lobsterroboto

So I plan on prepping my C7 for ST2


The car currently has a custom rollbar that I will have extended into a full cage but other than the seats, harness and rollbar I haven't done much else yet.

I have a few questions regarding classing and miscellaneous questions.


I want to stay in ST2 if possible instead of barely scraping into ST1 so I don't want to go crazy power wise.

Prior to swapping seats and adding the rollbar the car weighed 3340 w/driver & half tank of fuel.

I haven't weighed it since yet.

I want to add headers full exhaust with no cats and a tune but beyond that not much else in the way of performance modifications.

I'm on the fence about what headers to go with & what coilovers to use.

As far as tire size I'm pretty comfortable with 265/275 in the front and 305 in the rear.


Has anyone done a race prep on the C7 yet? I'm looking for a solution for a quick release steering wheel but haven't found anything yet so that's on my list.


I also have MSRC and moving to non MSRC w/coilovers has anyone had any issues using the MSRC simulator things?

fatbillybob

https://nasa-assets.s3.amazonaws.com...--12-27-16.pdf

You need to start with the rules. After that ask guys in ST2 like Tway motorsports and Oli on CF as they are up to date on current happenings in ST2.

I'm also considering a C7 racecar moving from my C5Z in SCCA T2. I'll be curious to hear about your build from an electronics point of view. In the C5 we can turn all the traction control off with 1 button.

Some cars the TPMS will limp mode you if it does not like the pressures race tires need. Some cars you can't turn off traction control like porsche PSM you can turn off but it is still there. Some cars have lane departure or collision avoidance and BMWCCA is talking a ban on some BMWS on track because of it. Vettes have mag ride control. I want to know what the C7 has and can it all be turned off?

lobsterroboto

yah I've already read the rules a few times, (probably need to read it a few more times anyway)

Right now the hurdle is the electronics.

Since the car is equipped with MSRC & has "PTM" I can disable TC & AH with the center console button but obviously won't be able to change PTM modes with a different steering wheel.

I have to balance the amount of weight to the amount of power but ST2 is fairly open (more so than SCCA T2 which is considerably more governed on modifications)

https://nasa-assets.s3.amazonaws.com...--12-27-16.pdf

That's the classing form, there is an excel sheet that does the calculations for you but considering I haven't done the weights and dynes yet it's kind of useless and I'm trying to speculate how much power to expect and how much weight I can shave.

Mark@AMT Motorsport

Can't speak to the electronics, but you'll definitely need to detune to stay in ST2. Sounds like your car is 3400 with a full tank and you. So when you add cage but remove weight maybe you can get it down to 3200 on empty with driver. That means you'll need to be at 400whp average. If it's 465 stock and you add headers full exhaust and tune, you can prolly bump that to 500hp or about 450whp. So you'd be way over on power, however now that ST2 is an average power class you'll be able to tune a real nice flat 400whp tune, so you're extra power is an advantage. Haven't seen an ST2 prepped C7 in the NE region yet but I bet those babies are gonna be fast with a good driver! Good luck.

lobsterroboto

Yeah it's surely going to be a numbers game. I'm not committed to the headers/tune I made the assumption I could probably do it without getting too much power, enough to bump me into ST1

Part of me is excited to be one of the first, but the other part wishes there were more fully prepped C7's. I'm talking to a local prep shop here next week we'll see what they have to say.

crimlwC6

I would get a dyno before getting headers and a tune. Might save you a couple grand. I would also try running with the suspension you have now. 2 cents.

BEZ06

I was just thinking the same thing about suspension.

Have you considered the DSC mag shock controller? Those of that have it love it!!

I run it with stock mag shocks, but if you go for the Tractive shocks it's reportedly even better - if the class rules would allow them.

Mark@AMT Motorsport

Only real rules in ST are power and weight. After that it's basically your wallet that dictates the rest!

lobsterroboto

im not even sure how I never heard of that. That is awesome I was looking at the tractive kit with controller it seems awesome

BEZ06

This thread is soooo looonnnggg I hate to even refer you to it, but here's a link to a lot of info about the DSC Sport controller that you may have already read about on their website www.DSCSport.com. Here's the long thread:

https://www.corvetteforum.com/forums...ervations.html


Also, Mike Levitas of DSC is a professional race driver (mostly Porsches), but he has a personal C7 Z06. He has done A LOT of research on setting up the C7 suspension, and maybe you've seen them before, but here's a link to his alignment specs:

http://www.dscsport.com/wp-content/u...nt-sheets1.pdf


A couple things to note in there:

A VERY important alignment spec for the C7 is to adjust the rear caster properly. The rear end is very susceptible to snap oversteer if the rear caster isn't set properly - and he has determined that the best rear caster is about +0.7° (actually a few us are running +0.8 to +1.0), which is the axis of a line through the rear lower and upper ball joint leaning slightly to the rear - the upper ball joint tilted back. Here's his alignment recommendations that a lot of us like very much:

http://www.dscsport.com/wp-content/u...nt-sheets1.pdf

Mike has done research on the "toe curve" (toe change during compression/rebound) and he found that, in a turn, as the outside rear shock compresses the toe will go to a toe-in condition.

In his alignment specs he has negative toe indicated for front and rear, which is toe-out. Many of us run very slight toe-out up front on the track for crisper turn-in, but everybody always recommends slight toe-in for the rear to keep the car settled better when accelerating during track-out.

Mike has a very slight rear toe-out spec so that it will actually go to the proper toe-in under compression. And that positive rear caster is essential.


Another thing I consider very important, that I put on my C7, is the AMT Motorsport Camber Kit and Stud Kit. Mark made a post a couple up and is a forum vendor, so do a search using his forum ID for his posts in this section about the kits. He also is a distributor for the Granatelli adjustable rear tie-rod type toe link. The stock rear toe-link is a solid rod that requires adjustment with the eccentric - difficult to adjust, especially to fine-tune your toe. The Granatelli tie-rod type link make rear toe adjustment easy and precise.

I don't race, just do HPDE's, so the above is just MHO about what I have on my HPDE car that I would for sure put on a race car.

.

Captain Buddha

Casey:

A few things....

Talk to Louis at gSpeed (based at MSR Cresson, let him know Brad referred you), you'll be there this weekend anyway. Odds are you'll be needing his services anyway.

Joe at Phoenix Performance (Philly area) is a great resource. I believe he built the first prepped C7.

You're going to cry after your first incident. Trust me when I say this. How deep are your pockets...? I don't want to see your personal finances but when crap happens it's going to be pricey in a nice, new production car. Tube frame is your friend. Ask me how I know...just throwing this out there...a good buddy of mine hit the Armco in his built C6R and it was $20k out of his pocket. You can buy a very competitive GTA car for $25k. When you hit the wall the cost to repair will be much, much cheaper, not to mention the safety aspect of it. Not trying to sway you but just giving a reality check.

lobsterroboto

Hopefully I'll have the time to run over there to chat, if he's around in the evening after the event that would be cool.

I'm prepared to total the car. Kind already committed to that eventuality by having the rollbar installed.
If I wasn't I wouldn't race it. At a certain point the risk vs reward thing plays very heavily and I'll probably end up getting another car anyway and using this one for TT1 or TT2 which runs similar but lesser risk.

Besides, I'm so indecisive that by the time I finally made my decision on buy vs build it was like the stars aligned.

brkntrxn

PM "Toilets" on here about his TT1 C7Z07. He has been working in and around the electronics on his car.


-Kevin

GSpeed

I would not recommend the DSC sport controller for race use. I in the limited use we have tested it across 3 cars, its not fully developed yet.

You can do much more with a proper penske setup, and actually develop the car, vs trying to get the car to work right around the leaf spring and stock shock.

For the occasional track day, the controller works fine, especially if you drive it on the street.


As for those alignment settings, I 100% completely disagree with rear toe out. These cars are evil with toe out, and having tested 0 toe, and 1/16 total toe in, they really like more toe in. Much more comfortable, and easy to drive into the apex.

GSpeed

When will you be at MSR cresson next? I can give you a nickle tour, and show you what we have done.

The beauty of partnering with Gspeed is the fact that when you make a change to the car, or would like to test or verify something, you can get on track with out ever having to load the car up, or unload it


Louis

lobsterroboto

I'll be out there tomorrow actually. not sure how much time i'll have though with the BMW race school it's basically classroom->track->classroom->track all day until 4 or 5.

How late do yall usually hang out in the evenings?

GSpeed

Tomorrow is easy to stay late. If youre not completely beat, we will easily be open past 5.

davidfarmer

i've yet to see a C7 light enough to make it a viable car if you want to be competitive, plus the "break away" frame will be a nightmare when you make contact. You have a much easier road to success with a C5 or C6.

ST2 is an easy class to build for, but if you want to be competitive it never ends. Exotic Aero, power-curve shaping for the averaging formula, etc.

The electronics, weak frame, and the weight of the C7 deter me from recommending it to clients.

fatbillybob

Dave and you be more specific with the issues of the c7? Why isn't the c7 a leap above like each previous generation? What is this c7 chassis issue? Break away frame?? Why can't c7 be lighten like c6? What is wrong with electronics? Can't turn off traction control? Things cause limp mode??

lobsterroboto

Just an update on the car.

I'm running TT2 for now and may just keep it as a time trial car and buy a dedicated race car separately.

Currently in my region, keeping it stock i'm not competitive at all in TT2

if anyone is curious the car dyno'd at 416whp & weighed in at 3392 race weight (with fuel and me)