Just as the topic says. Just wondering. Wed at the track it was about 102 degrees and not really sure what humidity it was and there was a 350z that was running in the 14.1 in 80 degree temp last week and wed he was running anywhere from 14.5 to 14.9 in the 102 weather. He thinks it's because of the heat.

Does the heat or humidity really kill time in the 1/4 that bad?

 

Heat, humidity and barometric pressure all effect how an engine runs. Combined together and elevation added in, they create a density altitude. The lower, the better. Best conditions are cool temperature, low humidity and high barometric pressure.

When it was that hot out, even with good air you could run slow because of poor traction. You want a warm track but you don't want the sun beating down on it. A sunny track is slippery and gives poor traction.

Don't worry about the ET from weekend to weekend. Concentrate on the MPH since that's the indicator on how much hp the engine is producing that weekend. When the mph drops, you know you're not making as much hp and the ET will usually be down.

 

Heat & humidity factor a lot I'd say.

Last year, the best my car ever ran was 14.0 @ 103 (temps probably in the high 90's, and extremely humid). THIS YEAR, without changing anything except running on a cool, dry night, the car ran 13.4 @ 106. Traction wasn't really much different (2.1 60' times consistantly) but the overall performance was definitely improved from the hot/humid conditions last year.

 

Yeah, they affect times that badly. This is how I beat an LS-1 that had run 87 in the 1/8th heads up on a hot evening. I have never run with a temp lower than 90. I am looking for some of that west Michigan coolness when I get the car running again.

 

DA was over 3000 feet last weekend. I was running 12.3's at 108.

My best ET is in the sig with good weather conditions.

 

mm'mm 3000 feet. I can only wish for good air like that

A couple of weekends ago I was running consistant 119-120 mph. My ET varied from 11.2 to 11.6 just from traction but the mph was still consistant. It was hot and sunny. The track was warm but the hot sun was making the track slippery. A few clouds that day would have really helped traction.

The following week was cooler and the DA was almost 1500 feet lower from the week before. That's the weekend I set all my best times almost knocking off a full 1/4 second just from better traction.

 

D/A at Sac Wednesday night was around 2800 ft ... wait till winter ... we'll see D/As at - 200/300 feet