AC - Other than tapping the data, Pecos was looking for a calculation. With advanced fuel/engine management systems, no variables are constant making a calculation more difficult. Obviously, if you can pull the raw data, then problem solved...

What about using a fuel flow meter intended for marine applications? The trick would be to plumb it in after the fuel return so you get a true reading of fuel used versus fuel sent to the motor which would include fuel used and fuel returned. This gonna cost ya some bucks though.

Toolmaker

If you engineers don't mind a suggestion from a "knuckle dragger".
Wouldn't working from the "HP required @ X MPH / engine efficency % = fuel usage" work? Kind of a balanced system we're working with here, and esp as the RPM vs MPH relationship is fairly constant (better with a manual tranny/clutch, but still close with todays "lock up" automatics).

TG,



You're right, but knowing the efficiency as a function of horsepower is the big unknown. Gas engines are (were) only 15 to 20% efficient.



But this is no different than determining your own "highway" mileage as folks do. If you really want to know for a given weight of truck, use the hp vs. rpm curve in the sales brochure and go down the highway!



P.S.



Some people are so gullible!! The hybrid cars are just a sales gimmick to make "people" feel better about themselves, and sell electricity.



Electric motors may be 95% efficient but the electricity that shows up at your house is only 25 - 28% efficient! So it is really in the same neighborhood as just using a gas engine. And, oh, all the coal-fired power plant pollution!



Oh, that's right, can't get anything for nothing!



P.P.S.



Speaking of being gullible, I have way more rifles than I could ever wear out!

Tool, I've already done some research on my own crazy quest and your idea is about the only way I've found to do it. And like you say the cost is prohibative.

Other than equipment for marine and racing applications, there really isn't anything SIMPLE and inexpensive that a guy can bolt on that will do what I'm looking for.

I think I'm wasting everyone's time. Sorry guys.

AC, that's correct. It's the XLT version with 2 wheel drive. Thanks for your trouble.

I tried to pose it as a "engineering question".
Back in the old days we used a "imperical testing" procedure, (updraft carbs and gravity supply) we would add a 3-way valve line into the pump supply line, and run the new line into a calibrated container of gas (let the passenger hold it and work the flow valve *grin*) do a steady throttle run and moniter the time/distance required to use a specified amount of fuel. Repeat at different speeds to plot the fuel useage vs MPH (or time) curve. This methiod does require a fairly windless day and reasonabley level ground, but it does compensate for the engine efficency/powerline losses along with the wind drag (a variable that dyno runs have a hard time reproducing).
The problem with this methiod today is the pump in tank, and return line, which would have to be duplicated in the "calibrated container" before it would work.

AC - I was just playing with my new Ford Ranger and wondering about such silliness. It has the 4.0 liter engine, automatic...not 4X4.

What got me started thinking was a 100 years ago I had a Volkswagon and it had a table in the owners manual which showed if you go this fast, you will get this mileage. If you go that fast you will get...yadda...yadda...yadda.

I'm starting to think I've asked a question WAY beyond the simplicity I was looking for. Everything wants to sell me $1,000 worth of far out monitors and pumps etc.

All the hell I wanted to know was what's the fuel burn at 1,500RPM, 1,600 RPM, 1,700 RPM etc.

Sigh.........
Nothing is ever easy for me.

I doubt even Ford has bothered to figure this crap out and I'm probably just wasting everyone's time.

TG et al, I ponder our discussion on the 40 mile drive to work today and realized the difficulty of coming up with a realistic answer to what I originally thought was a fairly simple question.

My truck is a five speed automatic and is always shifting in and out of one gear or another, usually so smoothly I never even notice unless I'm really paying attention.

And then we need to factor in headwinds and tailwinds etc.

Bottom line is there are just so many blasted variables at work every trip that I think I may as well forget this and just figure my mileage on a day to day basis.

Comparing my situation to airplanes was not a good idea. Aircraft are concerned with gph...NOT mpg. It's pretty simple to figure gph...but mpg is another matter.

I think I need to find something new to worry about.