Et drop with cooler temps?

[Stav]

Guys. I ran back to back 14.3's in summer 25 degree tepms and 40 degree track temps.

What improvement in et is typical from 25 degrees to say 15 degrees?

[northey]

Originally Posted by Stav

Guys. I ran back to back 14.3's in summer 25 degree tepms and 40 degree track temps.

What improvement in et is typical from 25 degrees to say 15 degrees?

It's a "how long is a piece of string" question. It's not a huge temperature drop; it depends on humidity as well.
It's why you see drag racers using specialist air density gauges to monitor air.... they measure in feet above and below sea level.
Good air like at the Winternationals at Willowbank could see 400 feet below sea level but it is also freezing cold.

Sorry I can't give a definitive answer but it depends on the car, tyres, track condition (dew, number of cars run). It may run a tenth or two but who knows.

[Stav]

My own experience has been from 15.2 in 30 degrees to 14.7 in 18 degrees.That is also with intake piping change and bigger cat. So I supppose only time will tell. I have not modified anything on the car since my summer run. It will be an interesting little experiment.

[Coupe460]

Originally Posted by Stav

My own experience has been from 15.2 in 30 degrees to 14.7 in 18 degrees.That is also with intake piping change and bigger cat. So I supppose only time will tell. I have not modified anything on the car since my summer run. It will be an interesting little experiment.

Whats more important that Ambient Temperature is R.A. (relative Altitude) and Humidity % When both of these drop it is a recipe for power and lower elapsed times and higher mph speeds.

[Quadcams]

Relative altitude is where you will see how good the air is, Ive found for every 1000ft drop in RA you gain about 1.5 tenths if everything else is the same (ie: 60ft, setup etc).

Here's a RA calculator, take into account WSID height above sea level is 230ft. Have a play and you will see what makes the most difference.RA calculator

Also take into account any air under 1000ft RA is becoming good air, the best Ive see myself at WSID is 187ft, as someone else said sometimes it can be below sea level reading, which is killer air.

[Stav]

So what numbers do we plug in? Timeslip show humidity,track temp,air temp and abs barometer. Ive put in 230 feet 10 degrees ..what is altimeter?

edit..altimeter is barometric pressure.

[Stav]

230 feet,77 degrees,29 altimeter,relative humidity 88%

=density altitude 1732 feet

absolute pressure 29.732 inches hg
relative density 95.%
This was from my 14.301. run .Is this good air?

With all else being equal to make a good impact to ra I need to run in 14 degrees or better.

[Quadcams]

Originally Posted by Stav

=density altitude 1732 feet


This was from my 14.301. run .Is this good air?

With all else being equal to make a good impact to ra I need to run in 14 degrees or better.

Not the best air Stav, needs to be under 1000ft and then it will start to be PB air.

[Stav]

Thanks for the info man..