Single channel O2

[Ed Wright]

Originally Posted by Floyd Staggs

I've got the FAST unit with one sensor. I'm going to add the second one.
It records and plays back on it's own screen.

Floyd, your using the XFI system? I bought the second FAST O2 for mine after fighting an injector problem through most of 2010, on the opposite side from the one O2 sensor. The second one does not read the same as the one that comes with the XFI system. Not even the same brand sensor. Very dissapointed. My two only agree around 12-1. If you have a carb, not the XFI, their stand alone wide band records air/ fuel versus time, not RPM. Air/fuel versus RPM is much more useful for tuning. I have seen way too many problems with the innovate deal. I personally wouldn't use it.

[Dean Oliver]

Racepak gets my vote too. I just have a single O2, but I have bungs in both collectors so I can move the sensor if I want. Call Greg Kelley at Innovate Motorsports at 609-265-2110. He has very good prices and most of all has great customer service. Very helpful if you need someone to walk you through any of the installation.

Dean

[Danny Ashley]

Racepak too. Never had a customer regret going with them. That's what I'm putting on my new Stocker. Phil Mandella told me you still tune by your time slip, the racepak just tells you which direction to go. I have racers call and ask what number to look for and I tell them there's no magic number for everyone. I have customers that range from 12.8 to 13.6 each with fast cars. When you get a wide band Dan, you'll need to go to a test session and work on calibrating your Q-Jet to run the fastest and that will be your "Sweet Spot". Then when you get in different weather conditions your wide band will tell you if you need to lean or fatten it up. One of my friends and Super Stock customers has a Racepak and went testing Saturday with a carburetor that was completely different than the Edelbrock 1901 he usually runs. His car likes mid 13"s on the O2's. He guessed at the primary and secondary jetting and made his first pass. He could feel the car wasn't right in high gear. When he came back and down-loaded the run, the O2's were 15 in high gear. As Phil said, the Racepak told him which direction to go. I feel that a Racepak is one of the best investments a racer can put in his car. Takes a lot of guess work out of it and quickens the learning curve.

[Michael Beard]

Originally Posted by Danny Ashley

I have racers call and ask what number to look for and I tell them there's no magic number for everyone. I have customers that range from 12.8 to 13.6 each with fast cars. When you get a wide band Dan, you'll need to go to a test session and work on calibrating your Q-Jet to run the fastest and that will be your "Sweet Spot". Then when you get in different weather conditions your wide band will tell you if you need to lean or fatten it up.

x2! I'm brand spankin' new to EFI, just off my 3rd weekend out. Even if someone runs the same combination as you, there can be something different in either the data collection (type or location of the sensor) or other variables that make things radically different. Ultimately, you have to listen to what the car is telling you on the race track to determine what A/F ratio works best for YOUR setup. Took me til 1st round of eliminations this weekend to figure that out! LOL In the ballpark now, though. I still have a TON of learning to do. One of my issues right now is that I have no basis for what the numbers mean relative to each other. Is half a point in A/F ratio a lot, .25, or is a full point a big swing? Along the same line, I'll need to figure out how much change a single number or single percentage point on the fuel table really is.

[Ed Wright]

Michael, if your VE table & injector flow rate are setup correctly a 1% change will get you a .1 change in air/fuel. For instance: +.1% will change 13.0-1 to 12.9-1, or -1% would make 13.0-1 to 13.1-1. If your 13-1 and want 12.5-1 subtract 5%. Are you using FAST XFI, or BigStuff3?

[Adger Smith]

Michael,
There are sooo... many varaibles in tuning with O2's. I really agree with the idea that there is no "one" number for every combination. Cam overlap is one of the biggest players in what goes out the ex pipe, even low compression vs high compression will make a slight difference in the best O2 number.When you change cam C/L or valve lash or timing on your own combination that you are familar with and have data.. the O2's can change, usually do. The new O2 reading may or may not be the place the engine is happy and making peak power. The old O2 point may not be the best power setting with the changes. You have to search the combination/tune up for what makes the engine happy. A happy engine will usually make you happy because it is making power.
Oh, Please Read the plugs when making changes.... (don't be lazy.. does a plug wrench still fit your hand?) I know, I know it is so easy to take a reading of the data and pound that key board to make changes,,,, but reading the plug is the way to tell what is really going on in the combustion chamber. :~)

[Charles Rainey]

Adger
I feel as you and others have stated, that there are so many variables, you cannot compare any two motors. What I like to do is have two (2) O2 sensor. One on each side. I do make sure they read the same side too side. But I also like to have at least one EGT on a cylinder that tells me when I have gone unresonably lean. I read spark plugs to keep me honest, but reading spark plugs, is very subjective from one person to another. And on top of that I have customers that just flat cant read spark plugs for crap. So I try to give them as much data as they can download and see. I tell them to always start out rich and lean down and watch time slips. When you get there, write down both EGT and both O2 readings. All this data are nothing but indicators. They are not the Bible. Some of it is scientific and some is black magic. It can mean the difference in .01 and .1 on the time slip.
sorry my .02 worth

[Michael Beard]

Originally Posted by Ed Wright

Michael, if your VE table & injector flow rate are setup correctly a 10% change will get you a .1 change in air/fuel. For instance: +.10% will change 13.0-1 to 12.9-1, or -10% would make 13.0-1 to 13.1-1. Are you using FAST XFI, or BigStuff3?

FAST XFI. Currently running in Alpha-N, closed loop, Target A/F at 12.5. Got it to 13.3 on Run #3 of the weekend at MIR, and it wouldn't get out of it's own way.

Question is, is 13.3 to 13.2 a big jump, is 13.3 to 13.0 a big jump, or is 13.3 to 12.5 a big jump? How much is 1,000' DA change likely to affect the A/F ratio (ballpark)?

[Ed Wright]

Originally Posted by Michael Beard

FAST XFI. Currently running in Alpha-N, closed loop, Target A/F at 12.5. Got it to 13.3 on Run #3 of the weekend at MIR, and it wouldn't get out of it's own way.

Question is, is 13.3 to 13.2 a big jump, is 13.3 to 13.0 a big jump, or is 13.3 to 12.5 a big jump? How much is 1,000' DA change likely to affect the A/F ratio (ballpark)?

Michael, 12.5 to 13.0 is a big jump. If you want to email me your calibration file (.gct) file and a log file of a run using it, I can probably put it to, or very close to, 12.5-1, then email it back to you.

[Ed Wright]

Originally Posted by Michael Beard

FAST XFI. Currently running in Alpha-N, closed loop, Target A/F at 12.5. Got it to 13.3 on Run #3 of the weekend at MIR, and it wouldn't get out of it's own way.

Question is, is 13.3 to 13.2 a big jump, is 13.3 to 13.0 a big jump, or is 13.3 to 12.5 a big jump? How much is 1,000' DA change likely to affect the A/F ratio (ballpark)?

Subtract 8% at the RPM that is 13.3 to get 12.5. Some guys have 1000' tunes, 2000' tunes, etc. Many simply adjust fuel pressure. 1 to 2 psi per 1000' is pretty common.