How to perform a speed vs fuel consumption analysis for a Ford F-250

[ChrisB21]

Hi All:

I am a mechanical engineer, however, I did not go the ICE route. How do I perform a speed vs fuel consumption analysis for a Ford F-250 pick up truck. Also, can anyone direct me to any internet sites that provide in depth information on this subject. Any help will be greatly appreciated.

Thanks In Advance,
Chris

 

[IRstuff]

Do a search here. There was a thread with an EPA fuel economy link with some data.

TTFN

FAQ731-376

 

[GregLocock]

Are you trying to calculate it or measure it?

Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[patprimmer]

I would accurately measure the fuel used over a know distance at he specified speed. You will need along straight fat stretch of road. Do it both ways for any accuracy. Do it several times both ways for more accuracy.

Regards

eng-tips, by professional engineers for professional engineers
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[ChrisB21]

Hi All:

Thanks for responding, I really appreciate all of your input. I trying to calculate fuel consumption at various speeds. Essentially, I am developing a fuel consumption calculator to approximate the cost of fuel for a truck traveling at low speeds (5-10 mph) for a mosquitoe spraying operation. Thus far, with the help of this forum, I have located the EPA engine certification coefficients and have calculated the horsepower at various speeds. Now, how do I correlate this with fuel consumption.

Again, Thanks In Advance
Chris

 

[BrianPetersen]

That speed range will most likely be off the bottom end of any scale. The power that it takes to push the truck along is almost irrelevant because the engine will be at idle speed or close to it.

I would be tempted to find out how much fuel the engine uses at idle (or at whatever engine speed it takes to go at that road speed) and then just go with that.

For what you are doing, if the truck is new enough to have OBD-II, you can get the required fuel flow rate from the on-board diagnostics with a scan tool. You've not stated which engine it has, nor what year it is.

 

[patprimmer]

The terrain and tyres will have some impact as I expect rolling resistance will become a significant variable depending on surface.

Regards

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Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[floattuber]

How old is the truck? If it's newer and has OBDII then you can buy a Scangauge 2, plug it into the computer and it'll tell you gallons per hour, instant mpg, and average mpg.

 

[GregLocock]

Unless you can locate the BSFC map for the engine then you won't be able to calculate it accurately, and they are rather hard to find. I think testing is the way to go. As Pat says, terrain will have a huge effect.



Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[tommyvr6]

You can get relatively close by logging the injector duty cycle, rpm, fuel pressure, and speed. If it's OBDII(as someone already stated) it will be real easy. If not, let me know I could look around for some stand-alone data logging equipment. The idea is that if you know the max flow capability of the injector(can be found in the factory manual) and the duty cycle, you can figure instantanious fuel flow at a certain rpm and load. You then match the instantaneous flow with the speed.

 

[GregLocock]

...and wind and terrain will still have a huge effect.

Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[tommyvr6]

Absolutely....wind and terrain make a huge difference