At the core of the CATRE's technology is the coaxial arrangement of an engine and its turbocharger, a more detailed explanation can be seen below.
Essentially we used the existing architecture of a Wankel style rotary engine, and modified it by drilling a hole long ways, through the center of its eccentric shaft (aka crank shaft). Next we utilized the basic design of a turbocharger, but we elongated it so that the compressor housing sat on one side of the rotary engine while the turbine housing sat on the other. They are connected via a shaft which runs directly through the middle of the crank shaft. The compressor - turbine shaft is not coupled to the crank shaft, so each device is allowed to operate run at it's individual speed.
Below, the CATRE proof of concept, can be seen. This is the "first draft" engine we designed and built in order to really get our head around understanding the fundamental challenges of designing & building a co-axial turbo rotary engine. This iteration is sized to produce around 75hp and by itself, weighs about 50 lbs.
The integration of the turbocharger co-axially with the rotary engine is what inherently facilitates the architecture's power density and simplicity. This architecture allows for a significant reduction in the number of components necessary to manufacture a downsize boosted engine. Further enhanced by the nature of a "Wankel" style rotary combustion chamber, and the valve architecture.
By integrating the turbo directly into the engine system, we can eliminate costly oil, fuel, and water lines to both components. These features and many other can be machined directly into the assemblies housings.