The game of the reverse solenoid piston motor

The single piston has a solenoid and primary winding on one end of the rod, and a combustion head on the other.  Part of the rod carries magnetic circuit, and the magnetic poles have lower bandwidth than charge fields, low enough that the mechanical rate can interfere and disrupt the magnetic flow.

Back EMF force can control the piston and rod motion, except it has no dirt control over the combustion acceleration. Within the range of 60 - 120 Htz, the magnetic field through the rod can become magnetically efficient as the back EMF smoothes the reverse motion at the bottom. Magnetic energy flowing smoothly to the secondary magnetic circuit, a cylinder wrapped by the secondary coil.

That means a long stroke and slower gas expansion, a dual combustion/expansion set up. But the variety of combustions, from stream to hydrogen to regular gasoline to compressed  to natural   are possible.  Back EMF give the controller optimum compression control and can apply back pressure to the combustion, like mass.  as long as the piston acceleration from gas expansion can be within the limit of the magnetic bandwidth, under EMF control. That likely means a two chamber, but this is all doable.

One moving part to the engine, other than combustion functions at the head. The entire drive is electro magnetic back to the wheel hub, making a complete car with four pistons and four wheels, eight moving parts. Fully regenerative breaking with capacitive loading.  Power capacitor is the heavy element, but need only hold charge for a few minutes. If one chooses a ceramic head for low temperature, then the engine and fuel weight can be much lower than any equivalent electric.

Naturally electro means the engines connects to many electric duct fans on the new electric helicopters.  We can have much longer range electric flyers, without the load of lithium batteries.

I back my total claim, where it all started. We are better off focusing on function combustion machines and use renewable power, at the source, to make liquid fuel. The trade is that no lithium and all the current pipeline technology prevails. We pay a high energy price up front, to cover the conversion to covalent bonds in liquid fuels.

One rod two combustion heads. Have the reverse solenoid bounce between two combustion chambers, using out of phase  combustion cycles. The solenoid circuit rides the middle of the rod.  No crank shaft anywhere.