At what point does the humid air adversly effect performance. Lets say 65% related to 70%. How can does this effect the motor at the track.

 

From my experience using a TAG weather station... ET is affected most in the following order

Barometer has the MOST effect.. next

Air Temp has effect but not as much as the Barometer reading

Humidity has the LEAST effect on your ET ..I'm not saying that applies to all cars at all tracks.. but I find the above to be true for my car...

Re: your specific question 65% to 70% should be almost nothing !! you may see a difference of .02 - .03 if it goes from 85% down to 30% .. & the Barometer, & Temp remain the same...

If you dont have a weather station its VERY easy to be fooled.. if the barometer gets lower, but you get a cool breeze by feel alone you'd think your going to go quicker.. but ...not true.. the lower Barometer will KILL ET even if you do get the breeze

 

So is the barometer is related to pressure at the surface? So a reading on the barometer of 31 inches is better than 28 inches. If I am correct here, a falling barometer is bad for ET.

 

YES with a 31 Bar reading I have run 12.2 with a 28 Bar I'd run 12.9

 

Great job JP, you nailed that answer

 

Humidity takes up space in a cubic foot of atmosphere, leaving less room for the air, which contains approximently 19% oxygen. It IS the oxygen that we're after. The more humidity in the air, the less oxygen available in every cubic foot. The fooler in the humidity reports is, that it is generally reported as "relative humdity".

Warmer air can hold more humidity than cooler air. Relative humidity is the amount of moisture in the air, "relative" to the capacity of the air, to hold moisture, at the reported temperature. I don't have the exact figures, but 80* air with 60% "relative humidity" may contain the same amount of moisture as 100* air at 50% "relative humidity". When the temp drops and the percent of humidity raises, don't assume the presents of more moisture in the air. Therefore the dew point and/or the vapor pressure are better indicaters of the actual amount of moisture present.

Barometric pressure is the number one factor in preformance, as stated. But don't be fooled by the radio or TV, especially if you race tracks at different altitudes. All common weather service barometer readings are "correct to sea level" readings. Denver and Death Valley may report the same barometer under certain conditions, but their air pressures will never be the same. *I* don't recall seeing an actual barometer over 26" at my home track. Last week, it ranged between 25.72" and 25.75" Denver would be still less.

Just a few "weather facts" for anyone that may care.

RACE ON!!!

 

Common over to NJ & see what its like to race with a Bar. reading of 30.77 Air Temp 47 deg. Humidty 30%

 

Air like that would really get the old Crossfire moving. This weekend we should have a bar about 25.70", air temp of 91*-93* (for time trials), and humidity about 18%.

RACE ON!!!