GT-R breaks its own Ring record

[Garissimo]

Originally Posted by footie

On this I am in total disagreement and so is Swamp, Bruce and a heck of a lot more. It's as plain as day that the ZR1 was pulling away from the start of the straight until the bridge, now what happened after the bridge is harder to determine but according to Swamp he is of the opinion that Suzuki never lifted until well past the curve after the bridge and on watching the ZR1 lap you can plainly see the Vette driver lift. This may explain how the GTR peaked higher but I am 100% certain that prior to the bridge the GTR was comfortably slower than the Vette and produced a speed more in line with the GTR Chris drove.

My head hurts after reading all that. I can agree that the ZR-1 is pulling slightly on the GT-R, but see no evidence of it walking away. This is what a ZR-1 does to a GT-R in a straight line race:

http://www.youtube.com/watch?v=OZlGMX8G3B4

Suzuki's GT-R is keeping up much better than one would expect given that example, and this should raise a major red flag.

I will PM you my e-mail exchange with Jethro. He seems like a very polite fellow and I'm sure would respond to questions, as long as he isn't bombarded with the same ones.

As for the speedometer glitch, I think it's highly likely Nissan uses a traditional wheel speed sensor corrected by GPS. This gives you the best of both worlds; plenty of resolution and terrific accuracy. This explains the "glitch" at the spot in the track which coincides exactly where cars are known to get airborne.

Have a good weekend, sir.

[footie]

Regarding the Youtube video provided as evidence, thanks for this, it explains things even better than I hoped possible, especially when considered against the data from Driver Republics 'GTR vs GT2' test.

Check out the GT2's peak just prior to the bridge, it was higher than the ZR1 by quite a few mph yet in the Motortrend video (on a ultra smooth track I might add) shows the reverse with the Vette being comfortably quicker than the GT2. My only explanation is that the Vette driver feathered the throttle the closer he got to the bridge, but why? I can only assume that it's suspension setup caused a behaviour in the car that caused the driver to hold back slightly.

Unlike Nissan, with GM we don't have any telemetry to show throttle input but I bet anything that it would show a slight lift as it approaches the bridge.

Bob

[footie]

I just thought of something that might explain why Suzuki's lap was so magical.

If the telemetry does indeed show that Suzuki didn't lift the throttle all the way from the start of the straight until well pass the kink after the bridge then that would just show how much more committed he was than Chris because by my estimates he must have entered that kink at about 18-20mph more than Chris which took it at 160mph. Now imagine this extra commitment and speed throughout the entire lap.

Edit.
On matching up the final straight for both Chris's GTR run and the 7:29 lap for Suzuki I discovered some pretty amazing differences.

1# Suzuki was comfortably quicker entering the final long straight

2# I later matched their respective starting points to the Audi bridge and the difference between that bridge and the last bridge wasn't that great which leads me to believe that the speed difference at this point is slight (just as Swamp estimated it should be).

3# The time Suzuki made up over Chris front the start of the straight to the finish line, it was SHOCKING, Suzuki crossed the finish line over 3 seconds sooner than Chris, on that one section where there was only about 6 corners he destroyed Chris's time.

I am more and more convinced that Suzuki would be miles quicker than just about anyone around the ring in a GTR and this is solely down to knowing that it can defy the laws of physics. No one seems to be pushing it half as hard as he did. Chris reckoned only 10 seconds difference between him and Suzuki after the tyres were equalled up, sorry Chris but I would say you would have to double that estimate.

[Garissimo]

Originally Posted by footie

I just thought of something that might explain why Suzuki's lap was so magical.

If the telemetry does indeed show that Suzuki didn't lift the throttle all the way from the start of the straight until well pass the kink after the bridge then that would just show how much more committed he was than Chris because by my estimates he must have entered that kink at about 18-20mph more than Chris which took it at 160mph. Now imagine this extra commitment and speed throughout the entire lap.

Bob, if Suzuki-san really entered that kink at 18-20mph more than Chris, it's a safe bet he'd be off the track. To be clear, I'm talking about the entry point at Antoniusbuche, represented by the yellow dot on page 19 of the DR test:

http://magazines.drivers-republic.co...c/thetruth030/

As far as the debate about who lifted the throttle when, I think both Chris and Suzuki-san were WOT through the kink after the bridge. Watch the video with Chris narrating his runs in the GT-R and GT2 at that section. He mentions having to get slightly on the brake for the apex in the GT2 and putting one wheel slightly off the track. He contrasts the same section in the Nissan; "a completely different experience" [paraphrasing] "I didn't even feel like I was going that fast"

[go to the 7:29 mark using the YouTube timer ]

http://www.youtube.com/watch?v=Jq1UZzJk6mw

Originally Posted by footie

Edit.
On matching up the final straight for both Chris's GTR run and the 7:29 lap for Suzuki I discovered some pretty amazing differences.

1# Suzuki was comfortably quicker entering the final long straight

Can you quantize "comfortably"? I can't gauge their exit speed delta based on the videos.

Originally Posted by footie

2# I later matched their respective starting points to the Audi bridge and the difference between that bridge and the last bridge wasn't that great which leads me to believe that the speed difference at this point is slight (just as Swamp estimated it should be).

I've looked at both videos and am confident in these numbers. Suzuki's GT-R takes 23.3 seconds to cover that distance (just over a mile). Chris's GT-R takes 24.7 seconds to cover that distance. That is quite a discrepancy. Even if you give Suzuki a 5mph edge when he hits the Audi banner, he's still accelerating away at a significantly faster rate.

Originally Posted by footie

3# The time Suzuki made up over Chris front the start of the straight to the finish line, it was SHOCKING, Suzuki crossed the finish line over 3 seconds sooner than Chris, on that one section where there was only about 6 corners he destroyed Chris's time.

Having an extra 70hp probably didn't hurt

Originally Posted by footie

I am more and more convinced that Suzuki would be miles quicker than just about anyone around the ring in a GTR and this is solely down to knowing that it can defy the laws of physics. No one seems to be pushing it half as hard as he did. Chris reckoned only 10 seconds difference between him and Suzuki after the tyres were equalled up, sorry Chris but I would say you would have to double that estimate.

It's safe to say we're both pretty entrenched in our positions and none of the available evidence is going to sway us. I'll be willing to budge when a GT-R not heavily breathed on by Nissan's small army of technician's comes within 10 seconds of Nissan's latest claimed times. What will it take for you?

[footie]

Originally Posted by Garissimo

Bob, if Suzuki-san really entered that kink at 18-20mph more than Chris, it's a safe bet he'd be off the track. To be clear, I'm talking about the entry point at Antoniusbuche, represented by the yellow dot on page 19 of the DR test:

http://magazines.drivers-republic.co...c/thetruth030/

As far as the debate about who lifted the throttle when, I think both Chris and Suzuki-san were WOT through the kink after the bridge. Watch the video with Chris narrating his runs in the GT-R and GT2 at that section. He mentions having to get slightly on the brake for the apex in the GT2 and putting one wheel slightly off the track. He contrasts the same section in the Nissan; "a completely different experience" [paraphrasing] "I didn't even feel like I was going that fast

Maybe we are viewing two totally different video or our opinions are totally different to what we are seeing. From the last bridge to the finish line Suzuki made up approx 2 seconds and none of that was to do with extra HP, it was solely the ability to push harder.

Originally Posted by Garissimo

Can you quantize "comfortably"? I can't gauge their exit speed delta based on the videos.



I've looked at both videos and am confident in these numbers. Suzuki's GT-R takes 23.3 seconds to cover that distance (just over a mile). Chris's GT-R takes 24.7 seconds to cover that distance. That is quite a discrepancy. Even if you give Suzuki a 5mph edge when he hits the Audi banner, he's still accelerating away at a significantly faster rate.

I counted 0.8s from bridge to bridge and I estimate that at the Audi Banner Bridge Suzuki would have been doing at least 5~8mph more at that point.

Originally Posted by Garissimo

It's safe to say we're both pretty entrenched in our positions and none of the available evidence is going to sway us. I'll be willing to budge when a GT-R not heavily breathed on by Nissan's small army of technician's comes within 10 seconds of Nissan's latest claimed times. What will it take for you?

If someone gets within 10 seconds of the Suzuki's GTR time then I will totally believe that his time isn't fake. Like I said before, I am more convinced that Suzuki will be miles quicker than any non Nissan test pilot.

I like yourself look forward to additional tests throughout these coming months to see just how close others can come to Suzuki's time. But one thing is for sure, Porsche won't be one of them.

[Doc]

MY brain hurts after all of this ! I so wish BMW could have joined the party with a CSL!

[swamp2]

OK time for a big surprise...

The key thing here as I mentioned a couple days ago is that Suzuki does not lift until well past Antoniusbuche whereas Chris and the ZR1 and ACR drivers all do (either lift or hit some limiter or something that stops their acceleration), well before even the bridge. It is as plain as day when you watch the videos that have the speed (ZR1) and just listening to engine tone of the ACR. This along with a careful comparison between Google Earth maps and the videos provide some more comparisons vs. simulation.

So how is this different than my previous (lengthy) analysis? That analysis only compared speed vs. time up to a point well before the bridge when all cars were clearly under WOT. Also, there I did not do any distance correlation.

1. The GT-R does not need 530 hp or about a 10% under rating to achieve 180 mph past Antoniusbuche as Suzuki does.

The bridge distance from the exit of Galgenkopf is about 6849 ft. I suspect an accuracy of this figure of less than 50 ft or well less than 1%. Just pop open Google Earth (link to Google maps here then use the link to and ruler in Google Earth) and verify it yourself. Running a CarTest simulation of a "RWD" (low loss) GT-R with 480 hp finds it will be traveling at 182 mph at the bridge as we know from video it took precisely 30.3 seconds to do so. I have again assumed a corner exit speed of 107 mph, which seems justified compared to the ACR and ZR1 on other tracks. A "RWD" GT-R with 530 hp doing so in the same 30.3 seconds would be way up at 189 mph. Suzuki finally lifts at 7:12 or 33.0 seconds after the Galgenkopf exit. It is indisputable given the telemetry screen grabs posted earlier that Suzuki is absolutely WOT all the way through Antoniusbuche. CarTest finds the 480 hp "RWD" GT-R going 185 mph at this time. Looking further at the elevations in Google Earth there is an 2% overall grade in this section. It dips at first then rises but on average is about +2%. Adding this detail we find a slightly modified peak speed prediction of 178 mph right on Tiergarten again for the 480 hp "RWD" GT-R. Nearly right on the money with the Nissan claim of 180 mph.

CarTest also predicts that in the time required to get to the bridge the 480 hp "RWD" GT-R would cover 6910 feet again comparing to the actual of 6849 ft we find less than a 1% deviation. The hypothetical 530 hp "RWD" GT-R could cover about 7048 ft in this same amount of time making that prediction high by nearly 3%.

2. CarTest, video and Google Earth are all consistent within 1% about the braking point and distance covered in this WOT run.

7:12 is 33.3 seconds of WOT acceleration from the exit of Galgenkopf and that is Suzukis lift/brake point. The total distance predicted by CarTest for a "RWD" GT-R with 480 hp begining at 107 mph is 7708 feet. This is consistent with the visibility of the large patch of trees on the left hand side of the track which you can see just as Suzuki lifts and brakes. The trees begin about 790 feet after the bridge for a total past the exit of Galgenkopf of 7639 ft. Once again prediction and observation are right at about a 1% difference.

3. DR/Chris' lap.

DR was clear on Chris reaching his peak speed of 168 mph 1800m past the exit of Galgenkopf. That is well before the bridge and before Antoniusbuche (since they are pretty much at the same point). Assuming he exited Galgenkopf at 97 mph (probably closer to 100, but as noted previously that is not a huge factor) in that distance CarTest predicts a speed of 170 mph, just a hair over 1% deviation from actual to simulation.

4. How much advantage did Suzukis daring and skilled WOT provide, well past the point where Chris lifted, in terms of lap time?

Here was the procedure. Assuming Chris and Suzuki both exited Galgenkopf at precisely the same time but with Suzuki going 107 and Chris going only 97 (again a bit of an educated guess there on the 97, the number was likely closer to or > 100, but 97 is conservative). Now we break the runs in two parts, part one is when both cars are going WOT, in the second part Suzuki is still WOT and I assume Chris holds steady at 170 (the CarTest prediction rather than his actual number). Then compute the time difference for Chris to get to the distance point where Suzuki lifts. This is the total time advantage as it contributes to a total lap time difference. It turns out to be a 1.6 second advantage to Suzuki for part 1 and only another 0.3 seconds for part 2. So this "cost" Chris, both the poor exit speed and not quite the nerve, only about 2 seconds. You can see as well how the exit speed difference hurts the lap time "more" than peak speed as at the distance point when Chris lifted Suzuki would have only been going 172 or 2 mph faster. Despite getting all the way to 178 (again the CarTest number, with grade, not the actual 180 number) vs. 170 that only helps the lap time a fraction of a second.

Although all of the above is absolutely in favor of Nissan's telemetry, video, an explanation of DR/Chris' peak speed vs. Suzuki's and even Nissan's stated hp. It does still seem to be quite contradictory with much of the other evidence; 1/4 mi trap speeds, the Nurburgring regression analysis and my prior lengthy analysis on just the initial part of Galgenkopf where the ZR1 was accelerating with WOT. I definitely need to revisit that analysis and do more work on the distance part of the correlation as done above. Many will now be keenly interested in where this leaves me in terms of my belief that the car is under rated. I still say there is enough other evidence for under rating and I do still believe the 7:29 car was under rated.

[swamp2]

Originally Posted by Garissimo

if Suzuki-san really entered that kink at 18-20mph more than Chris, it's a safe bet he'd be off the track.

My analysis put it at just about 18 mph, 178 vs. 160.

Originally Posted by Garissimo

As far as the debate about who lifted the throttle when, I think both Chris and Suzuki-san were WOT through the kink after the bridge.

I would say it is crystal clear Chris was not. DR was clear that the GT-Rs peak speed was 168 well before Antoniusbuche and at Antoniusbuche he was way down to 160.

By the way where is the DR/GT-R/Chris video of this section including Döttinger Hohe with actual times as opposed to built in video times? I would like to do some more work on this evidence as well.

[swamp2]

One more recent tidbit. Shortly after Porsche more or less accused Nissan of cheating August Achleitner, the boss of the regular 997 program, claimed the advantage over the Turbo and GT2 came down to tires and what the definition of "standard" is. This happened way back in October 2008.

Link to DR article.

[Garissimo]

Originally Posted by swamp2

My analysis put it at just about 18 mph, 178 vs. 160.

First of all, I appreciate you putting so much thought and work into this but I am going to disagree with you on both points.

As I told Bob, the yellow dot represents the corner entry speed into Antoniusbuche. The GT-R, GT2, and even the ZR1 for that matter slow to around 160mph to take that left hand turn. I simply can not believe Suzuki-san can carry an extra 18-20mph into that turn and still keep his car on the track. Perhaps we're talking about slightly different spots on the track?

Originally Posted by swamp2

I would say it is crystal clear Chris was not. DR was clear that the GT-Rs peak speed was 168 well before Antoniusbuche and at Antoniusbuche he was way down to 160.

a) The tach in Chris's GTR never drops until well after the bridge.

b) Again, listen to Chris's narrative of the two runs. He mentions having to brake in the GT2 to take the left hand kink. He says that same turn in the Nissan was a completely different experience. If he had to slow before the bridge as he did in the GT2, he would have mentioned it.

http://www.youtube.com/watch?v=Jq1UZzJk6mw

c) Carefully read the text that accompanies the speed data on page 19 of the DR test. It says "1800m after the exit of the last RH turn of the lap, the Porsche is travelling 17mph faster". The Porsche's peak speed was 181.1mph. Subtract 17mph from that. What do you get? 164mph. However, the Nissan's peak speed on the back straight is listed as 168.2mph. What does that tell you? Chris's GTR was still accelerating past the bridge and reached its peak at a point ahead of the GT2. My interpretation is that the dots are only approximations and shouldn't be interpreted too literally for distance data. Put another way - the Porsche and Nissan reach their respective peak speeds at different points on the back straight which is right in line with what the video shows.

Lastly, please look at the banner to bridge speed delta between Chris's GT-R and Sukuki's. I will back off a little bit on what I wrote to footie yesterday. It looks more like a 24.5 second split for Chris's GT-R. It's hard to get as precise because there is no official clock superimposed on the DR test so I'm using a stopwatch and trying to be as accurate as possible.

For Suzuki's GT-R, I'm using this video in HD because this appears to be Nissan's original timer, and even though it's a video of a monitor, it's still very clear and easy to pick off the two points on the track. I still get a 23.3 second split time.

http://www.youtube.com/watch?v=WLdaLV66XOc

I still contend that both GT-Rs were WOT through both markers and that time difference can only be attributed to a non-trivial difference in engine power.

EDIT: One more point:

Originally Posted by swamp2

[...] Running a CarTest simulation of a "RWD" (low loss) GT-R with 480 hp finds it will be traveling at 182 mph at the bridge as we know from video it took precisely 30.3 seconds to do so. I have again assumed a corner exit speed of 107 mph, which seems justified compared to the ACR and ZR1 on other tracks. A "RWD" GT-R with 530 hp doing so in the same 30.3 seconds would be way up at 189 mph. [...]

We have real world examples of the GT2 and ZR-1, both lighter and more powerful than a stock GT-R, running WOT right up to the bridge. Neither of those two cars are able to crack 182mph. I know you've downgraded those numbers due to elevation somewhat, but your simulation is predicting speeds that seem high. Another example; a Ferrari Enzo hits a peak speed of 189mph on the back stretch. Your simulation says a 530hp RWD GT-R would be hitting a similar speed. Something does not seem right about that. Please take this as constructive criticism.

[footie]

Thanks Swamp for proving many of the things I assumed purely from my experience in these matters. I too still believe the GTR is under rated to the tune of 10% and the only reason for this is a Nissan staff member admitting this fact.

As I said the difference is all coming from he total commitment and knowledge of what the car is capable of. I'm pretty sure someone will get closer to this time but it will take someone like another F1 pilot behind the wheel.

[footie]

Originally Posted by Garissimo

As I told Bob, the yellow dot represents the corner entry speed into Antoniusbuche. The GT-R, GT2, and even the ZR1 for that matter slow to around 160mph to take that left hand turn. I simply can not believe Suzuki-san can carry an extra 18-20mph into that turn and still keep his car on the track. Perhaps we're talking about slightly different spots on the track?

Though it does sound excessive there is enough variables that may account for some of the differences without even taking into account the definite skill differences.

1# Suzuki was on the stickier Dunlops which would account for some of that 18mph.

2# The difference in track temperature.

3# The extra moisture on the track.

4# The number of warm-up laps, on reading the article it doesn't sound like Chris had that many warm-up laps and he actually stated he was a little concerned with the track's damp conditions.

All of the above plus the undoubted skill and commitment of Suzuki could possibly account for such an unbelievable difference in speed. Also trying to tackle such speed in the GT2 would have definitely resulted in an off, but then that explained why it doesn't do it's lap in under 7:29 even though it is clearly quicker on the straights.

Originally Posted by Garissimo

a) The tach in Chris's GTR never drops until well after the bridge.

No one said he did, all we are saying is that acceleration stopped prior to the bridge and he braked at the kink. His reactions are similar to both the ZR1 and Viper drivers.

Originally Posted by Garissimo

b) Again, listen to Chris's narrative of the two runs. He mentions having to brake in the GT2 to take the left hand kink. He says that same turn in the Nissan was a completely different experience. If he had to slow before the bridge as he did in the GT2, he would have mentioned it.

Read the above, it explains what I believe happened. There is a world of difference between feeling something can take a corner quicker and knowing it for certain, that's the difference between Suzuki and all of the others, including Chris.

Originally Posted by Garissimo

c) Carefully read the text that accompanies the speed data on page 19 of the DR test. It says "1800m after the exit of the last RH turn of the lap, the Porsche is travelling 17mph faster". The Porsche's peak speed was 181.1mph. Subtract 17mph from that. What do you get? 164mph. However, the Nissan's peak speed on the back straight is listed as 168.2mph. What does that tell you? Chris's GTR was still accelerating past the bridge and reached its peak at a point ahead of the GT2. My interpretation is that the dots are only approximations and shouldn't be interpreted too literally for distance data. Put another way - the Porsche and Nissan reach their respective peak speeds at different points on the back straight which is right in line with what the video shows.

Maybe it's a typo error, even professional writer are accustomed to it as well.

Originally Posted by Garissimo

Lastly, please look at the banner to bridge speed delta between Chris's GT-R and Sukuki's. I will back off a little bit on what I wrote to footie yesterday. It looks more like a 24.5 second split for Chris's GT-R. It's hard to get as precise because there is no official clock superimposed on the DR test so I'm using a stopwatch and trying to be as accurate as possible.

For Suzuki's GT-R, I'm using this video in HD because this appears to be Nissan's original timer, and even though it's a video of a monitor, it's still very clear and easy to pick off the two points on the track. I still get a 23.3 second split time.

I still contend that both GT-Rs were WOT through both markers and that time difference can only be attributed to a non-trivial difference in engine power.

I still maintain that it's closer to 0.8s of difference but what the heck. I reckon the only way to really know for sure is to get the data from each test Nissan's and Driver Republic's and compare to see at what point acceleration stopped and what speed each car carried on to the straight. Until this is known we will never agree but at least now Swamp's data (with the additional info from Suzuki's telemetry) shows that a 480hp GTR in rwd form could match he's results, now we have to determine whether the GTR can indeed switch off it's front prop shaft completely and if not then by what percentage still remains and if so what effect on output would be require to maintain these results.

[Garissimo]

Originally Posted by footie

Though it does sound excessive there is enough variables that may account for some of the differences without even taking into account the definite skill differences.

1# Suzuki was on the stickier Dunlops which would account for some of that 18mph.

2# The difference in track temperature.

3# The extra moisture on the track.

4# The number of warm-up laps, on reading the article it doesn't sound like Chris had that many warm-up laps and he actually stated he was a little concerned with the track's damp conditions.

I think we could bat this one back and forth indefinitely. Really need to line up the speed data with the position and the throttle log. That's hard to do with what we have. If you look at Suzuki's throttle log, you see him WOT past the bridge (I never contended otherwise) but after that the log shows a lot of on/off transitions that are impossible to decipher.

Originally Posted by footie

No one said he did, all we are saying is that acceleration stopped prior to the bridge and he braked at the kink. His reactions are similar to both the ZR1 and Viper drivers.

If we're talking about the kink immediately after the bridge, he braked in the GT2. Where is the evidence he did the same in the GT-R? How can you be sure he stopped accelerating in the GT-R?

Originally Posted by footie

Maybe it's a typo error, even professional writer are accustomed to it as well.

The more I think about it, the more I'm convinced it's not a typo. Why would the GT-R and GT2 be hitting their peak speed at the exact same place on the track, especially if Chris braked in the Porsche at the bridge and stayed on the throttle in the GT-R? I'm of the opinion the text is correct and means to convey that 1800m after the last turn exit, the GT2 hit its peak and had a 17mph edge on the GT-R. Jethro could probably clear this up, though. Your turn to e-mail him

[EDIT: Add] Maybe this is the source of some of the confusion? DR's video narrative overlaying the GT-R and GT2 runs has a subtle switch of the GT2 and GT-R cockpits during the back stretch run. The GT-R starts out as the car on top, but the cockpits are swapped at the 7:18 point. If you were already aware of this, disregard.

Originally Posted by footie

I still maintain that it's closer to 0.8s of difference but what the heck. I reckon the only way to really know for sure is to get the data from each test Nissan's and Driver Republic's and compare to see at what point acceleration stopped and what speed each car carried on to the straight. Until this is known we will never agree but at least now Swamp's data (with the additional info from Suzuki's telemetry) shows that a 480hp GTR in rwd form could match he's results, now we have to determine whether the GTR can indeed switch off it's front prop shaft completely and if not then by what percentage still remains and if so what effect on output would be require to maintain these results.

I believe swamp's simulation is under-compensating for the elevation gain or not adequately taking drag into consideration. He has a 530hp GT-R hitting 189mph at the bridge, and that's well up on what the lighter, more powerful GT2 and ZR-1 are seeing in the real world.

[swamp2]

Originally Posted by Garissimo

First of all, I appreciate you putting so much thought and work into this but I am going to disagree with you on both points.

Like I said in the past, the more eyes looking at this the better and your keen observations and commitment are certainly valuable here as well.

Originally Posted by Garissimo

As I told Bob, the yellow dot represents the corner entry speed into Antoniusbuche. The GT-R, GT2, and even the ZR1 for that matter slow to around 160mph to take that left hand turn. I simply can not believe Suzuki-san can carry an extra 18-20mph into that turn and still keep his car on the track. Perhaps we're talking about slightly different spots on the track?

I agree that the yellow dot it the corner entry speed into Antoniusbuche which is pretty much coincident with teh bridge.

Originally Posted by Garissimo

a) The tach in Chris's GTR never drops until well after the bridge.

Not quite sure which video you are gleaning this from but the "peak speed" on Döttinger Höhe, red dot vs. yellow dot states with no uncertainty an 8 mph speed drop. The REQUIRES a drop from about 5780 to 5504 rpm.

Originally Posted by Garissimo

b) Again, listen to Chris's narrative of the two runs. He mentions having to brake in the GT2 to take the left hand kink. He says that same turn in the Nissan was a completely different experience. If he had to slow before the bridge as he did in the GT2, he would have mentioned it.

Yes, already listened to that. Your conclusion is a huge interpretive stretch. All I read from exactly what was said that one was calm and the other hairy, again completely consistent with all other comparisons of driving both of these cars either really fast or on limit.

Originally Posted by Garissimo

c) Carefully read the text that accompanies the speed data on page 19 of the DR test. It says "1800m after the exit of the last RH turn of the lap, the Porsche is travelling 17mph faster". The Porsche's peak speed was 181.1mph. Subtract 17mph from that. What do you get? 164mph. However, the Nissan's peak speed on the back straight is listed as 168.2mph. What does that tell you? Chris's GTR was still accelerating past the bridge and reached its peak at a point ahead of the GT2. My interpretation is that the dots are only approximations and shouldn't be interpreted too literally for distance data. Put another way - the Porsche and Nissan reach their respective peak speeds at different points on the back straight which is right in line with what the video shows.

I agree that the 1800m figure almost certainly represents either only the exact peak speed location for one of the cars or an approximation of the two. However, being that the same driver is attacking his slow/off throttle or brake point is likely to be quite similar for both cars. The fact that the Antoniusbuche speed is significantly less that the peak speeds for both cars is consistent with this. There is simply no way in either car that he got to the peak speeds listed, scrubbed off 8-20 mph for Antoniusbuche and then got back above the listed peak speeds. The 17 mph could indeed be a typo.

Either way you slice it there is simply crystal clear evidence that Chris did not maintain WOT through Antoniusbuche and that he did reach his peak speed in both cars before Antoniusbuche.

Originally Posted by Garissimo

Lastly, please look at the banner to bridge speed delta between Chris's GT-R and Sukuki's. I will back off a little bit on what I wrote to footie yesterday. It looks more like a 24.5 second split for Chris's GT-R. It's hard to get as precise because there is no official clock superimposed on the DR test so I'm using a stopwatch and trying to be as accurate as possible.

For Suzuki's GT-R, I'm using this video in HD because this appears to be Nissan's original timer, and even though it's a video of a monitor, it's still very clear and easy to pick off the two points on the track. I still get a 23.3 second split time.

http://www.youtube.com/watch?v=WLdaLV66XOc

I still contend that both GT-Rs were WOT through both markers and that time difference can only be attributed to a non-trivial difference in engine power.

I get 23.6 for the 7:29 lap for banner to bridge. The time I got for Chris was 25 seconds but with a fairly wide margin of error. That difference is 1.4 seconds. What part of my section #4 above did you miss? In that calculation I figured 1.6 seconds gained by Suzuki during the same section due entirely to a higher corner exit speed and no hp difference. We REALLY need Chris' true corner exit speed, not the as reported minimum apex speed. Again the evidence is completely clear that Chris simply was not WOT through Antoniusbuche.

Originally Posted by Garissimo

We have real world examples of the GT2 and ZR-1, both lighter and more powerful than a stock GT-R, running WOT right up to the bridge. Neither of those two cars are able to crack 182mph. I know you've downgraded those numbers due to elevation somewhat, but your simulation is predicting speeds that seem high.

The GT2 and ZR1 in a completely apples to apples acceleration contest will best the GT-R with either 480 or 530 hp, there is no question about that. In the GM video the ZR1 for one reason or another stopped accelerating somewhere between 18-22 seconds past the Galgenkopf exit. I'm guessing that was mostly about pure courage.

Originally Posted by Garissimo

Another example; a Ferrari Enzo hits a peak speed of 189mph on the back stretch. Your simulation says a 530hp RWD GT-R would be hitting a similar speed. Something does not seem right about that. Please take this as constructive criticism.

As I have seen from making incorrect assumptions myself in the past you have to know exactly when the car is WOT and when it lifts and or brakes, along with a good corner exit speed. The simulation is then capable of predicting both speeds and distances within 1% when you know the precise duration of WOT. I did not previously calculate the 530 hp "RWD" version, with the 2% average slope, with a corner exit speed of 107, from Galgenkopf exit to bridge. But I can tell you that that number would be in the range 180-185.

[footie]

Originally Posted by Garissimo

I believe swamp's simulation is under-compensating for the elevation gain or not adequately taking drag into consideration. He has a 530hp GT-R hitting 189mph at the bridge, and that's well up on what the lighter, more powerful GT2 and ZR-1 are seeing in the real world.

I agree that these are things we need to ask swamp about. If you are correct and elevation and drag are taken accourt for then that may explain why I have insisted that the GTR (all of them) has not the quoted 480hp but 10% more than that.

Another thing, are you suggesting that Chris had the throttle pinned the entire time considering that the Vette driver lifted slightly and the Viper driver decided to stick with the lower gear and ride the limiter the entire time. If so then I conclude that Chris is one of the balliest motoring reporters for any magazine, getting paid relative pennies compared to the likes of Suzuki for his services and taking the same chances. Sorry mate but I just don't buy it, much as I accept Chris being a capable driver he is not nor never will be as good as these test drivers.

[swamp2]

Originally Posted by Garissimo

I believe swamp's simulation is under-compensating for the elevation gain or not adequately taking drag into consideration. He has a 530hp GT-R hitting 189mph at the bridge, and that's well up on what the lighter, more powerful GT2 and ZR-1 are seeing in the real world.

Check Google Earth yourself. From Galgenkopf to midway down Tiergarten it is about 50m net rise in ~1 3/4 mi. This is 1.6%, I rounded up to 2%.

The cars drag force is pretty simple to model Cd = 1/2 p Cd A v^2. Cd and A are the needed quantities and they are typically available on the web. Sometimes I have been stumped and unable to find one or both parameters. I do certainly question the Cd and A values I used for the ACR. All of its aero components that produce huge down force also produce drag.

Last question has been covered, it is all about when you lift and apples to apples power to weight ratio is still the largest factor (and CdxA to a lesser extent).

[footie]

Originally Posted by swamp2

Like I said in the past, the more eyes looking at this the better and your keen observations and commitment are certainly valuable here as well.

Agreed, I welcome any additional point of view, even ones that disagree because they usually help you recheck and re-evaluate your own opinion.

Originally Posted by swamp2

Yes, already listened to that. Your conclusion is a huge interpretive stretch. All I read from exactly what was said that one was calm and the other hairy, again completely consistent with all other comparisons of driving both of these cars either really fast or on limit.

Couldn't agree more with this interruption of what Chris wrote on the subject.

Originally Posted by swamp2

I agree that the 1800m figure almost certainly represents either only the exact peak speed location for one of the cars or an approximation of the two. However, being that the same driver is attacking his slow/off throttle or brake point is likely to be quite similar for both cars. The fact that the Antoniusbuche speed is significantly less that the peak speeds for both cars is consistent with this. There is simply no way in either car that he got to the peak speeds listed, scrubbed off 8-20 mph for Antoniusbuche and then got back above the listed peak speeds. The 17 mph could indeed be a typo.

Either way you slice it there is simply crystal clear evidence that Chris did not maintain WOT through Antoniusbuche and that he did reach his peak speed in both cars before Antoniusbuche.

We seem to be on a roll you and I because again we are in total agreement, especially when the subject matter is the GTR.

Originally Posted by swamp2

I get 23.6 for the 7:29 lap for banner to bridge. The time I got for Chris was 25 seconds but with a fairly wide margin of error. That difference is 1.4 seconds. What part of my section #4 above did you miss? In that calculation I figured 1.6 seconds gained by Suzuki during the same section due entirely to a higher corner exit speed and no hp difference. We REALLY need Chris' true corner exit speed, not the as reported minimum apex speed. Again the evidence is completely clear that Chris simply was not WOT through Antoniusbuche.

Unlike the ZR1 vs GTR video which someone was kind enough to match up, the DR video and the Youtube 7:29 GTR lap are trickier to match up identically and that is why I believe we are all getting difference results. I got 23.5s for Suzuki and 24.4s for Chris's run. I did this by starting and stopping the stopwatch when the two bridges disappeared at the top of the windscreen. I did this 6 times and that was my averaged out time for each car. If I am right then this means that the two cars are totally stock to each other.

Oh, for the fun of it I checked the 7:38 lap time run from bridge to bridge and found it to take (guess what) 23.7~8s, seems that Suzuki found another 9 seconds from nothing more than more committed driving and not additional horsepower.

Originally Posted by swamp2

The GT2 and ZR1 in a completely apples to apples acceleration contest will best the GT-R with either 480 or 530 hp, there is no question about that. In the GM video the ZR1 for one reason or another stopped accelerating somewhere between 18-22 seconds past the Galgenkopf exit. I'm guessing that was mostly about pure courage.

I bet his bravery pills had run out by that point because for that point until the finish line it was Suzuki that was the quicker, less so against the ZR1 driver and hugely so against Chris. It's funny that both the ZR1 and the Viper drivers choose not to continue accelerating, with the Vette driver lifting the throttle ever so slightly and the Viper driver just riding the limiter. I guess this section of the track might be quite bumpy and request real commitment.

Originally Posted by swamp2

As I have seen from making incorrect assumptions myself in the past you have to know exactly when the car is WOT and when it lifts and or brakes, along with a good corner exit speed. The simulation is then capable of predicting both speeds and distances within 1% when you know the precise duration of WOT. I did not previously calculate the 530 hp "RWD" version, with the 2% average slope, with a corner exit speed of 107, from Galgenkopf exit to bridge. But I can tell you that that number would be in the range 180-185.

Until all of the available data is there to example fully we will never fully agree. With this additional data from Nissan's telemetry you are now producing the kind of results I reckon to be true all along. If DR can supply similar data on Chris's lap we can analyse and see where he lifted (of this I am in no doubt) and why his lap was 26 seconds slower.

[swamp2]

Originally Posted by footie

We seem to be on a roll you and I because again we are in total agreement, especially when the subject matter is the GTR.

Don't get your hopes nor opinion too high. I am very uncomfortable with the glaring contradiction between the foregone conclusion of 530 hp and under rating vs. the nicely validated CarTest simulations using 480 hp and "RWD" (again meaning losses equvalent to a RWD vehicle while under WOT).

[footie]

Remember swamp that the whole point was to prove that Nissan's GTR was stock to others being tested, the comparison to Chris's run shows two very similar results when we consider that Suzuki has the throttle pinned much longer and has a high exit speed which is obvious on viewing their respective commitment through this corner.

The problem you are facing is still the unknowns like wind and whether or not their AWD system can indeed disconnect the front shaft and diff etc. Best work on the assumption that it does indeed send power to all wheels and then start crunching the numbers as to how much lose it required to make the numbers look close to right, after that the wind has to be considered.

No one ever said it was an exact science, all it can do is point to the possibilities.

[Garissimo]

Originally Posted by swamp2

I agree that the yellow dot it the corner entry speed into Antoniusbuche which is pretty much coincident with teh bridge.

Alright, I'm flagging a screw up on my part. I had Antoniusbuche and Tiergarten transposed in my head. I was making comments about Antioniusbuch assuming it was a reference point well beyond the bridge, and that is clearly not the case. Apologies for any confusion this caused (mostly to myself, I guess.) I am still unsure where exactly the speeds DR reports for the "yellow dot" were measured. There is no distance reference given so it isn't clear if these are speeds leading into the apex (pre-bridge), or just out of the kink where he puts one wheel off the course in the GT2 and has obviously slowed significantly from his 181mph peak.

I also looked closely at Nissan's telemetry and have Suzuki WOT all the way up to 7:12 into it, just as you describe so we're in agreement there. Also, as you state, we know for certain Chris is down to ~160mph somewhere around Antoniusbuche so he's definitely letting off before Suzuki.

So you have Suzuki reaching a higher peak speed partly due to being in the throttle longer. How much longer is the subject of debate but I see it somewhere around 3-4 seconds. I find it very hard to believe 3-4 more seconds more WOT results in 12 more mph at these speeds for the GT-R, even with the slight downhill after the bridge.

You also have a higher exit speed out of Galgenkopf as a factor. This one is much harder to quantize. The camera angles are slightly different in the two cars and it's very difficult to accurately line up markers going around the curve. Suzuki shifts about 1 second earlier getting onto the straight, FWIW. I will say, the higher the delta is, the more plausible the 180mph end speed with "minimal" under rating seems. Tires/grip/weather player a larger role than I'd initially guessed in this scenario.

The lower the difference, the more I lean towards my initial hunch of a power "advantage" for Suzuki.

Also, I see you took the approach of measuring the impact on lap (segment) times enjoyed from higher peak speed versus vs. higher exit speed. I don't have a problem with that. I got (am) obsessed with trying to wrap my brain around a top speed higher or equal to those the GT2 or ZR-1 hit. However, you seem to be leaning in same direction that Porsche initially did and that tires allowed Suzuki to carry some spectacular speed through the turns.

[Garissimo]

Originally Posted by footie

Another thing, are you suggesting that Chris had the throttle pinned the entire time considering that the Vette driver lifted slightly and the Viper driver decided to stick with the lower gear and ride the limiter the entire time.

As I stated in my reply to swamp, I had Antoniusbuche mixed up with Tiergarten so my comments about when Chris lifted probably did sound a bit whack.

Originally Posted by footie

If so then I conclude that Chris is one of the balliest motoring reporters for any magazine, getting paid relative pennies compared to the likes of Suzuki for his services and taking the same chances. Sorry mate but I just don't buy it, much as I accept Chris being a capable driver he is not nor never will be as good as these test drivers.

Keep in mind that Chris was going some 10mph slower than he was in the GT2, or than the ZR-1 driver was or the Viper driver was, or most likely Suzuki was at that point in the track (leading into Antoniushbuche). I don't think it's that much of a reach to suggest he had the throttle pinned up to the bridge.

[swamp2]

Originally Posted by Garissimo

Alright, I'm flagging a screw up on my part. I had Antoniusbuche and Tiergarten transposed in my head.

No worries at all. No one is immune from mistakes. Like I said before more eyes = better.

Originally Posted by Garissimo

So you have Suzuki reaching a higher peak speed partly due to being in the throttle longer. How much longer is the subject of debate but I see it somewhere around 3-4 seconds. I find it very hard to believe 3-4 more seconds more WOT results in 12 more mph at these speeds for the GT-R, even with the slight downhill after the bridge.

I would place the figure much closer to 7 seconds.

Originally Posted by Garissimo

You also have a higher exit speed out of Galgenkopf as a factor. This one is much harder to quantize. The camera angles are slightly different in the two cars and it's very difficult to accurately line up markers going around the curve. Suzuki shifts about 1 second earlier getting onto the straight, FWIW. I will say, the higher the delta is, the more plausible the 180mph end speed with "minimal" under rating seems. Tires/grip/weather player a larger role than I'd initially guessed in this scenario.

The lower the difference, the more I lean towards my initial hunch of a power "advantage" for Suzuki.

Corner exit speeds are still a big variable. However, based on my simulations mathcing times, speeds and distances and based on examinations of other corner exit speeds on this track and others I do believe that the 107/97 figures are decent. Again If I really had to bet I would be more like 107/100 but 97 is conservative in terms of looking at over rating.

Originally Posted by Garissimo

Also, I see you took the approach of measuring the impact on lap (segment) times enjoyed from higher peak speed versus vs. higher exit speed. I don't have a problem with that. I got (am) obsessed with trying to wrap my brain around a top speed higher or equal to those the GT2 or ZR-1 hit. However, you seem to be leaning in same direction that Porsche initially did and that tires allowed Suzuki to carry some spectacular speed through the turns.

Again the corner exit speed gets you a bigger improvement in lap time than reaching a higher top speed does in this particular scenario. I am not quite sure if I think this is a general conclusion, the real track nuts who actually have any telemetry could likely answer that question for sure. This point of view is consistent with the argument about tires since those will obviously boost corner speeds while not affecting top speeds that much.