This article started at AirVenture 2024, when an eighty-minute taxi over rough grass fritzed the perfectly good Continental TSIO-520 in my Cessna Centurion. In 2025 I had a brand-new engine featuring a state-of-the-art JPI digital engine monitor. A modern engine monitor is the technology that enables lean-of-peak operations, a procedure with which I have long wanted to experiment. But researching the proper procedure is only slightly less difficult than climbing Mount Everest in tennis shoes. Not because data is rare, but because it is so abundant. And contradictory. And incomplete. And out of date. Who is right?
