First off my car is a stock 88 with the 350 and auto trans with 2.77 gears
the only mods-flowmaster muffler and k&n filters.

I've taken it to the drag strip six times now and have a few problems/concerns.

First off, the last 4 times I've been--my best run is always my first run!!!! This makes no sense to me---the air tends to get better the later in the day as I race. This should not be the case 4 times in a row.

Also, I am having a terrible time with my car being consistent--even with BFG drag radials my 60 fts are varying by .05 and my 330 fts vary by .08 and overall ET in the 1/8th varies by .10---this is weird to me because my procedure is the same each time and I keep the car at a constant temp. I have been been bracket racing for the better part of 10 years (I have owned a 2nd generation and 4th generation) and never had this problem before. The car goes up and down in et all day. Any idea on what to start checking on the car? Could this have something to do with the TPI? Any and all of your suggestions will be appreciated.
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Our 99Z28 does the samething. We can go out at 6:00 & run a low 13 and when it gets dark it slows down about 2-3 tenths. Air temp, Humid., all have alot. Some like it cold some not.

 

This may sound wierd to you, but, my '88 used to be the exact same way. Same set up too. 350, 2.77 gears and all. My first pass was always my best run of the night with the exception of one day, and I raced it for a little over 2 years. The one exception was I ran better on my second pass instead of my first...and I always ran it 3 times a night. Weather is always changing where I live though, so consistancy is pretty tough to tame. Just lettin you know you weren't the only one.

 

What were your other runs like though?----were they fairly close or would it be off by a bunch????

 

Check your tire pressure next time you run. Do you launch it the same way everytime? Do you run in the same lane everytime, or is a different lane? Could be any of these but I seriously doubt it has anything to do with your TPI.

 

I check tire pressure after each run

I have tried both lanes: back to back and alternating

I do the exact same launch---same count during burnout (about 5-6 seconds, 1 dry hop, then stage--leave at just above bare idle)

Do you think it could be any of the sensors or anything to do with the ECM? (there are no trouble codes)

 

If it was a code of some sort you would get your SES light. The hardest one I had to figure out was I'd get just passed half track and my SES light would come on and I'd lose power. It turned out to be my TPS sensor went bad. But, I'd think it would throw the code if there was a problem. Who knows could just be the track. I pulled a 2.18 60ft. my first pass Fri night, second pass went out and torched a 2.28 60ft... Who knows man, I'm sorry to hear you're having so much trouble. Try going to AutoZone and getting the free key and book for your computer and run the codes anyway, never know maybe it's not picking up the code...

 

Thanks for your help BADBOWTIE!!!

If you don't mind me asking--could you post some of your times...say for the same night at the track...I mean all of your passes for the same night---just so I can see and compare how your car performs from start to finish

Thanks again

Brian

 

I would make sure transmission is consistent...same shift points with fluid change for oil, rear, trans., etc. If your temp os always the same (difficult to determine accurately without a Scantool...then I would think that it would be you knock senspr causing you to retard your timing. No trouble codes would be present. Can determine if its knock retard by diconnecting the sensor. But you might want to have some excellent gas in the car when you do this.

Is the 2.77 rear an open rear ? One wheel spinner?
You can get lots of variation with a non posi.
Could even be something like a poor battery, bt that's just throwing out ideas.

Hope you get it owrked out. Mine usually is quite consistent except for poor tracks causing wheel spin, or knock retard since mine is high mileage. Better gas usually helps.