Question for Tuners/Stand-Alone Guys

[bmwman91]

What is the leanest you can safely run these motors (older ~10:1 CR ones, M42/M5x series) under a steady highway-load? According to datalogs, I seem to maintain between 25% and 35% throttle opening between 55 & 75mph cruising. The AFR seems to center around 14.1 or so, which is damn rich for such light loading IMO.

I would think you could run at LEAST 15:1 under such low loading. I thought someone on here said 17:1 was safe while cruising. Anyone have experience on this? Thanks a bunch! I have yet another wacky idea in the works right now that can hopefully net ~17% better mileage on the highway & certain around--town conditions (with a Wide-band O2 sensor anyway).

[generic]

Damn, i feel really not knowledgeable right now. I hope you get your answer though

[epic]

16.1 is normal too. But that is pushing it IMO.

try it out Let us know...