reidry

I was just reviewing the results from the 2007 SCCA Nationals. In super stock the entries are the c5z06, the Lotus, and the Porsche GT3. Finish 1 and 2 both went to the Porshe. What struck me odd is that not one c6z06 was entered in SuperStock.

While the c6z06 is much higher cost than the c5z06, the GT3 is higher still - so absolute cost alone cannot be the primary factor.

I don't have the dyno's overlaid, but the LS7 must have better low end torque than the LS6. And 2nd gear should yeild 84 mph at 7K redline so I don't think the c6z06 is handicapped by a bunch of extra shifts.

Is it simply the c5z06 is cheaper for good enough bang?

If your goal is to have a car that can win SuperStock and be a good Driver rare to occasional HDPE car is the GT3 the better choice?

Has the c6z06 just not had the alignment / driving style development time with the right drivers to earn a place in SuperStock?

Any other contributors?

Thanks in advance,

Ryan Reid
Cocoa, FL
(Perhaps a 2009 Cyber Gray Z06 would look good in the garage)

Jim_Harrison

It usually takes a couple of years to develop a new car, alignment, shocks etc. Also the C6 has a very high 1st gear, and second is a bit high. It is difficult being smooth with all that torque driving in 1st. With the C5 just launch and shift to second and run the whole course, some even launch in 2nd on slippery surfaces and run the whole course in 2nd. I think we will see a couple of the top Drivers this year in the C-6 and it will be in the top five at nats.

talon95

When the C6Z first came along, I did some calcs for TQ at the wheels in 2nd gear using an early dyno plot. At low speeds (sub 40mph), the C6Z had less TQ at the wheels in 2nd gear than the C5Z due to the gearing differences. I think it was around 10% less.

So, for a lot of Solo courses with relatively slow sweepers, that can be a factor. Certainly no advantage for the C6Z unless you shift to 1st. I do think it could have some advantage for someone that could effectively use 1st on the slower corners, particularly given the wider rear wheels/tires. Although if you end up doing quite a bit of 1-2, 2-1 shifting, that advantage might be lost.

As far as why there haven't been too many, probably several factors.

1. Questionable gearing.
2. Much higher cost.
3. C6Z has only been in SS for one year, it was on the exclusion list in '06.

As Jim said, we'll likely see a few more this year.

Dave G.

Solofast

with all of the above....

The rear wheel torque in first gear is the same for both cars. So if you can keep the C6 in first and not run out of gear, you will have a lot more torque off of the corners than a C5 in second. OTOH, you have about all the power you can put down in a C5 in second in the mid range, on corner exit, so how much help is it going to be to have more thrust available? Agreed that the C6 will pull you down the straights, but that would require a course with a lot of straight, something we don't see in autocross very much these days (I'm referring to Slow Car Club of America events here)

It's just a lot harder to drive any car in first gear, there is a lot more engine braking which can tend to make the car slow down too much on corner entry, and more torque to cause the tail end to get loose when you are on it. Matt Braun tends to drive most all the time in second gear for that reason, he feels like he has as much power as he can use, even at pretty low speeds, in second, and if you ying yang back to first it has got to be a pretty slow corner to make it worthwhile.

C6400hp

Were A6 Hoosiers in Z06 sizes available for the entirety of last season?

rfn026

I absolutely hate 1st gear during an autocross. I'll lug 2nd before I'll drop down into 1st. The good part is that very few courses will require 1st gear.

I've been to the last few SCCA Nationals and I think it's more driver than car in SS. The GT3 and the Z06 are pretty even. It's about who is dead on with their setup and who has the most driving skill.

Richard Newton

Autocross Performance Handbook

Wheel and Tire Performance Handbook

TedDBere

The C6Z was at Nationals last year (Gonzalez/Lanstra). I think you're looking at the ProSolo Finale results which did not have a C6Z entered. At nationals 1-2-3 finishers were GT3/Elise/C5z out of a field of nearly 70 competitors.

While many feel the C6Z needs to be developed to be competitive I think it may be more than that. Apparently it doesn't have the balance of a C5Z and while you can dial out some of the issues of a pushy nose and a loose rear, it seems to be difficult to eliminate both issues at the same time. This is not a problem with a C5z.

The rear bar can't be changed in SS and it appears to be too big for autox. The wheel stagger seems to hurt the car on an autox course and you'll need to move out of SS and into ASP to address both of these issues, smaller rear bar and better wheels.

The C5Z was expensive in it's early days but it was so apparently dominant that in it's second year the field was filled with them. Today the top cars are C5Z, Elise, GT3 and Viper. I don't think the C6Z has the dominance required to shake up this field.

Time will tell.

mikahb

with most all of the above. The biggest issue I've seen at the track is definitely the gearing issue. Where 2nd in a C5 is about right for any course, C6Z's struggle between the top of 1st and the bottom of 2nd on quite a few turns. Isn't the C6Z a little wider too?

With the limited adjustments available in SS, you need a car that has a lot going for it right out of the box. The C6Z does on a road course, but for autoX, it's just got a few things that may be hard to overcome, and that could make it a better ASP weapon than SS.

talon95

I'm not sure I understand that though. You can always bolt up a bigger front bar to compensate for the rear bar. I'm guessing you're down in Ar-Kansas talking to Mr. Ramey. One thing I will say, if he can't get the car to work this year, I'll be scratching it off my future autox car list.

OTOH, the wheel stagger is set of course. (although seems like the bigger rear bar would be a benefit here?)

And to another person's question about width, I think the extra width is just from the 12" rear rims. The car is about 3" wider total.

And one more thing, does anyone have a comparison of the C5Z and C6Z spring rates and swaybar sizes?? That might be interesting.

Dave G.

reidry

I was looking at the ProSolo results. I see that there were a few c6z06s in the field. Gonzalez's C6Z came in 20th with a score of 92.4x, winning score was Stewart's '05 GT3 at 88.3x in Super Stock. Scrolling down to ASP McGeorge placed 3rd in an '06 Z06 at 89.4x while 1st was 87.5x

You guys feel that the c6z06 is in striking distance for ASP? I've already gone the SM2 route with my old '85 so I'd like to stay pretty stock with my next car and focus more on driving.

Thanks again for all the input, keep it coming!

Ryan

XPC5R

Hoosier has a new rear tire that might help the stagger and gear problem - 315/30/19 - 12" tread, only 26.1" tall, shorter than the 325 and 345, and just as wide as the 325.

If the 315/18 would fit on the front, that could help too.

TedDBere

First time I've met Mr. Ramey, super nice guy.

The C6z has a problem with push so a bigger front bar might make that worse.

My impression from talking to a few C6Z drivers now, is that as an SS car it'll take some work to get it up to the other top cars' performance, and may never be better than the C5Z at autox.

We'll see over time. Chris was experimenting with tire widths today and seemed to do better with the setup today.

But I have to tell you, watching him run that car was like watching a drifting competition! I almost missed my start because I happened to be at the line waiting for the light when he was finishing. He was all over the place and I was mezmorized by his run and then I heard the tone go off and remembered, oh yeah, I have to start now....lol.

Viscerl

The reason you didnt see many C6Z06s last year in SS is really simple, and only one person mentioned it.

R-compounds *just* came available in 300+ 19"wheel size.

I bought some of the first 345/30/19 A6s made this winter.

I autoX'd it today and I actually like it more than the C5Z06. I havent messed with the FSB, dampeners, etc... and I like the balance of the car ALOT.

Viscerl

No.

Viscerl

I'm going to try 295/20/18 A6s in the front. I think with the right adjustable swaybar it shouldnt be a big deal.

The car is very easy to controllably rotate with the throttle in either 1st or 2nd, though it feels like a car that gets slow when you start to push it around a lot with the throttle.

I'm pretty sure with the new tire sizes some folks might be working with dampeners and front swaybars to turn the car into a decent SS weapon.

If only we could get rid of the seats.

reidry

What if I wanted to venture into ASP? Is there already someone who has the right setup?

Ryan

TedDBere

Rod McGeorge has been working on his ASP C6Z for a few years now but I don't think he's going to give up his learnings just yet.

Maybe Danny Popp would be willing to give you some set-up advise off-line. He goes by raftracer on this forum.

I don't think anybody has figured out this car yet, but a few are trying. It's an expensive experiment.

Good luck.

JCD

Didn't it take a few years before the C5's started beating the C4's in SCCA events? I would expect the C6Z will eventually surpass the C5Z, not only because the C6 has advantages, but because the C5 is getting older and the C6 isn't.

As for shifting: I'd learn to live with it. I watch my S2000 buddies up/downshift 6+ times on a 40 second course to get the most out of that car, it sucks but it's the fastest way. If you want to go out and have an easy drive just throw it in 2nd or get a FWD H stock car, if you want to push the limits you're going to have to work for it.*


*I haven't compared C5Z vs C6Z torque vs. gear curves, but I can't see where running to 60 in 1st would be a bad thing.

TedDBere

And these advantages, other than +100 hp, are????

And it didn't take years for the C5Z to dominate, the Elise to win Tour and ProSolo events and the GT3 to win either. The C6Z isn't even winning the regional stuff after it's 3rd year out.

It's a great track car but every change that GM made to it, as compared to the C5Z, pushed it in the wrong direction for Autox, except the reduction in length...IMHO. It was built to dominate at the track and that has hurt it at autox'ing.

Let's see what C. Ramey (Past National Champion) can do with it this year....

Shark Racer

Did someone mention the rear sway bar being too big for autox?