Oil & Fuel CUT/SCUT fuel consumption?

[smstonypoint]

The Nebraska Tractor Test Lab (NE Tractor Test Publications) reports fuel consumption for many utility and larger tractors. I'm guessing that the Nebraska data were used as a basis for the following: (Estimating Farm Machinery Costs A3-29 November 2009):

"Average fuel consumption (in gallons per hour) for farm tractors on a year-round basis without reference to any specific implement can also be estimated with these equations:
0.060 x maximum PTO horsepower for gasoline engines
0.044 x maximum PTO horsepower for diesel engines"

I am not aware of any fuel consumption data for CUTs/SCUTs. I am curious as to whether the "0.44 X maximum PTO HP" estimate provides a reasonable approximation of fuel consumption for those of you with smaller tractors.

Steve

 

[SSdoxie]

That figures out to .858 Gl/hr on mine. I think that is close when I am running at 2500 PTO RPM. @ 2000 RPM and just light loader work it will burn about .5 gl/hr but under heavy load at full throttle it will burn over 1.5 gl/hr.

 

[Groo]

When I was looking to buy a semi, was thinking a small engine with high boost might be the way to go. A friend inside the industry told me "while that makes sense, the customers who buy the small engined trucks generally care less about MPG, so its the big engines are the most fuel efficient". I think there might be a similar thing going on here. That said, the little Kubota just sips the fuel so slowly, getting an accurate reading has never crossed my mind. If there are a few gallons left over after we fill the dozer, the tractor get them. If we didn't do that, the tractor would probably go months between fill-ups. It gets filled so infrequently, gelling has been an issue several years.

 

[jenkinsph]

I think the fuel consumption rates would be close with the larger machines having the edge on efficientcy. That said fuel consumption in general is such a minor cost of operation I seldom think about it or measure it.

Now if you get to larger tractors under leavy loads fuel becomes more of an issue.

 

[RaydaKub]

I think the fuel consumption rates would be close with the larger machines having the edge on efficientcy. That said fuel consumption in general is such a minor cost of operation I seldom think about it or measure it.

Now if you get to larger tractors under leavy loads fuel becomes more of an issue.

Yeah, I think my cousin said his 400hp Ford takes 450 gallons to fill up and he does it every other day in spring or fall work. At $4 a gallon, that'll get your attention in a hurry. As compared to my BX that I've had for almost 9 months and have burned through about 15 gallons total.

It's a question to be answered for curiosity sake, but hardly relevant.

 

[smstonypoint]

It's a question to be answered for curiosity sake, but hardly relevant.

"How much should I charge to mow, plow, etc." is a recurring question fromTBN members with CUTs.

In order to answer that question, you have to know your variable (operating) and fixed (ownership) costs. There is a wealth of info for larger tractors/implements that folks can use/modify in estimating their own costs. There is a dearth of info for smaller tractors/implements.

I have been thinking about posting a primer dealing with estimating costs for smaller tractors/implements. If I do so, I will be using a numerical example and I want to make it as realistic as possible. Hence, my interest in the question.


Steve

 

[JDgreen227]

The Nebraska Tractor Test Lab (NE Tractor Test Publications) reports fuel consumption for many utility and larger tractors. I'm guessing that the Nebraska data were used as a basis for the following: (Estimating Farm Machinery Costs A3-29 November 2009):

"Average fuel consumption (in gallons per hour) for farm tractors on a year-round basis without reference to any specific implement can also be estimated with these equations:
0.060 x maximum PTO horsepower for gasoline engines
0.044 x maximum PTO horsepower for diesel engines"

I am not aware of any fuel consumption data for CUTs/SCUTs. I am curious as to whether the "0.44 X maximum PTO HP" estimate provides a reasonable approximation of fuel consumption for those of you with smaller tractors.

Steve

My Deere 4210 develops 22 PTO hp @2600 rpm (HST) and using that calculation gives me 0.968 gph. The majority of my 100 operating hours a year are mowing and I use the 2600 rpm pto speed for most of those. But I have calculated my fuel usage at about 0.625 gph which is quite different.

Interesting thread....I would like to see more posts here.

 

[RaydaKub]

"How much should I charge to mow, plow, etc." is a recurring question fromTBN members with CUTs.

In order to answer that question, you have to know your variable (operating) and fixed (ownership) costs. There is a wealth of info for larger tractors/implements that folks can use/modify in estimating their own costs. There is a dearth of info for smaller tractors/implements.
Steve

I meant "hardly" as in quite small, not "hardly" as in "not at all".
As JDgreen227 just posted, he uses about .625 gph. At $4 a gallon, you're looking at under $2.75 for the fuel. While that's not free, it is pretty small figure to add in. I would guess it would also be a fairly small portion of what you'd charge. :thumbsup:

 

[US American]

Deere lists gph consumption rates for full load at pto speed. The problem is that almost nobody ever runs full load all of the time. The only way to project your true usage is experience. But one can use the rated consumption to get a worst case scenario idea. Anything less than that would just be gravy.

If you are doing a job for hire start with a full tank and then top off. Measure the amount burned and if you are really honest you can pass along any fuel savings to the customer (assuming you bid the job by running the math at full load usage rates).

 

[woodlandfarms]

My machine is fully hydraulic. Engine is rated at 65 hp but calculating it all it seems like we are closer to a 35 or 40 pto hp.

So at 65 it is 2.5 gph, 40 puts me around 1.5. 1.5 is much closer to my actual burn.

 

[284 International]

I think those guidelines are good baselines when there is no other frame of reference, and the tractor is used in generalized utility applications. That is, it isn't exclusively used for heavy tillage, thick mowing at high ground speeds, etc, or barely loading the machine for the lightest tasks, light towing a garden cart, easy loader work, and so forth.

I have an array of older compact machines dating from the days when the test lab DID publish data for smaller machines. I can say that the usage of the tractor really makes a vast difference.

I have two compact tractors with the same engine, but one has a loader and is used for light loader duty: smoothing driveways, carrying mulch or wood chips from piles, etc. The other is ballasted far beyond what is advised in the manual, and is used almost exclusively to pull the heaviest disk possible. The loader tractor very rarely sees half throttle, and quite literally sips fuel. I have put 30 hours of meter time (so under-representing the clock hours, since operation is at low RPM) on less than 5 gallons of fuel, while I have emptied a 5 gallon tank discing with the other machine in a single afternoon.

I have 3 sets of Nebraska data available for compact diesel tractors I own. I own 4 machines of those tested, one of which is a loader equipped machine, and the other is a bare tractor used for disking, tilling, and mowing, mostly. I have one compact gasoline powered tractor with Nebraska data available, and one utility diesel tractor. Another pair of loader equipped and non-loader tractors I own supports the fuel consumption disparity between tillage and loader work (accurately, light vs heavy demands on the power plant).

I have compared my experience using the tractors with the Nebraska data, and they tend to confirm non-empirical but attentive measurements. Running hard, my usage is about 1.5 gallons per hour in a 20 PTO horsepower tractor. Doing basic loader work with the same model machine burns about 1/2 gallon per hour clock time.

My gasoline compact burns more fuel than the 0.06 gph/PTO horsepower suggested. I suspect this is because even at idle, the gasoline tractor consumes more fuel per unit power output. Operating the gasoline tractor at idle, as when I run the cement mixer or post hole digger, the gas consumption is noticeably more than a diesel machine doing the same work. Mine increases more than the diesels under heavy loads, but doesn't decrease as much under lighter loads.

Comparing the Nebraska data, the figures of 0.044 and 0.06 correlate well to their average PTO horsepower readings for average power produced vs fuel consumed per hour. If I took my tractors and averaged their fuel use, it would fit well with the guideline, but I think a tiered model may be more useful to the average compact tractor owner.

If one is doing light duty work (clearing horse stalls, smoothing gravel with a drag, etc,) I would suggest a preliminary number of something like 0.037 GPH/PTO horsepower. For average use, I think 0.044 is good, and for heavy use (Running a high powered generator often, very heavy mowing, rototilling, heavy disking, etc) 0.050, all for diesel engine tractors. For gasoline versions (And there are a very scarce few; all are old that I'm aware of, and actually DO have Nebraska test histories) corresponding guesstimates would be 0.056, 0.060, and 0.072, based on my machines, memory, and calculations.

I am interested to hear other responses to this.

 

[smstonypoint]

<snip>


Comparing the Nebraska data, the figures of 0.044 and 0.06 correlate well to their average PTO horsepower readings for average power produced vs fuel consumed per hour. If I took my tractors and averaged their fuel use, it would fit well with the guideline, but I think a tiered model may be more useful to the average compact tractor owner.

<snip>

Thanks for your informative post.

Estimates of fuel consumption are available by type of field operation for ag. tractors (e.g.,Estimating Farm Fuel Requirements ,Fuel Required for Field Operations A3-27 October 2005), but only a few of the operations are likely to be performed by a CUT on a custom basis. I will try to illustrate alternative operations if I decide to proceed with my primer.

Thanks again.

Steve

 

[ruralruss]

I had estimated that my Kubota B3200 used about 1 gallon per hour during heavy to medium hogging with a 5 ft cutter. The formula says 1.012 gallon per hour. Pretty close.

 

[jinman]

Steve, my 45 eng/39 pto hp tractor has to be pushed hard to burn 1 gallon per hour. That puts it around .7 gal below the formula (39 x 0.044 = 1.716 gph). I'm thinking that the larger tractors would all be turbo-charged and that would make them use more fuel under load. Of course, a turbo-charged engine is very efficient if you stay out of the boost curve.

 

[Baby Grand]

After 368 hours I am burning fuel at a rate of .54 gal/hr (all the fuel loaded/time on the clock) with 26.5 POT HP. When it's running, it's usually working at snow plowing, tilling, chipping or hogging.

 

[dodge man]

I have a BX2350, a pretty small SCUT, and have about 17 to 18 pto horsepower. That computes to about 0.75 gal/hr, and when its working hard, such as mowing, thats a pretty accurate number.

 

[JDgreen227]

Deere lists gph consumption rates for full load at pto speed. The problem is that almost nobody ever runs full load all of the time. The only way to project your true usage is experience. But one can use the rated consumption to get a worst case scenario idea. Anything less than that would just be gravy.

If you are doing a job for hire start with a full tank and then top off. Measure the amount burned and if you are really honest you can pass along any fuel savings to the customer (assuming you bid the job by running the math at full load usage rates).

I keep seeing the term "full load" here but don't quite understand what it means. Suppose I am running the MMM at the 2600 rpm PTO speed in heavy grass, is that considered full load? Or suppose I have a 800 pounds of sand in the FEL bucket while running the MMM as outlined above, is that full load? Or maybe I am doing both, plus pulling a 4,000 pound trailer, maybe that is full load?

 

[284 International]

For the Nebraska tests, at least in the older ones I'm familiar with, full load is rated RPM (or peak power RPM if higher) and maximum load that can be sustained at that same RPM. Attached is the version for my IH 284. There is a section called "VARYING POWER AND FUEL CONSUMPTION" where you can see they run the machine at 0 horsepower, and 2962 RPM, for a certain fuel consumption per hour. That is how much fuel it takes simply to run the engine at nearly 3000 RPM, with no load. Just above it is a rating at 23.36 hp at 2774 RPM, so the engine is applying 44 foot-pounds of torque to a brake at that RPM (Technically it would be much higher torque applied to the brake, somewhere around 200 foot-pounds at whatever the PTO shaft speed is, but it's all the same)

Really, it is the maximum output of the engine. So if cutting in heavy grass can achieve that, it is full load. Data I find especially interesting is the horsepower-hours/gallon. It measures the efficiency of the engine at turning some amount of fuel into power. A bigger number is better in this case. It allows comparison of small, lower horsepower engines to bigger ones, because it is a measure of efficiency, not only quantitative data. I wish this information were available for newer compact and subcompact machines.

 

[rsewill]

Steve, my 45 eng/39 pto hp tractor has to be pushed hard to burn 1 gallon per hour. That puts it around .7 gal below the formula (39 x 0.044 = 1.716 gph). I'm thinking that the larger tractors would all be turbo-charged and that would make them use more fuel under load. Of course, a turbo-charged engine is very efficient if you stay out of the boost curve.

Hmmm, I'd rather also pour more air than just more fuel into my engine to get the same HP. Or, to put it another way, a lighter, smaller turbo engine will be more fuel efficient at continuous full turbo boost than a larger NA engine putting out the same HP. Correct me if I'm wrong.

 

[JDgreen227]

I belong to a truck/trailer/towing forum elsewhere and in one thread I started maybe 15 years ago about being sure your new tow vehicle had enough power plus a reserve, somebody asked "why should I buy a bigger engine that has reserve power when the smaller engine has enough for my purposes?"

He was convinced that a smaller engine running at 80-90% output while towing would be more economical in the long run than a bigger engine that had enough power not to require operating at near full output. The thread was back before turbocharging became available in tow vehicles and I wonder sometimes how that situation would play out today.

Sorry if this is off topic. I got to thinking about this because of the comparison of turbo vs. non-turbo engines rsewill mentioned in the previous post.