LMM Diesel cruise timing

[camcojb]

I have searched forever, but haven't seen a definitive number. I do know that most of the tunes I've received only have about 6 degrees of timing at cruise areas of 55-75 mph and no load. That seems very low to me from a mileage standpoint, which is the next area of my tune I'm working on.

Does anyone know how much timing you can run cruising down the freeway at say 70 mph? Truck is an 07.5 2500HD LMM duramax crew cab 4X4.

Jody

[camcojb]

ok, it appears that much over 7 degrees is negative for mileage, thanks.

Jody

[killerbee]

I have found improvements to 10-12 degrees on the LLY. But it depends on air temp, engine temp, and fuel pressure mostly. Boost level is also a factor. More boost accelerates ignition, less boost permits more timing for economy.