Race Track video.. Z06 vs Porsche 996 turbo

[Maxx schlick]

Here is a link to some footage from Pueblo Motorsports Park. I was in my Corvette Z06 trying to keep up with a Porsche 996 turbo. The all wheel drive P car was on Hoosiers and I was on Bridgestone Pole Position run flat street tires. The turbo all wheel drive had the advantage hooking up the power and the traction, coming out of the corners, and had way more power than my Z.
I knew the fastest line and the braking zones a little bit better than he did, since this is my home track. You will see me almost loose it on lap 2 in the hairpin ( I got a little high up into the marbles), but I did some desperate steering wheel work (3 minute mark), gathered it up and ran him down.
At the end of the long straight we were doing between 138 and 142mph
Click the HQ button, and Crank the sound up!
http://www.youtube.com/watch?v=_hZMxj8Ytf8

[LoCore]

Time to get some race rubber for the 'Vette!

[Maxx schlick]

I know a lot of guys from the Corvette forums who have gone the R compound route, and here is the story:
The Z06 guys who have been using the R compound Hoosiers are pulling so many more Gs than the street tires. Other parts aren't designed to take the extra stresses. Stock Front Wheel hubs can't take it, so you need to get the LG Motorsports stronger race hubs $$. The already impressive 8 Qt dry sump oil system will still starve the engine of oil in sustained (more than 3 second) left hand turns, and many LS7 motors have been lunched because of this $$$$. The thing with these cars is the oil system needs to be upgraded with a $$ Lingenfelter 3 sump oil pan, a $$ Katech high flow oil pump and a 10 or 12 Qt dry sump system $$ if you expect the motor to last when using slicks. I've seen pictures of broken stock wheels as the stock pressure cast wheels are not strong enough and will break. If you go R compound, you are nuts if you don't get a set of forged CCWs $$ or HREs $$$. I don't even want to think about a wheel grenading at 150 mph. Then of course you can't put a tire trailer hitch $ on the Z car with the stock bi mode muffler system, so you gotta get an after market exhaust $$, and a tire trailer $, or even better an enclosed car trailer $$$$ and of course a motor home $$$$$$$ to pull it all. It is a slippery slope my friend. See how many $$$$$$$$$$ signs are in this paragraph.

Or you can drive the Z (with stock run flat street tires) off of the show room floor, straight to the track turn the AC on full blast, and go almost as fast any R sticky tired, caged out, fully race prepped, car out there. :eek: You don't even need to adjust the tire pressure from stock, unless you go over 175 mph. If you want to go 200 mph you are suposed to add 5 lbs all around. Any body got an air tank I can borrow?

[LoCore]

All good points--and a lot of $$$'s :D You seem to be having plenty of fun with the current setup.

[gordon0412]

Nice vid. I've been reluctant to run race rubber at the track wanting to improve my skills on street tires first. I'll be honest I hadn't thought about what it could do to the car, especially a basically stock one. I think I'll likely replace my used up Kumho 710's with the best street legal tire I can get (Bridgestone's?), and use those at the track. I'm spending the $'s for safety gear, but want to keep the car pretty much stock.

For now ;)

[rob_k]

Very cool. I'm hoping to get mine out there next season.

[Maxx schlick]

Nice vid. I've been reluctant to run race rubber at the track wanting to improve my skills on street tires first. I'll be honest I hadn't thought about what it could do to the car, especially a basically stock one. I think I'll likely replace my used up Kumho 710's with the best street legal tire I can get (Bridgestone's?), and use those at the track. I'm spending the $'s for safety gear, but want to keep the car pretty much stock.

For now ;)
Hoosier R6s are street legal. That is why they have a DOT certification.
The 2 circular grooves make them pass as a treaded tire.

[khammack]

Hoosier R6s are street legal. That is why they have a DOT certification.
The 2 circular grooves make them pass as a treaded tire.

Not according to the Hoosier Web site:

[gordon0412]

Hoosier R6s are street legal. That is why they have a DOT certification.
The 2 circular grooves make them pass as a treaded tire.

Street legal or not, they are not IMO "streetable". I'm thinking more of a tire along the lines of what the ST's guy run for autox, something along the lines of say Falken Azenis which won't melt like snow, and has some grip when it's cool.

[Maxx schlick]

Gordon , here is what you need Michelin Pilot Sport Cup $589 each.

http://i116.photobucket.com/albums/o14/maxxschlick/Jokes/mi_sportcup_ci2_l.jpg

Or even better get the Pirelli P Zero Corsa $648 each.
http://i116.photobucket.com/albums/o14/maxxschlick/Jokes/pi_pzero_corsa_asim_ci2_l.jpg

http://i116.photobucket.com/albums/o14/maxxschlick/Jokes/kermit_1_.jpg

[GingerGSR]

Street legal or not, they are not IMO "streetable".
Considering you get what, 500 miles out of a set of R6's? You'd have to have pretty deep pockets to run them "on the street".

[Solo2GS]

Gordon,

I can't vouch for the C6Z, but I can for the C5Z. I ran mine stock for years with race rubber on some of the West coast more challenging tracks with no problems. Buttonwillow, WSIR, the Streets of Willow Springs, and California Speedway. Other han replacing brake pads and fluids I put a lot of miles, sometimes 2-3 trips a month to the track with 3-4 hours of seat time each event...

To buy $400-$600ea streetable tires to me is just reduculous when you can get V710's / R6's and a tire trailer for a lot less!

[mannix]

I'm having trouble with the notion that the cars just fall apart - hubs, engines grenading, etc - if you run race tires on them.

What do the Corvette _racers_ do? Those in limited-prep classes; showroomstockish, T-whatever, classes where you can't start changing a bunch of stuff?

Do the cars really disintegrate? Ehhhhh. Weird.



Iain

[Built-By-Bones]

I'm having trouble with the notion that the cars just fall apart - hubs, engines grenading, etc - if you run race tires on them.

What do the Corvette _racers_ do? Those in limited-prep classes; showroomstockish, T-whatever, classes where you can't start changing a bunch of stuff?

Do the cars really disintegrate? Ehhhhh. Weird.



Iain

I do know that the T1 Vette drivers that are serious will go through 3 or 4 motors in a season, and install a fresh one for runoffs, and a fresh one again for the championship race at runoffs

Grant

receipient of more than one ex-Phoenix racing LS motor

[mannix]

Do the motors explode or just wear out? Oil starvation != "just worn out," IME - seems like an oilstarved motor does Bad Things to bearings, really quickly - I suppose if it is caught before things get REALLY ugly, all you'd have to do is grind the crank & replace the bearings.

That's a small target, though;).



Iain

[Maxx schlick]

Only as strong as the weakest link.
Too many corner Gs..Oil tank goes dry, sucks air, 7000rpm, bearings don't get oil for 4 seconds and BOOM
High G left hand turns are the problem. (like at PPIR turn 1)
The weak links in the 2006 C6Z are..(me) then the Clutch, oil system and rear axels.
2007 they went back to the C5 axels that were actually stronger than the C6 axels
2009 they went from the 8 Qt sump to a 10qt system with a better pump, baffeled pan and scavange.

If you really want to see some hard data on the oil starvation problem with the LS7 Z06 Dry sump oil system..check out this link . You will see I am not just being paranoid.
http://forums.corvetteforum.com/c6-z06-discussion/2323798-oil-starvation-on-track-hard-data.html

And here is some data from the Lingenfelter upgraded oil system...
http://forums.corvetteforum.com/c6-z06-discussion/2384872-oil-starvation-on-track-lpe-tank-results.html

My G meter only goes to 1.28g and Every time I come off the track my G meter is maxxed out at 1.28g ...That is from street tires!!!

The Z06 was engineered and designed as a very balanced system. It is a
"GT car" or a "sports car". It is not a race car. If you upgrade one part, it over powers the rest of the balanced system. Bolt a super charger on it bumping the HP to 800 and the tranny, rear end, axels, motor mounts etc will have forces beyond what they were designed to tolerate.

Same with the tires, they are part of the balanced system. The oil system will keep the motor healthy for 100,000 miles with stock tires, but if you get a tire that increases corner g forces by 125% of what the system is engineered for, all bets are off. Almost every LS7 motor that has popped has had Hoosiers hooked into the equation. Lots of guys have been using Hoosiers and have not blown up yet.

The Z was not made to be a drag race car and subjected to repetive hard launches. Some of us (that would be me) launch it like we stole it, and take our chances. There have been lots of cases of broken axels, rear ends and trannys.

I have done about 100 drag strip passes and lots of burnouts, but everytime I pop the clutch, I know it might result in failure. The guys using drag radials have signifigantly more failures than those who stay stock.

The C5 Z is very strong system but a completely different animal than the C6Z which has pushed the envelope a bit further.

[LoCore]

I vote for Keith to put on the supercharger!

[Built-By-Bones]

Do the motors explode or just wear out? Oil starvation != "just worn out," IME - seems like an oilstarved motor does Bad Things to bearings, really quickly - I suppose if it is caught before things get REALLY ugly, all you'd have to do is grind the crank & replace the bearings.

That's a small target, though;).



Iain

Of the 5 motors I have bought and sold, one was low on oil pressure (not death knell low either) and the rest were fine, no problem at all.

I guess a fresh motor (deck the head slightly and thinner head gasket within allowances) is worth up to 15HP over a season old motor.

Most of those T1 entrants seem to have healthy checkbooks, and from a race shop perspective are probably an easy sell to upgrade to a fresh block for run-offs.

[Maxx schlick]

I vote for Keith to put on the supercharger!
:D :D :D Robert Scranton has a brand new $7000 Vortech Super Charger in his basement still in the box. He bought it and was going to bolt it on his Z06, but it turns out the guys who have bolted one on without building the bottom end have a bit of an exploding engine problem. The stock bottom end is fine for 500hp, it has an Aluminum block, Titanium connecting rods, and Sodium filled Titanium valve stems. But if you want to go with 800hp to 1000hp like you can with a screw or a blower and maybe a little spray, you better get the LSX steel block, forged rods and pistons, double behive valve springs, titanium valve spring caps etc. Tripple disc Exedy carbon ceramic clutch. And then stand clear of the flying rear end, tranny and axel parts, if you forgot about uprgading those as well.

I'm glad I decided to not buy Lee's $700 set of SSR wheels, cause now I still have enough $ for a down payment on 1 Forged Piston.

[Maxx schlick]

This guy from the Corvette Forum summed it all up pretty good...
I think the results indicate that this is a needed modification to '06-'08 Z06s if your car is capable of exceeding 1.0G for 4 seconds on left hand turns, as a result of prior suspension and/or tire upgrades.

On racing tires, or with other suspension upgrades, this is possibly, or probably more prone to happen, than on stock runflats and the stock suspension.

Very few compeletely bone stock down to the tires, failures at the track due to oil starvation, have been described on this forum. You can probably count them on one hand.

But if your car has been modified to where it is capable of exceeding 1.0Gs in a left hand turn, for 4 seconds or more, then you will probably need to make this other modification to it, in order to avoid possible oil starvation issues.

So from what he has posted so far, one can derive that: If you have made any modifications to your '06-'08 Z06, which would allow it to exceed it's already phenomenal handling capabilities on a road course, well then you may, and probably do need to make yet another slight modification to the oiling system.

If your car is completely stock, then you should be fine, the mere handful of completely stock track failures due to oil starvation that we have seen in here notwithstanding.

Reviewing the posts on this forum, one finds that there have been more LS7s to pop on the road course due to oil starvation while on tire, brake and suspension upgrades, than there have been on stock , brakes and stock runflats. If an LS7 equipped Z06 popped on a road course, then chances are it had one or all of those modifications done.

The thing is, some people look at tire upgrades as "minor" and sometimes even neglect to list them in other posts or surveys logging the failure. Tire upgrades can make a significant difference.

As mentioned before, it is extremely rare to see a description of a showroom stock Z06 fail on a road course due to oil starvation.

[gordon0412]

Geez, I could almost buy a complete set of Firestone wide ovals for the price of one of those. Duly noted Ron. I'm sticking with the Goodyears this year. I figure my Kumho's have 2 autox events left (the last 2 at DSGP), and then late next winter I'll decided what I'm replacing them with. I ran the Z on the track 4 hours + in early July. The coolant temp shot up briefly late in the day (it was nearly a 100), but other than that the car hasn't missed a beat at the track. It's all I thought it'd be and more.

[LoCore]

Interesting. What direction was Mr. Pickles turning at DIA when his original motor asplode? I think it was a fast left hand sweeper leading uphill.

Wow, and I thought M3 parts were expensive. Yeesh!

[LoCore]

Geez, I could almost buy a complete set of Firestone wide ovals for the price of one of those. Duly noted Ron. I'm sticking with the Goodyears this year. I figure my Kumho's have 2 autox events left (the last 2 at DSGP), and then late next winter I'll decided what I'm replacing them with. I ran the Z on the track 4 hours + in early July. The coolant temp shot up briefly late in the day (it was nearly a 100), but other than that the car hasn't missed a beat at the track. It's all I thought it'd be and more.

Not sure if they come in Vette sizes, but the ST tires that we've had luck with on track are the Dunlop Z1 Star Specs. I don't think they are big enough. Supposedly, the Yokohama AD08 are good out on the track as well, but again, don't know if the XXXL sizes are available.

Other not-as-sticky-as-Hoosiers to consider would be the Toyo RA-1s, Nitto NT-01s, and Toyo R888s. CTTers have had good luck with all of them.

[pcharles]

I always ran an extra half quart or so of oil in the c5 z06. In the c6, with the dry sump, read that was not recommended and potentially problematic.

Sustained force readings on g-tech pro were 1.0G's on street tires and 1.3-1.4G's on race rubber.

Never had any problems in 5 years of autocross (except for a particular encounter with a curb.)

Seems like autocross would be just as, or potentially more, demanding on the chassis, and road course would be more demanding on the engine and brakes.

-pat

[cojsl]

Interesting. What direction was Mr. Pickles turning at DIA when his original motor asplode? I think it was a fast left hand sweeper leading uphill.

Wow, and I thought M3 parts were expensive. Yeesh!

I think this is it at 2:21. It was a long (~8 sec) left hander- http://www.youtube.com/watch?v=BnJIt9M1umc