PRE-Z06

You’re correct, one too many O’s.

So with all those better things on the C8Z06 what do you speculate the outcome would be if the C7ZR1 had Cup2Rs? The Cup2Rs are the biggest improvement on the C8Z06, it’s not a knock against the car it’s reality that they’re the hardware that makes the biggest difference and when every generation upgrades tire compound it makes it hard to realize how small those other changes are worth.

CaddyRacer

Agreed, we don't know what these tires will do a Corvette but at $800/tire is a serious expense
......"you can go as fast as you can afford"

UnhandledException

Cup2Rs would give 1s advantage per 1 minute lap. This has been widely documented and proved across the board from Lars Or Kevin making comparisons to people actually drove with them in various tracks in Porsche GT cars. I’m pretty sure ZR1 would land a 2:35 VIR lap time with those tires. If it had the CF wheels, the advantage would probably 1.2 seconds a lap, so perhaps 2:34 is possible if ZR1 was wearing the same shoes so to speak. When I ditched the stock wheels in the ZR1 and went to forged wheels, I saved a 25 lbs of weight (which is a lot as its rolling weight) even though I went with a 295/345 tire size. Theoratically if I went with regular Cup2s, same size, cup2 threads (much less than PSS threads), I would save around 30 lbs. ZR1 rear wheels weigh about 32.5 lbs. My replacement wheels weigh 20 lbs.

Telepierre

If you look at the GT2RS Nurburing posting directly from Porsche it is clearly indicated they were not breaking the 7:05 with regular CUP tires and therefore for Porsche the CUP2Rs were definitively worth more than one second for minute lap.

Z0HS1CK

Giving FI to the C7Z was one of GM's BIGGEST mistakes. Thank god GM gave us what we want for a final farewell.

Telepierre

From a primal track point of view there is plenty of anecdotal evidence and credible statements from Jim Mero better tires at par with CUP2Rs or the better ones mulled by Jim would have taken the C7 ZR1 into the high 6:40s. Again TORQUE which now the C8Z06 does not have (thanks to the EPA) so now its RPMs and credit to Corvette for adding more payload to the car but without the ZR1 pull we have a car with more sophistication but less pull.

jimmyb

I'm confused why people are comparing the C8 Z06 to the C7 ZR1? If, as Tadge states (and I believe) that the C8 Z06 will "hang" with the C7 ZR1 on track, then we're looking at the C8 Z06 being considerably faster around a track than the C7 Z06 (probably 4-5 seconds a lap faster).

jimmyb

I disagree that the Cup2R's are the "biggest improvement". Playing this "what if" game is never ending..."what if" the C7 ZR1 had a DCT? "What if" the C8 Z06 had a manual? Etc...
Point is the C7 ZR1 did not come with Cup2R's.
And why aren't you comparing apples to apples (C8 Z06 verses C7 Z06)?
Because you KNOW what THAT outcome is going to be.

jimmyb

Porsche is notorious for playing fast and loose with the cars involved in these hero 'ring times. Manthey modifications, etc...

Savoy2001

What if’s as far as tires are concerned are not the same as what if it had a dct or any other hard ware modification done. Tires are on and off and can be used on just about any car. Bad example. Jim Mero did day many times the zr1 would have performed allot better if they would have given him the bespoke tires he wanted in that car. So equal tires on both cars is a valid thing. Also put cup2r’s on a stock c7zo6 vs c8 z06 and let’s see lap times. Fair I would say. What say you?

PRE-Z06

I think he meant 1 second per mile not minute.
I think the difference in the C7Z06 and C7ZR1 could be made up if the C7Z06 had Cup2Rs and the C7ZR1 had Cup2s as well probably depending on how many corners/straights the track had.

Since tires make the biggest difference as anyone who races knows, making that equal is a fair comparison to see what difference the other changes truly make.

ZRacerLE

I'd put money on this one

UnhandledException

Where is this posting Telepiere? Please enlighten myself and the rest of the forum.

BrunoTheMellow

theres a difference in horsepower between the c7z and c7zr but if you watch Tobolowskis cota laps with both cars. He only managed about 1 second better on the c7zr (but this was also due to track getting worse). On a low speed track the difference is minor. Maybe Half a second per minute. After all the cars are essentially identical except for a bit of downforce and 100 more hp.

I agree the major difference is tires. Although the oem c7 cup2 ZPs are better than Porsche cup 2s. Porches still have their cup2s with rain blocks for Europe weather. Chevy said F that and made a semi slick.

Trust me on this, the c8z having MUCH better grip out of low speed corners will make a big difference compared to c7z. Hairpins are a major struggle in my car. High speed flowy corners. Well the c8z does make double the downforce of the c7z. I believe gm when they say that the c8z will run similar lap times to the c7zr1 because:

same downforce

better low speed traction

and better tires to make up the weight and power deficit.

UnhandledException

There is more to C7 ZR1 than 100 hp (btw, its more than 100 hp as ZR1 with a 93 octane pump gas dynos at 800 hp and 750 ft lbs). ZR1 has much better cooling, doesnt heat soak like Z06. It has better springs and suspension tuning. Brakes are better too with special coating and pads. Its downforce makes a difference above 120 mph and doesnt cause as much drag as the stage 3 on Z06. I’m not sure what track you are talking about but VIR is a track where ZR1 has over 4 seconds on the Z06. Thats quite a bit and 100 hp more wont simply get you that.

ZR1 also has a factory tune that can run 100 octane and it is optimized for that. It also works very well with 15w50 (only vette that calls for it). These bits and pieces add up quite a bit in helping it perform better.

PRE-Z06

The Cup2R is roughly a second faster per mile according to Michelin, so at a track like VIR it would allow the C7Z06 to run like a C7ZR1 on regular Cup2s I reckon given it’s 4.1 miles in length.

Torque Obsessed

It worked for Audi. I'm not a diesel fan and wouldn't want a diesel Vette, but they won Le Mans with diesel power eight times over a nine year span.

Audi R10 TDI

Le Mans Winners List

Telepierre

You are more than five years late on this request. Corvette Forum has been enlightened plenty with Porsche direct links and direct first photographic accounts on how the 'CUP2R game' was played throughout the whole 991.2 GT2RS and GT3RS marketing tour. Since you are new to the CF feel free to help yourself on this topic by searching.

Alternatively I'll gladly repost for you and the millionth time the whole lot IF you first offer the following:

1. You already acknowledged the whole video analysis for 5th gear was faulty. Also please acknowledge that your GT3 acceleration analysis was erroneously extrapolated by omitting the onboard VBOX data which clearly indicates real instantaneous GT3 speeds double digits lower than on board tachometer.
2. Please post substantiating evidence to your claims that a. Chevrolet offers a 100 octane tune for the C7ZR1 and b. such tune boosts the SAE rated power of 755HP to 800HP SAE.
For the record Chevrolet does sell an LT4 (Z06) octane tune calibration which does not boost power but diminishes the heat soak power degrade from the rated SAE Z06 650HP.
Link: lt4-100-octane-fuel-calibration-kit-12677967.pdf (chevrolet.com)
3. Clarify the claim the CUP2Rs are good for 1 second for each minute track. Did you mean to say 1 second for each mile or kilometer? this would be consistent with the double digit time improvement the GT2RS enjoyed with CUP2Rs at the ring.

Thanks. If you do your part, I do mine for you.

Telepierre

I think that claim referred to kilometers (Michelin being French) so we are talking about 2 seconds for mile. The GT2RS went from 7:05 to 6:48 with CUP2Rs. That delta is consistent with the 2 seconds per mile (1 second per kilometer Michelin spec).

EDIT: looked up the Michelin Nardo tests. Half a second for kilometer so you are more correct than I was. CUP2R good for approximately one second for mile. The Nurburing is 13 miles and it checks with the 15 seconds GT2RS time calculation although those were prototype CUP2Rs in development.

jimmyb

Tires ARE consumables so...put the same tires (any tires) on a C8 Z06 and a C7 Z06 and I will bet my life the C8 Z06 is considerably faster around a track. THAT is my point about playing "what if". Based on these numbers guys are throwing around, a C8 Z51 is a 2:44 car at VIR Grand Course with Cup 2R's...And we are ignoring that these various Cup 2R's are optimized for the car...Cup 2R's on the C8 Z06 are not the same tires as the GT2RS Cup 2R's (for one thing, the C8 Z06 tires are runflats).
BUT
There is a reason GM spent whatever they spent (I'm guessing $1 BILLION) to develop a mid-engine Corvette. Obviously tires are vital part of the deal but to suggest they are the most important part of it rather than being A part of the entire package is foolhardy. If tires are the biggest difference maker, why spend a billion? Just get Michelin to make some crazy, barely legal DOT tire and slap them on a re-styled C7, assuming that a "hero lap" is the MOST important thing to GM (which we know it's not).