Essentially, Smokey's "expander cycle" design is an amplification of the Otto-cycle, spark ignited, internal combustion engine where heat released in the combustion process is used as efficiently as practically possible to fully vaporize the incoming fuel charge for complete combustion while simultaneously artificially aspirating the engine. That sounds complicated and involved so we'll take it one step at a time, and when we're finished you'll marvel at the common sense logic of it-and probably wonder why you didn't think of it yourself. But be forewarned, it requires a complete rethinking of how to handle air/fuel mixture.
We'll begin with the vaporization of the fuel. The most common automotive fuel, gasoline, is not composed of uniform hydrocarbon molecules. Gasoline is actually a mixture of many different compounds that are distilled from crude oil, and each distillate has a different vaporization temperature, or boiling point, at which the liquid changes to a vapor. Some parts of gasoline vaporize very easily at low temperatures to help get a cold engine to start. Other parts have a much higher boiling point to prevent the fuel from vaporizing in the fuel lines en route to the engine. What this all comes down to is that in today's typical engines, only part of the fuel entering the combustion chambers is in a combustible state. To fully vaporize pump gasoline, and to keep it vaporized for complete combustion, the incoming air/fuel mixture needs to be elevated to between 400-440 degrees F. Smokey uses heat from the water in the engine's cooling system and exhaust gas heat to progressively warm the induction flow on his system to the 400-440 degrees.
First, all the hot water exiting the engine is channeled through a heat exchanger directly under the carburetor (or throttle body injection, TBI, unit). This plenum-like first stage vapor generator elevates the air/fuel mixture to approximately 200 degrees F. Next, the mixture flows through what looks like a small turbocharger, but this is not a turbocharged engine. The turbocharger-like device is actually a homogenizer and the second stage vapor generator. In the homogenizer an exhaust driven turbine drives what appears to be a rotary compressor totally wrapped with exhaust gas ducting. The homogenizer serves to mix the incoming air and fuel into one uniform, homogenous mixture while the surrounding exhaust gasses further elevate the mixture temperature to about 285 degrees F. From there the mixture flows through an intake manifold that is totally wrapped by exhaust gas ducting, elevating the mixture temperature to the desired 400-440 degrees F in this third and final stage. The fuel is now fully vaporized and distributed uniformly in a truly homogenous mixture that will burn cleanly and evenly in the combustion chambers without detonation or severe pressure spikes in the cylinders.