I spent last Saturday at Capitol and Sunday at MIR getting significant seat time in the 1320 for the first time since 2022. This car has always been very sensitive to heat soak from being stuck creeping forward in long staging lanes, or when I've run two classes that are back-to-back and basically hot-lapping me.

How are you adjusting dial-ins under these conditions?
--> Do you have enough data to be able to predict (reasonably) accurately how much you'll slow down?
--> Are you taking a s.w.a.g. about how much to change the dial-in simply cuz you know the car's gotten hot?

I got in 10 passes on Saturday and all I can tell you is... yes, the car gets progressively slower as the cool-down intervals get shorter. Disregarding some changes in the DA for the time being, the car ran the following when "cold"... 45-60 minutes between passes:
11.857
11.856
11.876

When the cool-down interval was only 20-30 minutes:
11.978
11.946

When I intentionally hot-lapped the last 3 passes only about 8 minutes between them:
12.228 (spun)
12.024
12.059

So I'm wondering how other people account for this variability. Thx

We used to do a track rental. The most that I ever got in was 27 passes in one day. This was with my mostly stock Charger cruiser street car. Stayed from 13:60'-13:80's all day. That car doesn't vary much every.

Usually the first pass is .01-.02 slower because of fluid temps. Car usually repeats dead on after unless tremps or DA change radically. I've run 11.41 three in a row with no issues.

How much time between runs is safe? @ some test and tunes we've been able to go from the return road straight to the burn out box

I assume your engine coolant temp is well regulated? If so, I wonder if your fuel temps rising are what is responsible for the change.
I have "hot lapped" at Moparty as part of their "drag-n-drive" class, and my runs were pretty well identical back to back.

I've run as quick as 13 minutes apart. Car is usually .01-.02 quicker due to hot lubes. If your car doesn't have a fan/water pump system that you can run with the engine off it's going to be slower. Best thing we've done. Don't shut it off. Let it idle. Yes it'll be slower. Yes it'll be consistent.
Doug

It's a street car with electric fans and everything else stock, so it'll hold around 180 to 190 degrees water temp once up and running

The car has a 203* 'stat, but the big issue is while sitting I can watch the IAT climbing continuously until the car starts getting up to speed again

Do you have a way to see air inlet temp? I bet it is much higher on a hot lap and the inlet sensor is also likely to respond pretty slow. It would be interesting to see if you could make a resistor that plugged in and locked the inlet air temp to a single number.

I moved my Barracuda over to a Rife brand inlet temp sensor because they respond very quickly. My car picks up under hood air from the hole in the hood at low speed and idle. So I leave the line with a higher than ambient inlet temp, sometimes as much as 30-60*. The original GM style inlet temp sensor is right at the top of the throttle body. With the GM sensor I start the run over ambient and it took almost the entire run for the sensor to read ambient again. With the Rife sensor it reads ambient almost immediately after I mash the throttle. That helped smooth out my tuning some because the slow response time was messing with the inlet air temp correction. I might have gained a few hundredths from this but for sure gained more accurate data. I am sure an OEM with border line safe compression ratios pulls timing and throttle response with higher inlet temps.

Yes; there is an IAT gauge option that seems to give pretty quick response to changes in airflow. It's generally about 5* above ambient while the car is moving a a reasonable pace, but I can watch it keep getting hotter the longer I'm stuck waiting to move.

Those hot runs hurt right from the 60', too. It must take a big gulp of the heated air and pull the timing, then it ramps it back in as the IAT comes down as the car picks up speed.

Have you tried running it with the IAT unplugged. It'll set a fault but in normal driving during tests I've never really felt a difference on numerous vehices.
Doug

My car is like yours. Always has been.

Last fall at test and tune.
>1 hr cool down:
11.762
11.761
11.789

Shorter cool down:
11.967 - < 5 minutes
11.916 - 13 minutes
11.892 - 31 minutes

After one pass the engine is so hot you can't touch anything under the hood. If I'm racing, I guess. But I suck, so that doesn't work. I got nothing for you.

I have a Tazer it does lots of stuff, one of them is you can run the cooling fans to cool the car down

I would expect it to default to max IAT range and trim accordingly if you unplugged the sensor.

Kevin