Contour Enthusiasts Group Archives Forums Modifications Duratec Performance Air/Fuel Ratio

To those with experience tuning, What have you found the optimal a/f ratio to be for a 2.5L N/A Svt motor?

I had an urge to post the following for some time, so this question might be a good excuse. I'll take the pictures down in a couple of days, so save them if interested. Chapter "Mixture formation" on page 4 is directly relevant.

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You posted all of that just to say that the theoretical ideal A/F is stoich?! Good lord!!

good point. I replaced pictures w/ links. Sorry.

I don't think that the text is as straightforward as you make it sound, though.

~14.7 to 1 is optimal

i was under the impression that A/F ratio changed at different levels of throttle and rpm. Am i completely wrong?

no you are correct in that at different RPM and throttle openings the air/fuel mixture changes, but that is what the o2 sensors are for they monitor the mixture in the exhaust gas and then adjust timing and fuel injector opening accordingly

Thanks demon. I guess I didn't ask the question correctly. So for dyno tuning I am assuimg you would be tuning for WOT and you would want a ratio of ~13:1?

Yup low 13's/high 12's is what you should shoot for.