Weather stations
 

I have a question for experienced sportsman racers and bracket racers. In your experience, how well does your weather station predict your performance?

Re: Weather stations
 

I have an old TAG hand held that hits mind very close unless it is very humid. Doesn't allow enough for high humidity.

Re: Weather stations
 

I do not claim to be very experienced, but I use crew chief pro software and a Altronics PC weather station. For example, the last race I attended we had a cross wind and tail wind. The prediction was dead on what the car ran.

Sean

Re: Weather stations
 

There are some that work pretty well and I surely can't imagine going to the track without one, particularly if you make a change to your car.

Re: Weather stations
 

I have an older performaire. I have a 25 run data base programmed in it. I do not add or subtract runs. I track +- on the prediction. Then base my dial in against the prediction. Its like any other tool in your tool box. It takes some practice to get used to using it. Wind and crazy swings in weather can make it difficult to come up with a good prediction.

Re: Weather stations
 

It also depends on which way you are tuned for AFR.

Re: Weather stations
 

Cad, please elaborate on what you mean by "Tuned for AFR"!

Re: Weather stations
 

I don't mean to intrude, but I imagine that he's referring to the fact that if you run your car on the "rich" side, that you would tend to pick up a bit more in very good conditions and fall-off a bit more when the air is real bad. On the other hand, if you run on the "lean" side, your car won't vary as much.

Re: Weather stations
 

What he said...

Re: Weather stations
 

That is the way I read it but I just wanted to make sure. This highlights the need to find the A/F ratio that YOUR engine runs best at, not what your buddy or what the forum said is the best! If you find that optimum A/F ratio for your engine, and you do whatever you have to maintain that A/F ratio as conditions change, your performance should only move with the changes in air density, which should make your weather station a more reliable predictor of performance.
Interestingly enough, the factors that the weather stations use as far as air density are the exact same factors (and the same math) that a true speed density EFI system uses.

Re: Weather stations
 

I completely agree with your first sentence, but if you run on the lean side of the ideal A/F ratio for your engine, you can have the same un-predictability in performance. As a matter of fact, it can even go the wrong way. I had a customer call me about a tuning issue, his complaint was that when he got in good air, his car actually slowed down instead of picking up. I asked him what his target A/F ratio was, he said 13.8:1, because "thats what everyone who is fast runs at".

Re: Weather stations
 

Good grief! 13.8?? I think somebody is surely pulling his leg. LOL

Re: Weather stations
 

Ed, you know the "Monkey See Monkey Do" mentality. For some application, 13.8 may be an ideal ratio, but it was not for this LS1. He refused to change it! He said it was the ECUs fault that his car slowed down in good air. I gave him the old "Garbage in, Garbage out" speech, to no avail! I try to communicate to people that an EFI system is just a tuning tool, it is only as good as the hands and mind that are using it.

Re: Weather stations
 

I have found that many wide bands, unfortunately, are like flow benches and dynos, as they don't all give the same numbers on the same engine. I have done this a while now, and have never seen anything on my dyno like 13.8-1 on any wide band of mine. I can't imagine him falling for something like that. He needs sharper friends. LOL

Mine always goes down the track quicker when a tad richer than it liked on the dyno.

Re: Weather stations
 

Ed - I know 14.7 is technically ideal, but what would a good range be for a Q-jet SBC stocker?

Re: Weather stations
 

Paul, 14.7-1 is not for wide open power. That is the target A/F ratio for computer controlled cars with cats. That is where the cats are most efficient in most cases. That is for idle and cruise, not WOT.

Most everything I ever worked with has liked between 12.5-1 and 13.2-1. Some depends on the fuel also. C11 likes a little richer. My car likes 12.8-1 with C11. Your results may vary. LOL

Re: Weather stations
 

Computech is my favorite , great support group and tell Jay "Nitro Joe sent you"!
and I know a good guy to bail you out if you have computer problems with there weather at the track, lol

Re: Weather stations
 

I should've said "stoichiometrically" ideal...thanks for the info.