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Discussion Starter · #1 · (Edited)
I have been messing around with Quarter Jr using stock '02 Z06 data. For standard day conditions (29.92 in hg, 60 F, 0 % humidity), the best prediction I got was 12.20 sec @ 112.8 mph. The launch technique that produced that time was to leave at 5000 rpm and slip the clutch to the 60' mark. It looks to me like clutch technique is everything.

Has anyone done times around this?

Please reply with your time slip data, including intermediate times, and weather conditions so I can validate the model.

I suspect a soft, slipper type, clutch could make other wise stock machines really run on OEM tires.
 

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RR

We got guy's doing high11's. & 12.14/'s in '01 Z's.............
I am sure the '02's with similar driving skills.......would be a bit better.....BTW, these #'s are STOCK '01's.................
One pulled, 11.985, and another with just a tric 12.14...............and neither of them launch ANYWHERE close to 5k..........
Go to the Perfomance Data Center.........................................................................................on the left, and pull up the times, and ride...............
 

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But at least one of those guys said they were running at an effective 700' BELOW sea level.

That is far superior than the "standard atmospheric conditions", and would produce a better time.

However, I agree with Z06LS6 in that this guy didn't leave at 5k rpm slipping the clutch. If I recall, it was more like 3k and he was going full throttle ~40' out of the hole. I probably have some of the specifics wrong.
 

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i think your computations are correct re: 1/4 et but not mph. when my car was stock, i was able to put down a 12.3 at 116 for my best et but my best mph stock was 118. I have since added a tric and a thermostat and have now ran a 12.1 at 118 with my best mph being 120 at 12.2. if you want the breakdown of my short times etc....do a search i think i posted them in a thread on vipers...i think me and performin norman were talking about viper vs. vette performance.
 

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Hear are some # for your simulation program. 50degF RH=43% BP=30.26 inHg DA=-665' these numbers are from my tag weather station. All the memorys from the run are just that,I left at around 3-3100 and sliped the clutch wial squezing the throtle on it is a guess on my part how far out I was when it was full but almost all the way through 1st. hear are the numbers from the run.
60'=1.773
330=5.040
1/8=7.718
mph=92.11
1000=10.028
1/4=11.985
mph=115.26 You need to know my car that day was 3224lb race weight. There is always some thing left on the table but this was very close to the best I will ever be able to drive my car. Ric
 

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i've always been amazed that you were able to get that time out of essentially a stock '01 Z....unbelieveable driving!!! that was the run of a lifetime! imagine what you will do with a few mods and some drag radials..... mid to low 11s!!!
 

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pwrshifter:

have you ever driven a stock 02 Z in the 1/4? ...given the trap speeds i have been able to lay down, i would guess you would turn out 11.8s or so......:eek:
 

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Lawboy, I haven't driven a 02 yet. I have been guessing that in the right conditions thay will run .2-.25 quicker than the 01. The key is the right conditions and a close to perfect drive at the same time. I personaly think ALOT of the improvement that is beeing atributed to the simple bolt on's probably it realy driver improvement and conditions. Ric
 

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i agree with you on both points. i think the difference between the two models is about .2 i also agree that a lot of the improvements we attribute to bolt on mods is really the result of a number of factors including better driving, better track conditions, better weather, car and tires are broken in more, and finally, increased performance due to the mod.....

notwithstanding the above, im looking to add headers and an x-pipe this winter and send it to MTI for heads/cam this spring....hoping to get over 400rwhp and get into the mid 11s.....we'll see! :D
 

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Discussion Starter · #11 ·
PowerShifter said:
I personaly think ALOT of the improvement that is beeing atributed to the simple bolt on's probably it realy driver improvement and conditions. Ric
I'm with you. That is what I am trying to sort out.
 

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My best were at a race weight (car plus me) 3270.

60'............1.856
330'..........5.170
660'..........7.885 @ 91.45
1000'......10.191
1320'......12.145 @115.85
Density Alt: 1703 Feet

60'............1.834
330'..........5.141
660'..........7.889 @ 90.65
1000'......10.215
1320'......12.170 @115.53
Density Alt: 1421 Feet

Stock shifter. Only mod is a Halltech Tric.

Ranger
 

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What Ric said

Stands to reason.................

When you have a car with 20HP more, taking longer.........to go the same distance, with TWO different drivers........

Experience(along with other variables) come into play........(weather cond).

Lawboy, I have been contemplating the MTI deal......with NO doubt, this mod will get you, and even me('01) into the 420+ rwhp...........range........BUT, there's one thing STICKING in the back of me craw...............

With the STOCK '01 & '02, WE already have problems getting what's THERE.....to stick........
So, while it may be a pile of fun for the increased TQ, and HP..........

Getting really significant results on the clock, is another story......
I have seen countless threads, where the HP is UP.........and the times are NO better than what PS, & Ranger lay down boneyard stock......some, most not EVEN as good............so, is it really worth the extra $7/8K, to go slower, or the same, and TEAR up your rig at the same time?????..........

Dunno...........I'm TINKING on that one...........:-?
 

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stop making so much sense! :D

i agree that these cars (like any other with this much power) have trouble putting to the ground the power they have right now......i fully realize that i should be running somewhere around 11.7 to 11.8 with a trap around 118-120....i just can't utilize every ounce of my car the way Powershifter can....he is obviously a better driver than i am....soooo to compensate...i have to add more power...of course....i will once again be unable to utiltize all of it....but hopefully it will get me down into the mid 11s .....when i should be running in the low 11s....


or i could pay powershifter all that money to teach me to drive better???? hmmmmm.....:p
 

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Lawboy said:
i agree with you on both points. i think the difference between the two models is about .2 i also agree that a lot of the improvements we attribute to bolt on mods is really the result of a number of factors including better driving, better track conditions, better weather, car and tires are broken in more, and finally, increased performance due to the mod.....

notwithstanding the above, im looking to add headers and an x-pipe this winter and send it to MTI for heads/cam this spring....hoping to get over 400rwhp and get into the mid 11s.....we'll see! :D
The value of mod's is in the eye of the beholder. If you don't mind the tuneing and posible drivability diferance then I would say headers are a good one, once you get the exaust flow then an air filter system makes some sence to me. When you go beyond that point to cam and/or heads you add lots of power but get into clutch and traction issues that may or may not fit what you want from your car. I find myself enjoying the balance of the Z06 to the point of reluctance to do any major mods.Have an 02 lid in a box in garage for spring. Ric
 

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Discussion Starter · #16 ·
Thanks Ranger! That is the information I am looking for.

My first thought for lower ETs is clutch technique. Second is a counter weighted type clutch so it wuold be repeatable. Next is a cam change to move some of that low end torque to above 4500 rpm.
 

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Ric

I understand what you are saying. For me, the Z is not my daily driver so I dont have a lot of the same driveability issues that others may. My Z is for fun and to be driven hard and fast be it on the track or the street. It is pure pleasure. Im not in the car enough to have the idle or noise bother me. instead, those very things are joys to hear and feel....as for the clutch etc....i will work those bugs out as they appear.

btw, even though i have read the posts by both you and ranger 300 times, i still dont know how to drive my car like you drive yours.....but maybe after driving that 8 second camaro of yours, :eek: everything else seems like it is going in slow motion!!!
 

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You're a better driver than you think.

I agree with PowerShifter that there are many variables at the drag strip.

With that said, once you hit a certain level of proficiency in shifting (and staying off the limiter), then the the biggest improvement will come from running at a well-prepped track. In our area there are two, and one is still consistently better than the other. Both are about 75 miles from me. Worth the drive, every time. On those tracks, my 60' times are consistently in the 1.9s and 1.8s. On the local tracks with their crappy launch area and no-prep-down-the-track it hard to break below the low 2.0s and wheel hop is not infrequent. The difference is .2-.3 in ET.

So my advice is simple; spend some days at a great track, and watch you times come down. You'll find that you are a faster and better driver than you think.

Best to all,

Ranger
 

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Discussion Starter · #19 · (Edited)
1/4 mile model results

Thanks, PowerShifter & Ranger for the data.

As we suspected, the ET performance numbers are confusing until the data is normalized to standard day conditions (60F, 0% RH, & 29.92 baro) using the SAE correction factor (CF). That analysis shows how much weather conditions can affect times/mph. I have seen times on a couple cars that went 11.9s but most seem to be in the low 12s.

One very good run 11.985 @ 115.26
corrected to 12.04 @ 114.9 (CF .981)
with ET HP = 368, MPH HP = 384
hook factor = 1382 (Best I have seen.)

Another not as good run 12.145 @ 115.85
corrected to 11.92 @ 117.3 (CF 1.059)
with ET HP = 379, MPH HP = 409 (Best I have seen.)
hook factor = 1398

I was able to duplicate these runs in the model (Quarter Jr) using a launch rpm of 3000~3100. Still, the model shows high sensitivity to launch rpm (the higher the better to about 5000) and, as you guys know, clutch finesse.

Conslusion: There are better numbers to be laid down by working on clutch technique.
 

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Lawboy, When your raceing your car rather than thinking about all the diferent pieces of advice you get from others, paying close attention to what the car and track are telling you will pay the bigest divedend. Look at the time slips closely, so as you try things you can see as well as feel the results. I don't compleatly agree with ranger on blanket statments on one track over another. It is the rare wend night that you can get grate times at NED but sat-sunday are usualy better not ONLY because of track prep but there are more real race cars with 16-17 slicks preping the track and not as many street tires tearing the rubber off the line.(just one example of why)
My advice to anyone trying to figuer out how to get a street tire corvette down the track quick, is to start from thinking of the christmas tree as a stop light and slowly and SMOOTHLY build up the launch THINKING about what the car and time slip tell you. Ric
 
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