20mpg with Kennedy LBZ tune
It is a rarity that my '06 K3500 goes down the road without at least an empty, 3k# 24' deckover or 36' triple axle boat trailer in tow. Usually one solo trip to/from deer camp in the fall empty and thats about it.
However, two customer boats on their own trailers, 520 miles apart gave me an opportunity to test Kennedy Diesel's LBZ tune on the open road. I purposely kept my speeds to 68mph max, and only idled for about five minutes during warm-up and paperwork the second morning. Even ran a few errands around town, and moved an empty trailer ~30 miles on this tankful. Under more careful conditions, and slightly slower cruise speeds, I am sure 21mpg would be possible. All this with a bed full of at least 500# of gear! I am certain that the soft tonneau cover helps with the wind drag profile...
At $3 diesel prices and climbing, the time for ROI in fuel savings alone gets shorter and shorter. My dilemma has been, and will continue to be - how heavy and under what conditions to run extra fueling on the LBZ with heavy, variable, wind resistant loads over a range of summer driving conditions and topographies. For the time being, I plan to leave this tune in place and run the truck until I have reason not to.
My right foot likes it, after 8-10 months and ~35K miles of stock OEM hauling, plowing, etc... it is quiet at cruise, and growls under acceleration. My temptation is to be heavy footed on the on-ramps, even with 18K# out back off the hitch. Its almost scary how fast this tune will accelerate that load to highway speeds...much faster than average traffic accelerates.
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