Gas vs diesel
[edit] Gasoline
Gas engines operate at lower pressures but higher speeds ( RPM ). Lower pressure reduces torque and efficiency but also allows for lighter weight construction. Higher speed ( RPM ) on the other hand results in greater horsepower. Gas engines are best where power to weight ratio is more important than efficiency and also where the engine will not need to deliver maximum power continuously ( because continuous high RPMs would wear out the engine quickly ). Motorcycles and Sports Cars are natural applications for gas engines.
[edit] Diesel
Diesel engines are more efficient, especially at low RPM. Diesel engines have more torque, especially at low RPM. Because of the large low end torque Diesel engines can deliver, the same power while spinning slower which makes them last longer. To withstand the high torque diesels are capable of, these engines must be built heavier however. Diesel engines are best where longevity and efficiency are more important than weight, such as Truck engines, Train Engines, Ship Engines, Generators etc.
