A little something for your guys without a WB
TECH Senior Member
Joined: Nov 2001
Posts: 7,036
Likes: 1
From: Lake Zurich, IL
Agreed.. narrowband shouldn't be used for getting exact AFR ...
I know myself, before widebands became affordable, I basically just used the O2 sensors as safe, lean, rich
I generally tuned for 920s ... maybe drop a little ... but one days 920s are 940s another day so hard to tune like that...
Narrowband are fine for a "safe tune" meaning ... go overly rich... but past that a wideband is needed for max power safely
I know myself, before widebands became affordable, I basically just used the O2 sensors as safe, lean, rich
I generally tuned for 920s ... maybe drop a little ... but one days 920s are 940s another day so hard to tune like that...
Narrowband are fine for a "safe tune" meaning ... go overly rich... but past that a wideband is needed for max power safely
How would you blow a motor tuning with NB's if you always stayed to the rich side of Stoich ? (not particularly directed at you Horist, agree with your statement). I'm not talking about blowing it with detonation or even particularly FI motors, just NA motors. Brains, Bink, etc are acting like if you use a NB to tune you'll blow the motor. Well, with a NB, at the very least you can tell when you are at Stoich or richer, so why would Stoich blow a motor ?
The question is really how much more rich than stoich are you? Is 14.1:1 at WOT safe enough for a NA setup? Certainly not. Is 11.2 better? Sure, you won't blow it up but there's power left on the table. That's the argument -- you can't TUNE with a NBO2 at all, because its all just a guesstimate. You'd be better off reading the plugs and watching your track MPH than the NBO2 voltage.
TECH Addict
Joined: Jul 2002
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Originally Posted by TRex
How would you blow a motor tuning with NB's if you always stayed to the rich side of Stoich ? (not particularly directed at you Horist, agree with your statement). I'm not talking about blowing it with detonation or even particularly FI motors, just NA motors. Brains, Bink, etc are acting like if you use a NB to tune you'll blow the motor. Well, with a NB, at the very least you can tell when you are at Stoich or richer, so why would Stoich blow a motor ?
Originally Posted by Brains
The question is really how much more rich than stoich are you? Is 14.1:1 at WOT safe enough for a NA setup? Certainly not. Is 11.2 better? Sure, you won't blow it up but there's power left on the table. That's the argument -- you can't TUNE with a NBO2 at all, because its all just a guesstimate. You'd be better off reading the plugs and watching your track MPH than the NBO2 voltage.
Willing to learn if this is true for NA, but I don't think I've ever seen any data or theory that 14.7 or richer is "unsafe", as in excessive combustion temperatures.
TECH Enthusiast
Joined: Mar 2004
Posts: 647
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From: Australia
My narrowbands are only good for 14.5-14.9. Thats where they switch. Day to day, the NBO2s vary so much at WOT its not even worth considering.
You need a wideband - you can't tune AFRs without them. However, even most of the aftermarket WBO2s don't have temp. compensation and so can read lean by 0.3AFR from actual. No substitute for a good WBO2, and you have to pay $200+ for a decent one. IMHO even the LM1, DynoJet etc. is average, but far more accurate than NBO2s.
You need a wideband - you can't tune AFRs without them. However, even most of the aftermarket WBO2s don't have temp. compensation and so can read lean by 0.3AFR from actual. No substitute for a good WBO2, and you have to pay $200+ for a decent one. IMHO even the LM1, DynoJet etc. is average, but far more accurate than NBO2s.
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Originally Posted by HumpinSS
Brains where is our infamous member who has hp/tq numbers in his sig from his scan tool 
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Originally Posted by TRex
Your saying that 14.1 isn't safe for a NA motor ??? No arguement that there is power left on the table, but what is unsafe about being at 14.1 ???
Willing to learn if this is true for NA, but I don't think I've ever seen any data or theory that 14.7 or richer is "unsafe", as in excessive combustion temperatures.
Willing to learn if this is true for NA, but I don't think I've ever seen any data or theory that 14.7 or richer is "unsafe", as in excessive combustion temperatures.
I think you need to do some more research on the fundamentals of a reciprocating internal combustion engine, and I'm not saying that to be a jerk. Every engine and every fuel blend is different of course, but the gasoline we typically run burns most completely (read: best emissions quality) around 14.7 parts fuel to one part air. That is what your NBO2 is designed to read -- complete combustion. If you want to get technical, its not calibrated to a specific AFR, its actually reading lambda. What is lambda you might ask? Its simply measuring the oxygen content of the air stream to indicate complete combustion -- regardless of the fuel blend. So what might be 14.8 for one blend of gas, could be 14.6 for another, or even an alcohol blend that burns clean at 14.0:1, the NBO2 will still spit out 450mV when there's a complete burn. It doesn't MATTER what the ACTUAL AFR is when you're tuning for emissions, only that it burns cleanly.
So, the next question might be "well how does the PCM know how much fuel to add when I go WOT (or some other condition requiring more fuel)?" That's all in the tables, namely your VE table, PE tables, AFR vs coolant temp, etc. etc. etc. LOTS of stuff in there to "crutch" the fact you don't have a wideband O2 sensor. How are those tables built? With a wideband
