[olddog]

If you read the second part of the artical, there is a chart of exhaust gases plotted against the air fuel ratio from 10:1 to 18:1. They state that maximum HP is made at 12.5:1 A/F. O2 levels hit near zero at about 14:1 and they state that EFI O2 sensors can only read in a very narrow range around 14.7:1. EFI with an O2 sensor would not be capable of closed loop control at 12.5:1 as the O2 sensor is not able to measure that low. This would put EFI at a disadvantage when trying to make maximum HP. Some one around here stated that EFI on the exact same engine makes less HP in many dyno tests. I think this explains it.