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Air fuel ratio

D

dcala84141

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anybody want to comment on weather the air fuel readings seem in the ball game on my dyno report
 
12.8-13.2 is where the power is at.
Your'e a little lean indeed, to get that corrected is probably possible, the experts here will know how.
Guess it will be playing with emulsion.
 
Stoichiometric, the term for a "perfect burn" of fuel and air, is 14.7/1, but not all engines seem to run best there. Maximum power is usually around 12.5/1, but that also varies from one engine to the next.
I'm just confused that the op's dyno sheet shows two different fuel ratio columns.
 
33 IMP said:
Stoichiometric, the term for a "perfect burn" of fuel and air, is 14.7/1, but not all engines seem to run best there. Maximum power is usually around 12.5/1, but that also varies from one engine to the next.
I'm just confused that the op's dyno sheet shows two different fuel ratio columns.
Click to expand...

I never knew that, thanks for the heads up. So much for installing O2 sensors to tune my carb to 14.1 lol...
 
33 IMP said:
Stoichiometric, the term for a "perfect burn" of fuel and air, is 14.7/1,
Click to expand...

This part is so technically wrong, but I understand the point you're trying to make, which is generally correct. Maybe it is simply a matter of you trying to be brief, along with poor word choice,

But the statement below is so correct.
33 IMP said:
... but not all engines seem to run best there. Maximum power is usually around 12.5/1, but that also varies from one engine to the next.
Click to expand...
 
Those numbers would mean more to me if there was another pull done with a change to the A/F so you could see the effects. What do the plugs look like, all the way to the bottom of the porcelain? Plugs will tell the story.
 
Nick's Garage taught me that 12.9:1 is the goal under load of a full pull on the dyno. :)
 
Lean. As others said above 12.5 to 12.9 is good for WOT.
 
33 IMP said:
Stoichiometric, the term for a "perfect burn" of fuel and air, is 14.7/1, but not all engines seem to run best there. Maximum power is usually around 12.5/1, but that also varies from one engine to the next.
I'm just confused that the op's dyno sheet shows two different fuel ratio columns.
Click to expand...
Yes....Stoichiometric is an absolute term, but is influenced by several additional factors, such as temperature, density, bariometeric pressure and the heating value of the fuel consumed such as BTU/gallon or BTU/pound, as differrnt fuels require different O2 level to achieve complete combustion. Usually, a slight increase in excess air, say 1-2% of total, insures total fuel consumption but the cam profile and ignition advance characteristics factor in the final mixture's burn capabilities. Perhaps the best way to drtermine the "correct" mixture is a COMBINATION of down stream O2 (average) AND individual exhaust gas temperatures measured at the exhaust port. The EGT uniformity will show even fuel distribution and the sverage O2 will show the correct mixture levels. Just my opinion of course.
BOB RENTON
 
moparedtn said:
Nick's Garage taught me that 12.9:1 is the goal under load of a full pull on the dyno. :)
Click to expand...

Exactly, from the internet, on somebody else's dyno.

I have yet to see a typical HP full exhaust street car running their best numbers at the track with that reading on the wide band. Although, arguably, I have not seen a lot.

People get confused as to what an O2 meter is, what its measuring, and what it means. It is no more than a tool to understand change. How the car runs is what matters, not what the gauge says.
 
BSB67 said:
Exactly, from the internet, on somebody else's dyno.

I have yet to see a typical HP full exhaust street car running their best numbers at the track with that reading on the wide band. Although, arguably, I have not seen a lot.

People get confused as to what an O2 meter is, what its measuring, and what it means. It is no more than a tool to understand change. How the car runs is what matters, not what the gauge says.
Click to expand...
1pgnu6.gif
 
BSB67 said:
Exactly, from the internet, on somebody else's dyno.
I have yet to see a typical HP full exhaust street car running their best numbers at the track with that reading on the wide band. Although, arguably, I have not seen a lot.
People get confused as to what an O2 meter is, what its measuring, and what it means. It is no more than a tool to understand change. How the car runs is what matters, not what the gauge says.
Click to expand...
You've missed my (obvious I thought) attempt at humor, hence the smiley face at the end of it....
 
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