average GPM concerns
OK so I took my first trip that was more than 40 miles down the road. My 2000 F150HD 5.4L gas and the drive train in the truck are rated for 8700 towing, my 5ver was at approx. 7600, I was hoping for ...
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If you are getting GPM (gallons per mile) you have a serious problem :)
Our Expedition with 5.4 gets 8.5-9MPG, sometimes slightly more. depending on hills, wind and speed. I have yet to break 10.:(
The frontal area and associated aerodynamic drag is the major contributing factor.
Power to overcome rolling resistance (this is where weight comes in) is a linear function of velocity. Going twice as fast creates twice as much rolling resistance.
Power to overcome aerodynamic drag increases as a CUBIC function of velocity. Going twice as fast takes 8 times as much power!
To feel this effect for yourself hold your hand palm out while going down the road at 25. Now accelerate to 50 and see how much more force there is against your hand. Now imagine that against the front of the trailer!
So even increasing speed a little, or getting a headwind, can make a measureable difference.
Our Expedition with 5.4 gets 8.5-9MPG, sometimes slightly more. depending on hills, wind and speed. I have yet to break 10.:(
The frontal area and associated aerodynamic drag is the major contributing factor.
Power to overcome rolling resistance (this is where weight comes in) is a linear function of velocity. Going twice as fast creates twice as much rolling resistance.
Power to overcome aerodynamic drag increases as a CUBIC function of velocity. Going twice as fast takes 8 times as much power!
To feel this effect for yourself hold your hand palm out while going down the road at 25. Now accelerate to 50 and see how much more force there is against your hand. Now imagine that against the front of the trailer!
So even increasing speed a little, or getting a headwind, can make a measureable difference.
