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Spartan Fuel economy on long trip with light load

3K views 23 replies 12 participants last post by  DavidPhillips 
#1 ·
My friend and I drove from Houston, TX to Salt Lake City, UT and back last week (4k miles) in my superduty with 1 sportbike in the bed, and 2 more on a 5x8 utility trailer. The 3 bikes + trailer + gear totalled ~2k lbs. Running the Spartan 275 v3 tune we averaged 16.5mpg running 74 mph down the freeway. Lie-o-meter read ~22 mpg the whole time. My truck is a 250 SRW CC 4x4 with 3.73 gears. I hope this helps give people a decent long-trip estimate on mileage.


As an aside, going up some mountain passes in western CO the EGTs climbed to about 1100° when we left the cruise on. Not to shabby in my book.
 
#2 ·
Good info! Are you running on stock size tires? If so, I wonder how a set of 37 inch tires with the 3.73 gearing would affect milage at cruising speed....hmmm

Also, if you are on stock tires how can the lie-o-meter so far off?!
 
#5 ·
Stock tires. Only mods to the truck are a Spartan 275 v3, S&B intake, and powerstroker67 delete pipe.

My friend and I wondered how the lie-o-meter could be so far off. The only thing we can figure is that the ECU passes injector pulse width info to the trip computer, and the trip computer uses stock fuel info in order to calculate economy. However, because the rail pressures are increased, you're actually getting more fuel for a particular injection event than the trip computer knows about.
 
#10 ·
Purchased a package from Rudy's Performance. Did the install myself in my driveway. Took about an hour.

correct me if i'm cause i don't know everything about thee trucks..but you're saying that because the fuel pressure is raised that there is actually more fuel injected.. the programmer should be telling the computer to inject less fuel at a higher pressure to achieve the same atomization
Atomization isn't what makes power. More fuel is what makes power.
 
#9 ·
I believe the mpg calculation is based on calibration that is programmed in. It has no idea that there is more fuel injected it just knows your going faster for the calibrated amount of fuel / air ratio based on air flow so it shows your mpg is higher than it actually is when you install programming to increase fuel.

Going with larger tires will change the speed calibration to show less mpg. If you increase fuel and tire size and do not calibrate for the bigger tires the two would somewhat offset each other.
 
#13 ·
Sweet- I'm getting ready to haul a trailer up to Tennessee- my old gas burner logged about 9mpg with the load...I'll post the results (with trailer weight) when I get home. This trip will be with a S&B only, hopefully the next lift will have a Spartan... the wife is bending...
 
#15 ·
I got mine from Rudys Performance too off Ebay. He did the install in about an hour. Last check for fuel mileage I got 17.6 unloaded at 70mph all hwy driving. This is hand calculated on the 210 tune. Power is amazing. This is up 2 mpg from stock.
 
#18 ·
well unfortunately since I have really no accurate way of measuring the remaining fuel in the bottom of the factory 37 gallon tank I cannot give you a HARD number of fuel consumed correct? Even if we said it used 37 gallons of fuel it works out to 18.378 miles per gallon. Mods are Spartans complete package with dpf delete and cat delete, sb filter and 275 hp v3 tune. Since the needle was above the red mark I assume there is still fuel in the tank....you do the math.
Tank was filled to full in opelika.
 
#19 ·
I would estimate at 0 miles to empty on my truck there is 4 gallons left. If you were around 50 miles to E you likely had at leat 6 gallons left and consumed 32 gallons unless you top off your tank when you fill up.
 
#21 ·
Yes, but you mean to tell me that you didn't buy fuel and note how much was purchased?

On a recent trip my stock 2008 4x4 CC 3.55:1 axles, with 4 guys and all our stuff under a soft tonneau returned 16.8 MPG at 65 to 70 MPH measured at the pumps. Fool Computer was claiming 18.

On 75 mile trips (150 miles round trip) with two dirtbikes in back, some 65 MPH but just as much 45 and 55 MPH 2-lane typically claims 17.3 on the Fool Computer display.
 
#24 ·
Sounds like about 21 mpg or so.

That's good mileage but hardly impossible with some reasonable driving on a long trip.
 
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