Going back a few comments to the video of which would be considered a
pulse detonation engine. GE seems to hold quite a number of patents related.
Limiting parasitic loss is a large step towards efficiency from the mechanical side. Getting into recapturing thermal losses and making the conversion to a productive mechanical gain and or supplementing expending energy gains to the system is another issue of concern. Utilizing a higher percentage of the internal energy of the current available fuels is the goal of many labs here and abroad.
You all have talked about the many variables and means in which to do this. MIT and from the
Sloan school of automotive engineering have many papers available related to the variables and ideas discussed here. The
SAE site has many of the same and other white papers related as well. They will charge for some of these but much can be deciphered through the Abstract provided. Here's a fairly complete listing of all Sloan School
papers published.
There's always more to learn even when you think you have a good handle on the methodology and information. However nothing beats empirical and practical testing of your ideas by building them.