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      10-25-2007, 09:16 PM   #67
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Here's some simple math I did, and tell me how this is incorrect. I set up an equation where X/295 = 8400/6800 Pretty much we are solving for X. When you solve you get X to equal 364.41 torque. This is what you would need to equal the power of a car making 295 torque with an 8400 rpm. The Lexus makes more than 364.41, so if I am correct, if both cars have gear ratios in which their redline makes them shift at the same mph, the Lexus would be putting more power to the ground. I think ur program is flawed, no way the m3 should have more peak thrust than the lexus in first gear when according to your graphs it seems that they both shift at the same speed.
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      10-25-2007, 09:37 PM   #68
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Wrong again

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Originally Posted by gbb357 View Post
Me driving a Lexus has got nothing to do with this. I for one is a huge BMW fan as well. The point i'm making is your making a conclusion or assumption right away that Lexus is under rating the IS-F just base on it's performance without even having any real data is ridiculous. And just because you have used a formula to estimate the performance and come up with some data, all that is is an estimation. The real data is what the car will do on actual driving condition, no formula will come up with a better result than that. Now in terms of the figures that Car and Driver came up with, everyone knows that those numbers can change anytime. As a matter of fact, 4 different 0-60 times have been recorder so far for the IS-F that has quite huge discrepancy. Edmunds being the worst at 4.8 secs, Motor Trend at 4.7 and Automobile at 4.6. I just posted and showed you an actual dyno and yet your still arguing that the IS-F is underrated. Reading is fundamental. Everyone knows that the wheel hp is usually around 20% less than the crank hp. Calculate 416hp at 80% and you'll get around 330hp which is close to what Automobilemag came up with in their dyno test. Just because you don't like the results and it favors Lexus, does not mean it's not correct. I could care less if you "dogging" Lexus, but don't be such a fanboy about it. BMW makes some of the best cars out there, but that does'nt mean they're the best at everything.
We have all of the real data we need to determine if the car is under rated. We know the torque curve, transmission ratios, tire sizes that really about covers it all except for all the smaller subtleties of parasitic losses. I have indeed used "formulas" to model/simulate the car but it is much more than just formulas or ratios - it is physics. Phyiscs is the most predictive and exact science we have. Its "humble" formulae can predict things as small as subatomic particles to things as inconceivably large as red giant stars, things going as slow as an ant or as fast at light. If you doubt that physics and engineering can make accurate predictions based on sound principles and numerical techniques we simply can not have a debate. Do you know how much physics and engineering, formulae and simulation are used to design every car we drive, including yours.

Furthemore it is not true that a formula can not beat actual test data. This may sound unbelievable but think about it for a minute. How much variation do we see in real world testing. Just look at the performance figures thread where we track M3 and competitors performance on this board. In real world test it is impossible to precisely control all variables (temperature, pressure, tire conditions and inflation, individual car to car variations, driver skill, equipment accuracy, etc. etc., we could go on forever here). just look at the real spread of any performance spec of a car from a number of sources! What really matters is an average number and some idea of the statistical spread of those numbers. With simulation you should be able to get a good average number, and sometimes when clever, you can even simulate the distribution of results. Scientists do this regularly - one common technique here is called Monte-carlo analysis and guess what - it simply "works".

I am encouraged that you are tracking the IS-F numbers well enough to have observed this effect. These pieces of data will help me to compare my simulations to an average data point rather than the possible outlier point I noted in my first point.

Your comments that the wheel hp is 20% less than the crank is a drastic over simplification. The parasitic losses in a vehicle are from a few main sources, some speed dependent and some rpm dependent, other yet still temperature dependent. Losses come from friction, air resistance, bearing losses (friction) tire heat dissipation, etc., etc. An accurate quantification of these losses is essential in any simulation. These parameters are generally well known and modeled. Using a fixed number here, say 20% is just as bad as talking about peak hp and not the entire torque across the whole rpm range. It will tell you some things but by far not the entire picture. Note my previous posts showing how CarTest takes all of this into account!

If you would have read my posts more carefully you would see I have never once "dogged" Lexus. I am thrilled (yet very suprised) the car is performing as well as it did in the C&D test. Competition is simply great for everyone! If you take any time to read some of my posts here on this forum you will see I am quick to ciriticize the M3 and BMW as well as sing its praises. I just am not a fanboy.

I am not sure how many times I have to say it (adding a point here actually and refining a bit) but this is my conclusion. One or more of the following are INCONSISTENT:
1. The C&D performance figures acurately representing the average or even the peak performance of the car
2. The weight of 1690 kg
3. The reported hp and torque figures
4. The dyno results

This has nothing to do with brand loyalty, fanboy-ism, favoritism, bias, or any such thing. The "facts" as they are reported to us JUST DO NOT ADD UP. The C&D results for the car are too good given the specs and knowledge we have on it.
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      10-25-2007, 09:51 PM   #69
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Hint - final drive

Quote:
Originally Posted by ChitownM3 View Post
You would think that the high rpm would equalize that, but in fact, it doesn't! The fact that the Lexus has more hp means that it has more torque at higher rpms. While the Lexus can't rev up to 8400 rpms like the M3, the Lexus has tons more torque up to its redline of 6700 or whatever it is and will be pulling the m3 HARD until it has to shift at 6700 rpms.
Quote:
Originally Posted by ChitownM3 View Post
Here's some simple math I did, and tell me how this is incorrect. I set up an equation where X/295 = 8400/6800 Pretty much we are solving for X. When you solve you get X to equal 364.41 torque. This is what you would need to equal the power of a car making 295 torque with an 8400 rpm. The Lexus makes more than 364.41, so if I am correct, if both cars have gear ratios in which their redline makes them shift at the same mph, the Lexus would be putting more power to the ground. I think ur program is flawed, no way the m3 should have more peak thrust than the lexus in first gear when according to your graphs it seems that they both shift at the same speed.
I'll give you a big hint.

Car, 1st gear ratio, final drive ratio, gear ratio product
M3:...4.055...3.846...15.6
IS-F:.4.596...2.176...10.0

That is a 50% advantage in torque multiplication for the M3! When you want to determine instantaneous accelerative wheel torque (and force and then F=ma for vehicle acceleration) the wheel torque is simply multiplied by the product of the gear ratios (there is some scaling as well but that is not important to do a simple A-B comarison). So M3 torque in 1st gear x gear factor = 295 ft lb x 15.6 = 4602 ft lb. IS-F torque x gear factor = 371 ft lb x 10.0 = 3710 ft lb. No surprises here! Add in the much higher redline and you will see more of the picture. Hope that helps.
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      10-25-2007, 10:20 PM   #70
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Quote:
Originally Posted by swamp2 View Post
I'll give you a big hint.

Car, 1st gear ratio, final drive ratio, gear ratio product
M3:...4.055...3.846...15.6
IS-F:.4.596...2.176...10.0

That is a 50% advantage in torque multiplication for the M3! When you want to determine instantaneous accelerative wheel torque (and force and then F=ma for vehicle acceleration) the wheel torque is simply multiplied by the product of the gear ratios (there is some scaling as well but that is not important to do a simple A-B comarison). So M3 torque in 1st gear x gear factor = 295 ft lb x 15.6 = 4602 ft lb. IS-F torque x gear factor = 371 ft lb x 10.0 = 3710 ft lb. No surprises here! Add in the much higher redline and you will see more of the picture. Hope that helps.

Thank you for the info. Here's another question, does that program actually predict 1/4 mile times??? This is the thing, when Car and Driver was only able to pull 12.9 I was suprised they couldn't get it faster. As I have stated in other posts I feel as though the m3 can pull a 12.7 at an actual drag strip, but if your program is correct, and Lexus isn't lying, maybe it's possible for C&D to get a 12.6 out of the car?
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      10-25-2007, 11:24 PM   #71
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Whatever you like

Quote:
Originally Posted by ChitownM3 View Post
Thank you for the info. Here's another question, does that program actually predict 1/4 mile times??? This is the thing, when Car and Driver was only able to pull 12.9 I was suprised they couldn't get it faster. As I have stated in other posts I feel as though the m3 can pull a 12.7 at an actual drag strip, but if your program is correct, and Lexus isn't lying, maybe it's possible for C&D to get a 12.6 out of the car?
Again not my program. A publicily available program you can buy.

It predicts about anything you like (and more), 0-distance X time, 0 - speed X time, rolling starts, launches, in gear acceleration times from speed X to speed Y, works in US or metric units, wheel forces, parasitic losses, air drag force, graphs vs. time, acceleration vs time (g's), etc.

Have a look at some results where I used it to predict the M-DCT results and M-DCT M3 vs. R8 here. I had some subtleties to work out with the time stepping the in program that I did not get really correct until my last post in that thread. The conclusion of this effort was that M-DCT M3 will best the R8 in most speed contests and that we should see sub 10 sec. 0-100 mph in the M-DCT car.

You can also see some more nice screen shots from member T Bones use of the software here. I was a bit quick to criticize him back then for the difficulty in modeling the actual launch event (friction, tire slipping, etc.). But you know what, I was wrong, and although it is not perfect it is darn good.
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      10-26-2007, 12:25 AM   #72
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C/D numbers are very questionable. Look at the numbers that they tested on the 06 330i:
0-60mph 5.6s ? 1.0 faster than spec on BMW website?
0-100mph 15s

So 0-60mph = 4.2s for IS-F? I would add .4-.6s on top of that.
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      10-26-2007, 01:01 AM   #73
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Quote:
Originally Posted by Pretender View Post
C/D numbers are very questionable. Look at the numbers that I tested on the 06 330i:
0-60mph 5.6s ? 1.0 faster than spec on BMW website?
0-100mph 15s

So 0-60mph = 4.2s for IS-F? I would add .4-.6s on top of that.
BMW is always very conservative with there peformance stats. The E46 M3 did the 0-60 in 4.8sec or faster even though the BMW site had its time as 5.2sec.

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      10-26-2007, 01:06 AM   #74
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Quote:
Originally Posted by Swamp2
I am not sure how many times I have to say it (adding a point here actually and refining a bit) but this is my conclusion. One or more of the following are INCONSISTENT:
1. The C&D performance figures acurately representing the average or even the peak performance of the car
2. The weight of 1690 kg
3. The reported hp and torque figures
4. The dyno results


This has nothing to do with brand loyalty, fanboy-ism, favoritism, bias, or any such thing. The "facts" as they are reported to us JUST DO NOT ADD UP. The C&D results for the car are too good given the specs and knowledge we have on it.
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.
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      10-26-2007, 01:12 AM   #75
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Quote:
Originally Posted by Pretender View Post
C/D numbers are very questionable. Look at the numbers that I tested on the 06 330i:
0-60mph 5.6s ? 1.0 faster than spec on BMW website?
0-100mph 15s

So 0-60mph = 4.2s for IS-F? I would add .4-.6s on top of that.
As Jellis have stated, all manufacturers performance figures are usually if not always, very conservative.
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      10-26-2007, 02:06 AM   #76
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You are not reading nor thinking

Quote:
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.
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      10-26-2007, 02:08 AM   #77
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Quote:
Originally Posted by gbb357 View Post
As Jellis have stated, all manufacturers performance figures are usually if not always, very conservative.
Yes, but 1.0s on a 06 330? No way. I haven't seen any 06 330 0-60mph result from members < 6.0s yet. Is there any?
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      10-26-2007, 07:05 AM   #78
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Something else to ponder: Why does it seem the IS-F is so much faster than the E39 M5, a car which it is very similar in weight, power and torque (and not TOO far off in redline and final drive either)? I wonder what C&D's test numbers were for the old M5? Because just looking at these early tests, if you lined them up, the M5 will get killed.

Either the IS-F is underrated, or that is one very amazing transmission. Or both.

Either way, Kudos to Lexus for taking us all by surprise - at least in the straight line department. It will be very interesting to see the comparo tests vs. an E90 M3.
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      10-26-2007, 07:37 AM   #79
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Quote:
Originally Posted by swamp2 View Post
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.
First of all you did say "your conclusion", i even quoted you on it. There is always going to be variation on the results. I already have given you an example from 4 different magazines. The 0-60 range where from 4.2 to 4.8. No way any car even with the same driver will come up with the same figures all the time, let alone with different drivers from different magazines. C'mon that's a given. You're right, stop wasting your time, your not going to be right all the time. Making an example of a stock civic going 8 secs to 100mph is really pathetic. You seem to be very smart but your logic is comical at best and you lack common sense. See ya.

Last edited by gbb357; 10-26-2007 at 10:01 AM.
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      10-26-2007, 10:21 AM   #80
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Guys, I have lost track of the real difference of opinion in this debate. Swamp has done some detailed modeling of the 0-60 scenario with CarTest, which does seem like a fairly comprehensive and reliable simulation environment when it comes to that sort of thing. I believe he has validated the accuracy of the environment for several cars by using manufacturers' specs as parameters for the simulation and comparing the outcomes to the performance figures reported by magazines. That said, it is valid to question a simulation outcome--regardless of the comprehensiveness of the model being used--which I guess is what gbb357 is doing. For instance, my understanding is that C&D is using rolling starts in the 0-60 test. Does CarTest model that? Where does CarTest get the necessary data for modeling transmission losses, and how accurate are that data (I am not talking about the conceptual physics model that is being used to simulate the losses; I am referring to the actual parameters). Regardless, I think it is possible to say that, with some degree of confidence, an engine might be underrated if things simply do not add up in the end. Maybe the issue here is what level of confidence one can make such a statement given there might be uncertainties in the simulation model. Is that the basis of this debate? If it is, then I don't see how one can come up with a definitive answer in the absence of a larger statistical database which shows how CarTest simulation outcomes compare to reported real-world performance figures from multiple sources. Maybe the authors of CarTest have published that type of information?
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      10-26-2007, 10:42 AM   #81
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Autoweek IS F article

Didn't see this posted yet. Some snippets--

- Each cylinder has two injectors, one port and one direct
- Electrically variable titanium intake valves; hydraulically variable steel exhaust valves (lift stays same on valves)
- Upshifts take 0.1 seconds
- "'The goal is not to make a BMW M3,' Yaguchi said, though many people will see it as such. 'The M3 is fun for a realy good driver, but if you're not a really good driver, it's not fun,' he said. 'This is a car everyone can enjoy; with this car you skill level doesn't matter.'" -- Great!
- "This one (suspension) is softer than the previous M3's...but, it is a tradeoff we could live with."
- "Lexus cleverly chose to reveal its IS F just before BMW revealed its M3 (sedan). Or was that pure coincidence? In either case, everyone's stories about the Lexus IS F will come out before other stories about the M3. This will allow people to view the IS F separatels as a sports sedan unot itself. In such a context it is an unbridled success. Against the M3, we'll have to wait and see."
Attached Images
File Type: pdf AW ISF1.pdf (1.47 MB, 63 views)
File Type: pdf AW ISF2.pdf (1.58 MB, 58 views)
File Type: pdf AW ISF3.pdf (1.32 MB, 53 views)
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      10-26-2007, 10:52 AM   #82
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Quote:
Originally Posted by lucid View Post
Guys, I have lost track of the real difference of opinion in this debate. Swamp has done some detailed modeling of the 0-60 scenario with CarTest, which does seem like a fairly comprehensive and reliable simulation environment when it comes to that sort of thing. I believe he has validated the accuracy of the environment for several cars by using manufacturers' specs as parameters for the simulation and comparing the outcomes to the performance figures reported by magazines. That said, it is valid to question a simulation outcome--regardless of the comprehensiveness of the model being used--which I guess is what gbb357 is doing. For instance, my understanding is that C&D is using rolling starts in the 0-60 test. Does CarTest model that? Where does CarTest get the necessary data for modeling transmission losses, and how accurate are that data (I am not talking about the conceptual physics model that is being used to simulate the losses; I am referring to the actual parameters). Regardless, I think it is possible to say that, with some degree of confidence, an engine might be underrated if things simply do not add up in the end. Maybe the issue here is what level of confidence one can make such a statement given there might be uncertainties in the simulation model. Is that the basis of this debate? If it is, then I don't see how one can come up with a definitive answer in the absence of a larger statistical database which shows how CarTest simulation outcomes compare to reported real-world performance figures from multiple sources. Maybe the authors of CarTest have published that type of information?
I never doubted Swamp2's data or calculations. As a matter of fact i think it is quite valid and accurate if you look at it scientificly. The point that i'm trying to make is that you can have all the simulations, calculations and what not, it's not going to be as accurate as the real world testing. That is the final conclusion of all. Of course you're going to have mistakes, wheter it'll be instrumentation or human error. Can it be skewed or manipulated, of course it can. But these magazines don't really have any reason to do that especially if their reputation is on the line. As a matter of fact, i think it might be an incentive for them to get the best performance out of each cars they test. It's bragging rights. BTW, C&D's rolling start acceleration test is a seperate test. That simulates real world driving for you and me. That's why it is usually a lot slower compare to their regular test. And furthermore, the times that the IS-F got from C&D is not that far off from the M3's and RS4's results. And their specs are very close also, so i don't see this being controversial at all.
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      10-26-2007, 10:59 AM   #83
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Quote:
Originally Posted by gbb357 View Post
BTW, C&D's rolling start acceleration test is a seperate test. That simulates real world driving for you and me. That's why it is usually a lot slower compare to their regular test.
I shouldn't have said "rolling start". I meant to say that they start the clock when the car has covered some small distance after an optimized launch. I thought Bruce had posted some info on this a while back, but I might be wrong.
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      10-26-2007, 11:04 AM   #84
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Quote:
Originally Posted by lucid View Post
I shouldn't have said "rolling start". I meant to say that they start the clock when the car has covered some small distance after an optimized launch. I thought Bruce had posted some info on this a while back, but I might be wrong.
Seems only fair, the 1/4 mile doesn't start until you trip the lasers....
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      10-26-2007, 11:29 AM   #85
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Good summary

Quote:
Originally Posted by lucid View Post
Guys, I have lost track of the real difference of opinion in this debate. Swamp has done some detailed modeling of the 0-60 scenario with CarTest, which does seem like a fairly comprehensive and reliable simulation environment when it comes to that sort of thing. I believe he has validated the accuracy of the environment for several cars by using manufacturers' specs as parameters for the simulation and comparing the outcomes to the performance figures reported by magazines. That said, it is valid to question a simulation outcome--regardless of the comprehensiveness of the model being used--which I guess is what gbb357 is doing. For instance, my understanding is that C&D is using rolling starts in the 0-60 test. Does CarTest model that? Where does CarTest get the necessary data for modeling transmission losses, and how accurate are that data (I am not talking about the conceptual physics model that is being used to simulate the losses; I am referring to the actual parameters). Regardless, I think it is possible to say that, with some degree of confidence, an engine might be underrated if things simply do not add up in the end. Maybe the issue here is what level of confidence one can make such a statement given there might be uncertainties in the simulation model. Is that the basis of this debate? If it is, then I don't see how one can come up with a definitive answer in the absence of a larger statistical database which shows how CarTest simulation outcomes compare to reported real-world performance figures from multiple sources. Maybe the authors of CarTest have published that type of information?
A good/fair summary I think.
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      10-26-2007, 12:01 PM   #86
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Still missing the point

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Originally Posted by gbb357 View Post
First of all you did say "your conclusion", i even quoted you on it. There is always going to be variation on the results. I already have given you an example from 4 different magazines. The 0-60 range where from 4.2 to 4.8. No way any car even with the same driver will come up with the same figures all the time, let alone with different drivers from different magazines. C'mon that's a given. You're right, stop wasting your time, your not going to be right all the time. Making an example of a stock civic going 8 secs to 100mph is really pathetic. You seem to be very smart but your logic is comical at best and you lack common sense. See ya.
It is not about me being right all of the time. What you can not seem to accept, as many others here have, is that something simply does not add up. You keep sticking to your guns that the car is so similar to an Audi and that it's performance results are so similar that all is rosy and consistent in the world. If you dig just a bit deeper you will see that this is not the case both on 0-60 (AWD - hint, hint) and 0-100 (smoking the E92 M3 with way more power to the ground and less weight). The civic example was chose particularly absurd just to make a point, it was not a literal case study, but it seems even the extreme nature of that thought experiment does not help you broaden your perspective - even by a tiny, tint bit. Thank for your insightful opinions on my logic and common sense. Have a look in the mirror my boy.

Quote:
Originally Posted by gbb357 View Post
I never doubted Swamp2's data or calculations. As a matter of fact i think it is quite valid and accurate if you look at it scientificly. The point that i'm trying to make is that you can have all the simulations, calculations and what not, it's not going to be as accurate as the real world testing. That is the final conclusion of all. Of course you're going to have mistakes, wheter it'll be instrumentation or human error. Can it be skewed or manipulated, of course it can. But these magazines don't really have any reason to do that especially if their reputation is on the line. As a matter of fact, i think it might be an incentive for them to get the best performance out of each cars they test. It's bragging rights. BTW, C&D's rolling start acceleration test is a seperate test. That simulates real world driving for you and me. That's why it is usually a lot slower compare to their regular test. And furthermore, the times that the IS-F got from C&D is not that far off from the M3's and RS4's results. And their specs are very close also, so i don't see this being controversial at all.
Hmmm, you never doubted my calculations? That is all you have done.

Quote:
And just because you have used a formula to estimate the performance and come up with some data, all that is is an estimation. The real data is what the car will do on actual driving condition, no formula will come up with a better result than that.
Quote:
And just because you have used a formula to estimate the performance and come up with some data, all that is is an estimation. The real data is what the car will do on actual driving condition, no formula will come up with a better result than that.
Quote:
Again, as accurate as your calcultion can be, it does not calculate real world testing and situations.
What you continue to fail to realize is that every real world test is just a good as another. They all have variables and uncertainly. Unless they screw up big time, each is a valid data point. The same variation (at least most of it) can be accomplished with simulation and I have pointed out all of the variables and processes that go into simulation along the way. Despite your stubborness I think you are learning a bit here.

Last but not least when you say the M3, RS4 and IS-F "specs" are close you have to dive a lot deeper than hp! So on the surface you are correct but looking at what matters you are terribly and grossly wrong. You need peak torque, the enitire torque curve, the weight and last but not least one of the most important things you keep over looking is the importance of the transmission type and gear ratios (gears AND final drive). Did you happen to read my post about torque multiplication and showing how the M3 has about 25% more torque delivered to the ground than the IS-F in 1st gear (and similar but smaller advantages in other gears)? I don't, and no one who knows anything, gives a rats a$$ about the engine peak torque spec. or even rear wheel dyno torque results comparing the these two (or any two cars for that matter...). The torque delivered to the wheels divided by the weight is an absolutely essential factor. It is absolutely not about which car I like better or which has superior data sheet specs. - it is about consistency of all of the specs, testing, data and simulation. If the IS-F had the superior torque delivery and poor real world tests I would be just as confused and questioning everything as well!
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      10-26-2007, 12:10 PM   #87
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Quote:
Originally Posted by GregW / Oregon View Post
- "'The goal is not to make a BMW M3,' Yaguchi said, though many people will see it as such. 'The M3 is fun for a realy good driver, but if you're not a really good driver, int's not fun,' he said. 'This is a car everyone can enjoy; with this dcar you skill level doesn't matter.'" -- Great!
This seems interesting and weak. Then why did they stick a 420hp engine in it? Not the best way to differentiate a product. It sounds like they are hedging against potential failure here.
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      10-26-2007, 12:17 PM   #88
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Swamp, physics is not the strong suite of a lot of car guys. It gets in the way of things like big brake kits making the car stop faster.
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