this is a question I had on another thread. and really wanted to see an answer.
with an AFC you can control exacty what your F/A ratio is at any set rpm. of course you lose torque/hp so you try replacing that gas being cut with HHO.Lets say you have a 2.0 engine at highway rpms, say 2000 rpms, and producing "Y" LPM HHO, you can cut your fuel ratio down from 14.7:1 (isnt that the default in open loop?) to X:1. (X=air) and still have enough HP/torque to get up to 2000 RPMs and highway speeds.
We need the F/A ratio needed to run an IC on only HHO. I think you can find it here but its over my head or maybe someone knows the answer
( http://www.docstoc.com/docs/8568558/...sed-IC-engines )
knowing the A/F ratio of a HHO only IC engine we can find the value of X and know how far we can cut back our A/F ratio on a 2.0 liter engine while producing "Y" LPM of HHO and have enough HP/torque to drive the car at 2000 RPMs at highway speeds.