Tractor Engine Types Explained
Understand diesel vs gasoline engines, horsepower ratings, torque, and engine specifications for different tractor applications.
The engine is the heart of any tractor. Understanding engine types and key specs helps you compare models and choose the right powerplant for your workload. This guide covers fuel types, horsepower, torque, and other engine specifications you will see in our database.
Diesel vs. Gasoline
Most agricultural and utility tractors use diesel engines. Diesel offers better fuel efficiency, higher torque at low RPM, and longer engine life under heavy load, which is why it dominates in farming and construction. Gasoline engines are more common on smaller lawn and garden tractors; they start easily in cold weather and are simpler in some respects, but use more fuel and deliver less torque for their size under continuous load.
Horsepower (HP)
Gross horsepower is measured at the engine, usually at a given RPM. Net horsepower (or PTO/drawbar HP) is what is available after losses through the transmission and driveline. When comparing tractors, use the same type of rating—typically net or PTO HP—for a fair comparison. Higher HP means more capacity for heavy implements and faster work, but also higher purchase price and fuel consumption.
Torque
Torque (expressed in Nm or lb-ft) is the twisting force the engine produces. High torque at low RPM helps tractors pull through tough spots without stalling and reduces the need to shift. Diesel engines typically produce more torque at lower RPM than gasoline engines. Torque reserve—the ability to maintain or increase torque as RPM drops briefly—is especially useful in fieldwork.
Displacement, Cylinders, and Aspiration
Displacement (liters or cubic inches) indicates engine size. Larger displacement generally means more power and torque but also more weight and fuel use. Cylinder count (e.g., 3, 4, 6) affects smoothness and packaging. Turbocharging is common on modern diesels to increase power and efficiency while meeting emissions standards. When comparing tractors on TractorsCompare, filter by power and fuel type to find engines suited to your application.