Originally Posted by Snorman

I haven't had much time to respond to this today without explaining why I think it's ridiculous to use 100-150 mph intervals as an overall judge of track performance, so I'll try to explain it so you don't think I'm being "personal".

While I don't have access to vBox data for a C7 Z06 yet (or ZR1), I do have access to vBox data from my own cars and a number of others including a '14 GT3. For sake of comparison, I'll compare the rolling interval of 50-130 (I don't have data up to 150 mph for either) and the time elements. The starting speed of 50 mph is a good point, because it represents the approximate exit speed from a number of corners onto long straights on various tracks (Road Atlanta T7, for example). I fully realize at tracks like Roebling, Sebring, etc. there can be higher exit speeds on the way to higher vmax prior to the next braking zone.
This particular data isn't the best possible for either car. My GT500 has ran a 7.8 60-130. In this sample, it ran an 8.0. I'm sure in better conditions the GT3 would have done better as well, but we're looking at intervals, and at a -1.81 sec interval for the GT3, it's close to the ~1.9 sec 100-150 ZR1 advantage when comparing MT acceleration numbers for the Z06 and ZR1. Bear in mind, according to MT testing, the 50-130 advantage the ZR1 has over the C7 Z06 is .50 sec, which is obviously on different testing days as well.

The 50-130 interval for the GT500 was 8.68 seconds.
The 50-130 interval for the GT3 was 10.49 seconds.
The distance traveled during 8.68 seconds by the GT500 was 1228.58'.
The distance traveled during that same 8.68 seconds by the GT3 was 1168.25'.
The GT3's delta was -60.33' at 8.68 seconds. This is approximately 4 car lengths.
At 8.68 seconds the GT3 was traveling 121.34 mph compared to the GT500's 130 mph. Nothwithstanding acceleration, the interval required by the GT3 to cover the 60.33' advantage the GT500 had would be 0.34 seconds (GT3 is traveling at 177.97 ft/sec).

There is a reason that, assuming equal drivers, a GT3 will crush my GT500 on any track. It carries higher entry and exit speeds and completely overcomes the rolling acceleration deficit it has (in additional to better braking, chassis dynamics, etc.). As you are well aware, stock GT-R 60-130 times are sh*tty. As in, mid-high 9's sh*tty. As in, they'll get beat by a great many cars out there from a 50-60 mph roll when stock. Yet they do quite well on-track as a result of other advantages.

IMO, you are using a metric that is not a substantial indicator of track performance unless there is a much more serious deficiency. I'll also point out, the intervals you are using for your data were obtained by MT testing (CD only tests to 100 mph, and then quarter mile, correct me if I'm wrong). In the MT tests, an A8 car was used. We know from watching and hand-timing the intervals between the A8 car at Road Atlanta and the M7 car at VIR that the VIR car absolutely accelerates harder. The fact that at Road A you are accelerating downhill into the braking zone exacerbates this observation.

https://www.corvetteforum.com/forums...post1588662158

Finally (and you may have seen my post earlier ITT), you commented about the GT350 Nurburgring time, somewhat relative to a lack thereof for the Z06. As you may (or may not) know, the GT350 was there last summer. There are videos and pics of a heavily camouflaged car dating back to early-mid July 2014. Ford obviously did things differently than GM in how they tested and revealed the GT350.

S.

Originally Posted by vtknight

With each turn being equal to .2 of a second time reduction - and a single pull from 100-150 being equal to 2 full seconds of time increase - it requires 11 turns to make up for the 100-150 loss of 2 seconds.

Originally Posted by vtknight

I appreciate the time you took to respond Snorman - thank-you.

That said - the example you used - a GT500 and GT3 - beyond the 50-130 and other straight line metrics you used will likely not have the same affect when compared to the C7 Z06 and C6 ZR1 in my opinion as other parts of their performance (like chassis dynamics and braking etc.) will be much more evenly matched (as opposed to the GT500 and GT3 example).

My reasoning; although I admit the C7 Z06 is a better handling car due to a substantial increase in downforce and it's diff technology is superior - as you know and as I stated earlier - the C7 Z06 and C6 ZR1 are still very similar cars - sharing many of their components (from suspension, brakes and tires - as well as their dimensions) - power to weight is also very close (and likely in the ZR1's favour). Unlike the GT500 to GT3 comparison whose components and setup I think it is fair to say - are quite different from each other (above and beyond a live rear axle to independent suspension).

That is why I think the loss of time from 100-150+ MPH is much more significant in the C7 Z06 to ZR1 comparison.

Do I think it is ultra major world ending difference overall?

No.

But I do think it may have been just enough to reduce the time difference GM wanted to publicize - as again - the ZR1 has a very impressive time already.

Heavychevy is correct that getting paradigm shifting times is much more difficult today then when the GTR was introduced with 7:38:55 back in 2007 lol.

Every second is a seriously tough go now that everyone seems to be sub 7:20 at the Nurburgring.

As to the GT350R's time - it is true that I don't know if it is even official yet or not - or how long it took them to get it.

Cheers!

Originally Posted by tracyda

Totally agree. We should just simply expose the elephant in the room.

There are only two cars of this performance level designed for the track in the $80k-$100k range and one of them is faster than the other in the 100-150mph range. They are both stated from the manufacturers to be designed for the track. They are both geared the same. On the dyno, one has more power than the other. It also weighs ~200lbs more. From what we can guess, they have about the same amount of downforce. One has stated the exact numbers and the other relative #'s. One has a tire performance advantage, but on a track, will be replaced to the same, so won't matter. So, in a world where the two cars are so close, this performance issue in the 100-150mph range will be a disadvantage and should not be hidden or suggested otherwise. Is it a huge deal? Of course not unless they were equal in the other places.

So, we need to stop with the "assumption" the Z is going to carry more speed in/during/out of the corners until we have data to prove that. If people believe that to be true on a downforce assumption, that is risky business without knowing what it is...

Having said all of that, can't wait for some same day, track, driver comparisons that we can only discuss in the "other cars" section.

Originally Posted by Snorman

I haven't had much time to respond to this today without explaining why I think it's ridiculous to use 100-150 mph intervals as an overall judge of track performance, so I'll try to explain it so you don't think I'm being "personal".

While I don't have access to vBox data for a C7 Z06 yet (or ZR1), I do have access to vBox data from my own cars and a number of others including a '14 GT3. For sake of comparison, I'll compare the rolling interval of 50-130 (I don't have data up to 150 mph for either) and the time elements. The starting speed of 50 mph is a good point, because it represents the approximate exit speed from a number of corners onto long straights on various tracks (Road Atlanta T7, for example). I fully realize at tracks like Roebling, Sebring, etc. there can be higher exit speeds on the way to higher vmax prior to the next braking zone.
This particular data isn't the best possible for either car. My GT500 has ran a 7.8 60-130. In this sample, it ran an 8.0. I'm sure in better conditions the GT3 would have done better as well, but we're looking at intervals, and at a -1.81 sec interval for the GT3, it's close to the ~1.9 sec 100-150 ZR1 advantage when comparing MT acceleration numbers for the Z06 and ZR1. Bear in mind, according to MT testing, the 50-130 advantage the ZR1 has over the C7 Z06 is .50 sec, which is obviously on different testing days as well.

The 50-130 interval for the GT500 was 8.68 seconds.
The 50-130 interval for the GT3 was 10.49 seconds.
The distance traveled during 8.68 seconds by the GT500 was 1228.58'.
The distance traveled during that same 8.68 seconds by the GT3 was 1168.25'.
The GT3's delta was -60.33' at 8.68 seconds. This is approximately 4 car lengths.
At 8.68 seconds the GT3 was traveling 121.34 mph compared to the GT500's 130 mph. Nothwithstanding acceleration, the interval required by the GT3 to cover the 60.33' advantage the GT500 had would be 0.34 seconds (GT3 is traveling at 177.97 ft/sec).

There is a reason that, assuming equal drivers, a GT3 will crush my GT500 on any track. It carries higher entry and exit speeds and completely overcomes the rolling acceleration deficit it has (in additional to better braking, chassis dynamics, etc.). As you are well aware, stock GT-R 60-130 times are sh*tty. As in, mid-high 9's sh*tty. As in, they'll get beat by a great many cars out there from a 50-60 mph roll when stock. Yet they do quite well on-track as a result of other advantages.

IMO, you are using a metric that is not a substantial indicator of track performance unless there is a much more serious deficiency. I'll also point out, the intervals you are using for your data were obtained by MT testing (CD only tests to 100 mph, and then quarter mile, correct me if I'm wrong). In the MT tests, an A8 car was used. We know from watching and hand-timing the intervals between the A8 car at Road Atlanta and the M7 car at VIR that the VIR car absolutely accelerates harder. The fact that at Road A you are accelerating downhill into the braking zone exacerbates this observation.

https://www.corvetteforum.com/forums...post1588662158

Finally (and you may have seen my post earlier ITT), you commented about the GT350 Nurburgring time, somewhat relative to a lack thereof for the Z06. As you may (or may not) know, the GT350 was there last summer. There are videos and pics of a heavily camouflaged car dating back to early-mid July 2014. Ford obviously did things differently than GM in how they tested and revealed the GT350.

S.

Originally Posted by Snorman

No offense, but I'm not sure you're understanding the data I presented.
Earlier ITT, you (and others) were under the false impression that a ~2 second delta in the 100-150 mph interval translated into a 2-second delta in lap times. This is false.
When you make statements like this, it reinforces my suspicion that you do not understand the data I tried to explain:

You clearly stated that you believe a "single pull from 100-150" is "equal to a 2 full seconds of time increase". I just proved that this is incorrect using data that is close to that ~2-second interval (whether or not it's from the same interval or not), which only translates to a ~.3 delta. The capabilities and lap times of the cars being compared is irrelevant. What is relevant is that the delta you (and others) think exists as a result of mph-to-mph acceleration intervals is far less than you expect.
I would respectfully submit that you re-read my post.

This concept is analogous to roll-racing, which seems to be all the rage. It's obvious that most don't understand what a large effect the start of such races have on the outcome. That's another discussion entirely. But to hint: let's have a drag strip competition and turn off the RT's. It's interesting...in all the comments and posts about recent roll-races, the ONLY guy who seems to understand this is the owner of the modded Gen IV Viper who seemingly beats everything from a roll.
S.

Originally Posted by Snorman

It's interesting that you "agree", but have absolutely no actual data to support your supposition. Very likely, you fall into the category of people who think that a fixed acceleration delta translates to a fixed lap time delta but don't entirely understand those deltas.
The interesting thing about some of this stuff is that you can't defy basic physics, regardless of the outcome for which you are hoping.
S.

Originally Posted by vtknight

Thank-you again for your response Snorman - and no offense taken - I do not in fact understand what you have written - because I did in fact believe the 2 second delta between the C6 ZR1 and C7 Z06 would be experienced each and every time that happened.

I re-read your post - and the reasons you gave for why this 2 second differential is not seen on the track - and would actually be closer to 10 times less than that - was due to differences in entry/exit speed as well as topography - which I definitely agreed with you on when comparing the GT500 to GT3 as their dynamics, measures and setups are so very dissimilar.

Although I didn't address entry/exit speeds in my post - my point I was trying to make was that entry and exit speeds (at least I don't think) would be a large difference between the C7 Z06 and C6 ZR1? I stated the reason I thought that there wouldn't be much difference (all things being equal with driver and track conditions) - was because the cars were so similar in design, output, dynamics, setup and measures.

Therefore the factor of 10 you used to reduce the affect might in fact be a smaller number due to the above similarities of both cars.

If what I have written is inaccurate - then you are correct - the .2 second delta you have calculated would be nearly meaningless (especially at the Nurburgring).

As to rolls - where I have a lot more direct experience - I get your point clearly about RT.

Originally Posted by heavychevy

Right, so we are looking at about .5 lost when the 50-130 is about 2 seconds. .5 is a long time on a track to lose. Put that at VIR, that has a 50-160 (back straight) an 80-150+ (front straight) and another 90-140 (to esses).

Add them all together and it doesn't look great. Take it to the nurburgring and it looks downright ugly on the straight.

The manual is undoubtedly fast enough for it not to matter. I'm not yet convinced on the auto. Need some real world results to see if all of them drive like those Road Atlanta cars. Even 4 car lengths is a long way, and the auto gets worse from there.

Originally Posted by tracyda

No, I understand this quite well and do understand the point you are making. I actually agree with your point and you could also choose to not be condescending as well. I just think your example would be much better if it included the two cars that matter (that were in the roll race), instead of two that are not even competitors.

Once you remove your assumption one is carrying more speed in the corner, you will see my point of view. I am suggesting that because there is no head to head, same day, same track data to prove otherwise. Are you suggesting there is?

Originally Posted by shockwave

Great idea but it still won't work. The bashers have already arrived on this thread as well. Nothing will deter them. I just keep adding them to by ignore list if they aren't there already and don't have to read or even display their unconstructive comments.

Originally Posted by Snorman

I have absolutely zero concern over your accusation that I am being condescending. None.

Facts are facts. And figures are figures, either find data to refute them or continue to speculate. It's clear that you also don't understand the point of the data I presented. Pro tip: it did not include a full lap analysis.
S.

Originally Posted by tracyda

Now I am totally confused what you are debating or referring to in regards to my statement?

Simple point I am making, if two cars are evenly matched on a road course (same speed for turns (in/during/exit) and same acceleration from 0-100, but one is stronger in the 100-150mph range, then one car has an advantage, right? The only time this is not true is if the max speed for the track is <100. That is my only point, nothing more, nothing less.

So, what are you referring to that relates to my posts that makes you believe you have interesting data and I don't?

Originally Posted by Snorman

No...we are looking at a .5 advantage from 50-130 for the ZR1 (based on different days, different conditions). We could probably calculate, based on a ~1.4 ft/sec/sec straight line acceleration advantage during that interval what the distance advantage would be at the end of a given straight. But the point is, it's not as much as is being represented. "Bus lengths" not found. I understand that you look at data, so do I, but c'mon here. We're not talking hundreds of feet of delta from 100-150 mph. I don't have that data, but it's probably less than ~100'. And I think we both know that's a delta that can easily be made up in a number of corners.
S.

Originally Posted by heavychevy

not to a ZR1 it cant. Im starting to think some of the pdr speeds are a bit inflated because most of the minimum corner speeds are similar and sometimes greater than my race car, however

A bus length is 45 feet tops. So there is one represented in your first scenario. At .5 is at least 2. Its not as hard as as it seems.

Originally Posted by tonypittman

Lots of great information in this thread.

But, I think the simple point behind all of this is that the C6 Z06 came along at a time when for under $70k you could buy a Corvette Z06 that pretty much mopped the floor with its peers...and even killed most super cars. Whether it was a drag race, roll race, lap times...didn't matter. The Z06 wowed many...and GM set a very high bar for the Z06 brand. Many who fell in love with it got used to seeing it run away with all kinds of races, most notably YouTube roll races.

Now, 9 years after the 2006 Z06, we see another Z06 hit the market. And this time, it's different. Sure, it's a very good car...best Corvette ever, IMHO. But, it DOES NOT blatantly mop the floor with as many cars in-and-around its class. The game has changed.

Again, doesn't make the C7 Z06 a bad car. But, this time, if you are looking to spend "Z06 Money" and pretty much rule the drag strip, the track, AND the roll races, it won't be like it was with the 6th generation.

Simple.

Originally Posted by Snorman

At SM the PDR was within .002 of the SM transponder system. It appears the PDR is accurate.
Although, not sure why PDR is an issue?
S.

Originally Posted by Deathfly7

Look, I am not one to bash. I also love corvettes and wanted the z06 to be one of the best sport/supercars ever made. However the way GM marketed the z06 should cause an outrage among us enthusiasts, if we do not speak up they and other manufacturers will feel free to do whatever they want because they can.

1) GM should never find it acceptable to tell customers to tune and mod their cars to get the full potential out of it (i.e. excessive timing pulled etc). I mean you spend close to 100 grand on a car. You damn well want to keep the warranty ALONG with having the full performance the engine has to offer.. I think that is a very reasonable assumption many corvette owners have/had.

2) GM needs to realize that dropping big names like "better than porsche pdk" better be backed with more than just some graph I could have made in excel in 3rd grade. That was a total marketing gimmick that was honestly embarrassing. Having almost every reviewer note that the A8 was much slower than expected, along with many owners having to resort to "well its fast enough for me" or try to remedy the situation by saying how the actual gear change is faster despite the lag between pulls and shifts is just a bandaid at best.

3) It is not only GM or Z06 that have been bashed for doing things. If you remember when the GTR came out they were going to refuse warranty fixes to people who broke their trannys from launching their car... because of the outrage and hype it caused they were forced to remedy the situation and please customers or else they would have lost out big time on potential buyers.