SOI Advice

[Rawze]

Setting one to 4 or 4.5 (8 for smaller tier engines) is all about fuel mileage, and not for higher torque applications. It is ok to set one out that far only if you only use higher torque on occasion, and your average engine loads are 30% or less (typical of a highway truck in usa.). for higher torque applications though,.. this is a bit risky.

I would not recommend more than about 2 or 3 in constant high torque applications on one. I have even heard of a few guys set it to -0.7 for road trains for optimizing the 1650 RPM range.