While on the subject of improving FE heres a good read on the old adiabatic engine for anyone mechanicaly inclined
https://www.hotrod.com/articles/hrdp-1009-what-ever-happened-to-smokeys-hot-vapor-engine/Normally, different parts of a standard nonhomogeneous air/fuel mixture burn at different rates within the same cylinder, creating turbulence and colliding flame fronts.
Under such โnormalโ conditions, cooling the intake charge to create higher mixture density is beneficial to keep some of the fuel molecules from undergoing spontaneous combustion (aka detonation). But a standard Otto-cycle four-stroke internal-combustion engine utilizes only about 25 percent of its potential energy to make power.
The remaining 75 percent is lost out the exhaust or transferred as heat into the cooling system and radiator.
Hot-vapor technology attempts to recapture this heat energy, using it to superheat the incoming air/fuel mixture to more than 450 degrees F going into the cylinder, thereby achieving a homogeneous, perfectly vaporized condition thatโs said to prevent detonation while ensuring complete combustion.
To completely vaporize the fuel, Smokey used heat from the water in the engineโs cooling system plus exhaust heat to progressively warm the systemโs induction flow to the required temperature. There was a heat exchanger under the carburetor that used hot engine coolant exiting the motor to warm the mixture to around 200 degrees.
The air/fuel charge then flowed through a second-stage generator, an exhaust-driven turbine wrapped with exhaust-gas ducting. Smokey called this device a homogenizer, but it really was a turbocharger underneath the fancy ducting.
Not only did the device generate boost, it also served as a one-way check valve to keep the expanded, hot mixture from back-flowing out the carburetor. From the turbine the mixture flowed through an intake manifold also wrapped by exhaust ducting to reach its final, super-hot induction temperature.
