isx 870

[ynot]

From rawze's run down of the tune. It sounds like who ever turned it was trying to tune the 870 to be a 570, that SOI map looks a lot like a 570 ish map.

The other thing that leads me to believe he was coping from a 570 is the changing of the timing an fueling metering tables. Depending on the cpl in a 570 those tables can be vastly different, even for the same 4/6 cam wedging, it's strange but like Cummins couldn't nail down what was needed an trying different thing to see how it turned out out long term for the motors. The 870/871 on the other hand use the same fueling/timing metering tables across all cpl's an hp ranges.