when a new model is launched. Who would have given odds on Audi producing a world beating rival to the supercars and a car based on the dull-witted A4 then would not only beat the old M3 as a driver's car but win it's fair share on duels with the new one as well. I wouldn't have and I have been driving the bloody things for years. All I am saying is don't count your chicken that the IS-F would be on top sooner than you think. |
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12-11-2007, 06:52 PM | #212 |
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I might as well chime in here.
I think people are getting too excited about the simulations... Pro or Con. I will reserve judgement until someone does head to head testing. I personally think that the M3 will be slightly faster. The IS-F will have trouble gaining market share if it is priced higher than the M3. Their image and reputation has always been based on being slightly cheaper than their BMW counterparts.. it is what their customers expect. I personally think that the creation of the IS-F is BMW Japan's fault for overpricing their cars, especially the M models in Japan. I don't think that Lexus would have ever built the IS-F if not for this price gap. BMW Japan left a niche open and Lexus built a car based on local market conditions and extrapolated it to the world wide market. The IS-F is overpriced, especially in Japan. Almost all Japanese cars are similar in price to US prices except for the IS-F. It is only $1K less than the GT-R. I for one will not pay $65-67K for a Japanese IS-F. If BMW Japan didn't sell the M3 at $90K and the M5 at $128K, there would be zero market incentive for Lexus to build the IS-F or to even consider selling it at such a rediculous price. They can get away with it here but Lexus realizes that they must reduce their price to sell the IS-F in the US market. I'm sure Lexus and BMW realize the implications of their pricing for the IS-F and M3 and I'm hoping for a PRICEWAR. |
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12-11-2007, 07:27 PM | #213 |
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Now i was being civil about this, but you have to be your typical arrogant ass and tell me to butt out. Nice job. Anyway, i simply answered your statement, and i'm not helping Bruce because i'm sure he does'nt need my help with you. And the last time i checked, this is a public forum where anybody can respond to any comment as long as it is not to innappropriate. BTW, arrogant ass was very appropriate.
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12-11-2007, 08:44 PM | #214 | ||
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How did you miss the point you may ask? My last reply to Bruce on this was that his simulation that matched one metric from one test result is not all that significant (no more significant than any of my results be them right on or within a few tenths) when there are a variety of equally valid tests that are around .5 seconds different. You chimed in with, Quote:
Finally, note that my two results for 0-60 for the IS-F once the final drive was corrected were 4.5 s and 4.3 s, the spread accounting for a reasonable amount of unknown in the drivetrain losses or shift times. Those numbers compare very well to the fastest and slowest times from the magazines don't they (although probably not for the exact right reasons!). |
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12-11-2007, 09:43 PM | #215 |
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^^I understand your frustration as well and believe it or not i do see your point. I simply made a general statement that 0.4 is a huge difference and made an example out of it, nothing more and nothing less. I do apologize for having to retort in a rude manner, but you kinda left me with no other choice. I know it's not easy as i have proven it myself, but try to be more level headed. Not everyone is going to agree with you no matter how technical you're going to be.
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12-11-2007, 10:11 PM | #216 |
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12-11-2007, 10:38 PM | #217 |
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In comparison with the e46 M3, the RS4 won in C&D, MT, and R&T. In comparison with the e92 M3 which i've only seen one in a video from Europe, performance wise it was very close but the M3 won. But then again the RS4 is a 3yr old model that pretty much set the new standard 3yrs ago when it came out.
Last edited by gbb357; 12-11-2007 at 11:12 PM.. |
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12-11-2007, 10:46 PM | #218 | |
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I learned a long time ago that Best Car is not the same as Fastest car. Rather to me it means, car I would enjoy most. To me AWD dumbs down the driving experience. Great if you need to go in the snow or race in the rain, otherwise, not much value. For drivers that need a car that hides their mistakes and makes them look more skilled than they are, I am sure the RS4 is a good choice. |
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12-11-2007, 10:51 PM | #219 | |
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Last edited by gbb357; 12-11-2007 at 11:11 PM.. |
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12-11-2007, 11:38 PM | #220 |
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Lexus will have to get somebody 50 or under into their dealership before they can sell a lot of cars. When the average age of your drivers is "retired," you've got issues.
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