Tractor ride fuel economy

I was recently on an 80 mile tractor ride and topped off my fuel tank at days end on the WD-45 gasser with 14.9 x 28 BKT rear tires and wide front end. My fuel mileage figured out to be right at 11 MPG. So, a full tank of gas should take me 160 miles or so @ 14 to 15 MPH.  It's hard to figure the exact driving time, due to lunch break and three other pit stops. The actual pace also varies a little from 14 to 15 MPH depending on the lead dogs throttle setting. So, I figure the driving time somewhere from 5.3 to 5.7 hrs to travel the 80 mile ride. This then calculates to 1.22 to 1.32 GPH of fuel consumption.  When Nebraska Test ran the WD-45 gas thru their test lab, they show at zero HP and the engine running wide open throttle ( 1700 RPM no load at all) the fuel burn rate is 1.4 GPH. This was with no power steering. My tractor weighs 3800 lbs with me in the seat and no fluid anywhere. So, the cost of pushing the 3800 lb tractor down the gently rolling road looks to be about zero of a GPH??.. because the engine itself @ 1700 RPM is 1.4 GPH ??  My measuring wasn't done with an eye dropper, but it's pretty close.  A D-17 gas with power steering tested at 1.7 GPH and that would have been at 2,000 RPM no load high idle, whereas the D-17 diesel scored 1.4 GPH under the same test procedure.

Edited by DrAllis - 04 Jul 2019 at 7:37am

Do you think it could be that in the Nebraska test they were testing tractors that are not broken in yet? They seem to get better as the engine gets loosened up some. Sort of like me when I get out of bed in the morning.😆

DrAllis, thanks for sharing ride mpg info about your wd45. Eighty mile trip - wow! At first, I thought that was a great distance. But then I figured mileage of a WD45 tractor & 12’ disk tilling a square 40 acre field. In theory, without turns, it would travel 28-30 miles to disk it. So, your 80 mile trip would be equivalent to disking about 100-110 acres, minus turning of course.

You know, tractor drives are fun and all but I had enough seat time in the fields that the only reason I do go on drives at all is for the visiting before and afterward. 80 miles! I'd be out! But I might drive the car to the visiting site.

Many of those old tractors got overhauled with 4 1/8" oversized pistons and I guarantee you they will use MORE GAS, even on a tractor ride.

DrAllis wrote: Many of those old tractors got overhauled with 4 1/8" oversized pistons and I guarantee you they will use MORE GAS, even on a tractor ride.

The Nebraska economy tests were run while the tractor was doing work. I mean work where the tractor was delivering maximum horsepower. You can't compare that to the little work a tractor does while only powering itself. As for weight, they weighted the tractors so they could deliver maximum horsepower with minimum wheel slippage. This was done on asphalt, which bears little resemblance to traction on soil. This data may have been useful for comparing one tractor to another, but is less useful for predicting how a tractor would perform out in the field.

Usually there's a graph that goes along with the fuel/HP consumption. It shows as "HP hours per gallon." It shows the consumption at all loads. I've found it on almost every tractor on the tractordata(dot)com web pages for each tractor.

Another thing that matters is, RPM. The higher the RPM the more fuel that is ingested into the engine, unless the A/F ratio is changed, at that higher RPM, to accommodate a lighter load.

Looking at Nebraska test #440 for a WD, it shows about 12 HP Hours/Gal at about 32 HP. It shows about 8.2 HP Hours/Gal when developing about 16 HP. The tractor is obviously more efficient when used near maximum horsepower.

It shows fuel consumption of about 1.9 GPH at 16 HP and 2.8 GPH at 32 HP.

To further complicate things you have to figure that you seldom use a tractor at maximum HP all day long. The best you can do when comparing two tractors is look at the HP Hour/Gal at the horsepower you would usually work the tractor at.