Kestrel 4250 Features:

* Waterproof and floats * Backlight for low light conditions * Data logger (automatic and manual) * Customizable data storage – 2000 data points * Multi-Function 3-line display * Convenient averaging mode * Data charting * Humidity sensor can be recalibrated in the field with our Relative Humidity Calibration Kit. * User-replaceable impeller * Flip-top impeller cover * Upload to a computer (with optional interface) * Five languages (English, French, Spanish, German, and Italian) * US Patent Nos. 5,783,753 and 5,939,645 and 6,257,074 * 5-year warranty * Assembled in the USA

Kestrel 4250 Includes:

* Soft carry pouch * Neck lanyard * Batteries – 2 AAA * Kestrel Certificate of Conformity

FAQs about Kestrel Meters & Auto Racing

Why is it important to know the weather conditions, and how can the Kestrel 4000 help me win races?

Weather affects your performance. Period. If you are not using something to measure the weather conditions then you are missing a piece of valuable information that can help you win races. Environmental conditions such as relative humidity, density altitude, dewpoint and wind speed all influence your car. By monitoring these conditions and analyzing how weather patterns from previous races change your car's performance, you are able to make more informed dial-in and tuning decisions. Since the Kestrel 4000 Pocket Weather Tracker is portable and accurate, it enables you to monitor the weather conditions that concern you right at the track, not at the trailer miles away.

I've seen a lot of high dollar weather units on the market, yours is so inexpensive, can it really be accurate?

The engineers at NK have been working on the Kestrel's functionality for over ten years, and have been awarded four patents on their innovative engineering. Additionally, each and every Kestrel is calibrated against NIST-traceable standards, and can be recalibrated in the field or factory. We're so sure of Kestrel Meter's functionality that we guarantee each Kestrel for two-years, and each one comes with a Certificate of Conformity.

How can I be sure the Kestrel 4000 is giving me the altitude and barometric pressure readings that I'm looking for?

The Kestrel 4000 uses the same barometric pressure sensor used in most common barometers and altimeters. These sensors are influenced by the surrounding environment (the altitude), as well as the weather (barometric pressure). These two readings are inter-dependent, and you need to know one of them in order to measure them correctly.

The easiest thing to do is to determine the altitude of the track where you are racing. Google Earth is free software that pinpoints the altitude of any address. Simply enter this value into the barometric pressure screen as the "reference altitude". Then take the barometric pressure reading that the Kestrel displays and enter that as the "reference pressure" on the altitude screen. Now you're good to go!

Any suggestions where and when is the best time to take readings? Before or after a run, or both?

We don't claim to be racing experts, but here are some tips that will help. The one thing we can say is that consistency is a must. Pick a system and stick with it. It's often easier to record the weather data immediately after returning from a run. That way it won't matter if you get delayed at the start. Also, you can set the Kestrel to automatically store data every five minutes, and then just coordinate times with the time slip.

Lastly, for the most accurate readings possible, it's best to keep the Kestrel 4000 in the shade, and make sure air is circulating through the temperature sensor (the curly thing), either by holding it in the breeze or by waving it around.

I have E.T. prediction software and I want to make sure I am imputing the correct readings for my dial-in.

- If your software asks for station or raw pressure, simply set the reference altitude to 0.

- If your software asks for density altitude, you can use the value that your Kestrel 4000 automatically measures.

- If your software asks for barometric pressure and altitude, make sure you know your track's altitude ahead of time and enter it in as the "reference altitude."

I don't have E.T. prediction software, any help you can offer how I can dial in with the Kestrel alone?

We went to the experts to get an answer for this one. Here's how they do it at Martino Motorsports: The density altitude reading is the most important to us. For every 150 ft. increase in DA, our car will lose .01 in elapsed time, and for every 150 ft. decrease our car will pick up .01 in elapsed time. But we can get the same DA and have two completely different runs.

This is due to humidity factor. Although the DA might be the same, you can have a different temperature and humidity combination. For every 15% increase in humidity our car's performance will decrease .01 in elapsed time and for every 15% decrease in humidity our car's performance will increase .01 in performance.

Using a Kestrel for Racing

You don't race at your trailer, so why measure the weather there?

If you think the weather conditions at the track are the same as the information you are getting from back at the trailer, you need to think again.

Even slight fluctuations in weather conditions like temperature, humidity, barometric pressure and density altitude can affect your car's performance.

Kestrel Weather Meters provide quick, accurate information to help you decide what changes need to be made, before even making a lap around the track or a pass down the drag strip. Portable and easy-to-use, Kestrels give racers and pit crews relevant data to gain that competitive edge at a fraction of the cost of other systems currently on the market.

The Kestrel 4000 Pocket Weather Tracker is the next generation of weather monitoring. It measures every environmental condition with unrivaled ease and accuracy - and all in a cell-phone sized package. Wind speed, temperature, relative humidity, dewpoint, density altitude, altitude, barometric pressure, wet bulb temp, heat stress and wind chill are all continuously measured, and data is stored both manually and automatically. A 2000-point data log lets you keep track of the conditions for each race day, and the optional computer interface lets you upload all the data to your PC for in-depth analysis.

The Kestrel 4000 features the best portable sensors available, assuring that it's dead-on accurate. Each unit is individually calibrated before it leaves our manufacturing plant, and comes with a certificate of conformity. We even hold four patents on the technology our engineers have developed especially for the Kestrel line. They're so accurate that they are the choice of Meteorologists, Wildland Firefighters and Emergency HAZMAT personnel.

Did we mention that it's durable, too? Kestrels are built tough right here in the USA, and carry a two-year warranty. Each Kestrel is fully waterproof, floats and can handle being tossed into your tool box. They're the only hand-held weather instruments trusted by the US Military.

Increase your performance when it counts the most. Let a Kestrel Pocket Weather Meter help you with those last minute dial-in or tuning decisions.

Water Grains is a measure of how much moisture (water) is in a pound of air.

Since water grains is an absolute measurement of moisture, a racer can look at this value to determine if the engine will be more or less powerful in comparison to previous atmospheric conditions. For bracket and class racers, this helps determine the dial in or throttle stop timers. For professional drag racers, (or any type of drag racing where the first one to the finish line wins) it helps in determining adjustments to the clutch, fuel, ignition, chassis, etc., that may need to be made to compensate for the loss or gain in power. More water in the air equals less power, while less water in the air equals more power.

The New Kestrel 4200 automatically calculates the Water Grains.

This is another commonly asked Kestrel question. Typically, if you don't know what Density Altitude is, you probably don't need to worry about it! But just in case, here's a quick explanation of Density Altitude:

If you think about how your body feels at the beach versus standing on top of a 10,000-foot mountain, there is a big difference in the air that you breathe – it’s thinner and there is less oxygen per breath that you take. That’s why mountaineers need to “acclimatize” to new altitudes as they climb mountains, allowing their bodies to adjust to the new air. Additionally, weather factors – such as temperature, pressure, dewpoint and humidity – can affect the weight of a cubic volume of air, in essence making the atmosphere “feel” like it does at a higher or lower altitude. Density altitude is a calculation that adjusts your actual geographic altitude to the altitude that it “feels” like based on the environmental conditions of the atmosphere.

Increases in temperature and humidity can cause a reduction in air density- hot and humid conditions can make the density altitude significantly higher than the actual geometric altitude. Since water vapor is lighter than any other gas in the air, the more vapor in the air, the lighter it feels. (Even though liquid water would be heavier than oxygen or nitrogen, the gaseous form of water is lighter.)

So why is density altitude an environmental condition to watch? Denser air slows down objects because the air is heavier and the object has more resistance or “drag” moving through the air. That’s why it’s easier to hit a home run in Denver (where the ball park is a mile above sea level) than at a lower altitude park.

Density altitude is essential for pilots to monitor because it affects the lift, propeller efficiency and power output of the engine. Depending on the weather, an airplane may need a longer runway to take off and reach the same altitude. Similarly, a helicopter’s rotors have a harder time grabbing the air depending on the air density. Race car drivers and pit crews also monitor the density altitude because the car’s high performance engine will perform differently depending on the density altitude. Some long range shooters also consider the density altitude, as it can influence the bullet's performance.

The Kestrel Meter uses a formula to calculate the density altitude. And since density altitude takes station pressure into account instead of barometric pressure, there's no need to set a reference for an accurate density altitude reading. (Station pressure is the pressure reading assuming that you are at sea level, and barometric pressure is the pressure reading adjusted to your geographic altitude.)

You don’t have to take our word for it...

"The Kestrel 4000 is the perfect tool for making those last minute dial-in decisions in the staging lanes. The cell phone sized meter gives me fast, reliable data just seconds before my pass." - Bill Barr, Quaker City Raceway, Modified Class

"The unit itself is one of the most valuable tools in our trailer. It allows us to win races and rounds." - Tom Martino, Martino Motorsports Youngstown, Ohio

"The Kestrel 4000 comes in handy when we go to the staging lanes, and are delayed for some time, we can track the weather changes." - Dan Parker, Parkertech Racing, VIP Sports Dodge Stratus, TAFC 33

"Overall I'd say this is a trick little piece. All the readings were so close to matching up (with high priced weather station), I could have easily made the right tune-up decisions based on the Kestrel. We wondered why we were paying so much for our weather station (about $3,000)." - Jim Oberhofer, Crew Chief , Doug Kalitta's NHRA Top Fuel Dragster

"The auto store feature is key because once you get into later rounds, you don't have time to "log" all that data in your book. All I do is hit the auto store button before each round and fill in my log book whenever time permits." - Bill Barr, Quaker City Raceway, Modified Class

"It's what I use. I like to take readings but don't need a computer predicting my ETs for me. It's very portable and consistent at a fraction of the cost of the $2,000 plus trailer systems." - John Rollins, NHRA #2241 (ET, Stock, Super Street)

"I've found my Kestrel 4000 to be very helpful in winning 4 class championships and 2 overall track championships at National Trail Raceway since 2004. It was also instrumental in helping me win the NHRA Division 3 Sportsman championship in 2004." - Ray Block, Block Party Racing

"I finished #1 for my track in the Summit Super Series and can definitely say that my Kestrel 4000 was a big part of my consistency. The other racers saw that I was doing well using my Kestrel and asked many questions. The biggest one was what the weather was doing, especially the density altitude. Of course I had to start limiting the information and encouraged them to invest in their own meter. They started watching to see what I did with my dial-in numbers and then change theirs! Very sneaky, but good fun!" - George Jorgensen, Alaska Raceway Park (Super ET, Summit Super Series Champ)