Tractor makers have spent the last few years designing engines that will meet the EPA strict round of emissions standards called Interim Tier 4, which went into effect January 2011. Now we are getting a clearer picture of just how fuel efficient these tractors are.
In the last 18 months, the Nebraska Tractor Test Lab (NTTL), the testing facility for all tractors made in the U.S., has tested the fuel efficiency of close to 60 Interim Tier 4 tractors of various size categories.
“We’ve had one of the busiest seasons ever here of testing these new tractors,” says Roger Hoy, director of the lab, in between his teaching sessions at the University of Nebraska–Lincoln.
For this latest round of testing, NTTL had to revise its testing procedures to account for the extra fuel and fluids needed to meet the mandated 90% reduction of particulate matter, also known as soot, and a 50% drop in oxides of nitrogen, which forms smog.
Manufacturers have gone with one of two strategies to meet these cuts. One requires the use of an engine after-treatment called diesel exhaust fluid (DEF), which is sprayed into the exhaust at a rate of 1 to 2 gal/hr. AGCO, Case IH, and New Holland are among the manufacturers using this strategy. The other strategy, called EGR, used by John Deere, recirculates the exhaust gas before it leaves the engine to burn up the soot. This re-burn cycle requires extra fuel, which John Deere says is normally less than 1% of the total fuel consumed.
The Nebraska Test Lab factored in these extra fluids in its fuel efficiency calculations to come up with what it calls a “fluid efficiency rating” (see “How fluid efficiency was calculated” below). As with fuel, the higher the rating is, the better the tractor is on fluids.
Early results show that when the added fluid and fuel are factored in, it becomes possible to make realistic comparisons between tractors, especially those of different technologies such as DEF vs. EGR or tractors with either of the technologies vs. Tier 2 or 3 tractors that might be up for replacement.
“The results show what I expected,” Hoy says. “If you account for DEF consumption and fuel used during regeneration, you get a different landscape that is more meaningful than if you looked only at combustion fuel efficiency. Overall, I would say that Interim Tier 4 tractors are probably more costly than previous ones. That’s my personal viewpoint.”
Just how much difference do the numbers make?
How about the following: “Assuming diesel fuel is priced around $4/gal and DEF is priced similarly, 1 hp-hr./gal. of fluid consumption can mean a $1,300 difference in fuel costs over the course of a year,” Hoy says. “You must determine whether the fuel savings will ultimately justify a trade-in.”
Please note that only the makes and models tested are included in this report. (Go to our website to read tractor manufacturers’ explanations of the results relative to their perspective models.) Other brands, including Challenger, Massey Ferguson, McCormick, Fendt and Versatile will be covered once more test results become available. Also, while this report focuses strictly on high-horsepower row-crop tractors rated 150+ hp, future reports will look at large 4-wd tractors and small tractors under 150 hp.
Stay tuned to see how your tractors measure up (PDF download).
Statistician Scott Grau, marketing research manager, Penton Media, contributed to this article.
How fluid efficiency was calculated
Farm Industry News asked Roger Hoy, director of the Nebraska Tractor Test Lab, to help determine which numbers on the report would best reflect a typical use cycle for this tractor size category. Fuel and fluid efficiency ratings for this story are based on “Drawbar Performance” at 75% of pull at maximum power to reflect performance during typical heavy fieldwork. PTO numbers also are included for power comparisons.
Fuel and fluid consumption is reported in hp-hr./gal. The higher the number, the greater the fuel or fluid efficiency; that is, more work is being done in an hour with a given amount of fuel or fluid. Specific fuel consumption for a specific operating point is obtained by dividing the power output (hp) by the fuel and fluid consumption (gal/hr).
Ratings will vary according to the intended use of the tractor. So consider all operating points in the test report when making comparisons.
The NTTL will not endorse or recommend any tractor.