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Thank you for the account. Rest assured that anyone who has ever raced under such time constraints fully understands your feelings: good, bad, and frustrated... believe it or not.
I found your take (inside line) on things very interesting. A quick question, if instead of a last minute thing, if the Grand Sport Z07 manual had been fully dialed-in in your opinion what time could have been had?
I found your take (inside line) on things very interesting. A quick question, if instead of a last minute thing, if the Grand Sport Z07 manual had been fully dialed-in in your opinion what time could have been had?
Thank you
Robert
Hi Robert,
The GS was pretty much dialed in. I mean it was fully prepped.
Since I was driving a Z06 until that day, it was a piece of cake. What would have made it better was a closer ratio 4-5. I would venture to guess 3 perhaps 4 seconds. The data showed the GS pretty much matched or in more cases exceeded the corner speeds of the Z06.
The GS down almost 200 HP to the C6 ZR1 with PS2 tires yet only 1 second slower, pretty much speaks for itself.
The GS was pretty much dialed in. I mean it was fully prepped.
Since I was driving a Z06 until that day, it was a piece of cake. What would have made it better was a closer ratio 4-5. I would venture to guess 3 perhaps 4 seconds. The data showed the GS pretty much matched or in more cases exceeded the corner speeds of the Z06.
The GS down almost 200 HP to the C6 ZR1 with PS2 tires yet only 1 second slower, pretty much speaks for itself.
Thanks,
Jim
Hi Jim,
You touched a very good point there. I think the gearing of the GS is far from optimal. The gap between 3rd and 4th is already too big in my opinion, and it is even worse in 5th...This is really limiting the performance of the car at high speeds. Tadge gave us some anwers about that but I was not convinced.. Manual Z06 is better geared, and SS 1LE and ZL1 1LE (especially this one) are very well geared compared to C7, and unless I'm wrong they also use a Tremec Gearbox TR6060 (instead of TR6070) which is basically the same ? Do you have your own explanation of this less than optimal gearing ?
Thanks for your participation in the forum, this is great to have someone like you answering our posts.
I would also have a question for you about rear caster effect on bumpsteer and DSC Sport alignment settings which are pretty differrent from the one you developped for the C7 (.021° toe out front and rear, compared to toe in recommended by GM) but I don't know if this is the right place for that... Because man, these alignment settings along with the rear caster at 0.7° make the car so stable !
The GS was pretty much dialed in. I mean it was fully prepped.
Since I was driving a Z06 until that day, it was a piece of cake. What would have made it better was a closer ratio 4-5. I would venture to guess 3 perhaps 4 seconds. The data showed the GS pretty much matched or in more cases exceeded the corner speeds of the Z06.
The GS down almost 200 HP to the C6 ZR1 with PS2 tires yet only 1 second slower, pretty much speaks for itself.
Thanks,
Jim
First I really appreciate your time to comment. Yes I agree with your thoughts on the gearing. Im always wishing 5th gear was 1:1 not 4th. And very interesting on the Grand Sports cornering comparison to the Z06. If I dont move to a C8 I plan on having Katech build my LT1 into one of their 427 LT1 spec engines. Thanks again!
Before I ever read Mr. Mero's comments, looking @ C7 lap times vs. all the world's sports cars including the Ferraris, Porsches and Lambos: the C7 does appear to be the best handing sports car in the world given its relative lap times adjusted for the horsepower of the cars involved. So I've been wondering 'how the hell is GM going to make the mid-engined C8 that much faster?' And I'm sure the C8 WILL be faster, I have faith in GM's Corvette team. But I don't expect to be THAT much faster.
Still, if the base car has a more powerful engine and mid-engine handling, what could go wrong? Very interested to see the finished car and ever more curious to see how it fares when entities like Car & Driver, Road & Track, etc. get their hands on ir for testing.
Regardless, the C7 will remain a viable and relevant world class sports car for many years going forward, it's by far the best Corvette ever, and arguably one of the best sports cars ever produced period.
The 2012 C6 ZR1 ran 7:19 on first gen cups, factory "street" alignment and factory 93 tune and on the track before it was repaired(bad 1/4 mile section was replaced and also widened in that corner, increasing speed through that corner.
What would you expect the time would be if that 2012 ZR1 had been on cup 2 tires, running on the repaired track, and with a 'track" alignment and with a 100 octane tune, like the C7 runs, when on the track?
I ask because the article felt it was necessary to post the C6 ZR1 time from 2008, but not post the time for the 2012 ZR1. R&T clearly wanted to compare the C7 to the C6 ZR1, by posting an "old" time(and just lightly make mention of the "later" time, without posting the later quicker time).
If we are to get a true comparison between the C6 and the C7(I don't believe that R&T really wanted a true comparison), we need to see what they both run when they are "apples to apples".
Well, you asked, Jim. So here's my take. And I'm quoting dmaxx as well.
Very likely no one has more recent experience with the last few Corvette gens, re factory handling, driving for road course time and setup, calibrating, etc. For that/those reasons alone, I think one of your "topics" or maybe an entire stand-alone seminar could be your informed suggestions on how to drive the Corvette for handling. It could be relative to track-driving, or street driving---but both are needed.
I realize this would be "classroom-time" only, but there's a lot that can be taught in the seminar, IMO.
A separate or added portion can be on how to set up the car for track or street suspension, tire, pressure, etc.
My guess is that it will be standing-room only. Good luck!
Originally Posted by Jim Mero
Hi Bill,
Yes I will be there. Carlisle was gracious enough to provide me a booth in the installation area. I will also be doing a couple of seminars. They told me I could choose what I want to talk about. I'm a little perplexed on the subject matter.
As i am typing this message a thought just came to mind, a poll on the forum relative to the subject matter. Stay tuned, Occasionally I come up with a good idea. LOL
Thanks,
Jim
Originally Posted by dmaxx3500
thanks
now,your new job should be ''TEACHING'' people how to ''DRIVE''
I went to ''keith code'' motorcycle school ,[25 years ago] at elkart lake ,wis [road America] and I learned more in 20 laps then I ever knew about handling,and street driving
and since that time ive driven some of the fastest street/race cars [lambo,ferrari,corvette,etc],and those motorcycle laps still come back [even on the street]
thanks again for being here and telling us some of the inside storys of corvette development
You touched a very good point there. I think the gearing of the GS is far from optimal. The gap between 3rd and 4th is already too big in my opinion, and it is even worse in 5th...This is really limiting the performance of the car at high speeds. Tadge gave us some anwers about that but I was not convinced.. Manual Z06 is better geared, and SS 1LE and ZL1 1LE (especially this one) are very well geared compared to C7, and unless I'm wrong they also use a Tremec Gearbox TR6060 (instead of TR6070) which is basically the same ? Do you have your own explanation of this less than optimal gearing ?
Thanks for your participation in the forum, this is great to have someone like you answering our posts.
I would also have a question for you about rear caster effect on bumpsteer and DSC Sport alignment settings which are pretty differrent from the one you developped for the C7 (.021° toe out front and rear, compared to toe in recommended by GM) but I don't know if this is the right place for that... Because man, these alignment settings along with the rear caster at 0.7° make the car so stable !
Honestly, I don't recall the reasons for the drop in RPM's from 4th to 5th. I'm guessing it's fuel economy. Having said that, I do not believe being at any track in the USA that required 5th gear (perhaps Road America). The Nurburgring was the only track where we needed 5th.
As far as alignment, I know Bowling Green as well as the dealers struggle with rear caster. And it's not that difficult to set, Correcting an inadequate rear caster makes the biggest difference of the settings you mentioned. I've always run front toe out in every one of my race cars, but because of production tolerances, we were forced to that toe setting. Having said that, the difference between .05 deg in and .02 out in the front is not as much as you'd think as the the dynamic toe is out because of the scrub radius. I've never run toe out in the rear, or have had it suggested to me by anyone including friends at Pratt and Miller or a personal friend who has engineered cars in F1, Indy and NASCAR because it's an oversteer effect, . Nonetheless if you're content with it, carry on.
The 2012 C6 ZR1 ran 7:19 on first gen cups, factory "street" alignment and factory 93 tune and on the track before it was repaired(bad 1/4 mile section was replaced and also widened in that corner, increasing speed through that corner.
What would you expect the time would be if that 2012 ZR1 had been on cup 2 tires, running on the repaired track, and with a 'track" alignment and with a 100 octane tune, like the C7 runs, when on the track?
I ask because the article felt it was necessary to post the C6 ZR1 time from 2008, but not post the time for the 2012 ZR1. R&T clearly wanted to compare the C7 to the C6 ZR1, by posting an "old" time(and just lightly make mention of the "later" time, without posting the later quicker time).
If we are to get a true comparison between the C6 and the C7(I don't believe that R&T really wanted a true comparison), we need to see what they both run when they are "apples to apples".
Well, from shooting from the hip, I don't know...lol The C6 ZR1 clearly would have been faster than the 7:19. Power to weight was an advantage for the C6, but the major difference is the drivability between the 2 cars. I loved the C6 ZR1, but with I believe was a 30% increase in body structure, 500% increase in steering stiffness and perfect steering damping with the EPS makes a huge difference for the C7.
Honestly, I don't recall the reasons for the drop in RPM's from 4th to 5th. I'm guessing it's fuel economy. Having said that, I do not believe being at any track in the USA that required 5th gear (perhaps Road America). The Nurburgring was the only track where we needed 5th.
As far as alignment, I know Bowling Green as well as the dealers struggle with rear caster. And it's not that difficult to set, Correcting an inadequate rear caster makes the biggest difference of the settings you mentioned. I've always run front toe out in every one of my race cars, but because of production tolerances, we were forced to that toe setting. Having said that, the difference between .05 deg in and .02 out in the front is not as much as you'd think as the the dynamic toe is out because of the scrub radius. I've never run toe out in the rear, or have had it suggested to me by anyone including friends at Pratt and Miller or a personal friend who has engineered cars in F1, Indy and NASCAR because it's an oversteer effect, . Nonetheless if you're content with it, carry on.
Thanks for your answer Jim
Yes, I always ran toe in in my previous track cars on the rear at least. But here a lot of track junkies run with the DSC sport alignment setting and are happy with it, so it wanted to give it a try. For now my first test drives are really good (Main use of the car AutoX and Roadcourse)
06-28-2019, 04:55 PM
(Main use of the car AutoX and Roadcourse)