I know that I really don't have enough data yet, but figured I would ask you all any way.

Saturday
1st - 14.6 no nitrous
2nd - 12.7 nitrous
3rd - 12.9 nitrous
4th - 13.1 nitrous

Sunday:
1st - 14.6 no nitrous, 60 foot = 2.4
2nd - 12.6 nitrous, 60 foot = 1.8
3rd - 12.8 nitrous, 60 foot = 1.97
4th - 13.2 nitrous, 60 foot = 1.94

All pass were 15 to 20 minutes a part
Engine temp was always below 190.
Closer to 160 for the 1st 2 passes.

Car never spun.
outside temp pretty much the same

Im thinking maybe the tranny is getting to hot.
I lost the most time at the 330 mark.
The 60 foot time is actually better on the 4th run then the 3rd run.

I need to get more passes letting the car sit to get a better idea of
how long it has to sit before the speed comes back.

A 12.6 to a 13.2 is to large of a difference. Something strange is happening.

 

Is it possible the nut behind the steering wheel was getting worn?

 

8 tenths is a lot to drop off, from me being tired.
Don't think that is the issue.

 

what tranny?

 

an old TH350 without a stall or shift kit.
I have a new TH350 and a 3k stall, but it is still sitting in the kitchen.

 

And I spose you have an oven in the garage?
What about other variables? Your better runs were earlier in the day. What were the track conditions later in the day? If it was a hot sunny day, the asphalt would be getting progressively hotter (radiating heat up) as the day goes on....to a point anyway. Even though your temp gauge reads the same, your under-hood heat could be higher later in the day as well. Are you running a fuel chiller can? That would help give more consistent fuel atomization with the changing heat.

 

Have you talked with other racers to see if their times are dropping off similarly?

 

At first I was thinking track temp, still am. But then, was your bottle going empty? I couldn't get more than 3 runs out of a bottle. Your times dropped consistently both days. Same temps both days all day, in the spring?

You made 4 passes in a little over an hour? That would do it to the old Nova. Even with an electric water pump it didn't like to be hot lapped. Try popping your hood between passes.

Finally how do you know you weren't spinning? Just cause you can't feel it don't mean your not. Also I spent as much time watching my buddies Chevelle as I did driving. We tried to walk each other through the burn out box if we weren't both running. Some times I couldn't tell watching the tires as he launched. Solution, the big white stripe you see on some guys tires. Helps to see if your spinning on the rim too.

 

No garage, but if I had one it would have an oven in it.

Track condition had not changed that much in an hour. The runs were 15 minutes apart. It was not a hot day, it was kinda overcast. The outside temp had not changed. Other cars had not dropped off.

Heat under hood is an interesting idea. Hood is very open, not inner fenders, fender vents and lower grill cut, but still an interesting idea.


Will try marking the tires. I did have a friend watching. He didn't see any spin and the 60 time was faster. I lost speed at the 330'

What size bottle wouldn't let you get 3 passes? I have 8 passes and the bottle doesn't seem to have dropped. I do have a bottle warmer. I was told I would get tons of passes on one bottle. I would not spend $10 per pass for nitrous. Its $35 to fill the bottle, less then 3 passes is $15 a pass.

No other car dropped 6 tenths in an hour. That is a crazy amount to drop off.

Im still leaning toward the tranny being to hot, and possible taking longer to lock up during the shift.

I will try opening the hood this weekend. Hopefully I wont have any issues and I can get more time between laps.

 

10#, 175 shot. I got to thinking, are you purging? Before every pass.