Diesel engines utilize a heavier block design than gasoline engines and this allows for more efficient heat transfer. Diesel engines may typically last longer than a comparable gasoline engine, and will also generally produce better fuel mileage. However, in exchange for these benefits a diesel-powered motorhome will likely cost more than one that operates using a gasoline engine.

Diesel Pusher is a term used to describe a motorhome powered by a diesel engine that is located in the rear of the vehicle.

Along with the location of the diesel engine, where the radiator is situated should be taken into consideration. Radiators installed at the rear of the motor home usually weigh less because there is a fan attached to the engine that is designed to push or pull airflow over the coolant system. A side-mounted radiator may cost a bit more money up front, but you will find that service and maintenance takes less time than with a rear-mounted system. The side mounted radiator system may also create a bit more weight due to a hydraulic fan system that pushes air through the system.

Diesel engine systems are rated in torque and horsepower. Torque is a measure of the ability of the diesel engine to do work, and horsepower is the rate that work is done. For example, torque will determine whether the diesel engine can move a motor home through sand, while horsepower rates how quickly the motor home progresses through that sand. You may find it easier to think of horsepower as what determines how quickly the motor home can climb long hills while pulling a tow car.

The terms displacement, clearance volume and compression or expansion ratio are convenient. Displacement is the volume swept by the piston in one stroke. Displacement, to some extent, relates to horsepower and torque.

The ISL and ISC engines are electronic and both use the same high-pressure common rail fuel system. The bore is the same for 8.3 liter and 8.9-liter engines, but the stroke is longer, which is how they get more cubic inches.

Smaller engines require smaller transmissions and that will relate to lower fuel cost from less weight. You may choose to buy a smaller diesel engine just to cut the amount of oil and reduce the cost of maintenance. This may seem like a small detail, but can add up to big savings over time. However, smaller motor homes do not offer features that may be available on larger motor homes.

When looking at new or used RV's, ask questions about the engine. Mechanical types and electronic engines work and operate under the same principle, but differ with regard to EPA standards. For a full history on the motor home engine, request service records from the previous owner.