[cujet]

Ahh, the adiabatic engine. Smokey's shop ("the best damn garage in town")(or some other similar name) was next door to where I shopped for groceries. I lived right down the road.

We (my college roommate and I) would regularly visit, looking for answers. Smokey knew us well and the crazy things we would do. (we built rocket and gas turbine engines)

He spent a full afternoon explaining his adiabatic engine to the 2 of us. We were fascinated, but a bit skeptical, at first. After all, I was a college student, in Aeronautical Engineering and I understood exactly what he was doing. By the way, it was on a Dodge and not a Fiero (at the time).

First off, this is not just superheated and vaporized fuel or a 100 MPG carb. It was a complete system with a way to recover wasted heat and energy.

The exhaust contains energy in the form of heat. Heat can expand air and do work (that's how every engine runs). Using that ex heat to expand air and push the piston down, on the intake stroke is worth some MPG's and power. Yes, it's possible to size a turbocharger to create more intake pressure than exhaust backpressure, thereby creating a net gain. (as long as you don't lose heat in the process, think intercooler).

It takes time to understand. Consider it this way: If we could take the exhaust heat and transfer it (via magic) to the air in the combustion chamber, prior to combustion, (thereby expanding the air, driving the piston down) we would have recovered that wasted exhaust heat energy! AND, made a substantial improvement in our BSFC efficiency numbers.

The M1A1 Abrams tank does just this, using a heat exchanger that takes the exhaust heat and transfers it to the air just prior to combustion.