AgTech tests suggest that many farmers do not use their available horsepower effectively because they’re not operating in the most efficient engine load range. “You can use a 200-hp tractor on a 100-hp job or a 100-hp tractor on a 200-hp job and you can probably make either work, but the result is lower efficiency and higher costs,” Turner says.

“An engine is in its sweet spot at or near its point of maximum power produced for fuel used,” he says. “Remember that you are not lugging an engine when you load it enough to pull it down on its torque or power curve to the area around rated speed.”

When the engine is at its maximum efficiency range, then make sure traction is part of the equation. Turner reports that rubber tires provide their optimum power delivery at around 10% slip, rubber tracks at around 5%.

“If the slip is much below 8% for tires or 3% for tracks, and the engine is appropriately loaded at a reasonable ground speed, the tractor is probably too heavy,” he explains. “If the slip is much above 12% for tires or 7% for tracks, the tractor is probably too light.”