X25

I just would like to point out here, I had to choose either Grand Sport or Z51 when I bought the car last year for track use, and would like to summarize why I picked Z51: C7 Z51 does not give much beyond what Grand Sport already provides (besides small weight and air drag advantages), but can provide a platform with so many things you don't need not already paid for, like wheels, magna ride or CCB brakes. Any good C7 track car needs non-OEM wheels (no good tire/wheel choice at 19"/20"), and there is much to be gained with good coilovers, which is very easy to switch to with Z51 w/o magna ride. Keep in mind, '17 Z51 comes with all the cooler upgrades that also came with '17+ Z06 and Grand Sport (which I had to install myself, since I have a '16).

To keep it very short, if you'll leave OEM, Grand Sport seems to be the best option when price is factored in, but if you will modify the suspension anyway, Z51 suddenly becomes a great platform. Any C7 needs aftermarket wheels anyway, and with my CCW wheels, I was able to run 315/325 tires on LG G2 coilovers and sways on 18"x10.5" front and 19"x11.5" rear wheels shod inside the narrow fenders. I am very happy, especially with the front bite:

(Build thread)

Foosh

I think you'd be surprised what a DSC Sport Controller does for an MSRC car. I think it might well surpass what aftermarket coil-overs can do.

X25

I am honestly not sure one way or another. GM's magna ride suspension is sprung softer than it should be to provide comfort at the street, and extra stiffness is provided by the magna ride stiffening up compression (and rebound?) at the track, which also provides the advantage of softening up the suspension at the track beyond what a race suspension could ever do for traction in corner exits, etc. Same can also be done for increased turn in bite, etc. It's an amazing technology, and looks like it can be taken a step further with that controller. That said, you can only do so much by adding stiffness via a 'shock'. Aero is a great example for this (which demands static spring rate), as well as long sweeper turns where the stiff shocks lose their ability to add stiffness after a short while.

Looking at team Camaro, they have released their 6th gen SS 1LE and ZL1 using magnetic suspension, and they got great results with it. However, with their top-dog ZL1 1LE, they went with the multimatic suspension again (which is very similar to a set of quality coilovers). It was the same for 5th gen as well, where Z/28 came with multimatic suspension with 85% stiffer springs, while ZL1 had magnetic shocks. This tells me that, at least team Camaro also believes there is more performance to be gained from shocks tuned for track as opposed to magnetic shocks. Multimatic is no different than coilovers with excellent 'pre-made' adjustability for manufacturers.

Kamran has a '17 Grand Sport, and he has DSC as far as I know. I am looking forward to seeing what his car can do, especially since he is local to me. I really don't know how these different approaches fare, but I think it is hard to judge up front : )

JoesC5

One has to be very careful when comparing the various times and various cars at VIR.

The track has been repaved twice since the c6 Z06 and C6 ZR1 runs were made. The repaving helped lower the times of later cars/runs such as the C7 GS and the C7 Z06, so a direct comparison is impossible.

Same goes with comparing times at Nurburgring. Since the C6 Z06 and the C6 ZR1 runs were made in 2012, the track had a 1/4 mile section of bad surface repaired, which increased corner speeds(thus reducing times).

Also, are you not comparing a 2007 C6 Z06(that did not have the Z07 option) with the 2017 GS that has the Z07 option. Why don't you compare the times of a 2013 C6 Z06 with Z07 to a 2017 GS with Z07?

GM made it very clear when they were running the C6 Z06/ZR1's that they did it with the factory trim height and the factory alignment. GM also said that the C7's they ran on the road courses and provided to the magazines for reviews, were set up with a "track" alignment. How about comparing a C6 Z06/ZR1 set up with a non factory alignment to the C7's that GM runs that have a non factory alignment.

pdiddy972

Well then let's put it this way:

Do you think a C6 Z06 or ZR1 would be the equal of a $200K 2016 Porsche 911 GT3 RS? Because the Grand Sport was.


2017 Grand Sport - 2:47.1 <-------- NEW GRAND SPORT
2016 Porsche 911 GT3 RS - 2:47.0 (no AC, no radio, badge delete, fabric straps instead of door handles, etc)
2015 Z06 - 2:44.6

JoesC5

I can't explain why a C7 GS ran .1 slower than a 911 GT3 RS, nor can I explain why a Z28 ran .1 second slower than a C6 ZR1 at VIR. I don't believe that anyone believes a Z28 will be within a .1 second to a ZR1.

Can you explain why at the Ring a C6 ZR1 ran 7:19.63 and the 911 GT3 RS ran 7:33(13 seconds slower than the ZR1) and the Z28 ran 7:37.47(18 seconds slower than the ZR1)? The 505 HP Z06 was only 3 seconds slower than the ZR1 at the Ring. What has the C7 GS run at the Ring, so we can compare it on the track that the Big Boys play on?

pdiddy972

The Ring gets repaved too, so different days (or even years) times aren't as relevant as the times taken at VIR for the GT3 RS and Grand Sport, which if you'll notice were all run at the same time (Lightning Lap 2016). So the same thing you tried to suggest made the VIR times between the Grand Sport and the older-model Z06 incomparable is exactly the thing that makes the Grand Sport and the GT3 comparable - they were tested same time and weren't before/after repavings.

JoesC5

VIR had a complete repaving(twice) whereas the Ring only had a 1/4 mile section repaved to get rid of the bumps and to slightly widen the track.

At VIR the 2012 ZR1(before the repaving) ran 2:50.7 vs the 911 GR3 RS's 2:47.0(3 seconds difference) but at the Ring the ZR1 ran 7:19 and the 911 GT3 RS ran 7:33(14 seconds difference in the other direction).

Seems odd to me that the 911 GT3 RS was faster at VIR than the ZR1 but at the Ring that was reversed and the ZR1 was considerably faster than the 911 GT3 RS.

We know what the times are at VIR for the C6 Z06/ZR1 and the C7 GS, but what about the times at the Ring. I'm really having a difficult time comparing the C6 Z06/ZR1 to the C7 Z06/GS at the Ring(the track that most car companies use to show their "stuff" off, as GM did with the new ZL1).

The C7 GS ran VIR in the same time as the 911 GT3 RS, 2:47. Correct?

Then the C7 GS should run the same time at the Ring as the 911 GT3 RS. Correct?

The 911 GT3 RS ran the Ring in 7:33 thus the C7 GS should also run the Ring in 7:33. Correct?

The 2012 C6 ZR1 ran the Ring in 7:19. Correct?

That means that the ZR1 ran the Ring 14 seconds faster than both the 911 GT3 RS and the C7 GS. Correct?

The 2012 C6 Z06 ran the Ring in 7:22. Correct?

That means the C6 Z06 ran the Ring 11 seconds faster than the 911 GT3 Rs and the C7 GS. Correct?

pdiddy972

Irrelevant (unless you're suggesting it got repaved in the middle of Lightning Lap 2016 testing, such that the Grand Sport and Porsche 911 GT3 RS got tested on essentially different versions of the same track). I assume you're not claiming that, so my question remains:

If the Grand Sport equaled the Porsche 911 GT3 RS at VIR when tested back to back in the same testing regimen and same track, do you therefore think an older Z06 (like the 2009 model someone was referring to) is equal to the $200K 2016 Porsche 911 GT3?

Since there is no such thing as official Ring times anymore and since you've already stated that the times were opposite between the Ring and VIR for at least one car, I'm not sure we can use unofficial Ring times, done on different says, by different drivers, under unknown weather conditions, and with possibly different setups.

I think the same track, same staff, same methodology, same timeframe, same elevation (and presumably same weather conditions) for the LL test is more conclusive. Your opinion may vary.

2cnd Chance

FYI, VIR was repaved early 2014 before that years LL. It had degraded terribly by 2016 and was repaved again (after a lawsuit regarding its condition) in late 2016 after that years LL. The 2016 field was tested on a course falling apart.

It's been stated by Tadge I believe that the C6 ZR1 was .6 faster around Milford than the GS/Z07. Both wearing Michelin cups.

montoya

Nice lap, I love ORP. It's been too long since I've been there. It looked so familiar to me in terms of pace I had to check back to see my results from when I ran there with NASA and time trialed my GT3. Yep almost identical time- 1:51.79. Good comments on suspension dynamics, I'm picking up a GS in a couple of weeks with Z07, m7, comp buckets etc. No track, just a fun street car since I race in SCCA Spec racer ford now.

X25

Thank you, I love ORP, too! The ORP club does open track days, so I can easily test the cars out. I raised the car a bit since I did that lap, and I will try it again tomorrow; here's hoping I did not screw it up by raising the car : )

Congrats and have fun with your new Grand Sport!