いきなりですが、長文失礼します。しかも英文(^-^;
後で要約してますので、あれだったら読み飛ばしてください。
海外でこんなレポートがされてました。
Calculating track times.
An effective way to predict a lap time on any high-speed road course by measuring against others.
~ by Norm McAverage
There are some out there that act confused that some people find Nissan’s R35 GT-R manufacturer laps believable. So to answer the begged question; Why is that exactly?
Well what you certainly wouldn’t want to do is take one car specification, like power-to-weight-ratio, and blow it out of proportion. That might work in drag-racing, but not for any type of track where one must consider grip, weight distribution, center of gravity, or aerodynamic properties to improve lap times.
No, a more scientific way to do it would be to extrapolate based on how well a set of cars performs elsewhere during timed laps. Let’s verify by crunching some numbers.
If we are going to benchmark the GT-R here, it would be nice if we had a control car; something that always performs well against the Nissan. Viper fans will have one more reason to smile, because today we’re going to use the ACR as the standard to which all others are judged. It has been timed at more tracks than the Corvette ZR1 and performs better than all the other entrants.
We end up with a statistically relevant set of data:
We can graph these one-dimensionally to show the difference in seconds each car came in relative to one-another. As best as run-of-the-mill graphing software can promise, it’s all to-scale - time difference in time is denoted by distance on the graph. If you’ve noticed that the hash marks are not equal, that is true. They are not intended to be. We’re interested in relative position. So the gap between the first and the last time will be set equal on each graph.
This is very telling actually. You should see a pattern developing here. If not, maybe a little further analysis is necessary. How about extrapolation? Since tracks have different lengths, we can find out how many seconds each car is falling behind the ACR for every minute of timed racing.
Now, if we wanted to project how far behind the ACR each car will be on the Nurburgring, we can take the seconds they fall behind per minute, and multiply by the number of minutes the ACR took to lap the ‘Ring.
The math actually works pretty well. We can project how fast each car would go around the Nurburgring, whilst totally ignoring their actual reported ‘Ring times, and then compare.
It’s not a perfect calculation, but that’s only because we have a maximum of five data points. Given more data points, I think we’d see those predictions come closer to hitting right on the money. Also, manufacturers tend to push pretty hard around the ‘Ring for several tries, so it’s no wonder they beat their average on other tracks by a handful of seconds.
For those that need it explained, most of these cars perform very similarly relative to the ACR on other tracks, as they do on the Nurburgring.
This should not be looked at as a GT-R versus 911 only analysis. Technically, it is every car versus the ACR. But it is clear that the GT-R consistently posts better ‘best laps’ than the Porsche 997 Turbo.
Though there is some controversy left to be had. Based on the Turbo’s performance on tracks where it has been tested against the Viper, there is no way it should be putting down a Nurburgring time close to what Porsche reports. It is just so much slower than the Viper ACR everywhere else, that 7:38 doesn’t make mathematical sense.
Of course that does not prove that, with the right driver, the Porsche could not go 15 seconds faster on the Nurburgring. Without any evidence, we are in no situation to determine that Porsche lacks a driver to make up the difference. It would be foolish to debate that ‘Ring times are 100% repeatable with all the various factors to consider.
‘Worst times’ have no statistical relevance in a comparison of ‘best times.’ A car can always be driven slower than the best time if the driver and conditions are not ideal. It may also be true that any of the cars above could achieve a better ‘best time’ if driven harder. But we are not guessing, adding a correcting factor, or manipulating for the purpose of skewing the results in any way. Those are the actual reported times here, and they are all being treated equally, at face value.
Some things to keep in mind about these times may be that while the Toshio Suzuki timed lap was on the Dunlop tires mounted to the Premium GT-R’s knurled rims, most press cars were shod with the base-model’s Bridgestone footwear. Technically, that ought to make an even stronger case for the GT-R to be able to stay within somewhat distant visual range of the Viper ACR - but still out in front of the others - on any track.
Another thing to note is that these times are all different press cars with different drivers. It’s not like it’s a single ‘ringer’ snatching up respectable times for any company. Though the GT-R is the most readily criticized for using a ‘Ring ringer, its very similar competitive prowess on other tracks does not support this conspiracy theory.
It is also clear that neither power-to-weight nor traction has been an issue for the GT-R on other paved surfaces. The GT-R posts a phenomenal time in stock configuration, repeatedly.
If you are thinking, I know there are more tracks than this, you are correct. And in future updates, I will work to compare the GT-R to all of its common competitors. For right now, it is most convenient to compare to the Viper ACR. I should warn however, that after looking at the data that I will need to crunch for that eventual more detailed chart, the results will not be changing much. In short, there does not appear to be an environment where the GT-R does not perform as advertised.
While it’s not proof, it does yield a rough equivalency formula:
Viper ACR > Nissan GT-R ~ Porsche GT2 > Corvette Z06 ~ 911 Turbo ~ GT3
This mental calculation has been going on in many of the GT-R acceptors’ heads for some time, brought into focus in pretty colors - if not just to annoy a few more skeptics. It makes a strong case for the ‘anywhere, anytime’ capabilities of the R35 Nissan.
While it may not be the fastest sports car in the world; if you measure what a car can do by what it’s already done - statistically speaking - Nissan’s manufacturer’s claim is not farfetched.
要約すると、GT-Rの公表ニュルタイムを確認するため、各サーキットのラップタイムから以下のように統計学的に計算してみた。
①アメリカの各サーキットでダッジ・バイパーACRを基準にいくつかのスポーツカーのタイムの実績値を並べてみた。
②これだけではサーキットは長さもコーナーの数や上り下り様々なので同じ土俵で比べられない
③そこで各サーキットにおける基準車（バイパーACR）が1分当たりに走る距離を各スポーツカーが何秒で走る計算になるか数値を換算し、それを5サーキット分で平均化した。
④その平均化された係数をもって、ダッジバイパーACRのニュルタイム、7分22秒1から各スポーツカーのタイムを投影した。
⑤結果、各スポーツカーのニュルタイム換算値は公表とほぼ同じになった。ただ一台、Porsche turboを除いて・・・
てな具合です。実際に電卓片手に計算してみましたｗ
日本にも筑波のタイムでニュルタイムが投影できるって中谷明彦さんが論じてますよね。この場合、筑波サーキットを経験則で語っているのですが、上記は5箇所の平均値を用いているので、統計学的により信頼性が高い、ということですかね。
ただ、日本でも広報車疑惑がいつまで経っても声高に騒がれてますが、アメリカでも同じようなことで騒ぎになってるみたいですね。
恐るべしR33の呪縛（爆）
そしてこんにちはR35 7:29@The Ring！
ただ問題がひとつ・・統計された5つのサーキットに比べればニュルははるかに長く、「人間の集中力、精神力」のファクターが加味されてないことです（核爆）
R35 GT-R Nismo スポーツリセッティング 
GT-RBlogによると、例のFIA-GTにスポット参戦するマシンのスペックが明らかになりつつあるようです。
画像はWALDさんからお拝借・・・(^-^;
