Hey I think the model Diesel's are intresting, and certainly the thing to pick if looking for max torque and low fuel consumption, if not low fuel economy. But if you open any themodynamics book the Diesel cycle is described as a constant pressure power cycle. Gas engines are costant volume by vertue of almost instant combustion. In actuallity the Diesel is not completly constant pressure and Otto is not completly costant volume. The model Diesel engine by the thermodynamics books is constant volume because once ignited there is nothing to prevent it from quickly burning. Doesn't say a Diesel has to have a fuel injector, just the most common way to do this. Now maybe I am streaching the thermodynamics definiton to the real thing, but I think most engineers would agree with me.