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      10-22-2008, 07:20 AM   #1
swamp2
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Estimate of THE 7:29 GT-Rs power based on Nurburgring straight sections

For all that have followed the lively debate, here or other places, I think I am heading back toward the direction that the GT-R (ringer!) that achieved the 7:29 N'Ring time is not just slightly under-rated but substantially under-rated. Keep in mind anyone paying attention will realize that the GT-Rs that have been tested vary quite drastically. This is intentional, it can not be purely by accident or tolerances. What I am speaking to in the first analysis in this post is THE PARTICULAR CAR that achieved the 7:29 Nurburgring Nordschleife time.

Let's forget for a moment about the GT-R being faster through corners than a 997TT, or having a better AWD hardware and software and generally exiting corners faster than many competitors. Let's also forget that in some straight line competitions it bests some of its well known competitors but in others it loses. Let's simply consider the raw acceleration of this car when exiting a fast corner (around 100 mph at Schwalbenschwanz, at around km 16.5) and on to the long stretch (Döttinger Höhe). We surely can all agree that this is nothing but a speed contest, a rolling start drag (granted a pretty fast rolling start) and a hp war.

I used the following videos to grab some distance vs. time results and speeds where available (others have obviously found this particular car as suspiciously fast as I have...).
  • ZR1 vs. GT-R vs. Zonda (Long Straight): Link.
  • Viper ACR vs. ZR1. Link.
  • Viper ACR. Link.
  • GT-R "official" 7:29 video. Link.

All of this action for my analysis begins around 6:30 by the timer in the ZR1. Thanks to Chevrolet for providing more data than the other folks discussed herein!

The times are gathered for time to achieve known distance markers along the track consisting of a banner, various signs on the RHS of the track and the first bridge. I estimate the worst uncertainty in these estimates to be only about +/- 0.3 seconds. Go full screen, use quick mouse double clicks and take the data yourself, you will find you can get good precision. Do note I am NOT using youtube video times but the recorded times from the accurate in car timers. If you really want to follow along open the ZR1... spreadsheet attached in the zip file below and look at the first table. It is immediately apparent that all cars are accelerating quite closely. You barely need my analysis that follows but here we go...

It is VERY unfortunate that neither Dodge nor Nissan provided a speedometer in their videos but we can still do some basic calculations, modeling and predictions. We will begin with the ZR1. I ran some CarTest simulations for all of these vehicles. For those of you who have not read my previous posts CarTest is a physics based vehicle simulation software which includes a great deal of factors and phenomena such as engine power curves, parasitic losses, gear ratios, shift times, tire sizes, environmental conditions, aero drag, clutch drop/launch, etc.). Specifically for the ZR1 I used a total drivetrain loss of 15% which reproduced 0-100 mph, 1/4 mi time and traps within the range of various actual test values. The only other parameter I altered was shift time and I chose 0.3 s with .05 s for clutch activation. Since the ZR1 has the speed data along with the times in the second set of tables I can do some strong validation of this model. First I used CarTest to calculate a speed vs. time trace beginning at the known corner exit speed. I compared this to the known pairs of (speed, time). Coming out with a significant error and wondering why, I observed the difference between Vmax on this lap and the reported/observed/simulated top speed of the car (all within 1 mph of each other! at 206 mph). I read a bit more about this lap and GM was reporting significant winds. My first guess of a head wind on that straight was 15 mph. Placing this into CarTest my predicted times all fell within 2% of the recorded results (one slight outlier point had a mere 4% error). Pure luck on this guess.

Feeling quite confident with this model I moved along to the ACR. The ZR1 can outgun the ACR in a straight line test of raw acceleration based on both power to weight and simulation as well. However the ACR does corner like a race car and generates over 600 lb of downforce at around 100 mph. I estimated where the ZR1 exited at 109 the ACR was probably more like 113 mph (a bit more about justifying this number later). Simulating the ACR with no headwind finds the two cars very close, just like the video and extracted times. Since it was not supplied, I calculated both speeds and times for the ACR and in general was within about 5% accuracy. Finally on the the GT-R...

I concluded this from data in the Car and Driver Lightining Lap 2008 (Link here that the GT-R probably exits this corner closer to or slower than the ZR1. In that test, on one particular corner at VIR with exit speeds quite close to this one, the ACR blasted out at 113 mph and the GT-R trailed a bit at 107 mph. An exit value of 107 for this exit produced results that made the CarTest simulations consistent with an almost dead even acceleration to the ZR1 (again with the 15 mph head wind) but lagging slightly behind it. This is very evident when you watch the signs fly by on the RHS in the first video above. The KEY ASSUMPTIONS on the GT-R model is that it was simulated WITH 550 crank hp AND identical drivetrain losses to both other RWD vehicles (15% in this case). Here I am being generous and assuming a 100% transfer of power to the rear wheels by the GT-Rs ATTESA-ETS AWD system thus leaving any additional AWD losses zeroed out of the simulation.

Again the full data tables are included in the first worksheet of the attached/zipped Excel file. A graph showing distance vs. time of all of these vehicles is on the second worksheet and finally the CarTest tabular data is on the last worksheet. What we see from the graph is how similar a 550 hp "RWD" GT-R is to these other vehicles and how a GT-R with factory specified power is simply left in the dust. The tabular data shows how well the models predicted the initial burst of acceleration out of the corner compared to observations (the range of ~110 mph - ~145 mph).

I fully expect you could repeat a similar analysis for many straight sections of the track and find similar results. I'd wager on 530-560 hp WITH a drivetrain loss of a RWD vehicle (or 560-590 hp with a 20% drivetrain loss).

Conclusion #1. The 7:29 GT-R accelerated from around 100 mph, on to Döttinger Höhe, neck and neck with the ACR and ZR1. To do so at its stated weight it was producing approximately 550 hp and and had a conservative drivetrain loss comparable to the 2WD ACR and ZR1 cars. If the car has a drivetrain loss closer to 20% it was producing closer to 580 hp.

Next, just to be thorough, I revisited the power to weight vs. lap time regression armed with this result (see thread here). Again all tables and regressions are included the other Excel file in the attached zip file. We now find the GT-R with the new 7:29 time (and factory specified power) to be an outlier by a whopping 33 seconds which corresponds to 3.4 standard deviations outside of the model. This means there is about a 0.1% chance that this result is consistent with the model. It simply means something else is going on with the GT-R compared to all of the other cars. Again this is the single largest outlier in the model and is so by an enormous margin (it was already an enormous outlier with the previous time of 7:38). The next best over performers are both a bit less than 2 standard deviations better than the regression; the Porsche GT2 (and it was driven by Roehrl, not Horst) and E46 M3 CSL. (Note: I am not counting the Audi S3 here as I suspect a typo or some other anomaly contributing to it being a large outlier). If we simply give Tochio Suzuki's GT-R 550 hp the amount the car is an outlier is decreased to about 26 seconds better than the regression, which is 2.8 standard deviations. 550 hp finally gets us just inside the 3 standard deviation "rule" or the so called "3 sigma" rule. Still evidence of a very fast and capable car, even at this power to weight ratio. Also, a vastly more believable result. Those still suspicious of the regression and why we can't just use the linear formula to calculate this GT-Rs power keep in mind there are plenty of deterministic effects here contributing to the car over performing. These include but are not limited to: a suspension slightly tweaked by Nissan, fantastic rubber, tremendous practice of the track by Suzuki, the DCT system (which was conservatively modeled with 15 ms shift times), the advanced AWD and traction/stability control system, the car being generally accepted as being very easy to drive and push to the limit, potentially favorable track conditons and temperature, etc., etc.). Look at the existing variation in the chart, there are a lot of data points and many under and over performers. Many of which make perfect intuitive sense.

Not satisfied with just a regression for the Nurburgring I also did one for the Car and Driver Lightning Lap at VIR and for the Top Gear Track. For the Top Gear Track I deleted many cars I could not find data for or that were sort of "odd balls" as they have tested some rare not generally available cars (at least in the US). For the Lightning Lap the GT-R with stated power is still the largest outlier in the group, outperforming the regression by 7 seconds out of approximately 1.25 minutes. The interesting thing is that although it was again the single largest outlier it was "only" an outlier by 1.6 standard deviations. So much more believable than the 7:29 N'Ring result. The MoslerMT900S and Viper ACR being such "poorly tuned" track vehicles were "only" outliers by 1.3 standard deviations. It took adjusting the power of this GT-R to 500 hp to match the same level of over performance of the ACR and Mosler. Once again at the Top Gear Track the GT-R was the largest outlier and was so by 2.1 standard deviations. With the Top Gear data set it took the assumption that particular car was making 520 hp to bring the car in between the next two best over performers, the Cayman and Pagani Zonda F. Again real slouches in the handling/track department (immense sarcasm there for those who didn't pick that up).

Note that all three tracks while all exhibiting good R^2 values (0.83, 0.84. 0.70) exhibit predicted slopes that are drastically different, 16.7, 8.3, 3.0. Why? Just as I have theorized previously a faster track will have more time spent in drag like conditions (of course not meaning from 0 speed but still like a rolling start drag). For such tracks handling and cornering are less important as compared to what wins drag races for you - power to weight! Of course the slopes are ordered exactly the same way the tracks average speeds are. Power to weight matters on all tracks, even on a very tight non road course such as an autocross track, but how much faster you will go per additional hp (or per reduced lb), all else equal, is clearly less. Here the physics clearly agree with the regressions in terms of regression slope vs. average track speed.

So my conclusion #2 from this further regression analysis. A GT-R with 550 crank hp and a real ace driver producing a 7:29 N'Ring lap time is just within the 3 sigma realm of the regression model. The amount that the particular cars used in the Lightning Lap and by Top Gear for their tests were under-rated is not nearly as much as the car used for the 7:29 N'Ring run. This is consistent with the cars history of inconsistent performance.

I think most of us agree that an under rated car, a very practiced and top notch driver, favorable conditions and a tremendous track support team and marketing effort all contributed to this fantastic time for this fantastic car. Nonetheless, given the gut feeling from watching these videos and examining the times achieved by these other cars we can pretty quickly tell that this particular 7:29 GT-R was a real ringer, both in terms of power to weight and perhaps other favorable factors.

I will leave you with this great article with a balanced perspective on this whole issue. As if my analysis and post was not long enough! Do have a look here at Speedsportlife.com if you are at all interested in this particular "achievement" by Nissan, the ensuing Porsche-Nissan battle and to better understand the changing role of the Nurburgring.
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      10-22-2008, 09:01 AM   #2
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After about the third paragraph I wanted to commit suicide. Sorry swamp, it might have been needed necessary to fully cover all the bases but Jesus man it's a hell of long winded.

I promise I will read it and re-view all of the link and give a professional comment when I get time.
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      10-22-2008, 09:46 AM   #3
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      10-22-2008, 09:59 AM   #4
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OK swamp,

I thought I would look through YOUTUBE for the videos and found one which matched up the ZR1 with GTR, both coming on to the final straight at the same time.

Well to cut a long story short, when the bridge when out of view in the ZR1 the Nissan's time log read 7:06.38 and when the bridge when out of view in the GTR it was 7:08.99, over 1.5s later. Now I don't have either the equipment or the time to work this out so maybe you might be able to estimate the speed of the GTR at that point.

I'm guessing it's a good 10mph slower than the ZR1 which was doing 176mph at that time. If my estimates are right and lets say they both rounded the corner at the same speed (which I doubt) that means the Vette is pulling harder.

P.S.
I still believe that the time is constant with which another GTR could do and that all of them are under-rated by about 10%.
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      10-22-2008, 12:09 PM   #5
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do you not have a job
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      10-22-2008, 12:46 PM   #6
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Wow! Thank you very much for such detailed analysis. So is it safe to say that the GTR that the consumer will be purchasing from a dealer will not have 550hp which also explains why many GTR owners are getting around 12 seconds and no more than 118mph trapspeed in the 1/4 mile. And if by any chance that every GTR is making 550hp, is it still possible for it to have a lower trapspeed than other cars with similar power/weight or in some cases lower hp than the GTR such as the M6?


BTW, i'm exhausted from reading your post, regardless though, excellent post. Thansk again.
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      10-22-2008, 03:09 PM   #7
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Guys, if you don't like it don't read it. I am open to a discussion even disagreement/criticism but if you don't have anything constructive to say you can just say nothing.

Footie: We are slightly crippled by not having speedos in the other cars but not totally crippled. The time difference I have at the bridge is a mere 1.1 seconds, but not that 1.5 seconds would make a difference. My simulations show the times for 109->174 for the ZR1 and 107-174 for the GT-Rs are:

ZR1 with head wind: 18.0 s
GT-R "RWD" with 550 hp: 18.7 s
GT-R "RWD with 480 hp: 23.8 s

Differences from prediction:

ZR1: -0.2 s

The tables in the spreadsheet do not just address this single point but show how the cars I simulated match the videos across the entire section. Did you look at the Excel file (doubtful?)

I chose the 174 mph point as there was a fixed marker close with when the ZR1 first hit 174, after that speed it nearly entirely stopped accelerating (wandered up and down in speed a bit).

Feel free to provide an estimate for THIS cars power based on the 1.1 or 1.5 second difference if you like.

Last edited by swamp2; 10-22-2008 at 11:25 PM. Reason: Typos
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      10-22-2008, 03:48 PM   #8
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Quote:
Originally Posted by jaeS4 View Post
Wow! Thank you very much for such detailed analysis. So is it safe to say that the GTR that the consumer will be purchasing from a dealer will not have 550hp which also explains why many GTR owners are getting around 12 seconds and no more than 118mph trapspeed in the 1/4 mile.
Sure. I have no idea what "most folks" are getting when they buy. Using their 1/4 mi times will obviously exhibit a large range of numbers, some of the range is due to obvious things like driver skill and true environmental differences. I do think the range we saw in earlier magazine testing represents a larger range than what would be exhibited under controlled testing with most folks cars. Do note the spreadsheets I posted should not really be used for 1/4 mi trap comparisons. Since I wanted to give the GT-R the benefit of the doubt I simulated it a a RWD car! Of course the 0-60 times go down a bit when you turn the AWD back on in the simulations. Lastly, I do suspect that an average purchased vehicle with Suzuki-san driving will not achieve a 7:29.

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And if by any chance that every GTR is making 550hp, is it still possible for it to have a lower trapspeed than other cars with similar power/weight or in some cases lower hp than the GTR such as the M6?
I think you made a typo above?

Short answer, if I understand you correctly is, I don't believe so.

I find a range of trap speeds for the M6 that covers about 114-118 mph. You can find numbers slightly above or below those. My CarTest simulations give 12.4 @ 117, using the default drivtrain losses. Values are quite sensitive to assumed losses. Using more conservative loss values I find 12.1 @ 120. I don't think stock M6's can quite get there. A GT-R with 550 hp should trap pretty consistently at or above this upper range.

Even a GT-R with 480 hp has a substantially better power to weight (weight to power actually) of 8.0 lb/hp vs. 8.7 for the M6. 550 hp puts this figure in a totally different league at around 7.0.
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      10-22-2008, 04:54 PM   #9
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swamp,

I have watched and re-watch these videos (ACR, ZR1 and GTR), part way along there is fencing to the left as they start on the straight proper. Well from that point until the bridge the ZR1, ARC and GTR match each other, posting times in the 27 seconds (the Vette being 0.4s quicker than the GTR to that point) and the ACR somewhere in between. But look at the Viper, less than halfway down the straight it was hitting the limiter which it did on three occasions.

Now to me what this tells me is that the Viper would have easily win this if allowed to go harder which it clearly could have done, the Vette also seemed to reach the 170mph mark and then all but stopped accelerating. The only car who's engine seemed to keep increasing was the GTR which might explain why the times all but match each other.

We know why the Viper matched the GTR's time, that's easy because it was limited to a certain speed, but the Vette is harder to understand unless like you say, it was running into a head wind.

Which leaves the GTR?

I reckon based on the evidence here and acceleration figures else where that it was running a decent tail wind.

This still doesn't mean it's a ringer, only it possibly have more going for it on that day.
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      10-22-2008, 05:17 PM   #10
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Quote:
Originally Posted by footie View Post
swamp,

I have watched and re-watch these videos (ACR, ZR1 and GTR), part way along there is fencing to the left as they start on the straight proper. Well from that point until the bridge the ZR1, ARC and GTR match each other, posting times in the 27 seconds (the Vette being 0.4s quicker than the GTR to that point) and the ACR somewhere in between. But look at the Viper, less than halfway down the straight it was hitting the limiter which it did on three occasions.

Now to me what this tells me is that the Viper would have easily win this if allowed to go harder which it clearly could have done, the Vette also seemed to reach the 170mph mark and then all but stopped accelerating. The only car who's engine seemed to keep increasing was the GTR which might explain why the times all but match each other.

We know why the Viper matched the GTR's time, that's easy because it was limited to a certain speed, but the Vette is harder to understand unless like you say, it was running into a head wind.

Which leaves the GTR?

I reckon based on the evidence here and acceleration figures else where that it was running a decent tail wind.

This still doesn't mean it's a ringer, only it possibly have more going for it on that day.
Again this is specifically why I chose to look at the first point the ZR1 reached it's maximum speed. This is around 18 seconds after the exit. Up to this point we have nothing but a power to weight war (with aerodynamics properly accounted for in the real world and my models giving some benefit to the GT-R). I don't care too much about what happens after that point although the times to the first bridge are included in my spreadsheet.

What is your estimate of the power THIS car was producing. It is easier to critcise than commit isn't it ?
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      10-22-2008, 05:58 PM   #11
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do you not have a job
I think that the OP has demonstrated that he is quite skilled at quantitative analysis and moreover has addressed and rebuffed criticism of his methodology in a consistent and fair way.

Maybe these might be the kinds of skills that employers would value. I would anticipate that they might prefer his skill set to that of a reactionary member of the peanut gallery who apparently smells like poop.
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      10-22-2008, 06:06 PM   #12
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How can you estimate an output figure without all of the facts, like wind direction on the day, the actual exit corner speed, not a rough guess based on what was achieved at another track (a smoother one). Also, to my eyes the GTR looks to be coming out of that last corner faster than either the Vette or the Zonda.

I understand what you are trying to achieve here but feel you are working the numbers to conform to what works with your limited infomation.

I still believe that this car, like all the other GTRs are under rated by about10%. Why discount all the other independent evidence from customer's grey imports, not only Nissan press cars.
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      10-22-2008, 11:37 PM   #13
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Quote:
Originally Posted by footie View Post
How can you estimate an output figure without all of the facts, like wind direction on the day, the actual exit corner speed, not a rough guess based on what was achieved at another track (a smoother one). Also, to my eyes the GTR looks to be coming out of that last corner faster than either the Vette or the Zonda.
There is more work that can be done. Making estimates without 100% of the information is both art and science. I outlined my procedure very carefully and it seems pretty clear you do not follow it.

My analysis does not eliminate every single possibility. It is simply one more analysis to add to the large available set of cases which indicate the same general conclusion. I did assume no wind on this stretch for the GT-R. Would it make sense for them to run such a record breaking run on a windy day? I guess GM did but I think there is much room for improvement on the ZR1 time, the engineer driving was not top notch at all. Either way these cars performance differences based on driver differenes are mostly eliminated when doing this kind of analysis. There could definitely be more work done on a sensitivity study of the corner exit speeds for the GT-R but the preliminary work I did there (and did not talk too much about) shows a few mph here or there does not make a lot of difference. You can not make the exit speed too high (contributing to less under rating) simply because other than a small offset the cars are very close initially and up to 174 mph. Let the GT-R exit too fast and it is inconsistent with the observations. As far as comparing the ACR with the GT-R exits speeds, rough or smooth track, I think a trend would definitely be observed. The ACR has tremendous downforce and this is one of the dominant limiting factors in cornering and exit speeds.

By the way can you really see couple of mph in relative exit speed in these corners? If so please prove it, try to not make everything a simple hunch or guess or a "to my eye". Debate required more than opinions. Well good debate...

Quote:
Originally Posted by footie View Post
I understand what you are trying to achieve here but feel you are working the numbers to conform to what works with your limited infomation.
You obviously don't understand my desires and motivations. I did the study because the videos looked interesting and based on previous discussions on the forum about the GT-Rs time being from "dominance" in the corners, which has some contribution for sure, but I always believed that to be a small part of the puzzle. To me understanding > facts > brand lotalty > fanboy-ism.

Quote:
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I still believe that this car, like all the other GTRs are under rated by about10%. Why discount all the other independent evidence from customer's grey imports, not only Nissan press cars.
In my estimations a "RWD" GT-R with 530 hp (and a the same ratio over quoted as stock) would do the 107-174 run in 19.9 s as opposed to 18.7 seconds. Again this is the time to reach 174 NOT the time to the bridge. This analysis points to that car having more than 530 hp, i.e that is has more than 10% more than specification.

Lastly, I would say calling ALL GT-Rs 10% under rated absolutely contrary to the data. We have plenty of 1/4 mi times and traps that say this is not true. As well this was a conclusion of my regression analysis, which you also seemed to have entirely missed the point. I firmly believe the specific 7:29 car was substantially more under rated than the Lightning Lap and Top Gear cars.
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      10-22-2008, 11:39 PM   #14
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Quote:
Originally Posted by M3 LUST View Post
I think that the OP has demonstrated that he is quite skilled at quantitative analysis and moreover has addressed and rebuffed criticism of his methodology in a consistent and fair way.

Maybe these might be the kinds of skills that employers would value. I would anticipate that they might prefer his skill set to that of a reactionary member of the peanut gallery who apparently smells like poop.
Thanks much. Appreciate your comments. I do have an employer right now but do not use much of these skills in my job, maybe that is why stuff like this is just kind of a fun technical hobby. Cheers.
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      10-23-2008, 12:01 AM   #15
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Quote:
Originally Posted by M3 LUST View Post
I think that the OP has demonstrated that he is quite skilled at quantitative analysis and moreover has addressed and rebuffed criticism of his methodology in a consistent and fair way.

Maybe these might be the kinds of skills that employers would value. I would anticipate that they might prefer his skill set to that of a reactionary member of the peanut gallery who apparently smells like poop.
quite the wordsmith i see. i was merely pondering the quantity of time that the OP doth contain in his hands whence writing such musings. i wasn't trying to insult anyone, but the amount of time needed for the analysis and everything seems like it would be fairly substantial tho it is a hobby. either way it is pretty impressive.
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      10-23-2008, 02:35 AM   #16
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Quote:
Originally Posted by swamp2 View Post
Sure. I have no idea what "most folks" are getting when they buy. Using their 1/4 mi times will obviously exhibit a large range of numbers, some of the range is due to obvious things like driver skill and true environmental differences. I do think the range we saw in earlier magazine testing represents a larger range than what would be exhibited under controlled testing with most folks cars. Do note the spreadsheets I posted should not really be used for 1/4 mi trap comparisons. Since I wanted to give the GT-R the benefit of the doubt I simulated it a a RWD car! Of course the 0-60 times go down a bit when you turn the AWD back on in the simulations. Lastly, I do suspect that an average purchased vehicle with Suzuki-san driving will not achieve a 7:29.



I think you made a typo above?

Short answer, if I understand you correctly is, I don't believe so.

I find a range of trap speeds for the M6 that covers about 114-118 mph. You can find numbers slightly above or below those. My CarTest simulations give 12.4 @ 117, using the default drivtrain losses. Values are quite sensitive to assumed losses. Using more conservative loss values I find 12.1 @ 120. I don't think stock M6's can quite get there. A GT-R with 550 hp should trap pretty consistently at or above this upper range.

Even a GT-R with 480 hp has a substantially better power to weight (weight to power actually) of 8.0 lb/hp vs. 8.7 for the M6. 550 hp puts this figure in a totally different league at around 7.0.

What /weight/hp figures are you using for the M6?

The curbweight of the M6 is ~3900 lbs and the hp is 500 hp.

weight/power ratio of 7.8


The GT-R is ~3800 lbs and 480 hp

weight/power ratio of 7.91




As we've seen from the huge range of GT-R trap speeds, the M6 is right on par. And if you consider the BMW has a launch deficit and isnt able to use it's power as soon, and the GT-R loses 2-3 mph without LC (which voids warranty btw), they are essentially identical.

Though I am giving the faster GT-R's a credit of being around 500 hp and 480 for the lower ones (that are trapping 114 mph)


I'd really like to see them going from a roll, I'd bet the M6 would be equal to 1 carlength behind and maybe even edge the GT-R out in some cases.
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      10-23-2008, 03:04 AM   #17
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There is more work that can be done. Making estimates without 100% of the information is both art and science. I outlined my procedure very carefully and it seems pretty clear you do not follow it.
Seriously swamp, it was giving me a sore head just reading the thing. After a long day no-one wants to read anything this heavy on an empty stomach, it wasn't a case of not following you, just couldn't be ass-ed doing it.

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I did assume no wind on this stretch for the GT-R. Would it make sense for them to run such a record breaking run on a windy day? I guess GM did but I think there is much room for improvement on the ZR1 time, the engineer driving was not top notch at all.
Here's where your credibility when out the window. Do you really think that their goal every-time they take to the circuit is to break the lap record? Or that they stop a good lap from continuing because the final straight is windy. COME ON swamp, think of what you are saying here. You allow the ZR1 to run into a head wind because it works to your set plan, enough though it was also on a record lap but don't allow the thought that Nissan might also be facing a wind that day, only heading in the other direction.

The rest of this discussion is not worth discussing because of the above. You are looks to find fault because you can't bear to think that Nissan are able to produce a car capable of lapping 36 seconds quicker than the M3 for the same money.
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      10-23-2008, 04:06 AM   #18
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Seriously swamp, it was giving me a sore head just reading the thing. After a long day no-one wants to read anything this heavy on an empty stomach, it wasn't a case of not following you, just couldn't be ass-ed doing it.



Here's where your credibility when out the window. Do you really think that their goal every-time they take to the circuit is to break the lap record? Or that they stop a good lap from continuing because the final straight is windy. COME ON swamp, think of what you are saying here. You allow the ZR1 to run into a head wind because it works to your set plan, enough though it was also on a record lap but don't allow the thought that Nissan might also be facing a wind that day, only heading in the other direction.

The rest of this discussion is not worth discussing because of the above. You are looks to find fault because you can't bear to think that Nissan are able to produce a car capable of lapping 36 seconds quicker than the M3 for the same money.
Hang on, don't mind most of the comments & statements being made here but isn't there's $40k difference in price, M3 $60k, GTR $100k, even with discounts it's still $30k.

I don't mind comparing a GTR to a Pooch, although there is a hugh difference in price between those two cars but they compare in spec, but I have never compared a M3 to a GTR in performance, maybe in style, ride, looks, etc but the GTR may have the wood on a M3 but there's no stable in a Nissan. S**t I would have wait another 12 years before the next one came out and I would probably be dead by then.

Anyway, it is a fast car, give Nissan credit for that but not my cash.

Carry on fella's, I await the next installment. My $0.02
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      10-23-2008, 04:14 AM   #19
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Quote:
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Here's where your credibility when out the window. Do you really think that their goal every-time they take to the circuit is to break the lap record? Or that they stop a good lap from continuing because the final straight is windy. COME ON swamp, think of what you are saying here. You allow the ZR1 to run into a head wind because it works to your set plan, enough though it was also on a record lap but don't allow the thought that Nissan might also be facing a wind that day, only heading in the other direction.
Not sure I would call this a "credibility" issue. But is is absolutely worthy of further discussion so thanks for bringing it up. GM has reported strong winds during the day of their run, Nissan didn't. I can address this factor in my simulations and it matched the actual real world very well. I call this thorough, not biased. My ZR1 simulations without wind were right in the ball park with other reported values and without the wind they did not match the video. Hmmmm should I have ignored this? Nonsense, utter nonsense.

So let's get down to brass tacks now.
  1. Nissan is more than happy to talk endlessly about what tires they did or did not use and that the track was a hair damp on certain runs. Do you really think they would leave out strong head winds on a "record breaking" run?
  2. What if Nissan had a head wind and still performed just as well? All this would do is strengthen my case for the severity of the under rating.
  3. IF the Nissan had the same 15 mph wind but as a tail wind this can be simulated trivially. Hmmm, done, in an instant... I ran the "AWD" GT-R with 550 hp vs. the identical car with 530 hp (just used your guess for kicks) and a 15 mph tail wind. What happens? To about 150 mph they are extremely close. For the same 107->174 run the difference falls to about a 0.8 second advantage for the 550 hp version. So in short a 10% under rated GT-R (with all the aforementioned efficiencies making it have the losses of a RWD vehicle) could perform just about like the ZR1 with a 15 mph head wind in this particular track section. IF we learn of such conditions I then REVISE my models and estimates. Last I checked this is how decent science works, it adapts predictions as new information comes along.

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The rest of this discussion is not worth discussing because of the above. You are looks to find fault because you can't bear to think that Nissan are able to produce a car capable of lapping 36 seconds quicker than the M3 for the same money.
Herein always lies the problem with you and others. You second guess everything I present thinking I have some enormous bias. I don't and you can't prove that I do. How many times do I have to mention my admiration for the wonderful achievement that the GT-R is. Being a "techie" and a "car guy" how could I possibly not like the car. I don't find it aesthetically pleasing but that is not about appreciating, respecting nor admiring.

I really don't care how fast or not the GT-R laps except I do want some honesty. You readily admit a 10% under rating. Even if other manufacturers do this I call it unethical. 10% of nearly 500 hp is a good bit of power. What we are talking about is not if Nissan is lying it is simply how badly they are lying.

Hmmm next.... I don't consider the M3 and GT-R competitors. Many do and many don't. Personally I never considered the car for myself personally. I guess we will continue to disagree about the price difference between the cars as well. I think base price is a more fair comparison then trying to get the cars speced evenly then compare prices. This is simply opinion and preference, to each their own. However on that note I bet that the price is artificially low as well. I'd be willing to bet Nissan loses money on every GT-R they sell. It is for reputation and for halo marketing, not to make profit.

My search is for consistency and truth, that's about it mate. Take it or leave it. Ugh... I already know your answer, don't bother.
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      10-23-2008, 04:28 AM   #20
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Quote:
Originally Posted by heavychevy View Post
What /weight/hp figures are you using for the M6?

The curbweight of the M6 is ~3900 lbs and the hp is 500 hp.

weight/power ratio of 7.8


The GT-R is ~3800 lbs and 480 hp

weight/power ratio of 7.91




As we've seen from the huge range of GT-R trap speeds, the M6 is right on par. And if you consider the BMW has a launch deficit and isnt able to use it's power as soon, and the GT-R loses 2-3 mph without LC (which voids warranty btw), they are essentially identical.

Though I am giving the faster GT-R's a credit of being around 500 hp and 480 for the lower ones (that are trapping 114 mph)


I'd really like to see them going from a roll, I'd bet the M6 would be equal to 1 carlength behind and maybe even edge the GT-R out in some cases.
Mistakenly used the Vert weight instead of the Coupe weight . You are correct. For the GT-R I used 3830 lb (with side curtain airbag figure) and 480 hp. That gives 7.98 which I rounded correctly to 8.0. The other GT-R power to weight I was referring to was for a GT-R with 550 hp as per my predictions for their N'Ring ringer.

I don't really want to enter a debate on the M6 vs. GT-R. The problem with the GT-R is it is always WHICH GT-R are you talking about.
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      10-23-2008, 04:54 AM   #21
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swamp,

If Nissan did has a head wind which happened to give them an advantage on a major section of track on that particular day I would not be surprised to hear that they didn't mention it. Mentioning it would lessen their PR and their record lap.

The point I was trying to make is you can't assume anything just because it's not mentioned. As I said on listening to all the video, the only car which revs keeps increasing right to the bridge was the GTR, the Viper's were capped, that was plain to hear, the Vette sounds to me like it all but stop accelerating 2/3 of the way which matches the theory of head wind. But the GTR kept acceleration which leads me to think it had a tail wind of decent amount.

If you combine a better exit speed (3mph > ZR1) with a tail wind it is possible to match the results in the video.

That is my opinion and nothing will change that.
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      10-23-2008, 05:28 AM   #22
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swamp,

Regarding the price thing, it all depends on where you live. In the States the M3 is very cheap compared to other countries and that is a big deciding factor on any purchase, but here in the UK the GTR starts at £52K which is the same price as an M3 with DCT, so to not class them as rivals is silly .... here at least.

As for under estimating it's power output, all of them do it. The problem is proving how much without test them all at the crank because it's a guesstimate as to how much drive train lose there is in any system, especially one as advanced as in the GTR.

An example, I have hear ones stating the M3 has a 8% lose based on results from dynos. If the true figure is closer to 12% that is a 4% under rating of HP. I just can't see how we can guess these things without all the information.

I suppose I am a real life, hand on type of a guy. I believe in what I see and don't analise things to death. If like the GTR proves to consistently win it's comparison tests, even though it's slower in acceleration then I believe it's a very big possibility that it's ring time is true. Or should I say as true as any of the others.
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