June Tech 101 Article

By:Fran Pepi

A couple months ago I wrote about a new weather station I purchased prior to the start of the 2008 season. It’s the Kestrel 4000 and it’s manufactured by Nielsen Kellerman, located in Pennsylvania. This month I will give my evaluation of the unit. The 4000 measures temperature, relative humidity, wet bulb temp., dew point, barometric pressure, station pressure, altitude, density altitude, wind speed, wind chill and heat index. It is very user friendly and easy to set up. The really nice feature that I like is its ability to record readings, even with the unit off. You can set it up to sample once every 2 seconds right up to every 12 hours. I have been using it for two months now and have it set to sample every minute. I keep it at the trailer in the shade in the same way I always did with my old stuff. Knowing what time I made the run, I can scroll back through the saved data and enter it in my log book. During the later rounds, during round- robin racing, you don’t have time to record anything in your log book. As long as you know the time of the run, you can scroll back and look at the data. Many are of the opinion that you should bring your weather station to the lanes to get a more accurate reading. That’s true in order to keep track of changing conditions so you can adjust your dial-in accordingly. In my opinion, you could have entirely different conditions at certain points down track, so it’s a crap shoot and that’s why I keep mine at the trailer as I always have. Also, if I happen to be at the track alone, without my daughter, there is no one to hold the weather station. In that case, it would be impractical to take it in and out of the car and have to wait for the readings to stabilize.

I make my own log sheets using my computers spread sheet program and had to redo them for the added information given by the 4000. I added density altitude, wet bulb and dew point temperatures. I was hoping that density altitude would be my main reading for dial-in, but it didn’t work out that way for me. I had heard that for every 100 to 200 foot change, it would be about .01 et change. That may be for the ¼ mile and I mainly run in the 1/8. Even if I cut it in half, the numbers don’t add up every time. It didn’t seem to work out that way for my set-up. I think it may be because I’m running on the lean side to minimize large changes in et with changes in the air conditions. The Holley 850, #4781, I run on my .030” over Olds 455 is jetted with #82’s all around and the power valves are blocked.

Bottom line is that the Kestrel 4000 is a great data gathering instrument, easy to use, and has a reasonable price tag. I am glad I invested in one. Nielsen Kellerman has a new one, the 4500, that measures water grains which is another tuning aid and became available after I purchased my 4000. If anyone has info on their cars performance changes with density altitude changes, I’d be interested in hearing them. Questions and comments are welcome and can be sent to me at FP442@aol.com.

By: Fran Pepi