Has there been anything official on the overall downforce for the Z07 package? And more specifically, the DF numbers for the rear spoiler? If not, any ideas on what the rear spoiler with the wickerbill produces?

I have heard magazines claim 500 pounds overall but not sure if that's accurate or not

 

 

I believe it was 500-ish overall because the prior C6 created 150lbs or so of lift at 150mph...the overall gain in downforce was around 500.

 

From reading your posts it's evident you are quite knowledgeable, what is your feeling about these numbers for the Ring?

It is mine that it is not a big enough number based on all other criteria to get better than a 7:15, the ACR with it's massive D/F and corner bite at 7:12 with an N/A motor and near the same useable power output is super fast. I would think the entry speed and better bite the D/F offers is why the Z will not be faster, not that we'll ever hear a time.

Thoughts?

 

Thank you very much for this info!

 

Are those numbers rear spoiler only or overall? It would be great if we knew F/R

 

I think the biggest factors in the ring time improvement are going to be tires and the A8. Downforce will help with some cornering speeds, but will have a limitation in the straight line speeds. I suspect ZR1 will be faster through certain sections.

I've datalogged shift speeds over the years, and even power shifting a car (no lift throttle) which I don't generally do on a road course mind you, there is a visible unloading of the car for 5/10's of a second on each shift..minimum. Consider that Mero upshift 23 times in the 7+ minute lap in a ZR1. That's roughly 12 seconds of coasting versus the A8 accelerating the car.

In the technical sections of the ring, a track I know in my sleep, most turns for the ZR1 are in the 60-80mph range...aero on the Z06 is active there, but not tremendously so. The biggest thing with the ZR1 is the front end push and lack of turn in...I think the C7Z does that a lot better. Also, both hands on the wheel entering turns leads to smoothness, putting less heat in the tires from twitching while downshifting, etc.

There are a lot of reasons the C7Z should beat the ZR1...the e-diff is a big one, the A8 transmission and the Michelins. You also have some aero, along with much better steering feel. Lastly, the next gen mag ride, that Mero himself develops calibrations for, will have an impact.

You mention the ACR from the prior gen Viper...I've always looked at that time as the target for the C7Z. The Viper did that time, in somewhat crude fashion. It uses in your face aero, off the shelf coilovers and brakes...that Viper is a cool car, but it's essentially a race car.

I think the evolution of the car should grant it a 7:10 or so....and frankly I think that's on par. I don't think that's phenomenal in any way. I think the ZR1 with the A8 and some new Michelins would be right there with it.

As far as these times go...and this "block" so to speak. I look at Porsche and GM on that one. Viper and Koenigsegg stand by ready to topple both the 918 and C7Z instantly. Nurburgring is privately held and has financially struggled. It only makes sense to use their marketing value in exchange for funding. There is something at play here for sure.

I may have some slides on that...I have to check

Edit: Upon review, my slides aren't that telling, but I can tell you, it's overall...with all pieces in place for each stage. The one slide I have actually calculates the reduction in lift just from the hood extractor alone. This is calculated as an entire system.

With aero on any racecar, when you add to the rear, it affects the front of the car, and vice versa. If you add the rear stage 3 spoiler, you're lifting the front end by not adding the stage 3 setup in front. They are designed as a pairing. Also, running any front license plate reduces downforce and cooling.

Side skirts/splitters reduce drag, they don't add to lift/downforce.

 

Thank you for your expert and concise response.

I guess I should have included that I would want to see what the M7 does against the Gen IV ACR, to me running the A8 against is is like having two guys run the 40 but one of them is running downhill.

I also believe that the new Gen V ACR will annihilate the Z and most others, less a few paddle supercars.

 

Yeah, yet again, the new ACR is a race car...let's be real. Since we're making analogies I see the ACR like open carrying an AR15 because the law says you can. The C7Z is like open carrying a glock22 with a few clips....still visibly means business but doesn't blatantly make you fear for your life when you see it out in the wild. C7Z has the mag ride, the means to be daily driven...ACR...not a chance unless you're die hard.

Unfortunately, for the M7 and Z51 we'll never see Ring times...look how hard we work just to see the Z06. I think they could've at least released a sector time on the Z51 but...this is just where we are with this management team currently. I'm not thrilled.

 

Everybody keeps giving the nod to the A8 on the track, but didn't Motor Trend test one at Willow and it was decidedly slower than the M7?

 

I'm not giving the automatic a nod by any means...if I bought a C7Z it'd be M7... .5 seconds per shift be damned. The motor trend/willow was part of the "alignment debacle" where Randy couldn't get the car to get the power down and release. They said it was due to GM's media Z06 being aligned improperly. They retested it and it was faster...after an alignment and a suspension recalibration to go with it.

I certainly don't nod the tranny...but, when you're talking about a "time attack" so to speak, the A8 shifts faster and will lead to a faster lap time...if all functions properly, temps stay in check, etc. In the end, the shifts are one thing, but keeping both hands on the wheel, steady brake pressure, etc...it all equals smoothness and more speed...that's a fact. Plus you can full time left foot brake the A8, which makes your transition time quicker. It appears the A8 cars have more of an overheating issue than the M7's, but only if left in "D" versus shifting manually. Most people running A8's on a road course are shifting it manually I'd assume.

 

Thanks, that's what I assumed. My main reason for asking was because I've been debating trying out the stage 3 aero on my FE6 car. My concern was whether the additional aero would overwhelm the softer FE6 springs and I've lost the battle to ask Tadge if they ever tested that combination. Since we're looking at ~150 lbs of additional df it seems that this would be no worse than having a passenger in the car.

 

Well, you're thinking statically, not necessarily dynamically but...while the spring rate for the Z07 may have been in part to counter the additional downforce, I also think they felt the demographics that purchased a Z07 could handle a bit harsher ride in exchange for the tad bit higher capability. Remember, the Z07 comes with cup2's and the spring is more matched to the tire than anything...plus, as you well know, there is a lot to the FE7 beyond the spring rate...it's bushings, damper changes, etc. I think you'd be fine personally, as your setup is still all intact, with the addition of some aero which will add stability. I could be wrong but...that'd be my off the cuff theory.

 

GM said way back when talking about downforce that 80% of it was from the rear spoiler.