E.T. Prediction and Weather Station

What is everyone using? No CompuTech. Thanks in advance.

Performaire Eclipse , 20years+

We've been using an old TAG with O2 sensor. It's surprisingly accurate once it's built up a decent data base. If you a re constantly tweaking the combo like we do, it will skew the figures by giving more more of a "predicted deviation". We usually reset the data base if we have made a big change in the combo, we aren't proper bracket racers. We are usually chasing an ET's in a bracket class, as over here there aren't many heads up classes but it's the best way to run on a good track.

Been using this, its free and works good. You can use it on any track, just select the track and it gives you current numbers. DA, temp, water grains, etc, etc

https://play.google.com/store/apps/details?id=com.dragtuner.dragracingweather&hl=en_US&gl=US

Performaire Eclipse here as well, need to send it in though for update as the wind speed sensor they added years back has pooped out but other than that still running strong.

I've never used that one, but you would be surprised at who does.

Ask the guys in the dot 90 classes. They live or die by the weather.

Working on the car to make it consistent, know how to predict the track, cloud cover, wind, etc, and how it affects your car is most of it. Predictions usually get fudged by those things.

I use a Perfromaire Pro with a pager and also incorporate Crew Chief Pro. If I were a daily only bracket racer not sure all thats really necessary but multiple day events and especially for NHRA .90 stuff its almost a must have. Although I went to a few finals in .90 with a hand held Tag.

Used an old TAG for years. It’s predicting was very accurate.

I too get my weather online:

https://airdensityonline.com/tracks/?filter=222

I have an PreformAir handheld, but rarely use it.

For ET prediction, I use Family Software ET Predictor:

https://www.ifamilysoftware.com/etpPRO.html

How about an old B&G racing computer, some decent instruments and a log book.

Figure out ET/Air Density change ratio, throttle stop ratio, vapor pressure fudge factor, track, wind, clouds, watch everyone in front of you to see what they're doing, figure out how you want to race the guy in the other lane, and throw a number in it.

Worked pretty well.

Thanks for everyone’s opinions. I’m pretty certain, I’m going to use Family Software. I’ll need to talk to Bob, to decide what air sampler to get. I currently have a CompuTech race air sampler and Sharp hand held computer. The sampler has a failed humidity sensor, and they can only sell me a replacement, for $475. The sampler has failed twice. I realize it’s old, 2004, but it’s low use and always in the case, in my home when not being used. I can’t trust it anymore. Thanks again.

Just curious about your CompuTech Not happy with it ?

The air sampler has failed twice, and I’m not giving them $475 again. Granted, the first time they fixed it under warranty, but it’s failed twice out of the blue, without warning and when I needed it the most. I’m sure it’s anecdotal, and that’s fine, but I don’t trust the architecture.

How “Dead on” is Family Software ET Predictor? Thoughts on people using it Thanks Randy

Respectfully, don't expect accuracy in any ET predictor until your combo is more in line with what you have, what you paid for/built. This is what you gave in another post: 'Thanks everyone. Ted, tires are junk. Under 25 passes, but almost 6 years old. It’s a 388” B1BA, R1 tall deck roller motor. It’s always been an underachiever by .25 or so. 620hp and 535 pounds feet, on a stingier dyno. Should have gone closer to 10 teens at 130 @3150 with driver.'
something is off that it could pick-up in 'bad' weather...I hope you get what I mean without typing every possible scenario. Between this community and the names you listed helping you, you can dial it in better which I have no doubt will allow the prediction software to help you go rounds. Respectfully.

I knew there was something else I forgot... unless these tires were exposed to sunlight or poor storage. I doubt they are bad at all. I know of MANY successful racers who report way longer idle periods and use and have no trouble with their slicks. Share your combo and info and we'll dial you in in no time!!!

I've been happy with it, and it's gotten me a Win & RU in some NMCA Stock/Superstock combo races. Usually if it doesn't run the number it can be attributed to other factors (ie, driver error, quick changing weather, etc).

It's not too user friendly for index racing. I used it many years in NSS running an index. Here I had to determine the horsepower corrected weight to run dead on my index, then adjusted weight to match the HP corrected weight with the new conditions.

How "dead on" is anyone's ET prediction software? Really?

Is anyone using it without fudging the numbers for any of the hundreds of variables besides the weather every run?

I tried in a .90 application where the car needs to be adjusted to an index every run. LIke herding cats. Especially if you travel. Tracks are all different. Gave up on it.

Focused on getting a good handle on what a weather change did to the car. Humidity, grains of water, vapor pressure or whatever you are using to measure water in the air, is the hardest thing to deal with, especially with a small cubic inch, relatively low compression deal like I was using. Especially as it increased above ~ 60-70% and the performance loss really started to spike..

.01 ET change/100' DA change is what we want to know.. Use the first hit of the weekend, not the last 50 runs, as a baseline to see where the track is and work from there. Multiple day events are where knowing your car well pays off.

A data base with a bunch of runs from different tracks, different lanes, different areas, etc is junk to me. I adjust from the last run, unless it was a flyer and/or was way off without a good reason. Happens.

Throw in a throttle stop to deal with and it really gets to be fun.

Also respectfully, you are combining posts that don’t relate. I didn’t say the CompuTech Race Air is inaccurate, just unreliable. Meaning, inoperable.
Also, my car is very predictable. It doesn’t pick up in bad air, exactly opposite. I only indicated that I feel it is always been .25 slow, regardless of weather.
Again, respectfully, after a couple dozen sets of PH362 Phoenix (Firestone Drag 500, in the “old days”), once they get used, and then sit for more than 6 months, they loose that nice soft, suppleness. I can tell, as there isn’t any debris stuck to the tread face. When they are fresh, they actually make a heck of a mess, there is so much debris that sticks driving back after a pass. Anyway, that’s my take. Thanks!

I found just the opposite with a set of 16x33x15 Goodyears that had been on my current S/P car for over 6 years in Tuscon, AZ stored inside, they had been well used but had a little over 1/2 the wear indicators left even with one set of the cords on the side walls being broken.
I put a 650+ HP E 85 bracket motor in the car and did one long burn out and they work very well shocked the hell out of me
I have had similar experiences with the old Firestone drag tires when I ran NHRA stockers back before 1989, 50 runs max and replace and sell them at a swap meet for 1/2 price
I had friend who would put 15 to 30 runs on them and then put new ones on due them starting to slow down a little bit each run after they quit hooking well

I use a computech race air pro for weather but have not used the ET predictor part of it yet.

I never put faith in any et prediction software. I dial off my gut and the situation I am in at the time.

Wouldn't have been much predicting this weekend as every pass was a 5.57, but I looked at the weather off of it, got in the off the trailer bogey race Friday morning and won that with a 5.574 on a 57 dial.

I am getting good enough with it to do that now but the car has to work first. Getting That is harder than predicting the weather sometimes. I have tinkered with my setup for a year and a half to get it half decent and still things I want to try.

I think writing down the weather after each run and looking at it for the same track will show you the trend, mechanical computer based programs are just that, computer based programs somebody wrote
My first weather instrument I bought for racing was a old Moon air density gauge Graduated to a store bought barometer, humidity and air temp gauge and wrote those readings down, after learning to fly I bought a good aircraft altimeter and used it with the weather gauges, you can't have to much information The bad thing about aircraft altimeter is their readings are base on instrument standard conditions and you have to have corrected altimeter reading to set them properly, not the actual barometer reading were your racing with
Once I moved out of CA to central OR where it gets real cold at night in the winter I learned the hard way that the altimeters didn't like being left in the race trailers all winter, they(two different ones ) must have froze up and stuck the needle
I bought a early hand held racing calculator that would do E.T. Predictions based off of the 3 instruments I had, not like today weather stations.
My current Performaire Eclipse is not real accurate either, I still have to operate the throttle and brakes

I use a performaire hand held unit , but i dont dial off it .
I manually log weather when i press hold on machine , folder on bench seat . I then dial off what the car is actually running on the day , def prefer 2 qualifiers. I have to be careful cause often on the 5th or 6th pass it will start to speed up . Dont know why but done it with 2 motors and 2 transmissions

Tex

I can tell you having bee a .90 racer who had a far amount of success that we absolutely dial off the ET predictions software. I could generally pull into any track I have never run and hit the number first hit off the trailer, did it numerous times and am helping some friends this weekend do the same. The key is having differing weather conditions in the machine, meaning racing at different tracks at with wildly different conditions. We go from the high desert where actual elevations can be 5200' with humidity in the low single digits to sea level condition's where the air is wet and grains are high. The key is analyzing data and digging down in what it is that affects YOUR COMBO the most. And that can very wildly from car to car. I just straightened someones info out this weekend and he has gone from not finding the number to running dead on last night. However for what most here do bracket racing at their home track on a one day event it is much simpler than trying to run an event over 5 days with what has been different weather every day on a stop. For local stuff often a handheld or even a Kestrel with just weather conditions will yield enough info to accurately dial the car.

FWIW I have not found anything more challenging in drag racing than learning to interpret weather conditions over a multiple day race with a stop on the car. We rarely race on a day we had a time run in. In S/ST your first round is often first thing in the morning on race day with zero info from that day and weather that can be totally different than anything you have seen all weekend. If you cannot rely on a weather station, prediction software and a knowledge of what affects your combo you will be LOST. Headed out to the track now to run second round first thing in the am with completely different weather than we have run in this weekend.

Running multi day events at tracks all over will definitely teach you a few things.

Time shot or two Thursday. Couple of rounds Friday and Saturday. And if you're still in, last couple of rounds Sunday, hot lapping you because they want to wrap it up.

And if it rains...we got a time shot and a couple of rounds in at Englishtown one year, Thursday and early Friday, and it started to rain. Rained until Tuesday. Unload it and race.

Everyone is in the same boat. Just have to know your car.

Running index over a few days can be challenging. I've found the Crew Chief Pro with Altronics weather data to work very well. The system has easily paid for itself in winnings.
Doug

I definitely stand corrected on the slicks, the slicks I am familiar with are the M/T. This is good to know because I for sure wont be buying Phoenix tires. lol I still feel there is something in finding that missing 50 or so HP. Without a bunch of typing my reasoning lies pretty much with CMcallisiter (spelling?). One or more elements that are holding it back likely can throw predictability off. Either way again congrats on getting out there! Recalling my recent trials with support gear and misc BESIDE the car part definitly could fill a book. Regards!