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      10-26-2007, 03:06 AM   #76
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Drives: E92 M3
Join Date: Sep 2006
Location: San Diego, CA USA

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You are not reading nor thinking

Originally Posted by gbb357 View Post
Exactly what basis that you have determine that any of these are inconsistent? Base on your calculation?! Car and Driver's figures or any other magazine's figures are base on average runs, they don't run a test just once and just take that as a final number. The same with the dyno results and hp and tq figures. The weight!? How hard is it to weight the car?! Again, as accurate as your calcultion can be, it does not calculate real world testing and situations. It does'nt calculate how to launch a car to get the best and quickest time. You do realize that these are professional drivers testing these cars, they don't launch the car like a normal or regular driver would. As you have mentioned yourself, it does not calculate the road condition, air temperature, humidity, tire condition, and most of all, the human factor condition. Basically what your saying is, your "data" or your calculation is the final conclusion. It does not matter what results any actual real world testing is done and reported, if it does'nt add up or match your "calculated data", then it's wrong. LOL!!!!!!!!!!! Please tell me your kidding. So why even bother testing the car, just punch in the numbers in your little formula and start calculating, BAM!!! We got the figures! On the 20% loss of power, as i stated before, it's not exact science. It's a common number that many have known to get when testing cars on a dyno. It's usally around 15% to 20%. Again, i've posted the dyno results, there is actual real world data. Why are you still questioning it. And the fact that it is actually consistent with another car with similar figures, probably means it's on the ballpark if not dead on.
What if I told you that a stock Honda Civic went 0-100 mph in 8 seconds?

From that tiny bit of data you would know that something was clearly and majorly wrong. The case here with the IS-F is a bit more subtle (which you cant seem to appreciate) but the concept is the same. Get it, can't you abstract just a tiny bit? If you had more data on the car you could start to figure out what was wrong. "Stock" would be my first guess which includes power, weight and tires. Timing errors or simply going off a cliff might be other less likely possibilities . Look, it is basically F=ma, force equals mass times acceleration, also called Newtons Law. That is what governs 90% of the behavior of the acceleration of a car. If you know F and m you know a, you can not specify all three to you liking. Know why it is called a "law"? Because it can not be broken. Perhaps not even a strong enough term as people can indeed break legal laws.

Do you know how much variation exists with dyno tests as well? Apparently not. They are quite good for A-B comparisons, say after a mod with all else exactly equal, but for an absolute prediction they have large variation and they test the vehicle not the engine. I guess you know that different brands of dyno give different results as well? Clearly the car is not changing the measurement accuracy is!

I think it is also safe to assume that you are not aware that this software does have as on option and ability to repeatedly launch a car under a variety of conditions (clutch drop and clutch slip at any rpm for both and "power braking" as well for automatics, again at any rpm). Then the software automatically (in about 2 seconds) optimizes the launch to get the best acceleration. You then instruct the software to accept the optimized launch schedule before proceeding to get simulation results. Neat eh? This is not simply a formula or spreadsheet you plug numbers into. It is physics based numerical simulation that numerically integrates (do you know what that means?) in real time the behavior of many systems of a vehicle all coupled together.

Sure each magazine does multiple runs but again you did not read nor understand my comments about variability. I am not talking about that kind of variation, I am talking about the variation among all magazines (and all drivers) who by the way use journalists who are not professional drivers but are certainly good enough to get a good 0-60 or 1/4 mi time or whatever.

I can just keep going and going... I never said "my data" nor my calculations are the final conclusion nor did I say any reported results are "wrong". Each piece of data is a piece of what I consider to be a puzzle and all I am saying is something does not fit up amongst the data we have and SIMULATION can further provide insight into things not adding up.

I think I am going to stop wasting my time and do some more simulations which are interesting, fun, educational and useful. However, I am finding it less and less of these trying to discuss this with you. Of course I will continue to accept new data including more magazines results and other dyno results.