Duramax Fuel Economy

Hello Craig,

Look up your owner's manual for the following spec: max torque at xxxx rpm. You should get the best fuel economy at xxxx rpm in top gear/overdrive. Good luck.

Franko

Hello dperez,

If you have a stick shift, keeping the rpm at/near that reading in any gear will give you the optimum mileage for that gear (e.g., going up a very steep hill in 2nd at 1800 rpm, or a steep hill in 3rd at 1800 rpm, etc.). For automatics, if your tranny is gear-hunting, manually select the lower of two gears it cannot make its mind up on and keep it at/near that reading.

BTW, that's pretty good city/highway mileage. We get 22 mpg highway on our '98 6.5TD 4x4 Tahoe. 26 mpg highway on our '86 6.2NA 4x2 Sub. But they've got much less torque/hp than your D-max. Aaahhh, I can always dream...

So my 2004 GMC 1500 CC with the 5.3L will get the best mileage at 4000 rpm's since it makes its 335 ft-lb of torque at that rpm? I find that awfully high and probable an illegal speed to be traveling.

they're talking about the Duromax,not your 5.3.

Just curious, what are your truck's specs for:

1. Max Torque at xxxx rpm
2. Max HP at yyyy rpm

Horsepower: 295 hp Max Horsepower: 5200 rpm Torque: 330 ft-lbs. Max Torque: 4000 rpm

Just for "Max" comparisons:

Of course, the gearing/final drive ratio/tire sizes will determine the speed at the above RPMs (on the average between 55-65 mph). Nevertheless, the max torque figures at the specified RPMs will provide the most efficient mileage for the engines mentioned above.

gear/overdrive.

Maybe the engine is the most efficient at max torque, but I don't think that I will get the best mileage since I will be traveling far north of the speed limit.

Far north of the speed limit, I would have to agree as the engine would be expending much of the energy generated just pushing aside air. Again, gearing/drive ration/tire size all matter.