Wass

During testing the rims rotated more than 360 degrees inside the tires, so GM had to score the inside of the rims and provide some kind of beading to prevent it. Awesome car!

VIN666

Tire glue, like on my RC race cars LOL.

johnglenntwo

I believe the tire slipping is probably also a function of torque and weight!

NemesisC5

If indeed the Z28 is running R compound tires the damp pavement sections take heat out of the tires needed for maximum adhesion. Most of the run you can see a dry line of lighter gray pavement but towards the final part of the run there was a light drizzle that definitely cooled the tires. Additionally combine the damp areas with the 55* ambient temps (if you can believe the blue digital temp gauge on the video) and you have cool damp pavement, decreasing adhesion a little more. Those of you that have driven R compound tires around a track at speed will know that tire/track temps play a critical role in lap times. Concerning hydroplaning, there was not standing water necessary for that to occur. This is basic "tire 101" information and likely affected lap time by ~3 seconds like someone posted earlier in this thread.

I have not done any research as to what internal gear ratios the Z28 transmission has but I see it struggled to reach 161 mph and only did so for maybe a second. I think I remember the ZR1 reaching 184 mph and the ZO6 Carbon Edition reaching somewhere in the 170's on that same final stretch on the circuit. I know both Corvettes have less aero drag and less weight with the ZR1 having 133 more horsepower as well. Does the Z28 have the same close ratio tranny as the ZR1?

johnglenntwo

Tremec TR6060 six-speed manual
Gear ratios (:1):

First:
2.66

Second:
1.78

Third:
1.30

Fourth:
1.00

Fifth:
0.74

Sixth:
0.50

Final drive ratio:
3.91

http://media.gm.com/content/media/us...amaro-z28.html

I'm sure it wouldn't be to the same degree, but, I wonder if the production car suspension aspect is what has held GM back in the Zs downforce? I have thought they just didn't want to be too ricer, but, thinking about it I just wonder how well it would work? Would they have to make the Vette really stiff too?

NemesisC5

Thanks for providing the internal ratios, they are the same as the C6Z. The .74 5th gear ratio explains the lack of top speed climb in the heavier drag limited Camaro body. The added downforce created by front splitter and larger rear spoiler also add to aero drag, although it more than make up for it in the many high speed corners with combined with R compound tires. The ZR1 especially benefits from the track usable 5th and 6th gear ratios. It seems odd that the Z28 which is more focused as track than street with many comfort items not standard (or available) did not receive a more track focused transmission. Admittedly, many will never see duty on the Ring but there are a number of HPDE's at tracks like Daytona with a need for a 5th gear that will pull the Z28's weight and drag against the many Corvettes that attend these events. It's better to have it and not need it than need it and not have it.

Z06 1st gear - 2.66 ZR1 1st gear - 2.29:1
Z06 2nd gear - 1.78 ZR1 2nd gear - 1.61:1
Z06 3rd gear - 1.30 ZR1 3rd gear - 1.21:1
Z06 4th gear - 1.00 ZR1 4th gear - 1:1
Z06 5th gear - 0.74 ZR1 5th gear - 0.81:1
Z06 6th gear - 0.50 ZR1 6th gear - 0.67:1

LEAVINU

They do point out it's still in "development" although they refer more to splitters than anything else in that sentence. Maybe they have a time they want to hit on the Ring and anything is up for change to achieve that goal. Especially to meet the need of being in talks with GTR's and P cars.

Just a thought.

NemesisC5

Good point, at this time they only state that it exhibits downforce but have yet to publish numbers at any speed. The published 1.08g skid pad results are very impressive especially for a car that is 3847 lbs and with a higher center of gravity than the C7. I would guess (hope) the C7 Z06(?) has more than a few performance benchmarks we will be surprised with as well.

johnglenntwo

NemesisC5

Aero components contribute more to downforce as speed escalates and Magnetic Selective Ride Control can be dialed (stiffened) to handle changes in weight/downforce. With splitters, spoilers and rear diffusers GM is incrementally engineering downforce for much improved handling while still maintaining the looks of a sports car rather than a purpose built racer with what the road going public would consider ricer. I'm not sure if the masses are ready for Viper ACR style wings, splitters and double winglets. I like the styling of the old Viper ACR which is basically a street licensed race car with aggressive but functional lines. It held the production car Ring Record until recently when it was bested by the Porsche 918.

RC000E

With all this debate, what we DO know is...in a 7+ minute lap the Z28 posted a 4 second or so margin of victory over the ZL1. Granted, the Z28 likely, according to sources, has another 3-4 seconds in it they believe.

The ZL1 did 2:52.xxx at VIR and we KNOW the Z51 Corvette did VIR at 2:50's...Mero said so himself.

You can talk about tires and brakes on the z28 all you want, but I've said it before...I'm seeing the C7 Z51 at 7:35's (if they got a dry track to run)...I called it back in january.

I'm betting that because these will be the first Corvette C7 times released, that due to inclement weather, they are not releasing the times because they didn't hit the mark. They'll go back later, or again shortly on a dry track.

johnglenntwo

The new SCCA Camaro setup is exceedingly aggressive and pulled out (and stiffened up) all the stops. Spring Rate! Aero! That's all the ZR1 would have needed to run that 7:14 with that Lexus, obviously.

I think a SCCA Z07 454 could do the trick! Why Not?

johnglenntwo

The 2014 Z28 added MSRC AND spring rate. They didn't rely on MSRC alone to stiffen this car up enough!

NemesisC5

It does not have MSRC as I previously assumed. Z28 designed as track car so GM engineered the handling for tracks with a different system.
--------------------------------------------------------------------

As Published 3/23/13 GM Authority Website The DSSV Suspension
The Camaro Z/28 does not use Magnetic Ride Control like the ZL1. But it doesn’t need it. As we reported previously, the Z/28 is one of the first production cars fitted with race-proven, spool-valve dampers — the first being the Aston Martin One-77. Compared to a conventional damper that offers only two-way tuning for compression and rebound, a spool-valve damper allows four-way adjustment to precisely tune both compression and rebound settings for high speeds and low speeds. The wider tuning range allowed engineers to dramatically increase the damper stiffness on the Camaro Z/28 without a significant change in ride quality. Additional chassis changes include stiffer spring rates and suspension bushings for improved cornering response. All-in-all, the Z/28 is capable of cornering at 1.05 G-forces on the skid pad. Compared to 1 G in cornering, the increased 1.05 G can cut up to four seconds per lap around the Milford Road Course, keeping all other things equal.
---------------------------------------------------

As Published 10/18/13 Edmonds This Good, and It's Still Getting Better
GM says the 2014 Chevrolet Camaro Z/28 will circle a skid pad at 1.08g, and that's the only one of the typical performance yardstick numbers the company is ready to share. As of today, the car is still in development. Rest assured we'll learn the Z/28's acceleration, braking and slalom numbers well before the car goes into production late next spring.
---------------------------------------

It appears the Z28 improved .03 g's on skid pad performance depending on the source. If the last sentence of last paragraph is relevant to improved skid pad performance and they are not yet ready to publish other performance numbers there may still be more to this car. Could the C7Z emerge with more track oriented options to lower weight and increase performance similar to the 2014 Camaro Z28?
Intriguing possibilities for next C7 Hi Po variant....

Link to Multimatic website below explaining DSSV

http://www.multimatic.com/structures...ion/dssv.shtml

johnglenntwo

Good Stuff and VERY interesting! Confusions Good!

Thanks!

johnglenntwo

http://www.insidetracknews.com/news/...t-le-mans.html

Will The Z/28's Spool-Valve Dampers Make MRC Obsolete?

http://www.gminsidenews.com/forums/f...solete-117462/

NemesisC5

The MSRC definitely has it's place with the Grand Touring vehicles to offer adjustability for the street or track but the DSSV is intended as a no compromise performance option that still retains a reasonably comfortable ride. I would assume that Corvette owners that don't opt for Z51 suspension or firmer may feel the ride a bit too harsh. It seems reasonable to assume the next C7Z or whatever they name the Hi Po variant designed primarily for HPDE / Race duty will come equipped with DSSV.

Comments in the article say the Z28 still has some fine tuning to do and yet they published ring time in less than ideal conditions. It is also stated there was likely another 3-4 seconds left in that run due to conditions. I think it may be reasonable to assume some of the widebody C7's covered in black camo will have the DSSV and best the ring time of the C6Z Carbon Edition that came so close to the ZR1 ring time. Pure speculation but with the considerable effort and investment GM has put into it's "go fast cars" it may be possible in 2014 we see a C7 variant break the 7 minute 10 second mark.

obzidian

My fear with that much like the z28 a new z06 could also be more focused as a track car and thusly loose it's street comfort. With that, again like the z28 the new z06 will also be priced astronomically high... Perhaps to keep production to a certain figure.

In other words.... We might eventually see only z51/base vette with the occasional "zr1" car on the street with the even more rare z06 enjoying that one speaker and optional ac. Bummer as I really enjoyed (even with all the issues I had) my z06... Even after all these years it is still a benchmark car and one that most ford fans wish their beloved 13' gt500 would reach.

Lavender

Source?

johnglenntwo

And how'bout basically, or an order optioned combination of:

A MR shocked, SS tired, Iron braked, ~545hp Z06!?

A Spool shocked, Cup tired, CC braked, ~560hp Z07!?

A MR shocked, SS tired, Iron braked, ~700hp ZR1!?

A Spool shocked, Cup tired, CC braked, ~720hp ZR2!?

E85?....

And it is being said the Z51 is fast, but, it takes a lot of concentration. Doesn't sound like an easy and consistent Ring run, like before! Now a Z52 would....!?