6.6 fuel economy

[barry schaworski]

Has there been any progress with fuel economy with the 6.6. My 6.5 kicks 6.6 ass when it comes to fuel economy. I realize there are chips out there. Has there been any other solutions. Programming etc. The 6.6 is a superior product but the price of fuel brings concerns.

[Kennedy]

Dunno, both of my Duraax trucks will run 18-20mpg if I behave. My 6.5 generally ran 15-17mpg...

I'd like to push past 20 mpg consistently with the Dmax and hope to tune to this on the dyno...

[JohnC]

My 6.6 4x4 Allison is about the same as my '95 4x4 auto was on local driving, with a heavier truck. It's a lot better on the highway, about as good as my lighter '93 manual 4x2 was. Oh, the 6.6 has half again as much power... :D

[tommac95]

At a given rate of output the newer , direct-injection engines have proven to be a significant advance in terms of efficiency, and are simultaneously cleaner. The designers/mfgrs decided to build a larger output engine with the technical improvement.

At minimum output [<30 HP ??] the 6.5 might have an edge.