Could anyone out there Pleaseeeeeee give me some pointers on making a 94 Z/28 Consistant at the track, I have tried a # of things but nothing seems to work, My son has a 97 Z/28 and he is having the same problem, I am lauching the car the same and everthing like that, Having the Temp the same ever time, The car is not spinning, Anybody with any help please let me know something. You can make a time run and then the car will slow down 5 or 6 hundreds, Then you redail for those 5 0r 6 and the car will pick back up, It is just up and down. Please help this is costing me to much money. Thanks for your time

 

How consistant is each part of the run? If the 60' times are all over the place then you need to control that. If 1/8 mile times are all over the place then it's usually different shift points. 1/4 mile is strictly top end power.

It's hard to say what you need without seeing time slips or knowing exactly what you're doing.

Break down each run into different sections.

60' time of each run
Difference in time from 60' to 1/8 mile
Difference in time from 1/8 mile to 1000 foot
Difference in time from 1000 foot to 1/4 mile

Once the run is broken down into sections you can see where the car is slowing down or speeding up. It will give you a better idea on where to concentrate. Did you launch at the same RPM. Did you shift at the same rpm. Use a shift light for better accuracy. A pointer on a tach is not very accurate. Is the tire pressure the same on every run.

My car fluxtuates like that but for me it's usually all in the 60' times. My 1000 foot to 1/4 mile difference is usually within .003

 

I agree with Stephen. Post a few time slips. It should be easy to analize them. A few details on your car would be helpfull also. Are you running slicks? How much cam are you running and where do you shift? I usually short shift the one-two shift during eliminations.

Best Regards,

Daren

 

The timeslips will help you isolate the areas of the vehicle most likely affecting performance. If you have accurate weather information for each run that is also important to isolating the inconsistencies. I have a '94 too and it is generally very consistent.

 

60' times change ET by 1.5 times. How far off are your 60'? I try to cut dead on 60' each run.

Where you stage also will affect et. Do you stage exactly the same place. I try to just turn on the stage light. Again I try to stage exactly the same place every time. A little deeper will add a little ET.

The other factor is the wind. How hard and from what direction. If the track has a flag check it out to see direction and wind strength.

And there is the bad run. This just takes experience to pick out. If I have what I think is a bad run I toss it out and don't use it to predict my next ET.

Dial the car a little easier. If I ran a 13.519, 13.483, and 13.465 I would dial 13.50 or 13.51 depending on the wind and air density. You can always take off at the end (tap the brakes before the finish line).

Last is just keep good logs and practice, practice , and practice. The more runs the better you will get. Usually I run double cards (run in 2 classes) each week. Hard core races run double cards at two tracks and spend 1 or 2 nights at the test and tune sessions.

 

Guys, My car is almost stock I run street tires, My car shifts at 5800 RPM evertime I am brake stalling the car the same, My 60Ft times are the same, My car is going crazy at the 330 ft mark and by the way we just run the 1/8 here. Thanks

 

Just a wild guess. Can you be spinning on the 1-2 shift? Do you stay in the grove of the track all the way down? I would suggest going to a set of drag radials either BFG or Nitto.

Second guess is maybe the knock sensor is retarding the timing? I would put in a LT4 knock module. (Do they have them in the 94's?) In a stock car it shouldn't be an issue but ??????

Do you manually shift or leave the car in D. I would leave the car in D to see if it runs more consistant.

 

Kazman, The car is not spinning it has a 2.73 Gear, I also have a LT4 module And i leave the car in OD and let i shift its self. Thanks

 

5800 may be a little high for a stock cam. Is the motor falling off any? The factory cam peaks at about 5200. When I ran Pure Stock I shifted at about 5400 rpm. I experimented a lot and that is where I was most consistent.

Daren

 

GUMP, The car is set at the factory to shift at 5800 RPM, The car pulls hard to 5800.

 

Just because the it has 2.73's doesnt mean it isnt spinning. Is the tranny slipping at all?
The factory in dash tach is wrong,usually 2-400 rpm high.
Have you ever scanned the car during a run? what are the readings?
My car runs consistently n/a........and most of the time i could bracket the thing when it's on the bottle.

Still could use some more info here

 

If the sixty foot times are consistent and the car is tight until the 330 mark, and if you are launching at a consistent rpm, my best (very general) guess is the transmission is shifting at slightly different rpms which would account for several hundredths in the 1/8 mile...

Little things mean a lot, particularly in the 1/8 because everything happens more quickly and you have less time to recover from a mistake. Also, it is much easier for a good driver with a good car to run "right on" in the 1/8th...

Weather can certainly account for a lot of variance. You probably want to pay careful attention to humidity as that does affect our cars significantly. I have seen my car vary up to 2 tenths over the course of an evening at our local 1/8 mile track. The difference is with my weather station I can dial for the changes.

Also, if you street drive the car like I do the first run is usually a throwaway run in getting whatever crap burned out of the motor.

I always run with a full tank of gas to keep the car weight consistent.

Also, I launch just off idle. Each car will react differently to different launch rpms.

As was mentioned earlier, staging the exact same way each time will also help with consistency because you will have the same rollout each time.

 

As a racer I always tell people that I don't watch the racing. The only cars I see going down the track are the 2 in front of me when I'm sitting in the water box. Watching a bracket race is boring and I'll admit it.

BUT
Get behind the wheel and try to do it and it's a whole different story. Trying to get a good light and make the vehicle run consistant to figure out a dial-in isn't as easy as it looks.

Everything mentioned above is correct. I caught one point that you run street tires and 2.73 gears. That's not consistant. Unless your 60' times are identical, you're still spinning the tires.

Brake stalling the same rpm every time isn't consistant. Even 100-200 rpm change will affect the run. The only way to launch at the same rpm every time is with a 2 step.

All these little things are done to reduce or eliminate the variables.

What tranny is used, A4? 2.73 gears, stock 26" tall tires and an A4. Does the car even get into 3rd gear before the 1/8 mile? If not then you're only making one shift.