Hey guys I know the weather (especially temp) has a huge effect on performance and associated 1/4 mile times but I am curious as to how humidity has affected your runs. I went from running 12.26 @ 112 on sunday when it was 68 and very low humidity (nice crisp air) to an average of 12.35 - 12.50 @ 110 and 111 mph last night when it was cooler (57 - 60 deg) but extremely hazy (95 percent humidity).

I am familiar with the fact that more humidity means less oxygen going into the motor but I am wondering how much this has affected others because I was hoping to better my 12.26 in the cool air. Should I have jetted up or down to compensate?

On a the plus side...I managed my best ever 1.84 60 ft (my avg is 1.95) on my 255 - 70 - 15 Radial TA's. Even with the better short time I only managed a 12.26 @ 109.

Looking for some education here...

Thanks,

All the air conditions affect vehicle performance...temp, humidity & barometer (tied into altitude).

The barometer & humidity have more effect than just temperature does.

First, humidity is simply a measure of moisture held in the air. The more dry air an engine can take in, the more potential for making power. Since humidity is water in the air, the water displaces air which reduces power output.

Barometer is a way of measuring air pressure...basically a high barometer is natures way of a mini-super charger and packing more air into the chamber, thus giving more power.

Altitude is tied into barometer as the lower your altitude, the denser the air which is available to enter the engine.

There is no real specific answer to say how much your car will lose with different air changes, unless you have a weather station with ET perdicting software used by many bracket & heads up racers.

Typically, late evening hours lose air quality as the due comes out and the humidity rises...kills power even though the temp may have dropped up to 20 degrees from earlier in the day.

Many racers try to tune their cars to run consistent through the day and be least affected by temp & air changes.

EDIT: Forgot a couple things...weather stations are used to calculate "corrected altitude" which is used to be able to compare runs from different days, yet be able to make comparisons knowing how the weather/air was each day.

Also, a little trick I learned to know what the humidity is doing without a weather station...watch the burnout area. If the smoke dissipates quickly, then you have low humidity. By the same token, if the burnout smoke lingers and hovers a long time, the air is quite humid.

I lost 2 tenths with no changes from 60 degree weather with 60% relative humdity to 80 degree weather with 95% humidity. And on the hotter day my 60ft was .08 faster but my 1/4 time was still 2 tenths slower.