D K

Hello

I'm looking for some info/feedback from people who have tracked both the C6 and C7.

Essentially what I'm trying to find out is if both platforms had equal mods (aero, suspension, etc.) and most importantly equal power - which would turn a faster lap time?

The engine power level doesn't matter, as long as both are the same. So both could be the base number, or you could compare the C6 ZR1 to the C7 Z06, etc.

If you have links to previous posts or articles on the matter, feel free to share.

Thanks in advance.

ErnieN85

Depends on the driver and if the C7 is aligned correctly

D K

I don't understand your comment.

Obviously I would expect both cars be aligned correctly. As with the driver.

KnightDriveTV

It's a pretty complex question though, because you're implying a pretty modified car. I think if you're really saying, all things being equal, I think there's no question the C7 has the better chassis...it's more rigid, the steering is better/more rigid, etc. You don't speak to weight though...obviously the C7 packs in a lot of interior weight so are these cars gutted/caged or?

I think the question is too complex to really answer reliably. In simpler terms I'd say a GrandSport with 505hp crank, vs a C6Z would likely be a GS win on most tracks, if not all.

Bill Dearborn

The question is harder to answer than you think as power isn't the biggest factor in turning faster lap times. It is the ability of the chassis to put the power to the ground and how well that chassis gets around a turn.

Depending on which cars you are comparing there is somewhere between 200 to 300 lbs more weight on a C7 than a comparable C6. A C6 Z06 with the Z07 option (ceramic brakes and PTM capability) will weigh about 300 pounds less than a C7 Z06/Z07. That means it takes more power to accelerate that weight, better brakes to dissipate the heat from slowing that greater weight and different tires to provide the extra grip required to go around a specific corner. Despite weighing more the C7 has some advantages over the C6 platform, one is the eDiff which can electronically move power from one rear wheel to the other depending on wheel speed information, steering angle, yaw rate and g force information the car receives from the ABS system. That lets it put down the power coming out of a turn better. On top of that the C7 has a rear caster setting which when set right helps to reduce bump steer. The C6 suspension doesn't have adjustable rear caster. I have had the pleasure of running my stock 08 Z06 around Carolina Motorsports Park chasing another instructor driving a 14 Z51 A6. He was doing a lead follow exercise for me so I could learn the track. The cornering ability of that car was outstanding. He had a passenger with him so the car weighed about 400 lbs more than my car, it had the same power and torque production from the LT1 that the LS7 has up to 4000 rpm where the LS7 keeps gaining in power all the way to 6300 rpm and can easily rev to 7K. Going into a corner on the same line he was on I could be on his bumper until mid corner when he started rolling onto the throttle. That car would leap off the corner and if the next straight was a long straight I could catch him about half way down the straight. However, he could come off the corner much harder than my car could. We played like that for 20 minutes but I couldn't get my car to corner as well as his did.

Within a year I had a C7 Z06 and that is about the fastest car on the track. It passes everything except the gas pump. I can get more than one 20 minute session on a tank of fuel but have to cut the next session in half so I end up filling the tank between sessions. I could go through 2.5 sessions with a single tank of fuel in the C6Z so only visited the gas pump at lunch and the end of the day.

Bill

BrunoTheMellow

The newer car is always faster with similar weight and power. Thats the simple answer.

davidfarmer

But the newer car is a lot heavier. The only technical advantage I see in the c7 is the locking/unlocking diff. Both are very good cars.

Suspension and drivetrain designs are very very nonstops s platform issue to me, but one of personal preference. Dedicated track car....save a fortune and build a c5-c6. If you like the c7 or want some if semi current, get a c7. It will be “old” in a year also

BrunoTheMellow

A stock c7 z51 runs with a stock c6 Z06 on the track. That says a lot.

D K

Thanks guys.

First off, I realize this is a little bit of an immature question.

However, Im after a specific bit of data, so it is what it is...


it doesnt matter what the actual hp number is. Whether its base vs base or ls9 vs lt4.
I was just trying to see what the laptime delta was.


I got some ideas already and looking forward to additionall comments/experiences.

RapidC84B

Had a bunch of C5s, sold C5 racecar, bought 2014 C7 as a street car, can't enjoy street-only car so was going to build another C5, but decided to build the C7 for TT2. The C7 has a lot of nice things that you have to mod into the earlier cars. Ultimately my 2014 C7 with 56K miles isn't worth a massive amount more than a C5 with all the supporting mods needed so I decided to keep it. Once the C8 is unveiled it will be worth even less. The C7 is only heavy because of all the extra content. Once you make one a trackday car it will be on part with the C5/6 with similar size brakes and coolers and drysump. C5 will always be light because no dry sump, tiny brakes, no coolers. Neat stuff the C7 already has:

1. Strong SKF hubs that can withstand some track abuse; no need for SKF race hubs.
2. Strong toe/tie rods with integrated OEM heat shielding; no need to add balljoint shields.
3. The latest and stiffest upright design; no brake pad pushback.
4. Excellent brakes - My OEM Z51 rotors and calipers are better than the Wilwoods I ran on the C5 racecars. Only mods so far have been Carbotech pads and SRF fluid.
5. Great rotors - The OEM rotors still aren't close to min thickness (a lot of that is due to Carbotechs being easy on rotors). I have DBA 2-parts waiting, but no need for them yet.
6. Factory dry sump
7. Factory active rev match - Once you use this you'll never heel-toe again.
8. Robust OEM driveline - Strongest one made yet.
9. Strong clutch & hydraulics - No funny business like the C5s needing a Tick master and sticky clutch pedals and changing fluid all the time.
10. Factory trans/diff coolers mounted in proper locations with quarter inlet ducts and bumper exhausts. Even if you add them to a C5 you don't have the same trick airflow.
11. Targa top - Makes it easier to crawl around in the car working on it vs. my FRCs.
12. Electric Power Steering - No pump, no fluid, great feel. As C5/6s age the racks are starting to bleak and remans are the only thing available and often the magnasteer wire in C5s still leak.
13. Brake cooling ducts factory - The OEM ducts have proven sufficient so far. No need for aftermarket ducts and spindle adapters.
14. Good assortment of OEM-type aero bits. Radiator is already laid forward, hood vented, and various decent splitter options.
15. OEM rubber bushings that don't squish out with track use - No need for aftermarket bushings unless building a full-time track car.

That's about it so far.

D K

This was exactly the kind of feedback I was looking for.

Thank you.

I have 2 C5's at the moment nearing completion for Spec Corvette and TTx and I'm parting out the other one, so I don't need another race car, but I do need to decide what to use as my next track/street car.

So I was thinking of stepping up to a C6, but the difference in performance to my C5 seems pretty little compared to the cost hence the interest in C7. I'm considering the SS 1LE or ZL1 also.

My goal for this car is to do events like Optima and even possibly the One Lap.

I'm a pretty experienced driver, so I'm really looking for a chassis that will really respond to setup changes, aero etc.
I do a little bit of coaching as well, so car will be very much multi purpose. It does not need to have street manners since it will not be my daily. Even though my commute is 1.5 miles.

I also like the idea that the C7Z came with the 2.29 ZR1 gear stack in the C7, but dont' like the fact that the Grand Sport didn't get that trans as that would be my ideal option.

Again, thanks for the comparisons and I will keep digging.

David

RapidC84B

I was extremely close to pulling the trigger on a Spec Vette build, but I would have been the first in my region. It's very close to what we had back in the NASA PTA/TTA days; basically stock C5 Z06s with a cage and tires. I really enjoyed that before they kicked us out of the class and pushed us to ST2. I then had full aero, coilovers, custom radiator,etc. etc. It was a lot more tinkering than just driving. Lots more $$$/fab time at stake when you had an oopsie as well. I decided to do the TT build with the C7 as it's a new platform that not many are pushing, it's still street legal for taking to car shows with my daughter, and I have competition around here in TT2. No, I can't W2W race it, but we'll see.

In a perfect world I'd have a Spec Vette and a C7 vert. I've looked into Optima, but there's just nothing really close and NASA weekends at VIR scratch the itch better for me.

If you're gonna get a C7 I'd get a GS. The supercharged cars are heavy and have overheat issues. However, for a TT car that's moot give 2-3 laps running max. Don't buy a C7 until the C8 breaks cover. They will flood the market with C7s for everyone who wants to get a C8.

D K

Good info!

I really like the GS. I just really wish it had the 2.29 gearing. I really like the idea of sending the heads to Pray Performance, camming it with headers and Bob's your uncle.
Hopefully I will find a Z06 gearbox for cheap.

I started my SV build when I lived in SoCal where all the buzz started, but some life changes and that, and now I'm in Denver. Not much action around there for SV, but I will have some places to race that are a few hours away and the class is growing, so before long it will be a national class, Im' sure.

Back to the C7...how are the consumables? I know on the earlier years they loved to eat tires and rotors. I assume it might be better now since everything is stiffer?
What's the biggest size wheel up front? Can you get a 18x12 in there? Also, how is the dry sump system? I remember the C6Z's as having many issues in the beginning.

Lastly, were there changes over the years? As in did the GS change from 14 to now? I do work for Chevrolet dealership (not in sales) so I hope to get some parts discounts as well as maybe find a cheap car at auction?

D

RapidC84B

how are the consumables? I know on the earlier years they loved to eat tires and rotors. I assume it might be better now since everything is stiffer?
Consumables have been excellent with my Z51. They have 2 piece cast rotors on the early Z51s and I ran 4 HPDE instructor weekends last year and have no need to change them yet. Running Carbotech XP12/10 F/R. I have gone through a couple set of front pads, but still on the original rears. No issues running OEM tires on a spare set of OEM wheels all last year with an aggressive street alignment with -1.4/-1.2 camber F/R and 0 toe.

What's the biggest size wheel up front? Can you get a 18x12 in there?
Widebody vs. my narrow body is apples to oranges. I have a narrow body car. Widest up front is the 10.5 I'm fitting now with a 295 Hooosier. See my TT2 build thread in here.

Also, how is the dry sump system? I remember the C6Z's as having many issues in the beginning.
No issues at all, that said I haven't run the car on an oval with race tires and aero, but I have not heard any chatter of oiling issues across the entire C7 platform.

Lastly, were there changes over the years? As in did the GS change from 14 to now?
Too much to type out. 2014 Stingray only, 2015 Z06 comes out, 2017 GS comes out, 2019 ZR1. No material changes other than the auto going from a A6 in 2014 to A8 2015 and up. For the Z06 they changed the supercharger lid and intercooler bricks for 2017.

D K

Thank you again!
Very useful.

CJ Willys

Have a C6, but watch the C7 guys on the track. Personally, I think the better technology in the C7 makes it a better track car. But. The driver is 95% of the equation.

6SPEEDZ

Caster is adjustable on the C6Zs. True race car build I would stick with steel chassis C5s and 6s. Far easier and safer for roll cages. Less electronics to complicate matters. When you get to serious grip levels the electric power steering on the C7 is worry some. Engine wise it’s also more economical and lighter with the LS vs the LT. Service wise the C7s are going to be interesting to see how long the wiring/ fuse block holds up on a track car. They are only designed to be removed and installed so many times before terminals start loosening up.

BrunoTheMellow

You can get a 315 up front. Just gotta raise it so the wheel gap is the same as a Z06 and put spats on or decrease suspension travel. X25 did this. Wide body cars don't fit wider front tires the same way any other car did. GM just raised the fender cutout 1 1/4" so that you can't hit it. The fender width is the same. The plastic pieces are just rock guards.

That's why Z06 guys think their wheel gap is crap.

BrunoTheMellow

Only major change was 2017+ cars got extra trans cooler for autos or extra radiator for manuals. Z06s also got better intercooler bricks and lid for the supercharger.

RapidC84B

Have you seen any actual issues with the EPS? I haven't yet. As far as the fuse block... yeah it's dumb, I haven't had to remove mine yet.

Raising ride height to "fit" a tire is silly IMO.