5.4 is a screamer!!!
I took delivery of a new 26 ft camper that weights just under 6,000 pounds. GVWR is 7,650, but it is empty right now. I live in Texas which has a lot of rolling hills. It rarely goes into over drive, ...
Forum Discussion
Terryallan wrote:
NO you don't need to go to 4.30 gears. a waste of money, and NO they won't give you better MPG. 2500 RPM is 2500 RPM no matter if you are in OD or 3rd gear.
Best thing. Lock out OD. That little button on the end of the shifter. Press it, and you will see a little icon on the dash that will tell you OD is turned off. It will then hold 3rd gear longer, because it can then lock the torque converter. With the OD on, and running in 3rd. the torque convertor is not locked up, and can cause the trany to heat up and the engine actually runs at a higher RPM that 3rd gear. Locking out OD will stop that.
The TC will lock in 3rd gear if the conditions merit it whether or not OD is locked-out. Locking out OD stops it from dropping into 4th and lugging and/or constantly shifting in and out. If it'll hold OD on the flat-lands without hunting between 3rd and 4th, let it. It's not going to hurt anything. If it won't, lock out OD and let it do its thing.
I agree that it's got to rev to make the power you need to move the shoebox through the air. Personally, I though tthe 5.4 was a dog in my 2000 F150, let alone in the super duty (another 1500 lbs of truck) pulling a bigger trailer... It's not going to set any land speed records, but it'll get you there.
Getting back to the original question, I don't think you're going to see any significant mileage gains by re-gearing, and if they do, they'll be miniscule, if they can be measured at all. It takes a certain amount of energy to do the work of dragging the rig over any given hill, and there's no guarantees that the engine running a couple-hundred RPM higher will gain you any efficiency.
