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Assuming a good driver in both cars, the Z ain't got nothing to worry about, whether its M7 or A8. Just my lousy 2 cents.
I had a C7 Z06 and a Lingenfelter 427 2003 Z06 that I raced at the track. Let’s see what happens when the test results come out, it’s all speculation at this point. I can tell you a DCT makes a significant difference and makes a average driver a lot faster. The A8 trans in the Corvette shifted slow with many magazines complaining even dopey You-tubers, that had a lot of seat times in a DCT. Tadge wanted a DCT for the C7 but packaging and pricing did not allow this to happen.
Surprised no one has commented on the ground clearance... Its much better than I expected. My SRT charger has 4. 6 inches today and only scrapes once in awhile. 5.3 sounds pretty good and saves me $1500 by not needing the front lift.
Z51's have always been better "track cars" and that's what the package is designed to do. However, I would guess that the base, like the base C7 , will still handle really well. If I recall correctly the base C7 allegedly handled as well as a C6 Grand Sport. I think the Corvette engineers just make these cars handle better and better with each generation. Just saying...
I had a C7 Z06 and a Lingenfelter 427 2003 Z06 that I raced at the track. Let’s see what happens when the test results come out, it’s all speculation at this point. I can tell you a DCT makes a significant difference and makes a average driver a lot faster. The A8 trans in the Corvette shifted slow with many magazines complaining even dopey You-tubers, that had a lot of seat times in a DCT. Tadge wanted a DCT for the C7 but packaging and pricing did not allow this to happen.
A DCT is my favorite transmission type so I am a happy camper the C8 has one. Regarding the A8, my limited experience with it showed that when left in auto mode it shifted well. In manual mode, not so much. Manual shifts with the A8 are clearly not as responsive... up or down.... as a good DCT. Auto mode felt fine but auto mode on the track would overheat more quickly on a hot day by keeping revs high consistently.
So after seeing this new data with the performance numbers being so close Is anyone else thinking of dropping Z51 package and upgrading to 2LT With performance exhaust?
The Z51 is for track usage. It will lap faster and it will resist heat better across multiple systems than the base car. Z51 has never really been about acceleration times. If you aren't going to a road course, no need for the z51. In fact, the base car will be more than fine for the occassional track day user too. Serious track enthusiasts will want the Z51.
OK, I have done more spreadsheet crunching on the gear ratios and the results are "interesting"
If I got the rear tire diameters correct from Tire Rack, the Z51 is looking at top speed of 35.5mph in 1st and 58.7mph in 2nd. These are stunningly low speeds. Of course maybe DCT yada yada yada. For AutoX this is worthless, unless 3rd could be made to serve. Typically for a stock high power car the sweet spot is 68-74mph for 2nd or at least some gear that is serviceable in this range. 3rd gear on Z51 is 84.5mph.
Let's look at the ratios for the track. The gap from 3rd to 4th is huge for a track car. 84.5mph 3rd to 117.6mph for 4th! That is a 33mph spread which is NOT close ratio. Worse at 41mph to 5th at 158.19mph, 6th 203, 7th 260mph etc etc. Now these top ratios are for cruising not top end. 7th gives 80mph cruise rpm at 2029 and 8th is 1700-ish.
Tracks in the US are typically what I call "regular" vs "jumbo" Regular tracks have a top speed in a street corvette of 130-150mph range. The big tracks like Sebring, COTA, Road America etc. have top speeds in the 160-180mph range. Typical weekend warriors just use the taller cruise gear on the big track where necessary. Hardcore racers have different setups with different gearing.
Maybe these numbers are just the "new normal" for DCT, but they don't seem fit for purpose. Hence given the conflict with previously published Chevy Final drive ratios, these are suspect in my mind.
Which I see changes could be being made, which I could buy about the final drive, I don't buy for the internal gear ratios. FAR too much validation required along with the ECU tuning, ride and handling etc to wholesale change the ratios at this late date. Just my $0.02.
Surprised no one has commented on the ground clearance... Its much better than I expected. My SRT charger has 4. 6 inches today and only scrapes once in awhile. 5.3 sounds pretty good and saves me $1500 by not needing the front lift.
What I am worried about is the front overhang with that pointy nose. Even if the ground clearance is good, given a dip in the road or a slight incline, like a storm gutter leading to a driveway, it will scrape.
Nice data. Though I thought the Z51 rear axle ratio had been documented as 3.86:1? As for the performance numbers, those are obviously Chevy numbers so if history proves a good indication I would expect the Test numbers to be a few tenths slower...as a point of reference Chevy said the C7 Z06 was a 2.95 sec 0-60 and Motor Trends best number was 3.0...the Porsche Turbo S MT number is 2.5 seconds and 10.43 in the 1/4 mile. There is a youtube video of a '16 Z06 A8 bone stock with only 500 miles running back to back 11.03 and 11.06 1/4 mile runs...so looks like C7 Z06 owners will still have the advantage when a C8 base pulls up next to them at a stop light next year.
The tranny ratio's are really spread out. Low looks ok and great for the 0-60 but after the first three gears they go really high.
Thanks. That is very helpful. Have a 2LT Base with Performance Exhaust on order and was debating if I should switch to Z51. Now I think not as little performance difference, on 1/10 of second to 60mph.
No Z51 for me. These numbers show for most people who never track the car it's a waste. I'll never track mine
I'll never need the EDif. Ugly wing and low front splitter and additional drag. No real advantage in speed on city streets. I'll spend the money on an aftermarket exhaust and upgraded interior.
If Chevy offered Magnaride I would get it but for some dumb reason they don't so it's their loss.
they made the base car too good, which is fine by me.
Last edited by Sin City; Aug 27, 2019 at 11:38 AM.
Like I posted somewhere else, you can make that .1 by using the same tires. Yes, the gearing is different but Z-51 is optimized for tracks with turns, hence the lower top-speed. If all things are the same (wheel size, rotors, dry-sump, etc.) non-Z51 may be the way to go.
OK, I have done more spreadsheet crunching on the gear ratios and the results are "interesting"
If I got the rear tire diameters correct from Tire Rack, the Z51 is looking at top speed of 35.5mph in 1st and 58.7mph in 2nd. These are stunningly low speeds. Of course maybe DCT yada yada yada. For AutoX this is worthless, unless 3rd could be made to serve. Typically for a stock high power car the sweet spot is 68-74mph for 2nd or at least some gear that is serviceable in this range. 3rd gear on Z51 is 84.5mph.
Let's look at the ratios for the track. The gap from 3rd to 4th is huge for a track car. 84.5mph 3rd to 117.6mph for 4th! That is a 33mph spread which is NOT close ratio. Worse at 41mph to 5th at 158.19mph, 6th 203, 7th 260mph etc etc. Now these top ratios are for cruising not top end. 7th gives 80mph cruise rpm at 2029 and 8th is 1700-ish.
Tracks in the US are typically what I call "regular" vs "jumbo" Regular tracks have a top speed in a street corvette of 130-150mph range. The big tracks like Sebring, COTA, Road America etc. have top speeds in the 160-180mph range. Typical weekend warriors just use the taller cruise gear on the big track where necessary. Hardcore racers have different setups with different gearing.
Maybe these numbers are just the "new normal" for DCT, but they don't seem fit for purpose. Hence given the conflict with previously published Chevy Final drive ratios, these are suspect in my mind.
Which I see changes could be being made, which I could buy about the final drive, I don't buy for the internal gear ratios. FAR too much validation required along with the ECU tuning, ride and handling etc to wholesale change the ratios at this late date. Just my $0.02.
Long time no chat Fred! I think you're right on the money, and the car is going to fall on its face at triple digit speeds, and be constantly stuck between 2-3 in autocross. Most of the potential of the DCT 'box is wasted as it is reduced to effectively a 2 or 3 speed box for almost all tracks.
I put together a "were I Tadge for a day" gearing choice, which isn't rocket science, and is more or less what Porsche (who has more experience than anyone in DCT boxes) uses in their GT cars.
Given the overtly compromised nature of the C8's gearing for track use, one has to wonder at the nature and balance of forces (i.e. fuel economy, focus on 0-60 and 1/4 mile, leaving easy wins for later Zxx models, on-track cooling concerns with frequent shifts) led to such an awful place in what is an otherwise great package.
Long time no chat Fred! I think you're right on the money, and the car is going to fall on its face at triple digit speeds, and be constantly stuck between 2-3 in autocross. Most of the potential of the DCT 'box is wasted as it is reduced to effectively a 2 or 3 speed box for almost all tracks.
I put together a "were I Tadge for a day" gearing choice, which isn't rocket science, and is more or less what Porsche (who has more experience than anyone in DCT boxes) uses in their GT cars.
Given the overtly compromised nature of the C8's gearing for track use, one has to wonder at the nature and balance of forces (i.e. fuel economy, focus on 0-60 and 1/4 mile, leaving easy wins for later Zxx models, on-track cooling concerns with frequent shifts) which led to such an awful place in what is an otherwise great package.
Last edited by jrhoades; Aug 27, 2019 at 12:47 PM.
Long time no chat Fred! I think you're right on the money, and the car is going to fall on its face at triple digit speeds, and be constantly stuck between 2-3 in autocross. Most of the potential of the DCT 'box is wasted as it is reduced to effectively a 2 or 3 speed box for almost all tracks.
I put together a "were I Tadge for a day" gearing choice, which isn't rocket science, and is more or less what Porsche (who has more experience than anyone in DCT boxes) uses in their GT cars.
Given the overtly compromised nature of the C8's gearing for track use, one has to wonder at the nature and balance of forces (i.e. fuel economy, focus on 0-60 and 1/4 mile, leaving easy wins for later Zxx models, on-track cooling concerns with frequent shifts) which led to such an awful place in what is an otherwise great package.
Nice work.
Since the OP's numbers do not seem to jive with what Tadge has said about the final drive ratio, maybe the OP's numbers were an early attempt or test set and Chevrolet's engineers have moved on. I am going to assume so until we see something official. We have here a big engine with lots of torque and a DCT/final drive combo that if set correctly can keep the power band between the torque and hp peaks all the way through 5th gear and still have 3 cruising gears for fuel economy. That is what I am going to assume Chevy gives us, at least in the Z51 car in track mode (i.e. no early shifting).
Last edited by quick04Z06; Aug 27, 2019 at 12:58 PM.
